Hacker News Reader

Comment by synapsomorphy | Hacker News Reader

I just interned at the NASA office (at Ames) that designed large chunks of and did a lot of flight planning / analysis for Ingenuity. It had some really awesome people behind it and its success inspired a number of new Mars rotorcraft missions (rotorcraft will be an integral part of Mars Sample Return). Flight is going to be a huge part of future solar system exploration efforts and Ingenuity paved the way.

View on HN

Isn't Mars Sample Return pretty much dead at this point?

I contributed to the helicopter design for it so I'm biased but I think it'll happen eventually even if the funding isn't approved this administration/year/decade. The already-stashed samples will be up there basically forever, and we'll probably want samples from a few different areas anyways, so it makes sense to go grab them.

Mars has weather, unlike the moon. Will the samples really still be there a decade or two from now?

Mars' famous dust storms aren't so good at causing damage, because the air's really, really thin, so they can't pick up heavy particles even with high wind speeds. A serious problem if you need to keep grit out of fine machinery or electronics, not so much if you're worried about erosion (I mean, yeah, eventually it'd be a problem, but it's slow-motion compared to the erosion of something exposed to sand storms on Earth)

I guess it could eventually get buried, but I'd expect that to also be a slow process on most parts of the planet, for similar reasons. The only forces seriously driving weathering on the planet are radiation and wind—the radiation's pretty bad but not a problem for metal + some rocks that were already on the surface, at least over a span of a couple decades, and the wind just can't deliver much force because the atmosphere's so very thin (that's also why it's fairly difficult to fly on Mars).

As a fun anecdote this is one of the very few things that was completely faked in "The Martian" - book and movie alike, which is otherwise a hard sci-fi book. I think it's quite telling when your instigator for a disaster scenario on Mars has to be faked!

Well at least intentionally faked. It turns out Martian regolith/soil is also much more moist than expected so getting water will be relatively easy, but at the time of the book this wasn't known!

> The Martian

The thin atmosphere bit is acknowledged by the author, you can watch his talk here around 32:35:

    I just want to be as accurate as I possibly could.  There are a few places that are inaccurate.  The biggest place that's inaccurate is right at the beginning.  Don't tell anybody, but if you're in a dust storm on Mars, you're not even going to feel it.  Mars' atmosphere is less than 1% of Earth's.  So a 150 kilometer an hour wind would feel like about 1 kilometer an hour wind does on Earth.  It wouldn't do any damage to anything.

https://youtu.be/gMfuLtjgzA8?si=8aZUEizDWuBhnaJg&t=1958

There is another clarification later at 35:34 saying the dust storm is basically like talcum powder.

I don't know anything about mars, but I've messed with windmill math. This really doesn't make sense to me.

A 150 mph wind in 1% atmosphere should be a way stronger a 1 mph wind on earth?

You know the old formula,

force = mass * velocity * velocity

But with wind and water the more velocity, the more mass you get hit with in the same amount of time, so we get to multiply by velocity again.

wind force = mass * velocity * velocity * velocity

(This formula is why people die in fast moving water.)

So a Mars 150mph wind (0.01 * 150 * 150 * 150) would have 34,000 times more force than a 1mph wind on earth. Which works out to around a 32 mph earth wind.

mass * velocity * velocity has units of energy. It's twice the kinetic energy.

Well yeah, he needed some sort of catastrophic event to set the rest of the story in motion, and a huge dust storm which forces an evacuation and then separates Mark Watney from the rest of the crew was just the thing, so he added it although he was fully aware that storms don't work that way on Mars...

> which is otherwise a hard sci-fi book

Hard sci-fi is still a story and doesn't need to nail everything. And it had other pretty "unrealistic" moments that put me more off than the storm. Foremost, how they fixed the missed orbital rendezvous, no never going to happen that way. Or that they could just revert their home flight and go once more back and back again, how much delta-v would that be, never could have had that much extra fuel at least in that world... and other minor things, but still superb story.

I thought in the martian they just looped the earth to go back, and then there was the supply rocket problem. They didn't do anything silly like just use the rocket to turn around and go straight back iirc.

To be fair, it wasn't even the only disaster scenario in the movie - but it's very difficult to come up with a realistic scenario where someone would get left behind with a livable hab.

