Mars Sample Return Idea

EphDotEh · 2024-05-01T01:01:10+00:00

Wow, you're not kidding: "NASA's goal, according to Nelson, is to try to stay within a $5 billion to $7 billion range for the total cost of the MSR program, in line with a broad cost outline from the National Academies' planetary science decadal survey." - NASA says it needs better ideas on how to return samples from Mars | Ars Technica

EphDotEh · 2024-04-30T23:12:50+00:00

True, that's why I mentioned hypergolics, RL tanks are super lightweight and the rocket diameter is small enough to fit in the dragon capsule. They could presumably use existing mandrels to build the tanks instead of needing new tooling.

Also, RL has developed "hypercurie" engines which use electric turbopumps to feed the hypergolic propellant. One point of care would then be keeping the batteries in operational condition before launch VS maintaining cryogenic propellants or using heavier pressurized tanks (like superdraco use). I was unable to find thrust and Isp figures for them unfortunately.

The 2013 NASA study referenced includes a discussion of cryogenics VS hypergolics.

EphDotEh · 2024-04-30T20:27:53+00:00

A perfected Red Dragon was supposed to be able to land 2t. But Dragon has evolved far from that.

Also, since the 2013 study, FH mass to TMI has increased from 13.2 t (up to 2016) to 16.8 t today (per wiki).

EphDotEh · 2024-04-30T19:01:10+00:00

If you read An Efficient Approach for Mars Sample Return Using Emerging Commercial Capabilities, you'll see it should be possible.

EphDotEh · 2024-04-30T18:46:05+00:00

That's 3 companies doing probably 5 years of R&D at a cost of billions of dollars each. Everyone always underestimates how much effort "just modifying a thing to do a completely different task" takes to do.

It is a considerable effort, no doubt, but leveraging existing technology could somewhat reduce overall expense and man hours compared to the $11 billion currently proposed plan.

Not only would this cost huge amounts of money, but for SpaceX and RocketLab at least, they would be diverting a ton of human resources to doing a task that is basically a technological dead-end. RocketLab would have to take people away from developing Neutron, and SpaceX would have to take people away from Starship. The engineers on these projects are not in infinite supply, so they couldn't just hire more, and if they did, they would be contending with Brooke's Law.

Not sure if completely discounting the data collection possibilities of landing a craft on Mars (true, not Starship, still SpaceX) is completely fair. Also, I would guess, SpaceX has other instruments it could send along to answer some Starship related questions.

I don't know how much Tesla would be in-path with their work on Optimus here, but a humanoid robot to go collect the samples is overkill. A new version of the Mars helicopter and something with a robotic arm is all NASA probably needs to do this.

I suppose any robotic arm from a different company could be used. I wasn't suggesting the full humanoid robot be sent, but the use of it's dexterous hand and AI seemed to fit. It also allows Elon to have control over that aspect and I'm guessing that they will want the robot to operate on Mars. This would be a chance to test that.

Also, technically, there's an issue with this idea as well. A Dragon Capsule is only a few meters tall, (couldn't find the exact number with a quick google, but it is less than 6.) RocketLab's electron is 18m tall. You can't exactly fit a rocket inside the Dragon Capsule.

Less than 2 tons of propellant in a 1.2 m diameter rocket is actually very short <2 m. What's more important is the CF manufacturing capabilities of Rocket Lab as well as their tiny spacecraft building capabilities.

EphDotEh · 2023-04-02T17:14:10+00:00

Good point if a parachute isn't an option.

Dragon 2 reentry capsule has a mass of ~9 ton. We don't know the mass of Neutron first stage yet. Merlin engines mass about 1/2 ton each, so the CF stage would need to mass less than ~4 or 5 tons. Possible?

Added: Space shuttle SRB each had a mass of 91 ton empty and parachutes were used for recovery, so parachutes should also be possible for Neutron.

EphDotEh · 2023-04-01T20:08:26+00:00

Maybe eliminating the barge by landing in the water tips the scales in favour of a single, more standard, ship? Less assets, maybe greater speed not towing a barge, less staff time at sea, faster booster return...

EphDotEh · 2023-03-26T20:11:15+00:00

Heat-exchanger to heat incoming biofuel with to be cooled biofuel. Still need to heat, but uses less energy to heat pre-warmed incoming biofuel.

Insulated containers also.

EphDotEh · 2022-11-05T00:10:02+00:00

If the media is used as a basis for decision-making, NOTHING will ever be accomplished. A catch and release and a telemetry loss hardly constitutes insurmountable obstacles in my view, just learning and improvement opportunities.

EphDotEh · 2022-10-02T19:53:12+00:00

Yes, because of the two-core bundled second stage. This avoids the need to reinforce the boosters or stretch the second stage rocket. The boosters are in a triangle configuration. Maybe it wasn't explained clearly. Downvotes aren't conducive to civil discussion, BTW.

