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>I'm 99% sure that if SpaceX's starship takes off, it will fly to Mars and back within a few years. Define "a few years" and I'll bet you it won't, with whatev

>I'm 99% sure that if SpaceX's starship takes off, it will fly to Mars and back within a few years. Define "a few years" and I'll bet you it won't, with whatever odds you want.

Robotbeat 6y ago
2031 is when the Sample Return Mission is supposed to return the samples back to Earth. Keep in mind slips happen in ALL sorts of space projects, not just SpaceX. I’ll take your bet. I want 2:1 odds: SpaceX returns a vehicle from Mars by the end of 2035 (UTC), and before the NASA-ESA sample return mission has returned its samples. I’ll buy you a beer/beverage (value not to exceed $10) if you win, and you’ll buy me 2 beers/beverages (value not to exceed $20 total) if I win.
- rsynnott 6y ago
  Is that something returning from Mars _orbit_, or returning samples from the surface?
  - Robotbeat 6y ago
    A SpaceX vehicle returning from the surface of Mars.
    - raldi 6y ago
      You're saying the vehicle will bring all the fuel needed for a return flight to Earth down to the surface of Mars and then back up again? Do you have a link with a description of how they're going to do this?
      - Robotbeat 6y ago
        No. It will make the fuel from Martian resources like water ice and the CO2 atmosphere. Using solar power. First to split the water to oxygen and hydrogen using electrolysis, then use the hydrogen with CO2 to make methane (& some water which is cycled back to the electrolysis step) using the Sabatier reaction. This is done on the International space Station today, by the way. The methane on ISS is simply vented (as the point on ISS is to recover the oxygen from the CO2, which is most of CO2’s mass). It takes a lot of energy, so there will need to be very large solar arrays on Mars, but it’s possible. This page describes the process: https://medium.com/spaceinmylifetime/how-spacex-will-refuel-on-the-surface-of-mars-3438bcc2aefe https://medium.com/spaceinmylifetime/how-spacex-will-refuel-...
        rsynnott 6y ago
        Call me overly cynical, but I don't see Musk getting this done in time to be back in 2031 and win the race.
        valuearb 6y ago
        Well, he’s competing against a gov entity, so his schedule slips are going to be much less than theirs.
  - raldi 6y ago
    Exactly. Returning from orbit is "easy", you just go into a free-return trajectory and don't even do much of a burn at Mars, if any at all. Getting a sample from the surface basically means you need to do a deceleration burn to get into orbit, and then the reverse after grabbing the sample (which itself must be accelerated to orbital speed). No small thing.
    - Robotbeat 6y ago
      SpaceX isn’t planning to enter orbit around Mars but instead do direct entry.
      - raldi 6y ago
        How do you retrieve a surface sample on a direct-entry mission?
        Robotbeat 6y ago
        You land on Mars. Refuel. And launch again direct to Earth.
    - mLuby 6y ago
      A free-return trajectory doesn't enter orbit around a body, indeed its appeal is that if your propulsion fails while on such a course, you'll coast home "for free" rather than enter orbit around your target or drift into deep space. Entering orbit almost always requires an orbital insertion burn, and in the case of an Earth-Mars Hohmann transfer definitely does. Your point stands though: returning from a fly-by (including a free-return) requires much less fuel than returning from orbit, and even that's much easier than returning from the surface. For fun, take a look at rotovators (AKA "momentum exchange tethers") that could make orbital capture/departure—and even landing/launch—"free" on bodies with minimal atmosphere.
      - raldi 6y ago
        Correct, I misspoke: My first use of "orbit", I should have said "the area up around the planet, not down on the surface. The difference in difficulty (mainly, fuel requirements) between a flyby and an orbit is a crucial distinction often overlooked.
- chriswarbo 6y ago
  Maybe put it on http://longbets.org http://longbets.org
  - Tepix 6y ago
    Why not https://www.reddit.com/r/HighStakesSpaceX/ https://www.reddit.com/r/HighStakesSpaceX/
- antonvs 6y ago
  Don't know about the person you replied to, but none of the dates you mention qualify as what I would call "a few years."
- itsoktocry 6y ago
  Well, I'm not sure 15 years qualifies as "a few years", but the price is right, so you're on I guess!
  - Robotbeat 6y ago
    Okay! Let’s put it in here, with a bunch of other SpaceX-related beer bets. If you make an account there, I’ll be able to message you. The site is pretty old and more active than ever, so it’ll probably still be around by the time this has been decided: https://forum.nasaspaceflight.com/index.php?topic=35196.0 https://forum.nasaspaceflight.com/index.php?topic=35196.0
pharke 6y ago
I think 10 (+/- 2) years is a fair estimate but I would start counting from when Starship reaches orbit. It would be close enough to their historical development timeline of the Falcon which went from Falcon 1 reaching orbit in 2008 to a crewed Falcon 9 mission to the ISS in 2020, with a propulsive landing of the first stage to boot. I would expect a number of missions within that timeframe that could possibly satisfy the condition of "fly to Mars and back" but I think they will be able to do a full surface of Earth to surface of Mars and back to surface of Earth crewed mission at the end of that period. Call me an optimist but I'm pretty sure that's what they're aiming for.

