Voyager 2 is back online after eight months of radio silence
theregister.com
theregister.com
Voyager 2 emerged from behind Saturn (as seen from the Earth) in August 1981. The scan platform had been moving feverishly—pointing here and there among the rings, moons, and the planet itself during the all-too-brief moments of close approach. Suddenly, the platform jammed. A stuck scan platform is a maddening predicament: knowing that the spacecraft is flying past wonders that have never been witnessed, that we will not see again for years or decades, and the incurious spacecraft staring fixedly off into space, ignoring everything.
The scan platform is driven by actuators containing gear trains. So first the JPL engineers ran an identical copy of a flight actuator in a simulated mission. This actuator failed after 348 turns; the actuator on the spacecraft had failed after 352 turns. The problem turned out to be a lubrication failure. Good to know, but what to do about it? Plainly, it would be impossible to overtake Voyager with an oilcan.
The engineers wondered whether they could restart the failed actuator by alternate heating and cooling; maybe the resulting thermal stresses would induce the components of the actuator to expand and contract at different rates and unjam the system. They tested this notion with specially manufactured actuators in the laboratory, and then jubilantly found that in this way they could start the scan platform up again in space. Project personnel also devised ways to diagnose any additional trend toward actuator failure early enough to work around the problem. Thereafter, Voyager 2’s scan platform worked perfectly. All the pictures taken in the Uranus and Neptune systems owe their existence to this work. The engineers had saved the day again.
Our hacks are nothing compared to the hacks of these old school nasa programmers :)
The amazing thing (to me) is that they developed the Voyager spacecraft in an era when space flight wasn't hugely popular and the budgets at NASA were being cut regularly. NASA went from a peak of $6bn a year in the mid-sixties under Johnson to almost half that under Ford and Nixon. The engineers were well-respected and they clearly felt the work was important, but they weren't particularly well paid. They did this for the love and the science.
I’d hardly call the graduate papers coming out of academia equivalent to the level of innovation & creativity of what the engineers above described. Perhaps they’re both underpaid, but one is certainly more amazing. Hardly the same.
Remember also that a large fraction if not a majority of the Voyager team almost certainly had PhDs or even came from academia. I think we can appreciate innovation and creativity everywhere without having to make it into a genital measuring contest.
You’re not familiar with how much money as a percentage of GDP we spent in the 1960s? It’s noteworthy.
https://en.m.wikipedia.org/wiki/Budget_of_NASA#Annual_budget
We were building the Space Shuttle and exploring the planets.
I wish we could spend money on NASA like we did in the 1970’s
I absolutely agree. It's far worse now. And, not at all coincidently, NASA is doing much less science now. A return to the 70s budget by GDP would be good, but a return to the 60s budget by GDP would be even better.
In the 60s, they were pushing to get things out and accepted risk levels that today we would consider intolerable.
Today we've developed a cost-plus contracting approach plus insane safety and success standards that mean it is almost impossible to actually get anything done. With one notable exception - SpaceX.
Just throwing money into Boeing and Lockheed these days would generate profits for them, but not a lot of science for us. We need to change culture as well.
I remember someone on HN telling me several years ago that Virgin Galactic would be back quickly.
I'd love to see NASA's budget increased, but not now - it would just get funneled into dead-end pork projects like SLS. I'd much rather wait till Starship is successfully operating (New Glenn would be a plus), and it is political viable to end the SLS entirely, and redirect all that money and some into missions (both science and exploration) rather than hardware development.
Or to put it another way, it isn't worth it to me to spend 1960's era money if we are only going to get 1960's era results. If we ever want to move on to bigger things in space, like colonization, we can't just throw money at the problem, we need to find ways to bring the cost down first.
My grandfather built satellites at Lockheed in Sunnyvale all through the 60s and 70s and it was a glorious time for him. For reasons that I never quite understood, he hated Reagan for "destroying the industry" in the 80s (by which time he was in Denver at MM).
- http://www.pouet.net/prod.php?which=63 (PC; page has link to source code)
I did recognize the style, and then reading the comments Isaw it was indeed by David “Elite” Braben.
Watch this : https://www.youtube.com/watch?v=3HbsfeubbRA Quite a journey from there to here
[0] https://trixter.oldskool.org/2015/04/07/8088-mph-we-break-al...
In space, however, you can only run the hardware in it's destined environment once. Software is critical to the design process regardless of the HW costs.
I would tend to assume they've thought of that though, and stuck with this part for reasons. Maybe there werent other space-ready alternatives or something.
On the other hand, if they had to budget for a second copy of everything in advance they may have never gotten to launch. Asking for the funding after already having good success behind them is likely a lot easier.
Things are tested all the time in factories. For how long? Till destruction.
When it comes to space missions, common sense starts bad and rapidly gets worse — there is no down, there is no “now”, metals can contact-weld without any supply of energy, exposed fluids boil until they freeze, radiation pressure is relevant, ionising radiation doses can be enough to break things, impact damage is radically different, launch times are prescribed by orbital dynamics, engines are more efficient when they are moving faster, fuel use is exponential with regard to change in velocity and nothing to do with distance, and the launch mass is heavily constrained. And that’s just the stuff I know from following Scott Manley and similar on YouTube — I’m a very long way from being a rocket engineer.
You hit the date, you test what you can, within that constraint.
(They were also heavily budget limited, and I’m sure everyone here has an example of a project which became more expensive because someone decided they “couldn’t afford testing”).
Even then, even despite people who probably have PhDs in specific engineering topics I can’t even name, half the time you can’t even tell what’s important to test vs “it’s common sense this will work fine for a thousand cycles” — hence the long list of missions which failed catastrophically.
It is rocket science.
They did an absolutely amazing job and I take it as a given that this was not some novice mistake.
