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Mass to space is a little expensive but not that expensive. NASA's refusal to just fly more payloads and join or coordinate them in space is a political one mor

Mass to space is a little expensive but not that expensive. NASA's refusal to just fly more payloads and join or coordinate them in space is a political one moreso than technical, and if they took the opportunity to get more payload mass they could stop worrying about minor mass margin issues. The very obvious price comparison here is that Mars Sample Return has a price tag meaningfully bigger than the two winning HLS bids combined, including demonstration missions. Yes, the moon is closer, but also HLS is moving living humans, not small rocks.

idlewords 3y ago
You don't seem to understand the constraint here, which is getting the mass of a rocket capable of reaching orbit down to Mars intact through an atmosphere. You can fly all the payloads you want without getting any closer to solving that problem. Sample return would be hard and expensive even if launches from Earth were free.
- Veedrac 3y ago
  No, the point is that this constraint is dominantly a mass margin issue, and if NASA wasn't politically handicapped their mass margin would look very different.
  - idlewords 3y ago
    Say I can send 1000 metric tons to Mars for a million bucks. How does that solve the problem of safely landing a heavy rocket on the surface?
    - Veedrac 3y ago
      NASA was broadly happy with technical feasibility for Red Dragon, which pretty much just repurposed Dragon 2's biprop abort motors to land >1 ton on Mars for their estimate of $150-190m/launch. They didn't go forward with it, but this was early 2010s so that's not much surprise. With infinite mass in Mars orbit, you'd presumably want to scale up, but while this marginally hurts aerobraking performance, you have vastly more mass margin to just bring a bit more propellant. If course, you'd probably still want to land something in scope of what you can launch from Earth dry in one flight, but for sure we're still talking >5 tons there, probably more like 10.

idlewords 3y ago

You don't seem to understand the constraint here, which is getting the mass of a rocket capable of reaching orbit down to Mars intact through an atmosphere. You can fly all the payloads you want without getting any closer to solving that problem. Sample return would be hard and expensive even if launches from Earth were free.

Veedrac 3y ago
No, the point is that this constraint is dominantly a mass margin issue, and if NASA wasn't politically handicapped their mass margin would look very different.
- idlewords 3y ago
  Say I can send 1000 metric tons to Mars for a million bucks. How does that solve the problem of safely landing a heavy rocket on the surface?
  - Veedrac 3y ago
    NASA was broadly happy with technical feasibility for Red Dragon, which pretty much just repurposed Dragon 2's biprop abort motors to land >1 ton on Mars for their estimate of $150-190m/launch. They didn't go forward with it, but this was early 2010s so that's not much surprise. With infinite mass in Mars orbit, you'd presumably want to scale up, but while this marginally hurts aerobraking performance, you have vastly more mass margin to just bring a bit more propellant. If course, you'd probably still want to land something in scope of what you can launch from Earth dry in one flight, but for sure we're still talking >5 tons there, probably more like 10.