[walrus01]

Without a significant drop in the $ per kg cost of putting stuff in low earth orbit, I wouldn't take that bet. I don't think SpaceX starship will be revolutionary enough to put probes in LEO cheap enough.

Once in orbit it's possible to reach things in the asteroid belt entirely through very high efficiency ion/hall effect thruster propulsion, which can have specific impulse as high as 8000.

Any probe capable of drilling or melting into the crust of ceres or Europa or similar will have to be quite large...

[valuearb]

The Space Shuttle payloads to LEO cost $40,000 per pound.

Before SpaceX commercial launch payloads cost $5,000 to $10,000 per pound.

Falcon 9 payloads cost around $1,500 per pound.

Falcon Heavy payloads cost around $1,100 per pound.

Starship payloads will cost between $100 and $500 per pound. It will be able to lift at least 100 tons to orbit. And using in orbit refueling, it will be able to accelerate that 100 ton payload 6.9 km/sec, making landing it on Ceres trivial.

[walrus01]

I am hopeful that Starship will really achieve those figures, but I am also skeptical... I'll believe it when I see it being done.

That's still not cheap enough to do lander/surface manipulation science in the asteroid belt without significant philanthropic or government funding.

At $500/pound, if a Ceres unmanned probe lander with drill/melting apparatus weighs 15000 kg when placed in low earth orbit (before whatever staging/fuel it expends to get to ceres and land), that's still a $16.5 million launch cost before you add the cost of the R&D to build the spacecraft, operate its command and control network, etc.

I will be very pleased and enthusiastic but also shocked if something like that is accomplished for a project budget under $30-40m in the next 20 years.

Not saying it's impossible but we're well within the realm of "big budget" science. Like the operating budgets of one of the smaller (not McMurdo or Amundsen-Scott) permanent research bases in Antarctica, or something like the this:

https://en.wikipedia.org/wiki/Chiky%C5%AB

Big enough that even top tier universities form consortia to collaborate in science projects such as the ALMA array.

[valuearb]

Starship will launch larger probes to Ceres than we’ve sent to Mars, for a lower launch cost. We will do what we’ve done on Mars.

[simonh]

True, but in orbit refuelling means 3 or 4 additional refuelling launches, so now your cost per kg is back up to a few thousand $ per kg again. Still cheap for Ceres though.

[imtringued]

Yeah, orbital refueling doesn't change the rocket equation unless you can manufacture fuel in space. The only benefit is that you don't need a bigger rocket.

[valuearb]

Orbital refueling absolutely changes the rocket equation in a huge way. The standard NASA human Mars plan involves a mega rocket large enough to lift the humans and their supplies in one shot from earth, along with the fuel to get to Mars and the fuel to get back.

Starship enters LEO with empty fuel tanks, meaning it can lift much more payload per pound of fuel. Being refueled in orbit is cheap, because fully reusable flights are cheap. And for Mars, Starship only needs enough fuel to get there, it can make fuel on Mars. That means it doesn’t have to carry even more fuel to fly the return fuel to Mars.

[rbanffy]

We'll eventually get to the point where Starship-like rockets only ferry people, cargo, and, maybe, propellant to LEO for transfer to spaceships that don't need to go deep into any gravity well. These ships will then take you to orbit around your destination so you can board another shuttle to the surface.

[valuearb]

That would be massively inefficient for travel to Mars, because you can Aerobrake to land and make fuel on Mars for your return.

[UnFleshedOne]

You could probably aerobrake to get into orbit instead. But eventually it might make sense to build ships that are never supposed to touch atmospheres, or only upper layers. Some design constraints can be relaxed then.

[SAI_Peregrinus]

Sort of true. The rocket equation doesn't account for the added weight of lifting the rocket itself, just the added fuel. Multiple launches can reduce the practical overhead, even if not changing the overhead in the limit of 0% rocket mass 100% fuel mass.

[eru]

You are right.

Manufacturing fuel in space would be the way to go.

Or eg have giant solar panels in orbit that power a laser to shine at your spaceships. Either to propel them directly, or to transmit power for their ion thrusters etc.

[valuearb]

A fully expended Falcon 9 launch costs around $50M. A partially reusable Falcon 9 launch costs around $25M.

Starship will be fully reused. It will launch a 5x larger payload than the partially reusable Falcon 9 at a lower launch cost. So somewhere in the $5M to $20M range.

Starship can be fully refueled in LEO with eight tanker flights, Even at $20m per flight, that costs no more than the Atlas V that just launched perseverance to Mars, only with 40 times more mass.

[eru]

What odds would make you take the bet?

And, perhaps let's talk about a conditional bet that removes the difficulty of space exploration:

The bet pays me X dollars, if human vessels can go to the asteroid belt and not find life. It pays you Y dollars, if we find life. And no payment in either direction, if we can't go to the asteroid belt and don't find life. Say, all limited to the next 100 years.

What's the ratio of X to Y that would make you accept such a bet?

[hyperpallium2]

(not OP) Another clarification: before you said "non-earth life". Panspermia[1] implies Ceres and Earth life are related, so that native Ceres life is hard to distinguish from Earth's (and arguably is the same as Earth life).

1. Backtrapolating exponential evolution finds an origin older than Earth. https://arxiv.org/abs/1304.3381

[eru]

To be more precise: what I meant is life on Ceres that hasn't come accidentally from any of our own probes since eg the start of the 20th century.

I'd be happy to pay up in case of pre-historic panspermia.

[Auracle]

Wouldn’t a nuke work?

[webmaven]

> Wouldn’t a nuke work?

Do you mean NERVA?:

https://en.m.wikipedia.org/wiki/NERVA

[eru]

Please elaborate.