> The call to Voyager 2 was a test of new hardware recently installed on Deep Space Station 43, the only dish in the world that can send commands to Voyager 2. ... Since the dish went offline, mission operators have been able to receive health updates and science data from Voyager 2, but they haven't been able to send commands to the far-flung probe, which has traveled billions of miles from Earth since its 1977 launch.
https://www.nasa.gov/feature/jpl/nasa-contacts-voyager-2-usi...
https://news.ycombinator.com/item?id=24826155
Dave Jones made a coupe of videos about the Deep Space Station in Canberra.
43 years for 0.00194 light years... makes me feel :( huh ... and nearest star Proxima Centauri is 4.2441 light years away ... :/
https://en.m.wikipedia.org/wiki/Project_Orion_(nuclear_propu...
Another interesting idea is to propel micro crafts with lasers. I think there was an article on HN about that.
I would guess that radioactive particles on the surface would be different that radioactive bombardment from space. You could shield your shelter from space, but if the soil had radioactive particles in it, then you couldn’t bring it in your shelter. For that matter, you would also have to shield the floor, or at least remove a layer of soil. You might have to do that anyway to build a foundation.
If it isn’t obvious, I don’t know what I am talking about.
It’s one of those designs that trades something considered largely meaningless, total engine weight, for something considered far more important exhaust velocity. This always ends up being a far worse trade off than simple models suggest.
PS: It could have very high acceleration before running out of fuel, but if the trip is going to take decades either way that’s not very important.
Project Orion is detonating nuclear weapons which consist of far more than just fuel, they also need high explosives etc, however much of the fuels energy is wasted both from low yield bombs being less efficient but also simply radiating energy in all directions. Nuclear powered ION engines however would be ejecting far more of their reaction mass of say xenon per KG of fuel that leftover fuel is basically irrelevant. In other words it’s a more efficient nuclear reaction, a vastly more efficient engine, and a much lower mass fraction spent on the physical engine.
This gets more extreme when you consider a crewed mission would need lots of power during the trip so they would want/need to build redundant nuclear reactors anyway.
Wait, if that is true, then the ION engine has a lower ISP than direct explosions, not higher. Unless the reactor is orders of magnitude more efficient than the bombs.
Smaller nuclear detonations are less efficient in that they directly liberate less energy from their fuel. A nuclear explosion in space also radiates most of it’s energy as X-Rays which on earth you heat the atmosphere but in space mostly just do nothing. So their directly turning less nuclear energy into motion. Further, a smaller percentage of that force is then collected by the pusher plate compared to the Bell nozzle at the bottom of a traditional rocket. https://en.wikipedia.org/wiki/Bell_nozzle
Now as nuclear is so much more energy dense than chemical energy on paper they look better. But compare ISP’s and you see just how much energy is lost.
All of that can be simplified by just looking at ION thrusters ISP and vs the ISP of hypothetical Orion rockets. At that point it’s just a question of what percentage of mass is reaction mass vs the reactor + fuel and it turns out you can get reaction mass well over 80% making at least 60% more efficient before considering the pusher plate assembly’s mass vs physical ION engine’s mass.
PS: And that’s when looking at existing ION engine designs. Hypothetically, you could eject matter at a large fraction of C using energy giving orders of magnitude higher ISP, at the cost of lower energy efficiency etc.
Would this help to increase the range of what discover can report and... hum, discover?
Would help us to have the info in two months instead in eight? (maybe splitting in a multipart message and broadcasting in several threads and different frequency bands at the same time or so?).
or would be basically useless?
Could be used to start a exploring outer web that would be improved with each new launching as other countries connect to it?
[1] I don't know how realistic, or technically difficult would be. Is an idea idea that just occurred to me
Perhaps on a bunch of objects at Lagrange points [0]?
[0] https://en.wikipedia.org/wiki/List_of_objects_at_Lagrange_po...
What you are proposing will absolutely work. Imagine a self-routing datagram trying to get closer to its destination at each step. In fact, that's exactly how the Internet is designed. Self-healing, self-routing, best-effort. Chop messages up into little pieces, and send them off to their destination, and hope for the best that they'll be reassembled correctly at the destination.
When I first heard about the Deep Space Network I thought it was something like this, and not a bunch of dishes on Earth.
1) Voyagers have turned off most of their instruments due to their diminishing power sources
2) Voyagers are moving away with speeds that are hard to match by even contemporary launches thanks to their gravitational assist trajectories.
If you wanted to do this "for real", the better option is to send a train of repeaters after the Voyager spacecraft in roughly the same flightpath. More effective, and vastly easier.
And yes, the repeater can both do tx and rx repeating.
That said, I'd expect Earth based (including earth based orbit) solutions to outperform at a lower cost for a long long time.
An older tour discussing how to contact Voyager 2 he gave at https://www.eevblog.com/2017/04/19/how-to-contact-the-voyage...
It's amazing, and it makes me happy every time.
The Dish: https://www.imdb.com/title/tt0205873/
Wait, so they sent Perserverance on it's way to Mars without comms in the southern hemisphere? Or is this a backup?
Furthermore, the locations of the stations aren't determined by the hemispheres. Everything DSN is used for is far enough away from Earth that it doesn't matter if the antenna is in the northern or southern hemisphere. The reason for the spread-out stations is the rotation of the Earth, which for half of the day puts the Earth in between the station and the satellite.
[1] https://voyager.jpl.nasa.gov/frequently-asked-questions/fact...
You're leading the rescue
Send help soon
Well I've seen spirits and children all waiting, waiting for you
They're all waiting for you
"Nothing."
"No, really, what's wrong?"
"I said 'nothing'!"
"Okay, So when you're ready, talk to me..."
...
Eight months later...