Mars in three years

[tater]

There is nothing we could tell NASA they haven't thought of. Docking upper stages (say F9 US) is something that might be more of a kooky SX idea.

[YNM]

51 minutes ago, tater said:

There is nothing we could tell NASA they haven't thought of. Docking upper stages (say F9 US) is something that might be more of a kooky SX idea.

I'm asking about the human, habitation and supplies payload. You need them before you can tell how many fuel you need.

Edited April 28, 2017 by YNM

[sevenperforce]

1 hour ago, tater said:

I'd think that the engine out abort modes need to be reconsidered in a more aircraft way. Airliners have engine out capability. Spacecraft with multiple engines seems to make the most sense, and dump the free return. Use a Centaur, those things are pretty bulletproof.

Another goofy idea, and too kerbal for reality, but what the heck. If you used a LV with a good upper stage, and landing/reuse of that is a pain, why not reuse it in space. 

Instead of the mass required for landing S2, you make a similar adapter that is in fact designed for docking and propellant transfer. Note that it might require EVA, that's fine. The design might have the docking/transfer stuff exit to the side, so it's not a nose to nose type docking. You collect the stages where your craft is (say stuff you are sending ahead to Mars), and the upper stages are ganged to form a transfer stage for departure. At some point after they are connected and pressure tested, you send up tankers. You now have a few Merlin-1DV engines, or Be-4U engines as your departure stage.

That's not too kerbal for reality at all. My proposed mini-ITS upper stage with two dev Raptors? Precisely the transfer vehicle I was considering to use for this. 141-tonne propellant tank, two 1100-kN engines, 130 cubic meters of payload space, and auxiliary thrusters capable of landing 40+ tonnes on Mars after a lifting-body re-entry. Perfect.

Propellant transfer port on the side or wing; docking port on the nose. Who cares if you have to switch back and forth? We have been docking spacecraft with the ISS for decades now; it requires some doing, but it is a solved problem.

All the ISRU proposals I have seen are ridiculously limited, because you have to somehow integrate a separate crew capsule. Why on Earth (or Mars, as the case may be) would you want to do that?? Make the ISRU unit self-contained and reusable, and send it up to Martian orbit to refuel your lander. Your lander needs fuel to land, after all, and it is a lot easier to do an RCS-assisted docking and fuel transfer in orbit than it is to try and do a fuel transfer via EVA.

You're going to need those high-specific-impulse, high-thrust chemical propellant engines to get off Mars, so why not use them for your transfer?

1 hour ago, tater said:

There is nothing we could tell NASA they haven't thought of. Docking upper stages (say F9 US) is something that might be more of a kooky SX idea.

I'm sure NASA has thought of docking upper stages, but consideration of propellant transfer might be a little low on their priority list, and reversible propellant transfer moreso.

I haven't run all the numbers, but back-of-the-envelope estimates suggests at least ten times more TMI propellant is needed for a straight chemical Mars Orbit Rendezvous than would be required for an aerobrake-assisted Mars Orbit Rendezvous.

[shynung]

22 hours ago, sevenperforce said:

The BEAM's expansion is a onetime affair, so you'd need a complete redesign.

I see. Guess we'll need a few more decades for a deflatable module, then.

22 hours ago, sevenperforce said:

Also, getting an expandable module inside an aeroshell is a tricky affair. The expandable module will have to be docked to a pressurized module while expanded, but will have to be deflated and removed from that module in order to be stowed inside an unpressurized cargo bay, but one which can be protected during aerobraking or re-entry.

I'd suggest using an aeroshell designed like a wingless Space Shuttle Orbiter, with cargo doors enclosing an unpressurized cargo bay, and a heatshield on the other side. The inflatable/deflatable module is connected to a rigid pressurized module by a swinging joint - to inflate the module, the joint swings the module out of the cargo bay (still attached to the rigid module via a pressurized tunnel/walkway), then inflate after the module is clear of the cargo bay. Stowing the module would be the opposite - deflate, swing-in, the close the cargo bay doors.

[NSEP]

Of course we can get a manned mission to Mars in three years! Not alive, just dead. Cremated people for example.

I heard that the person who discovered Pluto is aboard new Horizons. So technically we got (at least a piece) of a human to Pluto and the outer solar system.

