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Our lander’s asleep

blogs.esa.int

392 pointsjonnyscholes160 comments

It appears to be largely political issues that prevented this mission from using a Radioisotope thermoelectric generator , which would have eliminated this particular problem since solar panels would not be required. [1] This is how the Curiosity rover is powered.

If that is the case it's a massive shame - irrational fear of nuclear technology does a lot of damage.

1 - http://www.space4peace.org/ianus/npsm2.htm#2_3

The first (failed) mission to Mars was attempted as early as 1960 by the USSR, continuing with 1964, 1965 Mariner by the US. Rovers came after a lot of previous work done, including a lot of unsuccessful attempts. And the rover weights 900 kg, probably 40 kg of it is the nuclear power generator. Philae is only 100 kg and the first on the comet.

It's certainly not "fear" of the nuclear technology in Europe that prevented something. See for example:

http://en.m.wikipedia.org/wiki/Nuclear_power_in_France

It's that the engineering tradeoffs have to be considered.

While it seems perhaps uncharacteristic of a space agency to make engineering decisions based on politics, if I had to guess I'd imagine that the team was well aware of the PR effect of the power supply chosen for their lander. I would also guess that the same issue was considered at NASA while planning the Mars Exploration Rover (solar) and Curiosity (RTG) missions. Are you claiming that this did not factor into their decision at all?

that it wasn't a significant factor, at least

Fair enough. I don't know nearly enough about Europe or the ESA to volunteer an over/under on that.

Space exploration was always very dependent on politics.

As Neil deGrasse Tyson says, NASA was founded on the fear factor of USSR's Sputnik which was launched using the intercontinental ballistic missile technology.

BTW: According to the comments here, the solar power generation on Philae weights at least 20 times less than the nuclear generator would.

Any hypothetical RTG for this mission would almost certainly weigh less than the one on the Curiosity rover. This lander does not need 100+ watts of power for 10 years.

Consider that the RTG from the Pioneer 10 mission weighed less than 16kg: http://en.wikipedia.org/wiki/Systems_for_Nuclear_Auxiliary_P...

Thanks. That still makes some 10 times less weight for solar panels. Still, once US makes a mission, I can imagine they would consider using that, launching much heavier probe etc. This was an European mission, not having access to the US resources.

Wow, I just looked into it and it turns out the ESA actually hasn't used RTGs before, but planned to use one with this very mission[0:p78]. The only ESA mission I can find which used an RTG is the Cassini-Huygens probe[1], a collaboration with NASA.

[0] http://www.ianus.tu-darmstadt.de/media/ianus/pdfs/arbeitspap...

[1] http://en.wikipedia.org/wiki/Cassini–Huygens

Where do you see that ESA actually planned to use a RTG for Rosetta mission?

On the p78 is only "The consortium formed of leading institutes of Europe includes the scientific organisations of Germany, Finland, Italy, Hungary, Great Britain and Austria, which have not the technological capacity to manufacture RTGs. It was therefore decided to develop new high-efficiency solar cell for this deep space mission."

Here's the passage as it appears on page 78 of the IANUS paper[0]:

"Up to now there exists a number of projects developed by ESA which plan to use radionuclide power or heat sources. One of the most far progressed is the 'Rosetta' project."

[Update: When this paper was written, it looks like they might have been only planning to use an RHU to heat the lander:

"'RoLand' includes not only the solar power generator but also RHU on plutonium-238 of the RHU 'Angel' type. By the opinion of the project experts, the RHU use is the most desirable, sensible and reliable means for achieving the main goal of the mission."]

[0] Energy supply for deep space missions: Risks of nuclear power in space and prospects for solar alternatives. From http://www.ianus.tu-darmstadt.de/media/ianus/pdfs/arbeitspap...

Yes it's only RHU (Radioisotope heater unit) is mentioned,

http://en.wikipedia.org/wiki/Radioisotope_heater_unit

never RTG (Radioisotope thermoelectric generator).

"While both RHUs and RTGs use the decay heat of a radioactive isotope (usually Pu-238), RHUs are generally much smaller as a result of omitting the thermocouples and heat sinks/radiators required to generate electricity from heat."

But then there seems to be a contradiction here. If the ESA was planning to use an RHU powered by plutonium-238, which resource (your word) or technological capacity (from the IANUS paper) were they missing that prevented them from using a plutonium-238 RTG? Money?

It would have made the lander heavier, thereby increasing the size and cost of everything else.

RHUs are in no way comparable to RTGs: They are basically very small amounts of radioactive material fully enclosed in a thermally conductive container. Think of it as an always warm pebble stone. They are unregulated sources of (almost) constant heat and have no other purpose.

In aerospace engineering, they are used in just a few circumstances to augment the active heaters in a spacecraft: Heater lines, which are resistive heaters in a foil with a PI controller. You need active thermal control since your environment changes a lot (launch, preliminary orbit, transit, orbit) and thus its thermal parameters (some parts of a spacecraft may experience temperature gradients of a few hundred Kelvin within a few minuts). Most spacecraft designs have issues with overheating and thus RHUs cannot be used here.

An RTG's primary objective is to produce electrical energy (at an abysmal efficiency). The excess heat generated by an RTG is seldomly used for thermal control since it can also not be regulated and it emits simply too much heat energy.

It seems highly unlikely that any scientists would make subpar choices that may compromise a long-term project on the off chance that it might cause some political discomfort. The latter isn't even particularly likely since there is a large difference between nuclear power as an energy source on Earth and nuclear technology for scientific use in space. In addition most of the public doesn't even know or is interested in the technical details of a mission like this. Therefore it is extremely unlikely that using RTG technology would have caused any kind of political problems which makes avoiding said technology on political grounds simply nonsensical when it has the potential to compromise the overall mission.

I think you are 1) overestimating the amount of independence that a typical space agency project actually enjoys and 2) underestimating both the amount and variety of PR that a high-profile space mission like this one generates.

The issue is that Europe never developed RTG technology because of politics, so scientists couldn't even consider it as an available choice.

pound for pound, solar power is much cheaper. you cant disregard the weight considerations of a thermoelectric generator

Yes. I love nuclear, and think we should use a lot more of it both on earth and in space. But for things in the inner solar system not landing on a planet, solar is often the right answer.

(Aerospace engineer/student here)

While there were certainly some political aspects to the question, there were other more pressing reasons to not pursue an RTG design. First and foremost (as others have pointed out) is the lack of knowledge towards this technology within the EU/ESA member states. Also, there's little left of the fuel usually used for these generators (238-PuO2 in space applications), and while it can be bred, none was produced for centuries (last time I checked). It is expected that NASA can only launch a couple of addtional RTG-powered missions before its ressources are depleted.

An RTG also poses quite a few engineering challenges for the spacecraft itself. They are huge and heavy with low efficiency, and their design requires them to be positioned on the outside with sufficient surface area to radiate away their heat. One of their main benefits – almost constant power for a long time – is also their biggest flaw: Their power output cannot be regulated.

