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Comment by supermw | Hacker News Reader

Instead of offering dumb 1-way trips to Mars why not create round trips to the Moon and back? You can see Earth from the surface of the moon, see the lunar lander, drive a lunar rover, bounce around for a bit then hop in your module and head back home and live the rest of your life with a new perspective. More interesting than Mars, and doesn't take months to get there.

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That seems like a much harder sell -- telling people they are going to be the first people to colonize another planet is exciting. Sending them on a sightseeing cruise around the moon (without even stopping) seems less interesting since even if the trip is "free" (paid by others), it's going to be risky.

I had the money and it was relatively safe, I would jump at the opportunity.

I got my son a telescope last year and we have been watching the moon whenever we get a chance. It is another world.

Yes, of course, if it was safe and affordable lots of people would do it -- but you're not going to get safe and affordable space travel from an early spacefaring startup.

Mars One wasn't seriously aiming to colonize Mars. It was a glorified suicide mission. That isn't appealing to most people, especially compared to a trip round the moon you'd actually have a good chance of surviving.

Mars One didn't need to appeal to "most people", just enough people to fill their open seats. And they needed enough people to support their broadcast/merchandising rights based funding model, but I'm sure there'd be a lot of public interest in following a group of future mars colonists through training and the journey to Mars -- and I'm many potential viewers would be drawn in by the risks of the mission.

They claim to have had over 200K applications though I'm sure many of those people would have backed out if they were actually selected and thought through the ramifications of a one-way trip to another planet.

I think I'd be more likely to apply for a Mars One mission than a trip around the moon. After the moon trip you're back home again without much to show for the trip but the pictures... it seems a little like taking a bus tour where you're not allowed out of the bus and it takes 3 days to get there... and you didn't even have a unique experience since hundreds or even thousands of people did the same trip. But since space travel is still in its infancy, there's still a significant chance that you won't survive the trip.

The Mars trip had a much higher chance of failure (and no chance of return), but at least then you're part of a small group of people who are actually colonizing another planet. I think it's unfair to call it a "glorified suicide mission", since the goal was to survive, even if there was no way to come back again.

After the moon trip you're back home again without much to show for the trip but the pictures...

Literally every astronaut who's been in to space says it profoundly changed them as a person.

Citation needed! Consider, eg. https://www.thisamericanlife.org/655/the-not-so-great-unknow...

I have no doubt that it did - they are part of a very elite group of people doing something that literally no one else has ever done before and few could hope to do.

But when space travel is more commercialized and commonplace and anyone that can come up with $100K can buy a ticket for a trip around the moon and your instagram feed is full of people's snapshots from their moon trip, will it still have that mystique?

My grandmother was very proud of her first (and only) trip to Hawaii back in the late 1940's, she literally saved pennies over years to afford it, and said it felt like going to another world and she was a celebrity when she returned home to her small town. And even decades later she tells the stories from that trip (her only significant travel). But I've been to Hawaii about a dozen times, and while I enjoy it, it's not a profound experience that I'd save up for years and few people even care to hear about my trip when I come home, they just want to know if I brought them Macadamia nuts (the same ones I can buy at Costco!)

If you read the autobiographies of astronauts they talk about being in space as the thing that changed them and how they see the world, not the prestige of being an astronaut or act of going on a rocket.

Edgar Mitchell (Apollo 14) said "From out there on the Moon, international politics look so petty." I imagine that change in perspective is what going in to space would give you.

Don't discount the ability of the human mind to normalize experiences.

Plenty of people pay $$$$ to climb everest, even though they'll never be as famous as Hillary and Norgay.

To me your argument sounds like "Nobody space-tourists to the moon any more, it's too crowded" ?

I mean, if they send so many space tourists to the moon that going there isn't noteworthy any more, their sales would have to be really, really high.

I believe the comment you are responding to is referring to this: https://en.wikipedia.org/wiki/Overview_effect

...but at least then you're part of a small group of people who are actually colonizing another planet.

I believe the key is economics: by the time the price of fuel is low enough to put Mars at the reach of private tourists, imagine how far mining, industry and even tourism would be in the Moon.

And... a rocket factory in the Moon would offer a different perspective for Mars travel.

> and you didn't even have a unique experience since hundreds or even thousands of people did the same trip

You just described 99% of all vacations taken by humans on the planet. People still go on vacations, and even go on the same trip multiple times.