[tater]

I'd think that in fact the limiting factor on how soon any Mars mission could be done would be a combination of life support, and propulsive landing assuming landing was a requirement. ISS is under constant resupply, and they tinker with the LS (new parts, etc) fairly often---and any failure that was bad and could not be fixed before it became a problem would result in leaving for home within a few hours, max. Any LS system would need serious testing to demonstrate it could function under real crew demand for at least an entire mission duration. 

Landing would need to be tested to completion, IMO, with a flight-article piece of hardware, perhaps to serve as a backup on the surface, or as the MAV (assuming the mission could precisely land to be able to use it, which would also need testing).

[Codraroll]

Flags and footprints might be feasible. If you load something resembling a cluster munitions canister with weighted boots and flags with a heavy spike in the non-flaggy end of the pole, and manage to achieve separation in Mars' atmosphere at speeds that wouldn't turn everything to dust upon hitting the ground, then you could feasibly imprint the surface with some footprints, and make at least one flag stick upright in the Martian soil. I think such a mission could conceivably be executed in four years, provided you don't waste any time trying to make the mission achieve anything useful.

[HebaruSan]

1 minute ago, Codraroll said:

Flags and footprints might be feasible. If you load something resembling a cluster munitions canister with weighted boots and flags with a heavy spike in the non-flaggy end of the pole, and manage to achieve separation in Mars' atmosphere at speeds that wouldn't turn everything to dust upon hitting the ground, then you could feasibly imprint the surface with some footprints, and make at least one flag stick upright in the Martian soil. I think such a mission could conceivably be executed in four years, provided you don't waste any time trying to make the mission achieve anything useful.

Typical NASA overspending. Just order Curiosity to drive a loop in the shape of a big footprint, then an outline of Old Glory.

[sevenperforce]

19 hours ago, shynung said:

I'd suggest using an aeroshell designed like a wingless Space Shuttle Orbiter, with cargo doors enclosing an unpressurized cargo bay, and a heatshield on the other side. The inflatable/deflatable module is connected to a rigid pressurized module by a swinging joint - to inflate the module, the joint swings the module out of the cargo bay (still attached to the rigid module via a pressurized tunnel/walkway), then inflate after the module is clear of the cargo bay. Stowing the module would be the opposite - deflate, swing-in, the close the cargo bay doors.

Then, of course, we must compare the mass of that whole aeroshell and hinged stow assembly against the fuel that would be required for simply burning to orbital insertion. Aerocapture (using the atmosphere to insert from a hyperbolic swingby to an elliptic orbit, then circularizing once around) is a tricky thing; I have done it plenty of times in KSP but doing it IRL is rather challenging; I don't believe it has ever been done. Aerobraking to EDL, yes, but no actual aerocaptures into orbit.

[shynung]

12 minutes ago, sevenperforce said:

Aerocapture (using the atmosphere to insert from a hyperbolic swingby to an elliptic orbit, then circularizing once around) is a tricky thing; I have done it plenty of times in KSP but doing it IRL is rather challenging; I don't believe it has ever been done. Aerobraking to EDL, yes, but no actual aerocaptures into orbit.

NASA Mars Reconnaissance Orbiter mission used an aerocapture maneuver. This reduced the fuel needed for Mars orbit insertion by half.

[tater]

Even with a JFK-style time limit that was being pushed hard, I don't see 2024 as plausible. I think this is why Mars is always so far off, and continues to be. It would need real funding for the clock to start ticking, since that doesn't happen, it's always in the vague future.

Think about 2024. You'd need to launch some hardware in 2020. Not an experiment, like Red Dragon, actual mission, flight article hardware, but unmanned. If there is an issue, then you address it, and refly the next window, and only if that works do you send people. At some point, before 2024, you look at your mission duration, and you fly the transfer vehicle to LEO, and test the life support. Heck, you might send the actual vehicle up, and put people aboard for 3 years, but that means sending it up by 2021. After testing, assuming it's good to go, you attach the stages for Mars (an Earth departure stage, a Mars insertion stage, and a return stage), then go.

A free return seems like the only remotely possible goal that could be achieved in something like a 10 year window with real effort to me, largely because the spacecraft testing could be done entirely in Earth orbit. You could even test a stage, and send it to cislunar space for a while.

[sevenperforce]

2 hours ago, shynung said:

NASA Mars Reconnaissance Orbiter mission used an aerocapture maneuver. This reduced the fuel needed for Mars orbit insertion by half.