While these challenges are in no way unsolvable (they are used both in space and on Earth), they require a certain spacecraft design which makes them unsuitable for many missions. If you take a look at the design of Philae and where it was attached to Rosetta, there is no way an RTG would have fit the design and mission characteristics chosen.

They could have chosen a different design. Though the question is then: Would this have changed anything wrt science output and/or success of the mission? I personally don't think so: An RTG would have increased cost and complexity without a significant impact on science output. An RTG would not have helped with the harpoon and ADS (cold gas thruster) issues which are the primary reasons why Philae landed in the shadows.

Though certainly a malfunction has happened, I do not consider this mission a failure, quite the opposite is true! Due to the hopping, there's a slew of unexpected science data which awaits to be analyzed. Additionally, there's still the chance that Philae may regain enough power once the comet is closer to the sun. Lastly, the primary mission objective – analyzing a comet – is still well underway with Rosetta orbitting Tschurie.

Happily, Pu-238 is being manufactured again: http://news.discovery.com/space/nasa-plutonium-production-sp...

Another source I read at the time of the announcement said it will take a while to spin up, so there are some mission constraints over the next ten years. A Europa mission would wipe out existing supplies.

“Each night, when I go to sleep, I die. And the next morning, when I wake up, I am reborn.” - Mahatma Gandhi

Let's hope it will wake up and be reborn.

The chances for this seem not that bad, since the comet will heat up considerably as it approaches the sun, which will make it unnecessary to preheat the interior of Philae before starting to charge the batteries, while at the same time increasing the solar power reaching the panels (due to the sun being closer), so the lander might actually generate enough power to recharge the batteries and come alive again. Let's keep our fingers crossed.

They also managed to rotate the lander so it gets more sunlight

Yeah right, let's hope this helps as well! Of course there's the possibility that the panels will get more sunlight as the angle of the comet's rotation axis changes respective to the sun.

That's one of the most scary quotes ever. Way to write a horror story in 2 sentences.

If you've never thought about sleep that way, you should be scared! How do you know the person who woke up this morning is the same person who went to sleep last night?

How do you know the person who clicked the "Reply" button is the same person who wrote those words?

I've actually already been scared by it, investigated it, and dismissed it (you can't remember sleeping because you're not forming memories, not because you cease to exist). But it was interesting to see the idea phrased so succinctly.

Anthropomorphizing machines somehow always manages to twang my emotional snares. http://xkcd.com/695/

Good night, little lander. Hope you dream of electric sheep.

If you like that xkcd, this'll twang a few more heartstrings.

Imposter by The Doubleclicks https://www.youtube.com/watch?v=pHU67s5tOSA

When did machines begin tweeting as themselves? I find it odd as there are usually lots of tweets that no person would make such as "scientists are sending commands to repair my body." or "soon technicians will install new parts into me."

Welcome to the world of PR.

This is one way you take science to the masses. I think giving each Philae instrument its own Twitter account is a great idea.

I find it pretty deep in the uncanny valley.

I wonder if you are not the target audience?

http://www.youtube.com/watch?v=ayM68-4EioY#t=925

The first bit of Wall-E had exactly that effect on me. I think it's amazing how animators can make inanimate objects so expressive.

Wall-E is absolutely amazing in that way. My little ones have a total crush on him and I must have seen the movie about 400 times or so. I think I know the dialogue by heart and I still like to look at it every now and then to appreciate the skill of the animators.

And I'm sure most people here saw this compilation for Philae, but if you didn't: http://xkcd1446.org/#0

I'm really curious about the results. This is the first time something like this has happened, but with the results, actually knowing a lot of variables, not even from the lander itself other missions will have something to base their work upon.

The first programming languages (static, duck typed, ...), database systems, web frameworks, anonymization frameworks, ... all had a lot of things that were either far from perfect or are now considered stupidity. But when nobody did what you did, when you are a pioneer everyone following would be a fool not to look at your work.

Also a nice example: Operating Systems. In the early days they were considered a waste of energy, time, resources. Why would you want to emulate computers on other computers (no, not visualization, but running multiple programs) or why would you use that valuable memory/storage space to have multiple programs on a machine at once? Those used to be actual questions. But that's a bit far fetched.

The project was/is a real pioneering project and I have lots of respect for people investing all their lives (more than two decades in this case!) so passionately into landing on a comet. Not too long ago that was science fiction.

The first message on the internet (arpanet) was meant to be "login", but it crashed after the o. I think those people got further, even though without doubt it didn't run as hoped for.

Everytime I read about tech like this I cant help but wonder What kind of mainboard does this run? What CPU? What temp spec? what OS does it run? What is the main laguage? Would it use open source code?

Anyone has a clue or educated guess?

edit thanks to all answers provided, exactly the info I was looking for! And very interesting as well.

Most likely Ada, C or C++ with very strict code guidelines, which even make C feel like Ada.

Alongside real time OS like VxWorks, QNX, Aonix, ....

There was a presentation at CppCon about Mars Rover.

https://www.youtube.com/watch?v=3SdSKZFoUa8

Some details:

http://space.stackexchange.com/questions/593/on-board-comput...

Note that the RTX2010 uses Forth:

http://en.wikipedia.org/wiki/RTX2010

Regarding the power source, and why the mission depended on only solar energy:

"Why was RTG (Radioisotope thermoelectric generator) not used in Rosetta mission?"

https://news.ycombinator.com/item?id=8610585

Only US and Russia have the technology.

I don't know about Philae/Rosetta's hardware in particular, but there are very specific requirements to hardware that's sent into space.

I'm using the Mars Science Laboratory as an example here:

The MSL uses twin PowerPC RAD750 boards. If one of them fails, the rover could use the other as a backup. After all, you can't go out to Mars to fix a firmware update gone wrong. :) The RAD750's are hardened against radiation in space, and can withstand extreme temperatures. They run at about 200Mhz, and cost around $200.000 a piece. [1] [2]

It runs the realtime operating system VxWorks, which also happens to be what Apple uses for their Airport routers. :) [3]

NASA uses C as their main language, with specific coding standards. [4]

[1] http://en.wikipedia.org/wiki/Mars_Science_Laboratory#Rover [2] http://en.wikipedia.org/wiki/RAD750 [3] http://www.extremetech.com/extreme/134041-inside-nasas-curio... [4] http://lars-lab.jpl.nasa.gov/JPL_Coding_Standard_C.pdf

If one of them fails, the rover could use the other as a backup

Any idea how that works practically? I mean, there are two boards and one set of peripherals. Is there like an external controller which constantly checks if board A is doing fine, and if not, somehow reroutes all peripheral communication to board B?

The NASA website seems to imply that it's done manually: http://mars.jpl.nasa.gov/msl/mission/rover/brains/

Presumably there's some basic functions in the radio stack they use where they can trigger operations like shutdown, startup, reboot, switch boards etc.

NASA normally has pretty low-level stuff. To the point of being able to do full firmware updates — though obviously that's something they don't want to risk ordinarily.

Philae runs on an RTX2010 microprocessor: http://en.wikipedia.org/wiki/RTX2010

I wish there were a lot more of missions like these. We should accept some failures as well. If the cost can be lowered, the increased risk can be offset by more tries. It's better for the science as well if the missions are more diverse and the lead times are shorter.

