4 ms·

Unless I've missed something, the SpaceX estimates this seems to be based on miss the rather basic fact that the energy/time (and presumably economic) cost of M

Unless I've missed something, the SpaceX estimates this seems to be based on miss the rather basic fact that the energy/time (and presumably economic) cost of Mars trips varies depending on the synodic cycle. It's never just point and shoot. So the current SpaceX estimates are going to be for the most efficient and cheapest trajectories. If you want to ignore the synodic cycle and run missions every day for years, the costs are going to be much higher.

PartiallyTyped 4y ago
Is it possible for a mission starting at T1, to arrive later than a mission starting at T2, where T1 < T2 due to the sheer speed w/ which the planets are moving?
- deleted 4y ago
  [deleted]
- bombcar 4y ago
  Yes, and I believe this has already happened with some of the various probes sent out to the planets. Voyager 1 launched after Voyager 2 and overtook it; both overtook earlier probes to leave the solar system.
ncmncm 4y ago
Almost everything about SpaceX's Martian colonization announcements is very, very far from what could be practically realized with anything we can build today. For example, Musk repeatedly mentions a six-month trip. No, it is 9 months, at best. He talks about transporting 100 colonists for those 9 months, 6500 hours, in a ship with the room that an airliner uses taking that many with their baggage across the Atlantic Ocean, up to 9 hours. Might they not need food, water and, maybe, air for 9 months? The airliner pumps air through on the way. It collects its sewage, to deliver there. Maybe a pressure suit for when they get there? Change of underwear? By NASA standards, Starship has room for at most 17 crew for such a trip. That is if you know they all get along, or don't care how many kill one another on the way. More practically, 8 is probably the limit. Probably you need to send ships in pairs, so they can be swung on a cable between ships' noses for centrifugal gravity. That way their bones don't dissolve on the way. Will 1/3g be enough? Nobody knows. But it had better be. It is a good plan to send uncrewed cargo ships ahead of time with what they will need there. You probably need at least five of those per colonist ship. With on-orbit fueling, that amounts to ~80 Superheavy launches, 10 for each colonist. Will Starship be rated for launching crew? Maybe you need a couple of Falcon/Dragon launches, besides, for each Starship-load of 8 colonists. So for a million colonists, you need ten million Superheavy launches. At 10 launches/day, every day, that is 3000 years. Maybe breeding colonists in situ would be faster? Because over 3000 years, some will die. (Hopefully not all at once.) How many do you need to launch just to keep numbers from falling? Maybe later ones can move into dead colonists' pressure cans, so need less cargo? But a million colonists is very far from enough to be self-sufficient. No microchip manufacturing, no biochemicals, no Cybertruck. So you still need all the cargo launches, 10 every day, century in and century out. Hopefully the colony produces enough (movies?) to pay for that, because you can't bring them back. So, no, there will be no SpaceX Mars colony. But promoting it keeps Tesla stock price inflated.
- _Microft 4y ago
  If something sounds as implausible as you just made it sound, the explanation might be rather that they know more about the topic than you and that it is your numbers that are off.
  - ncmncm 4y ago
    You are welcome to try to find any other numbers, but all the evidence we have is that he is just making shit up as he goes along. Probably the most valuable things they could send back would be the vacuum Raptor engines they got there on, probably with their bells cut off.
    - extheat 4y ago
      Sounds like you have an axe to grind. Think about solutions instead of problems, nobody is asking you for anything. If the physics permits something to happen, if there’s a will there’s a way. If you don’t have the will there is never a way.
      - mxkopy 4y ago
        I don't know, I think appreciating the difficulty of getting to Mars is important, and puts things in a perspective that Elon Musk doesn't seem to respect when making these claims - which to be fair no successful hype man ever espoused a realistic perspective.
      - ncmncm 4y ago
        Yes, let's make it personal. That always turns out well. If you can figure a way to get a million-person Mars colony together in under, say, a thousand years, with SpaceX hardware, go wild. Freeze and stack colonists like cordwood? Nobody said they have to be alive, right? They'd keep. Maybe somebody will figure out how to revive them, someday.
        ffguuficc 4y ago

PartiallyTyped 4y ago

Is it possible for a mission starting at T1, to arrive later than a mission starting at T2, where T1 < T2 due to the sheer speed w/ which the planets are moving?

deleted 4y ago
[deleted]
bombcar 4y ago
Yes, and I believe this has already happened with some of the various probes sent out to the planets. Voyager 1 launched after Voyager 2 and overtook it; both overtook earlier probes to leave the solar system.

ncmncm 4y ago

Almost everything about SpaceX's Martian colonization announcements is very, very far from what could be practically realized with anything we can build today. For example, Musk repeatedly mentions a six-month trip. No, it is 9 months, at best. He talks about transporting 100 colonists for those 9 months, 6500 hours, in a ship with the room that an airliner uses taking that many with their baggage across the Atlantic Ocean, up to 9 hours. Might they not need food, water and, maybe, air for 9 months? The airliner pumps air through on the way. It collects its sewage, to deliver there. Maybe a pressure suit for when they get there? Change of underwear? By NASA standards, Starship has room for at most 17 crew for such a trip. That is if you know they all get along, or don't care how many kill one another on the way. More practically, 8 is probably the limit. Probably you need to send ships in pairs, so they can be swung on a cable between ships' noses for centrifugal gravity. That way their bones don't dissolve on the way. Will 1/3g be enough? Nobody knows. But it had better be. It is a good plan to send uncrewed cargo ships ahead of time with what they will need there. You probably need at least five of those per colonist ship. With on-orbit fueling, that amounts to ~80 Superheavy launches, 10 for each colonist. Will Starship be rated for launching crew? Maybe you need a couple of Falcon/Dragon launches, besides, for each Starship-load of 8 colonists. So for a million colonists, you need ten million Superheavy launches. At 10 launches/day, every day, that is 3000 years. Maybe breeding colonists in situ would be faster? Because over 3000 years, some will die. (Hopefully not all at once.) How many do you need to launch just to keep numbers from falling? Maybe later ones can move into dead colonists' pressure cans, so need less cargo? But a million colonists is very far from enough to be self-sufficient. No microchip manufacturing, no biochemicals, no Cybertruck. So you still need all the cargo launches, 10 every day, century in and century out. Hopefully the colony produces enough (movies?) to pay for that, because you can't bring them back. So, no, there will be no SpaceX Mars colony. But promoting it keeps Tesla stock price inflated.

_Microft 4y ago
If something sounds as implausible as you just made it sound, the explanation might be rather that they know more about the topic than you and that it is your numbers that are off.
- ncmncm 4y ago
  You are welcome to try to find any other numbers, but all the evidence we have is that he is just making shit up as he goes along. Probably the most valuable things they could send back would be the vacuum Raptor engines they got there on, probably with their bells cut off.
  - extheat 4y ago
    Sounds like you have an axe to grind. Think about solutions instead of problems, nobody is asking you for anything. If the physics permits something to happen, if there’s a will there’s a way. If you don’t have the will there is never a way.
    - mxkopy 4y ago
      I don't know, I think appreciating the difficulty of getting to Mars is important, and puts things in a perspective that Elon Musk doesn't seem to respect when making these claims - which to be fair no successful hype man ever espoused a realistic perspective.
    - ncmncm 4y ago
      Yes, let's make it personal. That always turns out well. If you can figure a way to get a million-person Mars colony together in under, say, a thousand years, with SpaceX hardware, go wild. Freeze and stack colonists like cordwood? Nobody said they have to be alive, right? They'd keep. Maybe somebody will figure out how to revive them, someday.
      - ffguuficc 4y ago