As I understand it, the MRO used its engines for the initial insertion, establishing an elliptic Mars orbit, then adjusted its periapse to gradually trim off orbital energy one orbit at a time to adjust. It was excellent for the mission requirements, of course, but it's very different from a much more aggressive "true aerocapture" where a single pass through the atmosphere moves you from a hyperbolic orbit to an elliptic one. MRO needed no special heat shield, while a true aerocapture requires a heat shield and high-gee resistance.

2 hours ago, tater said:

Even with a JFK-style time limit that was being pushed hard, I don't see 2024 as plausible. I think this is why Mars is always so far off, and continues to be. It would need real funding for the clock to start ticking, since that doesn't happen, it's always in the vague future.

Think about 2024. You'd need to launch some hardware in 2020. Not an experiment, like Red Dragon, actual mission, flight article hardware, but unmanned. If there is an issue, then you address it, and refly the next window, and only if that works do you send people. At some point, before 2024, you look at your mission duration, and you fly the transfer vehicle to LEO, and test the life support. Heck, you might send the actual vehicle up, and put people aboard for 3 years, but that means sending it up by 2021. After testing, assuming it's good to go, you attach the stages for Mars (an Earth departure stage, a Mars insertion stage, and a return stage), then go.

A free return seems like the only remotely possible goal that could be achieved in something like a 10 year window with real effort to me, largely because the spacecraft testing could be done entirely in Earth orbit. You could even test a stage, and send it to cislunar space for a while.

A Martian sample return could be launched in 2020, if enough money was poured into it. 

But right now we don't even have a hab that could make the journey manned. 

[tater]

6 minutes ago, sevenperforce said:

A Martian sample return could be launched in 2020, if enough money was poured into it. 

But right now we don't even have a hab that could make the journey manned. 

Yeah, that's my real point. We already agreed that 3 years was absurd, but even 8 is absurd. I think in 8 you might be able to get to the point of having defined the hardware to the point you could consider testing it. Unmanned in the case of any landing hardware, and perhaps manned in LEO for a transfer vehicle. That's with Apollo-like effort.

Given plausible lifters in that timeframe, I think that you'd dump aerocapture, and just bite the bullet and bring the extra propellant and pay homage to the god of the rocket equation.

There is a reason 2033 is often cited---there are opposition launch opportunities for ~1 year round trips with 30 days on the surface, and some have reentry velocities around 15km/s. Most other opposition windows put the Earth entry at closer to 20km/s. I think heat shield tech need to be tested in that regime, I'm also unsure of the g-loading calculations for the crew. Opposition missions minimize the life support issues, and might even allow for more redundancy in that area (spares, etc). With the current DRA, the MAV is sent ahead anyway, and that craft can do a direct martian entry I would assume. The descent vehicle would be able to be far lighter then, and dragging along the extra ~2km/s to insert to martian orbit might not be as insane.

[Spaceception]

22 hours ago, NSEP said:

Of course we can get a manned mission to Mars in three years! Not alive, just dead. Cremated people for example.

I heard that the person who discovered Pluto is aboard new Horizons. So technically we got (at least a piece) of a human to Pluto and the outer solar system.

 

Human DNA among the stars.

Really cool when you think about it.

[NSEP]

1 minute ago, Spaceception said:

Human DNA among the stars.

Really cool when you think about it.

Yeah. Pretty cool. But you know, all spacecraft we know of are man-made. And at least 1 of the deep space probes has at least 1 living bacterium on it, im pretty sure of that. So we could say we send life out of the solar system on voyager 1, and even if its completely clean, we still sent a bit of 'us' outta here, not only the golden disk, the spacecraft itself is pretty human.

[tater]

21 minutes ago, Spaceception said:

Human DNA among the stars.

Really cool when you think about it.

There's a Vonnegut story this reminds me of: The Big Space REDACTED.

[sevenperforce]

1 hour ago, tater said:

Yeah, that's my real point. We already agreed that 3 years was absurd, but even 8 is absurd. I think in 8 you might be able to get to the point of having defined the hardware to the point you could consider testing it. Unmanned in the case of any landing hardware, and perhaps manned in LEO for a transfer vehicle. That's with Apollo-like effort.

Given plausible lifters in that timeframe, I think that you'd dump aerocapture, and just bite the bullet and bring the extra propellant and pay homage to the god of the rocket equation.