I hope humanity grew up, so that failures would not produce so much backlash. Seems everybody feels so entitled in this age.

I'm sure they figured this out and decided against it, but I never understood why they often only send 1 device on missions like these. I understand launching things is very expensive, but you'd figure the R&D and risk associated with failure would cost much more.

Aye, most of the work is already done. I'm sure a second one could be launched at a fraction of the cost.

It's hard to wow the governments with "we are going to do the same thing again, much cheaper." Even though it's the good way to get the most science bang for buck.

It's not common, yes. Spirit and Opportunity come to mind.

Mars Express and Venus express were based on similar hardware.

Do not go gentle into that good night, Philae. Rage, rage against the dying of the light.

You made me look up that poem. I hold you responsible for the tears it brought.

What kind of data did the lander gather, and will it be open to the public?

It had better be given that the public paid for it at a minimum cost of 1.4 billion Euros for the strictly European input.

It will be given to the public -- in contrast to 99% of scientific research results published by private companies like Elsevier making you pay $30 per article (or less, doesn't matter: you must pay to get the results of a research funded by you).

Edit: most of it will be, not everything, as I've just found out.

Completely agree. It is outrageous. I am researching a topic at the moment and expected to pay £20 for the privilege of viewing a paper (with work funded as you say, by the taxpayer) published in 1960.

As to the project, the cost (open to correction by all means) was 1.4 billion. Downvote if you like; evidently this is my big mistake for not understanding that facts are apparently unwelcome hereabouts. If people assume that by mentioning this sum I am necessarily disapproving of the project then they are simply wrong and indeed had not one iota of evidence to suppose that. Now I know better - 'I must not mention the cost in case something thinks I am moaning about it'.

Just let me know what you need. I'm happy to forward to you anything I can get through my university access. I'm sure others here are willing to do the same so we should have most things covered.

Much of the Rosetta data is under embargo, because the instruments were not paid for by ESA but private organisations like Max Planck Institute.

Hence the paucity of hard data released to the public; the organisations have first dibs on the data to make their money back through publications and in attracting research funding.

As an example: http://www.mps.mpg.de/1979387/MPS-Beteiligungen_an_Rosetta

Basically, ESA provide the bus on which the science kit rides.

As an EU tax-payer I've raged against this in the past but that's just the way it is.

Source: direct question on this matter that I put to an ESA PR at a public lecture about Rosetta.

Yes, it would have been much much better for us Europeans to use that money to subsidize our agriculture a bit more... /s

The data should appear on http://www.sciops.esa.int/index.php?project=PSA&page=rosetta and http://pdssbn.astro.umd.edu/data_sb/missions/rosetta/index.s... and http://nssdc.gsfc.nasa.gov/nmc/datasetSearch.do?spacecraft=R...

The lander data includes infrared imagery, x-ray spectroscopy results, electrical conductivity measurements, temperature readings (from harpoons), acoustic data, gas analysis and magnetometer data http://nssdc.gsfc.nasa.gov/nmc/experimentSearch.do?spacecraf...

Thanks for the references! Do you happen to know when the first results (verified interpretations of the data) are usually published after such experiments?

I assume that Philae isn't meant to be powered directly by sunlight but has an intermediate battery? So wouldn't it make sense to simply wake him once this battery is full, do some experiment, send the data and go back to sleep until recharged again? Shouldn't that work even with low light conditions, just that the sleep phases would be much longer than planned? The article sounds like they aren't sure Philae will ever wake up again.

The space is unbelievably cold. The lander is in the shade, meaning the temperature there is probably mostly at least around minus 60 degrees. The battery has much higher operating temperature.

It's actually unknown whether there's an atmosphere there. Temperature in space is very cold, sure, but if there are no gas collisions nothing carries the heat away (like, say, on Antarctica). So the lander would only really be cold where it touches the comet, and the comet actually gets quite hot at times. Wikipedia mentions that Haley's comet was 70 degrees celcius (above zero) last time it passed by Earth.

Despite geostationary satellites operating in an environment that's nominally -265 or so degrees celcius, the problem they usually experience is overheating, not freezing. Blackbody radiation will eventually carry the heat away, but we're talking decades to get to -100 or so.

For instance, a human body at rest generates about 150 watts of power, which would kill you in geostationary orbit without a cooling system. It would kill you because it wouldn't take long for your body temperature to rise to 52 degrees, at which point your cell metabolism abruptly stops (your mitochondria will stop generating energy). It would take longer than it takes you to choke though. Though nobody's ever tried for obvious reasons, you should be able to exit a space station and get back in with just a helmet that protects your mouth and nose and ears from decompression. You wouldn't freeze, you wouldn't explode. You'd overheat in 10-15 minutes or so. If you survive that, you'd die 2 weeks later from radiation poisoning. On the moon you need heating, because it actually has an atmosphere that would carry heat away.

It is fun reminiscing about just how special our place in the universe is. Human bodies wouldn't be able to survive on planets 30% closer to the Sun, or about 15% farther away. We wouldn't be alive without a mostly oxygen atmosphere, because without the ozone layer, solar radiation would kill us. Without the earth magnetic field, solar radiation would kill us. Without the sun protecting us from interstellar radiation, we'd die. If our solar system was further to the outside of the milky way, we wouldn't survive the radiation, solar protection or not. If it was closer to the middle, we wouldn't survive. It's unknown whether it's a black hole at the center or something else, but it sure outputs a lot of radiation. Oh, and we're in the < 0.1% of the milky way that hasn't experienced a supernova explosion for about 3 billion years (a supernova explosion at 20 lightyears or less would kill all life on earth. 50 lightyears is considered the minimum safe distance for large mammals to survive). The milky way has collided with at least 3 other (tiny) galaxies, none of the collissions were (are) anywhere near us, as the tidal stresses would alter planetary orbits, and so on and so forth.

All of this is ignoring the physical necessities for life to exist. If the fine structure constant, for instance, was 0.1% bigger or smaller, there would be no chemistry, and no humans. If the speed of light was ~5% bigger or smaller, there would be no atoms, as there would not be any stable electron orbitals, and so on.

> "It is fun reminiscing about just how special our place in the universe is..."

I think you have it slightly backwards there. Life on earth, and us specifically, don't look the way we do because of chance. The reason we only operate in this specific environment is because we were shaped by our environments. Who knows in what environments life can exist. If you think of life as some sort of self-organizing system it's not unthinkable that 'life' could be possible in places that seem extremely inhospitable to us. Inside a star for example.

In order to have "life" in the sense that can be interesting to us (that means, not the "life" in the sense of something that is organized inside of a some star which is unreachable by us) the properties of chemical elements can be studied and apparently the properties of carbon are such that it is the most probable element for organic chemistry. There are possible alternatives, like silicon, but every alternative is less probable and less efficient that carbon:

http://en.wikipedia.org/wiki/Hypothetical_types_of_biochemis...