>I'm 99% sure that if SpaceX's starship takes off, it will fly to Mars and back within a few years. Define "a few years" and I'll bet you it won't, with whatever odds you want.

Robotbeat 6y ago

2031 is when the Sample Return Mission is supposed to return the samples back to Earth. Keep in mind slips happen in ALL sorts of space projects, not just SpaceX. I’ll take your bet. I want 2:1 odds: SpaceX returns a vehicle from Mars by the end of 2035 (UTC), and before the NASA-ESA sample return mission has returned its samples. I’ll buy you a beer/beverage (value not to exceed $10) if you win, and you’ll buy me 2 beers/beverages (value not to exceed $20 total) if I win.

rsynnott 6y ago
Is that something returning from Mars _orbit_, or returning samples from the surface?
- Robotbeat 6y ago
  A SpaceX vehicle returning from the surface of Mars.
  - raldi 6y ago
    You're saying the vehicle will bring all the fuel needed for a return flight to Earth down to the surface of Mars and then back up again? Do you have a link with a description of how they're going to do this?
    - Robotbeat 6y ago
      No. It will make the fuel from Martian resources like water ice and the CO2 atmosphere. Using solar power. First to split the water to oxygen and hydrogen using electrolysis, then use the hydrogen with CO2 to make methane (& some water which is cycled back to the electrolysis step) using the Sabatier reaction. This is done on the International space Station today, by the way. The methane on ISS is simply vented (as the point on ISS is to recover the oxygen from the CO2, which is most of CO2’s mass). It takes a lot of energy, so there will need to be very large solar arrays on Mars, but it’s possible. This page describes the process: https://medium.com/spaceinmylifetime/how-spacex-will-refuel-on-the-surface-of-mars-3438bcc2aefe https://medium.com/spaceinmylifetime/how-spacex-will-refuel-...
      - rsynnott 6y ago
        Call me overly cynical, but I don't see Musk getting this done in time to be back in 2031 and win the race.
        valuearb 6y ago
        Well, he’s competing against a gov entity, so his schedule slips are going to be much less than theirs.
- raldi 6y ago
  Exactly. Returning from orbit is "easy", you just go into a free-return trajectory and don't even do much of a burn at Mars, if any at all. Getting a sample from the surface basically means you need to do a deceleration burn to get into orbit, and then the reverse after grabbing the sample (which itself must be accelerated to orbital speed). No small thing.
  - Robotbeat 6y ago
    SpaceX isn’t planning to enter orbit around Mars but instead do direct entry.
    - raldi 6y ago
      How do you retrieve a surface sample on a direct-entry mission?
      - Robotbeat 6y ago
        You land on Mars. Refuel. And launch again direct to Earth.
  - mLuby 6y ago
    A free-return trajectory doesn't enter orbit around a body, indeed its appeal is that if your propulsion fails while on such a course, you'll coast home "for free" rather than enter orbit around your target or drift into deep space. Entering orbit almost always requires an orbital insertion burn, and in the case of an Earth-Mars Hohmann transfer definitely does. Your point stands though: returning from a fly-by (including a free-return) requires much less fuel than returning from orbit, and even that's much easier than returning from the surface. For fun, take a look at rotovators (AKA "momentum exchange tethers") that could make orbital capture/departure—and even landing/launch—"free" on bodies with minimal atmosphere.
    - raldi 6y ago
      Correct, I misspoke: My first use of "orbit", I should have said "the area up around the planet, not down on the surface. The difference in difficulty (mainly, fuel requirements) between a flyby and an orbit is a crucial distinction often overlooked.
chriswarbo 6y ago
Maybe put it on http://longbets.org http://longbets.org
- Tepix 6y ago
  Why not https://www.reddit.com/r/HighStakesSpaceX/ https://www.reddit.com/r/HighStakesSpaceX/
antonvs 6y ago
Don't know about the person you replied to, but none of the dates you mention qualify as what I would call "a few years."
itsoktocry 6y ago
Well, I'm not sure 15 years qualifies as "a few years", but the price is right, so you're on I guess!
- Robotbeat 6y ago
  Okay! Let’s put it in here, with a bunch of other SpaceX-related beer bets. If you make an account there, I’ll be able to message you. The site is pretty old and more active than ever, so it’ll probably still be around by the time this has been decided: https://forum.nasaspaceflight.com/index.php?topic=35196.0 https://forum.nasaspaceflight.com/index.php?topic=35196.0

pharke 6y ago

I think 10 (+/- 2) years is a fair estimate but I would start counting from when Starship reaches orbit. It would be close enough to their historical development timeline of the Falcon which went from Falcon 1 reaching orbit in 2008 to a crewed Falcon 9 mission to the ISS in 2020, with a propulsive landing of the first stage to boot. I would expect a number of missions within that timeframe that could possibly satisfy the condition of "fly to Mars and back" but I think they will be able to do a full surface of Earth to surface of Mars and back to surface of Earth crewed mission at the end of that period. Call me an optimist but I'm pretty sure that's what they're aiming for.