There is a reason 2033 is often cited---there are opposition launch opportunities for ~1 year round trips with 30 days on the surface, and some have reentry velocities around 15km/s. Most other opposition windows put the Earth entry at closer to 20km/s. I think heat shield tech need to be tested in that regime, I'm also unsure of the g-loading calculations for the crew. Opposition missions minimize the life support issues, and might even allow for more redundancy in that area (spares, etc). With the current DRA, the MAV is sent ahead anyway, and that craft can do a direct martian entry I would assume. The descent vehicle would be able to be far lighter then, and dragging along the extra ~2km/s to insert to martian orbit might not be as insane.

Aerocapture of the manned landing vehicle itself seems pretty doable. EDL on Mars requires heat shield and propulsion as a matter of course, so if you can manage direct entry and propulsive landing, you should also be able to manage aerocapture and circularization.

Then, as I outlined previously, you can take advantage of propellant transfer (assuming you solved this problem before, in order to refuel your vehicles for TMI) to beat the rocket equation. Using aerocapture to get your return prop into Martian orbit, then transferring it back to the tanks of the bus you used to insert the transfer hab while you execute your EDL, seems very advantageous.

And this allows partial or total reuse, which is nice if you can do it for cheaper than the alternative.

[tater]

Agreed. If you have the luxury of sending stuff ahead, then the trick is to create a modular architecture whereby you can add stages on either end of the trip. I'd think that whole stages would be more likely, even at the expense of moving the engines all the way there. They could just as well use drop tanks for those stages, using up the drop tank, leaving a fully fueled stage in Martian orbit (that stages engine(s) having been used to empty the drop tank, so you'd have taken the engine anyway).

The crew vehicle could include piping as spares for an EVA refueling should there be an issue with the placed-ahead stage's engines, I suppose. Still, I'm not seeing it in 8 years.

[sevenperforce]

17 hours ago, tater said:

Agreed. If you have the luxury of sending stuff ahead, then the trick is to create a modular architecture whereby you can add stages on either end of the trip. I'd think that whole stages would be more likely, even at the expense of moving the engines all the way there. They could just as well use drop tanks for those stages, using up the drop tank, leaving a fully fueled stage in Martian orbit (that stages engine(s) having been used to empty the drop tank, so you'd have taken the engine anyway).

The crew vehicle could include piping as spares for an EVA refueling should there be an issue with the placed-ahead stage's engines, I suppose. Still, I'm not seeing it in 8 years.

There are so many tradeoffs.

The idea of ISRU is really attractive, on the surface. You can give Tsiolkovsky the middle finger and use local resources. But actual utilization is challenging.

In theory, the most straightforward ISRU approach is to land an empty MAV with the ISRU unit already attached and plumbed in, and let it collect its own propellant. For simplicity, you can just let it collect LOX in-situ and let it bring its (less massive) fuel along with it. But there are a lot of reasons why it's sub-optimal.

The concept of having the crew leave their descent vehicle and head to a separate ascent vehicle is not attractive at all. You'll probably need a very sturdy rover as a primary mission survival requirement, just to allow the crew to get to the ascent vehicle, so that drives up mass. You have to have a separate airlock, cabin, and ECLSS in the ascent vehicle, and all its systems need to be able to be landed long in advance and remain perfectly ready for at least 2 years without maintenance or checkups. Are crew members in IVA suits or EVA suits? EVA suits take up much more space, but you need to bring at least one along in case there is some mission-critical problem that needs to be correct in order to allow ascent.

Most disturbingly: no landing abort mode. None. From the moment you start entry, you're committed, and your survival depends not only on successful EDL, but landing in a site that will allow egress, and allow you to unload your rover, and allow you to make it to your MAV safely. Imagine how much riskier Apollo would have been if Buzz and Neil had been forced to head off to a separate ascent vehicle!

Now, since the lander needs descent engines, you can size them a bit bigger and use your lander for ascent as well. Just go the ITS route and transfer propellant from a pre-launched ISRU unit to your sole crewed vehicle. But that requires an even greater landing precision, and I don't think anyone is comfortable with the idea of hooking up hoses for propellant transfer in an EVA on another planet for the first time.