"Sagan used the term "carbon chauvinism" for such an assumption. Carl Sagan regarded silicon and germanium as conceivable alternatives to carbon; but, on the other hand, he noted that carbon does seem more chemically versatile and is more abundant in the cosmos."

This is the anthropic principle, and applies to some of the coincidences. But there are open questions ...

If life can adapt, why isn't Mars green ? Why isn't Venus ? At the very least, why aren't the landers picking up cells constantly ? We're seeding those planets with fresh living cells on a daily basis according to a number of papers published 2 years ago.

Second it is very unclear how it applies to other required coincidences, like the fine structure constant, or the speed of light. If they weren't in a very narrow range, and at a specific fraction of each other, there wouldn't be any real amount of complexity in the universe. No way in hell there'd be life. You should consider just how narrow the range is and the fact that there's over 20 constants that each have their narrow range. If you wanted to "try" them all, have you considered just how huge a project it would be to search a 20-dimensional space for the right values ?

But yes, at the moment the Copernican principle stands in the "consensus" sense, I personally don't believe in it. I don't know where people get it from, in my data space does not look uniform at all. So, please, do realize what it is : it is an article of faith, nothing more. There is no data, nor theory, to justify it.

I will say, of course, it is a useful principle. Any pattern you see should be assumed to be nothing special, as that will make you search for new science, which is good. That's just good practice, a way to avoid over fitting. But in popular science it is a dogma, and that's not at all what it's intended to be.

Battery can't be charged in low temperatures. It has to be heated to 0 C to be charged, and there may be not enough energy to do that in the short period that the sun reaches solar cells.

Rosetta wouldn't have some mirrors, or even reflective surfaces, would it? It could position itself to reflect sunlight onto Philae.

I mean, I'm sure Rosetta has neither (in useful conditions), but there's a thought for next time :/

This was asked in a French Q&A session with the ESA and they dismissed it as "science-fiction" :)

http://www.lemonde.fr/sciences/article/2014/11/13/philae-peu...

Well, I meant it more as "hopeful pondering", but point taken :)

That would be possible in theory, a few problems though:

You would need a flat surface to reflect light towards Philae, so the only appropriate surface would be the solar panels. The solar panels are not mirrors however, they would probably only reflect about 5%-10% of the sunlight towards Philae. This is even assuming the solar panels are sufficiently flat.

Also the location of Philae is unknown (AFAIK), so there is the problem of where to aim the reflected light.

Finally the relative direction from Rosetta would presumably change as the comet rotates, which means the solar panels or Rosetta as a whole would need to be continuously aimed at Philae, using propellant and/or other energy.

Apollo retroreflectors.

https://www.xkcd.com/1441/

This was a very interesting mission, and sticking the landing alone means that it was a success.

Well done, let's hope some interesting data was collected as a bonus.

Is that a grammatically correct contraction for "Our lander is asleep"?

Yes.

Hey dang - I noticed the comment below I made which stuck to the top for most of this thread's life dropped to the bottom at the time you commented here.

What's the process for penalising posts in this situation?

Is it just an individual decision where you've decided it distracts from a valuable discussion?

I see I could have been a little less harsh with the damnning commentary (only to a point), but ultimately if we're all scientifically-minded then knowing that the internal targets were airbrushed for the public is a bit of a cerebral 'what?' I'd expect we're down with exploring on HN.

This is the sort of thing the HN guidelines ask you to email us about: hn@ycombinator.com.

https://news.ycombinator.com/newsguidelines.html

We shot that fridge from earth and guided it for 10 years and prior to launch we had it in planning for another 15 years or so to have a battery depletion on the second day?

Why didnt they just use nuclear energy?

As late as 12 November, the ESA's own FAQ [1] was stating that Philae's minimum mission target was one week of surface operation (powered entirely by primary batteries), with even more operational time powered by back-up batteries (themselves recharged by solar) - resulting in an expected surface operation period measured in months.

They airbrushed the FAQ on 12 November to remove mention of the minimum one week mission target, and inserted among other things '2.5 days'. [2] A diff of the two versions would probably be interesting.

Now with the lander mission prematurely ended an associated scientist is tweeting a very rosy summary [3]:

"What a perfect ending. All the science completed, data received. Primary mission successful. Well done everybody."

How can a week of carefully-planned scientific activities be 'completed' in only 2.5 days? It seems implausible.

How did the primary and secondary batteries not power the lander for the calculated one week+ of operation?

Why aren't they open about what clearly seems to be a major failure with the scientific mission?

It seems a case of intense bureaucratic / political pressure to change targets after they aren't met, and the fact scientists are participating in this is pretty disappointing.

[1] https://web.archive.org/web/20140805030451/http://www.esa.in...

[2] http://www.esa.int/Our_Activities/Space_Science/Rosetta/Freq...

[3] https://twitter.com/rocketeddy/status/533421309553016832

The targets have to change during the mission. The initial plan was even the another comet. It shouldn't matter.

http://en.wikipedia.org/wiki/Rosetta_%28spacecraft%29

"Rosetta was set to be launched on 12 January 2003 to rendezvous with the comet 46P/Wirtanen in 2011.

This plan was abandoned after a failure of the Ariane 5 carrier rocket during a communications satellite launch on 11 December 2002, grounding it until the cause of the failure could be determined."

No reason to blindly stick to the initial target when you're doing something for the first time ever. It's not that you planned to drive from your home to the shopping mall and have to excuse to your other that you went drinking beer instead. You would probably complain that it's not an initial comet now too?

The device landed on the darn comet! After travelling 6 billion km in 10 years. Managed to work a few days and send the data! First time ever! Powered only by the solar energy! (+) In the outside temperature of absolute zero. How many firsts do you need?

https://www.youtube.com/watch?v=uEY58fiSK8E

Nothing built by humans was ever on the comet surface before. This thing even worked.

+) Edit: Thanks to jdiez17 for pointing that the lander used a non-rechargeable battery on the comet surface. It was all the time planed to do the main work with that battery. The solar powered work wasn't the primary objective.

To be completely fair, it was not powered by solar energy - the experiments were run on power from the non-rechargeable battery. Which is fine, this is what Philae was designed to do. It looks like they completed all the objectives in the First Science Sequence (FSS), which was the lander's primary mission.

And also to be fair, the whole mission didn't depend on any RTG technology, used only by the US and Russia in space:

https://news.ycombinator.com/item?id=8610585

While it would have been convenient to have a RTG onboard, it would have made the lander too heavy (with the current RTG technology. Smaller nuclear generators are possible in theory but none have been built yet.)

Yes, the lander was around 100 kg, whereas RTG would weight around 40 kg alone. And it would anyway be needed only in this case of unfortunate landing in the shadow.

Once we talk about details it's clear how a lot of the complaints are based purely on a huge ignorance. It's good to ask to learn. But when somebody starts from the position that people who managed 25-year mission missed something to him "simple and obvious"...

> It's good to ask to learn.

In that spirit, I have a question. How heavy are the solar panels? If their weight is comparable to 40kg then it makes RTG more attractive.