Not as simple as you would think. Mars has atmosphere for capture braking, for parachute landings. The moon requires lots of powered deltav to get onto the surface from low earth orbit, more so than mars iirc.

Are you suggesting that going to Mars is easier than going to the moon?

Going to? If you are sending a robot, yes mars can be in some ways easier (less deltaV). Getting back is a totally different equation. Musks tesla, with a heat shield and parachute, could have made it to the surface of mars. Putting it on the moon would require more energy, a bigger rocket.

Hmmm... Mars' atmosphere is <1% Earth's. So far, everything landing there has needed either retro rockets or (if light enough) elaborate airbags. I don't think a parachute is enough to keep the Tesla intact after "landing".

The atmosphere is not thick enough for a soft landing of heavy rovers, but it helps a lot with slowing spacecraft down into an orbit around the planet.

A spacecraft attempting that would have to scream past the surface at extremely high velocity and low altitude and get really lucky not to intersect with terrain (mars is not a perfect sphere). It would also require many orbital passes to lower apoapsis to merely circular orbit (i.e., a lot of time). It is probably not practical.

You're right, it takes a long time and is probably unsuited for a manned mission, but it has been done before and can be useful for getting supplies to a Mars base. https://mars.nasa.gov/mro/mission/timeline/mtaerobraking/

> It lasted about six months [to circularize to a ~450 km orbit].

There's still a lot of orbital energy left at 450km orbit around mars that you need to get rid of some how, and a parachute probably isn't going to do it.

It worked for me in Kerbal Space Program! Don't ask how. Please don't ask.

I always found soft landing on Duna via aerobraking somewhat challenging :-D.

That is how it is done. Mars landers dont do orbital insertions. They crash strait into the atmosphere. 1% is more than enough. The retro rockets for landing only cover a few hundred m/s, all vertical. The atmoshpere is what bleeds off the several thousand m/s of horizonal velocity neede for capture.

Some probes used no rockets. Parachutes and airbags can land a small probe on mars. That isnt an option on the moon.

In terms of delta-V, Deimos is about as far as the surface of the moon. In terms of travel time, it's a hundred times farther away. For humans that is a crippling difference, but for rovers not so much.

Mars is not Deimos of course. My point is merely that from a delta-V perspective, the solar system suddenly looks very different.

Downvoted by people who know nothing about space physics. Deimos is indeed just about the same distance as the moon in terms of energy required. With one exception. When approaching a multi-body system there are gravity-boost options for slowing a spacecraft. Not an option when aproaching the moon.

Yeah, I'm a bit surprised to get downvoted for posting an interesting and unexpected truth. I'd love to hear what kind of reasoning the downvoters have for this.

I'm personally quite fascinated by Deimos. It's far away and yet relatively easy to reach. Some people believe there might be quite a bit of water on Deimos. Put together, that might make it an interesting option for a base, for refuelling, if nothing else. Especially once Mars gets a colony and we start mining asteroids, I wouldn't be surprised if Deimos turns out to be a nice central point between the three.

Or not. I'm not a rocket scientist, but I find this a fascinating subject.

It is a tuesday. HN is full of millenials who think they know everything. Id bet most of the haters in this thread had to google "deltaV". The smart people show up on the weekends. Im only here because im visiting family and work doesnt have my cell number.

Moon is less fuel and risk.

The Martian atmosphere is extremely thin — per wikipedia, "the atmospheric pressure on the Martian surface averages … about 0.6% of Earth's mean sea level pressure."

It is not really sufficient for capture braking / parachute landings with any efficiency or safety.

Also, mars takes more delta v than the moon.

That's almost exactly backwards. For any decent-sized payload there's too much atmosphere to ignore (so you need heat shielding) yet not enough to exploit (so you need heavy rockets), parachutes rip off of big payloads... the skycrane was the least ridiculous device JPL could come up with for their rover.

The Moon is much easier, it's just a rock and some delta-V.

Lol, ignore atmosphere. EVERY mars lander has used massive aerobraking with a combination of shields and chutes. 99+% of thier speed was shed passively, without rockets. That Final touchdown is a drop in the deltav bucket. Check any deltav map.

Earth-moon surface = 2.66km/s

Earth-mars surface, with aerobraking = 1.06km/s +0.1 to .5 for final hover/touchdown depending on payload.

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