The only other option for ISRU (other than bringing the ISRU unit on the lander, which is a non-starter because of the time it takes to collect propellant even if dry mass wasn't an issue) is to have the ISRU vehicle autonomously land, collect propellant, and then return to Martian orbit on its own, to transfer prop to the manned vehicle prior to crew EDL. This is the lowest-risk option, because the manned vehicle has all the propellant it needs for ascent before committing to entry. It's also promising from a dry mass point of view; if your lander can drop up enough payload on Mars with a single direct ascent (projected mass to TMI from a fully-reusable Falcon Heavy with my mini-ITS upper stage is 4.5 tonnes plus the entire dry mass of the vehicle), then you can end up with about 35-40 tonnes of propellant available for transfer in low Martian orbit. Of course, you've wasted more than half of your fuel getting that fuel up into orbit, but you don't have to worry about finding a way to transfer propellant on the ground. And it would take much more than a single reusable Falcon Heavy launch to put 35 tonnes of propellant into a TMI; 35-40 tonnes of propellant is what the Falcon Heavy + mini-ITS tanker combination can manage for LEO.

The biggest advantage of the last option is that your EDL and ascent double as tests for the parallel manned mission.

[sevenperforce]

Eye candy:

[Ultimate Steve]

If the future of humanity somehow depended on it (say aliens told us they'd destroy us if we didn't get to Mars, just being hypothetical), then yes.

Easy. Put all funding into Red Dragon so it launches in 2018, pack a bunch of food and stuff (There is already technology to recycle water and air and stuff) and ask one suicidal person to go to Mars.

Now, if those aliens said we had to go there and return by Dec. 2020, then that's a whole different story.

[wumpus]

On 5/1/2017 at 10:18 AM, sevenperforce said:

There are so many tradeoffs [for ISRU]
...
The biggest advantage of the last option is that your EDL and ascent double as tests for the parallel manned mission.

I'd go so far as to say it is absolutely necessary for any near-term Mars expedition.  This even includes nuclear rockets as the hydrogen they used going from Mars to Earth will leak out for the return journey (and hopefully CO is good enough for the way back).  It is absolutely insane for an 8 year program (although presumably the ISRU would land in the "test run").

Since the 4/8 year window is essentially tied to NASA funding, are there any other potential windows that it might be possible in?  Any idea what tech needs to be in place to make this happen?

Inflateable habitats (if only for the trip there and back again): don't underestimate this.  A huge chunk of delta-v goes into moving the habitat and you can't cram a crew into a Dragon for 2 months.
ISRU: I'm guessing this is mostly a straightforward chemical engineering challenge, only with restrictions (mass, mass, radiation hardening?, mass) that few chemical engineers consider.

heavy lift: Presumably Elon Musk will have the Raptor plans/budget in his back pocket every time he is near NASA or DC.  I'd expect such things to be possible (with Kennedy-style budgets) with Falcon Heavy, Delta Heavy, or SLS.
propellants:
hydrogen storage: hopefully the James Webb Telescope will confirm a few things about zero-boiloff cryosystems, but hydrogen will still leak out.
nuclear space systems: good luck.  I have to wonder what kind of results you can get from a somewhat upgraded NTG (i.e. a low-level reactor that is nowhere near critical and expected to produce power at a level on the order of the ISS solar panels).  Needed for ion power, VASIMR, and similar (note VASIMR has addition issues like hydrogen storage, ion systems won't fit in the timeframe).

I'm sure there is a ton of tech needed, but these are the ones that wildly inflate the price tag if the aren't ready.

[Nothalogh]

On 4/30/2017 at 0:20 PM, tater said:

bring the extra propellant and pay homage to the god of the rocket equation.

Words to live by, right there

[Green Baron]

I cannot judge how serious this is but to me it seems like a step towards reality:

https://arstechnica.com/science/2017/07/nasa-finally-admits-it-doesnt-have-the-funding-to-land-humans-on-mars/

tldr: NASA chief for manned spaceflight says that there is not enough money, technology and manpower for sending humans to Mars in a foreseeable future (30's/40's).

A single expendable SLS launch costs a billion funds, they say. Not even the moon is within reach at that price. That is as much as the TMT or 0.7*E-ELT cost, which are planned for 50-75 years of work (upgrades in between of course).

[jsisidore]

Why won't we go to Mars total recall style, the brain won't know the difference. Plus anyone can go.
I just googled the 2020 mission and it's a rover mission in preparation for the 2030 manned mission so we got time to go there for real.

Yeah we're getting there said a flea.

Edited July 14, 2017 by jsisidore