I'm not sure about the exact weight but perhaps an estimation can be derived from the specifications available in the fact sheet [1]

- Contractor: Galileo Avionica SpA

- Cells Type: Si, Hi-ETA LILT

- Cells Size: 3x3 cm2

- Power equiv. @ 3 AU: 32W

- Total Size: 2.2m2

- Lifetime: 10 years

[1] - http://www.dlr.de/rd/Portaldata/28/Resources/dokumente/rx/Ph...

The weight of solar cells used on the Earth comes from making them protected from the environment, the material that produces the power itself is very thin.

http://sbir.gsfc.nasa.gov/SBIR/successes/ss/3-027text.html

Note "1 kW/kg" specification but it's probably in the Earth's orbit, using the inverse square law, it should be an order of magnitude less where Philae now is. Still, it appears it can remain quite light to have 2 m^2 of cells there.

Anybody has more exact details for the weight of the cells on Philae?

1.7 kg, I think:

    TABLE I
    Mass breakdown of Rosetta Lander, including sub-units on the
    Orbiter.

    Unit                          Mass (kg)
    
    Thermal Control System        3.9
    ...MLI                        ...2.7
       ("multi-layer insulation")
    
    Power System                  12.2
    ...Electronics                ...2.0
    ...Batteries                  ...8.5
    ...Solar Generator            ...1.7   *****

    Sum [Lander]                  97.9

    Sum [incl. Orbiter units]     111.0

Excerpt from table 1, page 208 of

[paywall] http://link.springer.com/article/10.1007/s11214-006-9138-2

[PDF mirror] http://www.researchgate.net/publication/257664668_The_Rosett...

Thanks, but now I wonder. Mass is different from Weight (absolute and relative respectively). Are we comparing apples and oranges here?

We compare correctly: we measure everything on Earth (that means, under the same gravity) and the proportionality holds, so it's still more than 20 times less mass to carry for the power source with the given solar panels vs. the RTG. The mass doesn't go away, the amount of stuff remains, the weight is how much something pulls down the spring in the spring scale and that depends on gravity, but we conveniently measure on Earth.

Since an RTG creates more "waste" heat than actual electricity, would that obviate the need for the thermal control system? Or at least reduce the amount of insulation needed?

Typically it wouldn't "obviate the need for the thermal control system," see fbender's answer:

https://news.ycombinator.com/item?id=8614514

"An RTG's primary objective is to produce electrical energy (at an abysmal efficiency). The excess heat generated by an RTG is seldomly used for thermal control since it can also not be regulated and it emits simply too much heat energy."

I'm just raising the kind of precise, detail-oriented questions that typically emanate from this community.

Your response relies on an appeal to emotion rather than logic, and doesn't seem particularly interested in engaging with the substance of the questions raised?

The logic is: to get something at least approximately close to your goals done for the first time ever, you have to adjust your targets as you go. Every other strategy simply doesn't work. You are welcome to just stick to your initial goals in your endeavours. Write now absolutely exactly what you plan to do for the first time. Than please report in some time and stick to describing your failures. Observe how motivated for more you'll be.

And to paraphrase Louis, since when the 25-years lasting mission that you've learnt it existed only recently owns you exactly seven days of function on the darn comet?

To be more serious: of course the scientists will learn a lot even from every thing that went wrong. That's exactly how science works. It still doesn't mean that the public attention should concentrate on that now. See also my comment response to the "mistake" claim.

Of course you adjust your targets. But it doesn't imply you must rewrite your expectations to fit with reality after the facts as if those expectations never fluctuated. You actually lose data points by doing so.

Data points? The poster justsee actually complains about the FAQ page which didn't even have to be precise in the first place and doesn't have to be now. It's a web site directed to the uninformed public. Honestly, who do you expect to use the FAQ page for anything serious?

Among other questions on that page are

"Why is it so important to study comets?"

"What is the difference between asteroids and comets?"

You don't bother public with engineering stuff like "we have 1000 Wh power budget from the primary batteries, which will last depending on what happens when, and the different devices have different energy needs and we aren't actually sure what can happen but we prepare for as much as possible with the hope of at least something giving us some good results." They just switch off. We at least know where justsee switched off in being interested in the details: the expression "during a week" he understood as somebody promised him "exactly at least a week of entertaining news from the lander."

> It's a web site directed to the uninformed public.

The `uninformed public` deserves to be better considered, thank you.

It's not about the quality of explanation or the depth of the technical details in the FAQ but about the way it gives the feeling facts are being rewritten to fit reality (if there are no mention on the page it is being edited to accommodate for mission updates then it's completely understandable people would frown over number shuffling).

Did you count the words on that FAQ ? Any `uninformed` person who would read that FAQ would have questions about why the wording change over time.

Because it's a FAQ, not a live update.

> Honestly, who do you expect to use the FAQ page for anything serious?

Really ?

The FAQ is rewritten as the facts change. They wanted a week, but the landing didn't go well, so they figured out they could get 2.5 days, and they changed the FAQ. It's not complicated. It's not a conspiracy. No one is being cheated.

Sigh...

> [..] if there are no mention on the page it is being edited to accommodate for mission updates then it's completely understandable people would frown over number shuffling [..]

Did I say I feel cheated ? No. Did I say there was a conspiracy ? No.

The web page has all the qualities of a static web page (no `live update`, no `last modified` label, etc.) and it's on the ESA website which gives it some kind of an official vibe. Yet, they are updating it to reflect mission objective changes (which is totally fine as far as I am concerned, by the way) which lead to confusion and questions such as "Did they just changed their stated goals to accommodate for the fact Philae is going to operate for a short time than planned or expected ?". Add to that some Internet tweets about how "it smoothly perfectly gone well and all the data we wanted are there" and someone goes back to the FAQ and spot changes (1 week turn into 2.5 days).

Allow me to take you for an idiot as well: It's not complicated. to understand that web page is a bit misleading. It doesn't relay the information that the mission parameters and objectives changed (and of course I know they changed, were likeley to, etc.). If you go back to that document in 20 years you'd have no idea there was some problems with the landing.

> I'm just raising the kind of precise, detail-oriented questions that typically emanate from this community.

This better get included in the next "fake HN frontpage" that gets posted :)

And also that (I'm happy to say, an intentional joke) comment that I can't find now (please post the link here if you know it!) that explains that the communication of the lander and Rosetta is done with web technologies (web servers, htmls and stuff) and suggests that they aren't modern enough.

(In reality, as discussed here: https://news.ycombinator.com/item?id=8611274

"Philae is controlled by 2 RTX2010 CPUs (hot red), further 8 control the Experiments. 13 CPUs (10* RTX2010, 1* ADSP-21020, 2* 80C3x) in total. © https://twitter.com/philae2014/status/427842417920712704 ")

Historical revisionism is not honest and it raises serious credibility issues.

That's bad for science. It's quite similar to adjusting your hypothesis to fit the data. Not as bad as manipulating the data, but not ethical, either.

Not at all, unless the "hypothesis" was that you would reach a particular comet. I think the scientific hypotheses were more likely related to the composition of comets, than the abilities of the engineering teams, reliability of Ariane, etc.

Their mistake was to state a _minimum_ target mission like that in the first place, when you know that this is an incredibly complicated mission.