How about a fight between members of the crew causing the mission to be cancelled, and one of the member left for dead after a violent interaction with another member who then lie about it.

I remember some nasa administrator laughing about that at a conference. "So at the end of the movie the atmosphere is so thin that he can fly through it at thousands of miles per hour without harm, but at the beginning a sandstorm at hundreds of miles per hour destroys the ship? Also the spacesuits ... no."

Yes, they will. The weather on Mars can't do much to metal tubes. They probably won't be buried either (the area they're in doesn't get much net deposition, you can tell from how rocky it is), but if that does happen, each sample's position and the terrain around them is very precisely mapped so it would be extremely unlikely that any get completely lost.

https://mars.nasa.gov/news/9337/nasas-perseverance-rover-com...

We are talking about 6 inch long titanium tubes. What do you imagine the weather doing to them in a few decades?

The samples are meant to survive the vacuum of space but can't handle some weather? That seems unlikely.

How erosive is the vacuum of space meant to be?

You mean that place that smells of burnt metal and is full of hard radiation? Surface of Mars is definitely more hospitable.

> Overall, astronauts often compare the smell of space to "hot metal, burnt meat, burnt cakes, spent gunpowder and welding of metal," according to Steve Pearce, a biochemist and CEO of Omega Ingredients, who combed through astronaut interviews to help him craft a NASA-commissioned scent: https://www.livescience.com/space/what-does-space-smell-like

Guess I'm one of today's 10,000.

Wouldn't it be the smell of space suits and space stations, rather than space itself? I don't think astronauts have tried to breath the few particles in the vacuum.

The smell is apparent when one doffs their suit after a spacewalk.

They made a perfume of it.

https://eaudespace.com/

Not less erosive though.

I'd wager yes since Mars has less extreme thermal cycles than the moon

I would expect muskonauts will make the samples redundant by then.

I hope the development of the MAV will bring us closer to building launch vehicles capable of getting humans off Mars. Seems like the MAV is preloaded with fuel and pretty small but should provide some good data for future missions.

https://mars.nasa.gov/msr/#Ascent-Vehicle

No. It's probably better to think of the multi-mission MSR "campaign" as being reformulated to be lower cost and complexity.

It depends on sample location. After discovering patches of water ice, the planet is more interesting than ever.

Why do you say that?

> o7

I never came across this emoticon, but with what you wrote, its meaning became clear immediately. It's perfect.

It is a very common theme in Elite Dangerous, to the point that the station controller will sometimes say "Oh seven, commander" to you.

Also ubiquitous in Eve Online since about 15 years ago. Did it originate in Elite Dangerous?

No, predates broadband at least. Certainly was around on Usenet in the nineties.

This is where I was first exposed to it. I'm not surprised it's got a longer history than that, though.

Same, I thought I was terminally online but I've never seen this before.

Oh, God, these comments may be the trigger to my mid-life crisis.

I remember being a terminally online teen thinking i would never fall out of “what’s hip” bc i enjoyed being online so much at the time. I have since never once installed or used TikTok and I have no idea what’s happening I am sure

If it's any consolation, it's been around since the 90s

See it quite a lot in Twitch chat

orz

For the people who weren't aware... https://knowyourmeme.com/memes/orz

Funny, I didn't see it as a salute... I thought it was a "flex".

Looks like a swimmer to me... what do you see?

The 'o' is a head and the '7' is an arm giving a salute.

Here, let me help you with that...

   O7
  /|
   Λ

That's ridiculous, nobody swims up a waterfall

(but actually, thanks for the illustration... my dad was in the military but apparently long enough ago that I entirely missed this)

Edit: oh! You used a capital O rather than a little one! That makes loads of difference... the "hand" placement in o7 is way over the forehead, while O7 (or is it 07? either way) is much closer to a proper salute! Perhaps the military culture hasn't entirely worn off after all...

It's also the wrong hand. But I think the little o looks more like a head in this case. O7 just looks like a hex code or something.

Right hand if you're standing behind him...

Ah... it makes sense. I thought it was a head being scratched.

It's a salute. :)

It's a salute.

A salute

> o7

Someone saluting

Reply on news.ycombinator.com