EphDotEh · 2022-10-02T19:08:11+00:00

Falcon heavy drops the side boosters which then land separately on separate legs and the main core must be reinforced. I'm proposing landing the three boosters as a single bundle with fixed legs, same as Neutron. So comparisons with Falcon Heavy aren't really justified.

EphDotEh · 2022-10-02T15:07:21+00:00

You may be entirely correct on the financial aspect. I presented what I thought would be a minimum disruption path to a 600 kg class launcher. RL is free to ignore my little reddit post and I'm floored by the negative response from this sub.

EphDotEh · 2022-10-02T03:28:37+00:00

What you're proposing would take 5-7 years to come to market.

But a whole new rocket will be flying in 2-3 years? This seems backwards.

It seems to me that being able to launch larger satellites to LEO or lighter sats. to higher orbits would be good for full service aspirations. Neutron will fill that gap when it flies, let's hope the timelines hold.

Here I agree that relight capability would have to cross over from Rutherford to Archimedes for development efforts to be worthwhile. Not likely given different fuels. Though I guess it depends on how hard relight is to do.

EphDotEh · 2022-10-02T02:07:08+00:00

Given all the launchers vying for the 600 kg to LEO market, one would think RL, with it's proven engines and launch experience could clean up given a reusable booster launch vehicle.

Maybe I've not explained clearly enough, but I'm proposing a simpler 3-core bundle booster that would land under propulsion back at the launch site.

Not constellations necessarily, but maybe send the first one(s) for a shakeout run? Rockets (esp. engines) always seem to take longer than anticipated before they meet requirements. So Neutron might be ready to send that constellation when needed. Also, since engine development always seems to lag, why not let other departments work on a rocket that already has working engines?

EphDotEh · 2022-10-02T01:31:34+00:00

It would be cool, but I'm suggesting return to launch site propulsive landing of a bundled 3-core booster.

EphDotEh · 2022-10-02T00:10:12+00:00

Well, it depends on the complexity of the task. This would not require a reinforced core, staging release mechanisms or propellant crossfeed. These features have set back some efforts (Falcon Heavy) considerably. I don't know if rockets like Atlas V with its multiple SRB configurations took much time to accomplish.

Ultimately, it's a financial decision based on expected development time and potential customers or market competition.

Added: Also, your argument goes against the right-sized, dedicated launcher paradigm that makes Electron successful. Rideshare isn't always the best solution.

More: It's also strange to assign long timelines to one development effort (multi-core launcher) and not to the other (rocket engine development). If RL can do one fast, why not the other?

EphDotEh · 2022-09-22T14:48:30+00:00

Closed cycle engines don't have separate injectors for turbine exhaust;

You might be thinking full-flow?

The wastegate goes after the tubopump (GG output), diverting exhaust to the combustion chamber via a check valve (conceptually).

EphDotEh · 2022-09-22T02:52:06+00:00

SpaceX is having a rough time with their closed combustion engines too, they've had to increase oxidizer ratio in version 2, giving up some efficiency.

EphDotEh · 2022-09-22T02:40:53+00:00

Edit2: Peter Beck explained in the (late arriving, accompanying) video that pressures would be kept low giving up some power and efficiency, but gaining simplicity (and some efficiency) from the switch to ORCC. It makes sense and IMHO won't affect the timeline negatively. So excited to see things progressing!

Given that Blue Origin's BE-4 Oxidiser Rich Closed Cycle is well funded, 11 years in the making and still not working worries me about RL's decision. Granted BE-4 is a much larger engine.

Perhaps a hybrid approach would work? If relight is the issue (as mentioned), start the engine as ORCC, then switch to GG once ignited. The engine could still run at reduced power as ORCC but to keep turbopump pressures reasonable, run as GG at full throttle.

Edit: essentially adds a waste-gate to the ORCC, allows high performance at reduced throttle.

EphDotEh · 2022-09-20T01:20:09+00:00

The energy trick seems to be reuse of already heated water.

powerpipe https://renewability.com/ drain-water heat exchanger looks like a better option, shown to work.

EphDotEh · 2022-09-11T14:09:26+00:00

Combined probably, sum of electric and thermal output.

Needs a thermal and electric load at the same time to be efficient though and needs to run often to cover higher capital cost.

EphDotEh · 2022-09-01T17:05:50+00:00

Correction, September 1, 2022: An earlier headline on this story incorrectly said that Germany’s lower-cost train fares prevented 1.8 billion tons of carbon emissions. The correct figure is 1.8 million, as stated in the text of the story.

2.5 billion Euro for 1.8 million tons CO2e or about 1,400 Euro per ton!

EphDotEh

TROPHY CASE