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Comment by Robotbeat | Hacker News Reader

Really excited about this one. It’s a sample cacher, so is the beginning of the sample return effort. It also has an in situ resource utilization demonstration involving capturing CO2 from the Martian atmosphere and splitting it into oxygen (and carbon monoxide fuel) using a solid oxide electrolysis cell. That kind of tech is critical for human missions.

And, of course, the helicopter!

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>> And, of course, the helicopter!

It is cool, but is being falsely reported as the "first extraterrestrial aircraft", which it certainly is not. The Russian Vega mission had aircraft (balloons are aircraft) flying on Venus back in the 1980s.

https://en.wikipedia.org/wiki/Vega_program#Balloon

That's cool!

Why NASA didn't opt for a balloon too for this mission?

Because they wanted to test a helicopter

And because anything that can float on the light martian atmosphere can be blown away by the light martian wind.

Mars's atmosphere is very low density, so the balloon would have to be unreasonably enormous to fly anything useful. Venus, on the other hand, has an extraordinarily dense atmosphere. So dense that folks have hypothesized floating entire cities.

Is this fact the inspiration behind the floating city in Star Wars V? (Serious question)

The inspiration was the gas giants, planets with no practical surface on which to land.

Because the atmosphere on Mars is orders of magnitude thinner (depending on altitude), making balloons a bigger challenge (and less useful in some ways).

Venus atmosphere is so thick light beach balls pumped with regular Earth's air would floating in it.

Mars atmosphere is so thin it's almost impossible to make a ballon float in it.

Yes, well aware of the Soviet Venus missions, including balloons. NASA is promoting it as the first extraterrestrial powered aircraft. Analogous to the Wright Brothers.

So "aircraft" is narrowed to the subset powered + heavier-than-air aircraft. But there too I would argue with NASA. NASA itself has already flown a heavier than air powered aircraft on mars! They landed the Curiosity rover using a rocket-powered "sky crane". That device was a powered aircraft. It controlled the decent of the rover, delivered it gently onto the ground, and executed an escape maneuver. That was a heavier-than-air, powered, aircraft flying/navigating/performing tasks, over Mars, in 2012.

https://science.nasa.gov/science-news/science-at-nasa/2012/3...

At most, I'll give NASA that this is the first extraterrestrial rotary winged aircraft, the first helicopter.

No, I meant that NASA stipulated that it was the first powered flight, a nod to the Venus mission as being the first extraterrestrial (unpowered) flight.

I would call this the first "fully-functional" or "multi-mission" aircraft. Vega was a balloon with no controls. Curiosity descent stage was a spacecraft that performed landing maneuvers. Both of these crashed into the surface as part of their mission goals. They barely could qualify as aircraft, and only in the sense that they floated in air briefly before crashing. Neither could be used for multiple missions or actually take off and land under their own power.

The balloon was airborne and transmitting data for 40+minutes. I'll be impressed if this tiny helicopter lasts that long.

I think there is more reason to be excited about the microphones it is reportedly carrying than the helicopter, if it works it would be the first time we would hear the sounds of the wind in Mars.

the insight lander used its seismometer and air pressure sensors to convert the sound of the wind into audio https://www.youtube.com/watch?v=yT50Q_Zbf3s - not exactly the same, but thought you might be interested if you hadn't seen it.

Thanks for sharing.

How will the probe return the Martian samples? Is there going to be a round-trip mission to Mars in the future which will be able to take these samples back with it?

No, leaving them in place for possible future mission

That's neat, but I can't help but wonder how it's more cost-effective than having the possible future mission reach a scoop out once it gets there and collect its own samples.

"Hi Mars Recon 1! I'm Mars Perseverance! I brought you some decades-old rocks and dirt!"

"Uh, thanks Perseverance. I, uh, might get my own though." ;)

You only need to send something optimized to pick something up and launch it. You don't need to send the digging gear/packaging gear that this Rover was going to use anyway

Digging and packing gear has been demonstrated many times, and sounds way less risky and complicated than robotic rendezvous and transfer on a planet's surface, which I believe has never been done. Moreover, why not just make the digging mission and sample-return mission the same mission?

Like, was it really the case that (1) the current digging mission could not be delayed AND (2) there is little independent value for a later new digging mission AND (3) it is easier to rendezvous and transfer than just re-dig?

I defer the decisions made by hundreds of scientists to the HN armchair general

The point of my argument is not to challenge their expertise, the point is to either understand the technical motivation or to uncover non-scientific (e.g., political) motivations.

Robotic rendezvous isn’t particularly hard, as long as you can land nearby. Robotic rendezvous happens regularly at ISS, and being on a planet should be even easier as you don’t have to worry about orbital mechanics or the fact that in orbit, things are moving around. On the surface, speeds are low and everything is sitting on the surface so it’s basically quasistatic.

Also, except for the landing bit, it’s basically done by autonomy-assisted remote control. It’s not “Level 5 Self-Driving” or whatever.

Also, picking a random sample near the landing site is not optimal. You want to pick really good samples. A rover like Perseverance that can take years to collect the very best samples over distances of several miles is much better. Remember, we already have “random” samples from Mars in the form of Martian meteorites on Earth. We want particularly good samples.

The ISS has human operators in real time, so it's just remote operation. And ISS work still requires human intervention (with hands) for most complicated things. The only things that are done without real-time control are things that were failure prone in the past but have be mastered over years. And even then, the Russian autonomous docking system recently had major issues.

The mention of self-driving cars, orbital speed, and the suggestion of sampling near the landing site all appears to be responding to an argument I didn't make.

Most importantly, you haven't addressed my point, widely appreciated in spaceflight, that novel untested mechanisms are always one of the primary sources of risk.

I have yet to hear a good explanation for this. Rendezvous on the surface of the planet sounds much more challenging than simply taking new samples, even assuming you need significant equipment to ensure you're taking the most interesting samples.

Perseverance will land using terrain-relative autonomous navigation, demonstrating fairly precise landing.

There are multiple reasons to split the mission. Perhaps the main one is that ~1 ton is approximately the upper limit of existing Mars landing technology which is enough for a powerful rover like Perseverance that can carry several sample return canisters (and live long enough to find really good samples) OR a rocket capable of returning the samples back (with just a small, basic canister retriever rover). Yeah, you could just put a sampling arm on the rocket lander, but that's a lot of wasted opportunity (heh).

Perseverance should have plenty of range, and the autonomous landing navigation tech should have sufficient precision that surface rendezvous should not be a major challenge.

Go do some research and report back to us please. I would be happy to hear what you find.

If they had a rover that could do all the same science and collect and return all the same samples as Perseverance, well they would send that instead of Perseverance.

The mass budget for a return-to-earth mission is tiny.

While simply scooping up some dirt and returning with it would be amazing, the potential science that could be achieved is far less than finding and collecting good samples will allow.

Neil Armstrong is still revered by scientists today because he was such a good geologist - knowing what areas to investigate and samples to collect is essential.

Perseverance will do the geologist work, and is set up for that purpose. Find, investigate, and collect samples that are likely to enable good science.

The retrieval mission can focus on the extremely difficult job of getting them back to Earth.

Yes.

ESA and NASA are collaborating to get samples from the surface to Martian orbit, and ESA is responsible for getting them the rest of the way back to Earth. Airbus just got a big contract for the return vehicle

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