Even that isn't the mistake at all. It's a good strategy to prepare to do a lot, then when some things go wrong, at least some of all things we're prepared for work. If you set the goals too low, you'll do much less. Therefore, the basic plan was to do the most of the work during a short time period. But they prepared to be able to do something interesting for much longer, if everything goes as perfect as it ideally could.

The mistake would be allowing others to feed on smaller-effect non working stuff instead of the things that amazingly worked.

Yes but you don't need to announce that in a public FAQ ;)

Damn straight. The top commenter treats the public FAQs of some kind of post-mortem report.

> It seems a case of intense bureaucratic / political pressure to change targets after they aren't met, and the fact scientists are participating in this is pretty disappointing.

This is a big leap to make from the available evidence. Mission targets change all the time. It's a very fluid situation with many unknowns, so I don't find it at all surprising. I think calling foul play is premature to say the least.

Do you think changing the mission target of a 12 year mission on the day of landing has a scientific or bureaucratic / political motive? I'm inclined to believe it is the latter.

Until 12 November the FAQ [1] stated:

During the first week – the minimum mission target – a first run of the most important scientific measurements will be completed. During this phase the lander can operate on primary battery power, should this be necessary. In a second phase that is meant to last up to three months, a secondary set of observations will be conducted, using backup batteries that will be recharged by the energy from the solar cells on the lander. However, no one knows precisely how long the lander will survive on the comet.

Editing to omit the minimum mission target on 12 November [2] indicates something was already wrong at that stage, which would presumably relate to the two batteries that were to power the lander over more than a week, but no public announcement of any issue like that was made. So we should instead assume the batteries were fully operational.

Instead we have ESA announcements and news articles asserting that the reason for the very short period of operation was a lack of solar power, but solar was never planned to be required for over a week at least.

It seems obvious that they had a battery failure. That would not be surprising, but why not openly announce it?

[1] https://web.archive.org/web/20140805030451/http://www.esa.in...

[2] https://web.archive.org/web/20141112043243/http://www.esa.in...

Because it's not important. What is more important is that the First Science Sequence was finished. In a detailed report, you may find that the battery didn't last as much as they thought it did (perhaps because of the double landings Philae had to make, etc.), but a public-facing article is not the place for it.

Also, there are probably N things that didn't happen as they thought it did. It is better to mention the K important things (K << N), than the N unimportant things that they got wrong.

If Philae, for example, didn't land on the comet at all, then they would have announced something like this: "Philae took a drive-by of the comet 67 p, and has done in-air experiments that would be valuable for us".

It may not be important, but it's still interesting. We have two pieces of information about an interesting subject which appear to be inconsistent; attempting to resolve that inconsistency is the natural act of the curious mind.

Should we really give any weight to the two versions of the FAQ page, which contains also answers to the questions like "What is the difference between asteroids and comets?" What is the relation between FAQ page and the details of how many experiments, in which order, which schedule and using how much power at once are going to be done? Do you really believe something written for an uniformed person can ever be exact enough? If your cell phone battery lasts 5 days in stand by and you speak 5 hours and it's empty, everything is still according to the plan: you just used it more in shorter time frame. It's the experiments, not the lengths of time given as "during the first week" that matter.

If it's not important, why lie about it?

Every once in a while I'll wake up, unplug my iPhone from it's charger and go to work, doing my normal planned routine, and have it die before I'm able to get back home to recharge it. Does that mean that my iPhone is a failure and I should sue Apple for failing to deliver on their promise of X hours of battery life? No. That's stupid. In agreement with you, sometimes things just don't work as desired, but the usefulness of the device isn't diminished, it's just altered.

The time variance is not very interesting to me at all, but the question of how or if they were able to get at least a week's worth of science done in 2.5 days, is very interesting to me. Was all the science completed, or just a fraction of it? Did they originally plan for only doing a day or two of science (with anything else being a plus), so the short mission life wasn't a problem?

How about first learning which experiments were actually supposed to be done? Can you list them? Can you explain what they are about? Then we can try to consider how much of which of those were done and what are the actual consequences of different schedules in their execution.

We can expect the years of scientific papers based on the analysis of the raw data made by this mission.

Here's a word diff between the two FAQ versions you posted: https://gist.github.com/avar/29d060e178e8fac4e2a3#file-faq-w...

Just search for "[-" to find deleted entries and "{+" to find added entries.

They got there, landed and carried out the primary science mission. They didn't even start on the secondary work (AFAICT), but that's called secondary for a reason.

At a guess, the primary science mission was done so quickly because that's what they did. They might have spent more watts on locating the lander, for instance, or on taking pretty pictures.

It seems a case of intense bureaucratic / political pressure to change targets after they aren't met

This is essentially the European Union's modus operandi.

It's disappointing that this is the most upvoted comment in this thread. The mission was a success and will enable the scientists to understand much more about the whole thing. Plus, the orbiter will continue to track the comet and there is a chance the lander will come back from hibernation mode once there is more sunlight available.

I think people in general have come to expect the incredible lifetime of the Mars landers as the norm. It's not.

But since this is HN, I'm sure we all in the IT world are pretty confident in our estimations and our projects are a complete success all the time. Might explain why we are so disappointed with ESA. </sarcasm>

Many might not agree with the conspiracy tone of the comment, but we can see that there's something to be explained.

The mission was not a success: it did not meet their minimum goal of one week.

Failure happens and is nothing to be ashamed of when trying for such an ambitious goal. ESA needs to own it and move on.

Tough crowd.

It’s not a failure, though. Clearly not. Obviously not. To call this a failure is flat out insane. It has no connection to any reality.

Also, it’s not a dichotomous failure/success condition. Some things worked, some things didn’t. That’s the actual situation. That much is obvious. It seems they actually managed to fulfill all the primary goals, though you will probably have to wait for the published papers to assess the quality of the collected data. Could take a couple years.

Either I am failing to grasp what you are saying or you are completely naive about the humongous risk involved in cutting edge science of any kind.

This ain't some piddly kickstarter trinket. And exactly what was promised that you didn't get your money's worth for?

Speaking as a researcher in the biological sciences, funded by public tax-payer sources only (don't forget, I also pay taxes), the risk of failure is absolutely astronomical with every project I have ever undertaken. The fact that those projects have succeeded the way they did, is, at least in my mind, phenomenal. Even then, none of these projects, or any projects of any other scientist in my field, have ever achieved all their stated goals.

If this rankles you, move to a place without public funding of science and bet your money on trinkets put up on kickstarter. Or if they are not trinkets, but are true attempts at solving hard problems(curing HIV/cancer, landing on a comet), I hereby guarantee that none of them will succeed 100% of their stated targets.

> This ain't some piddly kickstarter trinket. And exactly what was promised that you didn't get your money's worth for?

Parent never stated he wanted his money's worth. He points out some obvious history rewriting which highly harm Science's image (IMNSHO). In no way does that diminishes this mission's outcome, results, feats and the admiration it rightly deserves.

I don't understand the hostility here for a valid question about something that has nothing to do (obligatory political rewriting, maybe ?) with what was achieved.

