6 ms·

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 land

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.

sandworm101 8y ago
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.
- loeg 8y ago
  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.
- ukulele 8y ago
  Are you suggesting that going to Mars is easier than going to the moon?
  - sandworm101 8y ago
    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.
    - stickfigure 8y ago
      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".
      - adrianN 8y ago
        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.
        loeg 8y ago
        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.
        adrianN 8y ago
        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/ https://mars.nasa.gov/mro/mission/timeline/mtaerobraking/
        loeg 8y ago
        > 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.
        Cthulhu_ 8y ago
        It worked for me in Kerbal Space Program! Don't ask how. Please don't ask.
  - mcv 8y ago
    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.
    - sandworm101 8y ago
      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.
      - mcv 8y ago
        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.
        sandworm101 8y ago
        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.
- mav3rick 8y ago
  Moon is less fuel and risk.
- andygates 8y ago
  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.
  - sandworm101 8y ago
    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.
Johnny555 8y ago
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.
- Alterlife 8y ago
  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.
  - Johnny555 8y ago
    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.
- onion2k 8y ago
  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.
  - Johnny555 8y ago
    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.

sandworm101 8y ago

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.

loeg 8y ago
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.
ukulele 8y ago
Are you suggesting that going to Mars is easier than going to the moon?
- sandworm101 8y ago
  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.
  - stickfigure 8y ago
    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".
    - adrianN 8y ago
      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.
      - loeg 8y ago
        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.
        adrianN 8y ago
        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/ https://mars.nasa.gov/mro/mission/timeline/mtaerobraking/
        loeg 8y ago
        > 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.
        Cthulhu_ 8y ago
        It worked for me in Kerbal Space Program! Don't ask how. Please don't ask.
- mcv 8y ago
  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.
  - sandworm101 8y ago
    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.
    - mcv 8y ago
      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.
      - sandworm101 8y ago
        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.
mav3rick 8y ago
Moon is less fuel and risk.
andygates 8y ago
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.
- sandworm101 8y ago
  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.

Johnny555 8y ago

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.

Alterlife 8y ago
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.
- Johnny555 8y ago
  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.
onion2k 8y ago
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.
- Johnny555 8y ago
  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.