> I hereby guarantee that none of them will succeed 100% of their stated targets.

But you don't lower your expectations after the facts and state "look, we did it as we told we were going to do it".

This is because parent and you are confusing a FAQ meant as a "what is the project going to do in its current state" for the general public with the blueprint and historic objectives and logs of the mission.

The mission's goals changed a hundred time since the project conception in the eighties, each of those version is archived, but it makes sense that the "space tourism" text meant to explain to everyday Joe what the mission is doing / has done reflects the up to date status.

If you deny there can be some confusion brought for by the fact the FAQ is a live document but nowhere on the web page is it stated then I don't see ground for discussing the matter at hand.

What? It’s the fucking web. Of course it’s a live document! If it wouldn’t be that would be a colossal failure. It also doesn’t tell you anything about the actual goals of this mission that would be relevant for future missions.

What’s with the conspiracy brigade being out in full force?

Reading his other comments on this thread, he's obviously a troll and/or someone who needs to criticize this mission or ESA. He is not having an actual debate, only repeating his points ignoring any answering element he gets.

> Reading his other comments on this thread, he's obviously a troll and/or someone who needs to criticize this mission or ESA. He is not having an actual debate, only repeating his points ignoring any answering element he gets.

1. I do not need to criticize this mission or ESA and I'd like you to quote any sentences that makes you think so (and yes I believe a FAQ page being live updated should state it is being updated as the situation evolves becaues if not it brings confusion).

2. I answer with honesty to every replies directly made to me. Feel free to point out anything you believe I willfully ignored.

3. Regarding the elements I got: I mostly saw a (rather stupid IMO) point about how a webpage is live tech. so its content is updated (are we really missing the difference between editorial content and packets on a network ?) and another about how I would be expecting blueprints and the smallest technical details from a webpage presenting itself as a FAQ. I find these ridiculous and quite condescending.

FWIW, I have been following the Rosetta mission for the past 6 years, had a nice chat a the Paris Air Show with some ESA members even though there never were any lectures about for the past 10 years there, and for the life of me I don't understand how you could believe I would troll about it. Or any other topic for that matter.

I'm off.

The confusion does not come from it being live (it's a web page, duh !), it comes from you taking a page about current status/faq for the public and consider it as the official mission's objectives list.

All you need to do is look at the right document, and if you can't figure that out I certainly wouldn't want you making judgment about any science project involving my tax dollars (well, euros).

> The confusion does not come from it being live (it's a web page, duh !), it comes from you taking a page about current status/faq for the public and consider it as the official mission's objectives list.

Absolutely not. I am of the opinion that having a public FAQ on a website being updated without any notices it is being updated (there is not even a mention such as "last updated xx/xx/xx") is going to lead to some confusion and rightfully so.

Thank you for taking me for an idiot that would believe a FAQ stands for a technical document for any project.

> The confusion does not come from it being live (it's a web page, duh !)

And I am the troll ? Of course the confusion comes from it being live without clearly stating it is.

I wonder what your reaction would be, for instance, if every poster around these parts would go on editing each of their posts according to the evolution of the topic being discussed because "hey, it's live, it's a webpage, duh!)".

> it comes from you taking a page about current status/faq for the public and consider it as the official mission's objectives list.

No, I don't. Please quote any of my posts that make you think so.

If a project fails to meet its goals, do you go back after the fact and change the goals or do you admit that you didn't meet them?

Lets go back and look at the history of human knowledge about comets for a moment.

1) The composition of comets were largely unknown until ~1950 when Fred Whipple hypothesized that they were largely icy objects instead of rocky objects, which was only confirmed in 1986 when Vega 1 and 2 flew by Halley's comet.

2) This idea was flipped in 2001 when Deep Space 1 took photos of the comet Borrelly, which showed a hot and dark surface.

3) The Stardust mission in 2004 discovered that the dust of a comet was actually a crystalline structure, created by very high temperatures.

4) The Deep Impact probe in 2005 was the first physical contact humans had with a comet's surface, which resulted in us combining the two previous hypotheses into an object filled with an icy dust mixture protected by a hard and hot dirt shell.

5) Finally this year we landed Philae onto a comet's surface by launching a probe in 2004, a mission that started as far back as 1992.

This means that we were planning on landing an object onto the surface of a comet long before we knew what in the hell a comet really was. To say that we failed to meet the goal of a one week operational timeframe on the surface disregards the entirety of knowledge learned during the operation of the mission in which we were conducting. Just after Rosetta launched we figured out that the surface of a comet was probably more ice than rock, and had to conduct retroactive experiments in order to determine whether or not the harpoons of which had already been engineered, designed, manufactured and launched into space (which failed to work, so the result is somewhat moot anyways) would in fact be capable of holding the lander on the surface of the comet. The main goal of this mission was to learn more about comets, not spend a defined time on the surface like a game of "King of the Mountain" at some elementary school playground. The mission was successful. We obtained data about the surface of comets and discoveries and observations resulting from the collection of this data will continue to happen over many years to come. Would have it been better if we were able to keep a probe operational on the surface of the comet for years instead of weeks, or weeks instead of days? Yes. But the goal was to learn shit, not get in a pissing contest with a nonexistent alternative lifeform that has already landed an object on a comet and kept it alive longer than us.

Your rant is completely irrelevant. I don't have an issue with the mission ending the way it did. I have an issue with retroactively changing the goals and then saying the mission had a perfect ending.

What the fuck. Who retroactively changed anything? It’s an FAQ. It doesn’t tell you anything about anything valuable in this case. Updating it with current info is obviously the right thing to do, too.

What’s with the insane conspiracy theories?!

Not directly relevant, but why not spend the minute necessary to google whether the explanation for "How did the primary and secondary batteries not power the lander for the calculated one week+ of operation?" is readily available? (it is:

The harpoons failed to deploy leading the lander to bounce off of its landing target and land in a crater where the solar panels intended to increase its battery life had limited sunlight. http://www.vox.com/2014/11/13/7214941/philae-comet-rosetta

)

1. The primary non-rechargeable battery was designed to power it for a whole week.

2. The secondary rechargeable battery was designed to continue powering it for months after that.

The detail you include is only relevant to 2, and keep in mind it is reasonable to assume that the secondary battery was fully charged before descent.

> it is reasonable to assume that the secondary battery was fully charged before descent

Actually, no, it's not, unless you show something to prove that. Have you ever designed the device with two different power sources supposed to work on a comet after travelling 10 years through the space and being launched from the orbiter? I haven't, and can't claim it's reasonable to assume, whereas being an engineer I can imagine a lot of reasons for the directly opposite claim. What are your experiences or citations that allow you to claim that? Please state them or avoid uninformed claims.

Specifically, if the secondary batteries were supposed to be fully charged before, why would the non-rechargeable batteries be the primary batteries at all?

And technically, there are more primary batteries and more secondary batteries in Philae, the primary batteries having 1000 Wh, the secondary batteries having 140 Wh. Note that if you use e.g. 30 W during experiments, you use the primary batteries in some 30 hours. The scientists had to decide the rate of the battery use. Just like your mobile phone lasts only hours if you speak all the time on it. The lander being in the shade had different temperature environment than in the ideal case. It's extremely cold there and the high enough temperature is necessary for the things to work.

Compare all that with your modem constantly using 10 W, your computer, if notebook, using probably 20 W for serious work. Even without the heating problem, you wouldn't be able to use internet and work for more than 30 hours with Philae's primary batteries, and certainly not for 4 days.

The primary objective was always planned to last few days, and it did that part pretty much perfectly (80-90% of results were received). After these few days, there was a secondary objective, which was to turn Philae into a kind of weather station on a comet, with pretty much every instrument turned off.

It would have been great if it had worked of course, but compared to the main objective it doesn't really matter. What they really want to know is the chirality of the water on the comet and wether or not the comet contains certain elements, it seems like they manage to get this data.

Also the secondary objective is not totally abandonned, since there is still a chance to see Philae back in some months, with the comet getting much more sunlight and warming considerably.

Plans change with time, and the FAQ is adapted to those plan. Hell iirc there wasn't even suppose to be a lander in there initial plan 25 years ago.

"Why aren't they open about what clearly seems to be a major failure with the scientific mission?"

Human nature. Haven't you worked in a corporate environment where people try to spin to the positive? A lot of money was spent and people want to feel good about the results.

When they sold the project, the PowerPoint needed to present a great show or it wasn't going to get funded. A 1 week minimum was probably needed.

Anyway, I could go on but just try observe human nature, otherwise people will accuse you of being negative.

As for me, I thought it turned out to be a great because it became a mainstream story. We should be putting 4k video cameras on new craft. Get people excited so we can get a budget to build 10 times as many vehicles.

Bandwidth's surprisingly limited on these missions, so 4K cameras, while awesome, would be problematic.

I'm assuming they burned through much of the initial battery charge trying to establish contact, determine orientation, right the lander, etc. So it may have been able to operate for a week had they not had to do a lot of things they hadn't planned on.

Yes, they want to give things a positive spin, but they aren't being disingenuous. They have learned a lot from this, and they got to run tests with all of the equipment on the lander. Calling it a major failure is way off base. You often learn more from things going wrong than from when they go right. Maybe not the things you were planning on learning, but this is very far from a failure.

I also think you're over-interpreting their "minimum mission target". That was an "if everything goes to plan" target. Everything didn't go as planned, but here's the thing: that's also in the plan. It is not possible to do this kind of mission without things going wrong. Usually when things go wrong, you get no data back. But despite the landing going terribly awry, we still got a lot of data back!

If you consider this a failure or a disappointment, then I'm glad you don't work for the ESA. You are far too cynical to be able to get this kind of science done.

Why is this comment at the top? Why do I have to scroll down so far to get to any sort of interesting discussion about the lander? Pathetic.

So I went ahead and actually used kdiff. Here are the relevant passage.

Honestly it looks more like live rewriting of the FAQ to take into account the fact that Philae had a bumpy landing. I don't see an intention to deceive. It's awkward to present the document without mentioning it's not the detailed mission objectives.

That maybe the `perfect ending` considering we have some data back and well.. it's the only ending we have so rosetta exploding before philae could even be launched might have been labeled `perfect` too because it's the first time we put something into the orbit of a duck-like comet.

They certainly wished they had more philae time though. That would have been even more perfect. I wouldn't qualify this a `major failure` though (does the hostility come from that ?).

> The science observations will start immediately. During the first week – the minimum mission target – a first run of the most important scientific measurements will be completed. During this phase the lander can operate on primary battery power, should this be necessary. In a second phase that is meant to last up to three months, a secondary set of observations will be conducted, using backup batteries that will be recharged by the energy from the solar cells on the lander. However, no one knows precisely how long the lander will survive on the comet.

And then:

> The science observations will start immediately. During the first 2.5 days the first series of scientific measurements will be completed. During this phase the lander will operate on primary battery power. In a second phase that may last up to three months, a secondary set of observations will be conducted, using backup batteries that will be recharged by the energy from the solar cells on the lander. However, no one knows precisely how long the lander will survive on the comet.

Having read the two different versions of the FAQ, I also have to dispute your thesis here. On November 12, that FAQ page was probably getting more hits in an hour than it had in its entire history up until then. Say you're in charge of communications, and due to the landing problems, the mission profile has just changed from best-case to medium-case. What's the point of a FAQ that's wrong? The question is "How long will the lander operate on the comet's nucleus?", not "How long did you originally promise the bureaucrats the lander would operate?"

As the answers change, the FAQ page changes. The previous version of that page on the Internet archive doesn't mention the landing at all. So this isn't even a long standing promise. Probably they were making estimates and new guesses every few days as they got closer to the comet and learned more about it. The target mission duration probably depended on the location they landed, which wasn't decided until a few weeks ago. Anyway, the FAQ page is not the official mission planning document, and it's not meant to be a history of every change in the plan. It's a place to answer questions that the public and the press have about the current state of the mission.

I read somewhere that the odds they places on getting the thing to stick the landing at all was between 50 and 75%. We put a lander on a comet, I'd be celebrating the upside too if I was them.

While you work on those discrepancies, I'm going to enjoy this version of the story and let myself get a little teary-eyed over this astounding success:

> @ESA_Rosetta I'm feeling a bit tired, did you get all my data? I might take a nap… #CometLanding

> Thank you, @ESA_Rosetta! I did it! I became the first spacecraft to land on a comet & study it! But it’s not over yet… #CometLanding

> My #lifeonacomet has just begun @ESA_Rosetta. I'll tell you more about my new home, comet #67P soon… zzzzz #CometLanding

https://twitter.com/Philae2014

will it get more energy once it gets closer towards the sun? will it still be operational once it gets there?

It’s an FAQ. It tells you precisely nothing about anything. Don’t be stupid, don’t be conspiracy mongering please. Why is this trash up there? It’s insane that this crap is seen as a valuable contribution.

This is the second thread in as many days that's been completely derailed by embarrassing, irrelevant crap. Embarrassing because somehow the comments still have scores over 0.

I couldn't help but wish there was someone of NASA's calibre with respect to public outreach "handling" this. I really think they got the tone wrong -- 99% of the THOUSANDS of people watching this really just wanted to experience the adventure, warts and all. We know it's hard, we empathise. We wanted to experience the trill, terror and wonder. There really wasn't any need to clam up like they did. If only they had someone (higher profile? I really have been looking for a good feed from with ESA) who could walk around and ask for the pulse of the investigation. "We have no idea, and this is why ..." would still be fascinating. Edit: And I LOVE that NASA just has a raw feed of the images as they come down. I'm thinking of the Mars rovers here. I can't fault how those programmes are communicated.

The FAQ on a website is a current document. Once it became clear that only 2.5 days of work was possible, that is the new reality and it is not wrong to update the FAQ to reflect that.

The original mission parameters were well documented--that has not changed because an FAQ was edited. There will undoubtedly be a detailed technical review that investigate every change from plan to execution. Again, a website FAQ is not the forum for that.

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