Buzz Aldrin's Mission to Mars via the Project Aldrin-Purdue Concept

[Mr. Scott]

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[KelvinZero]

I think there should be a saying "no mars plan survives contact with the moon"

..what I mean is not that the moon is the enemy, but that there is no point having a plan that goes via the moon and pretending you are going to stick with it. You go to the moon if you think it is worthwhile and you learn a bunch of stuff and get good at a bunch of stuff, much of which you probably guessed correctly will be useful, and then you go to mars with a plan that probably looks quite different from what you came up with before you learnt all that stuff.

[redliox]

Moonbases, aerocapture, and Phobos were the main things I can approve of.  I don't think Congress or even the whole international community could afford this whole scheme.  It smells like SEI with a 21st century tang.

I laugh at the irony of Aldrin proposing 3 Moonbases when I once suggested just 2 and got criticized at the 'unfeasibility' of it.  Well nay-sayers?    Seriously though, we'd be lucky to have one Moonbase, and if it's not at the lunar poles the best compromise would probably be one in a crater on the lunar terminator between near/far sides.

The biggest thing I'm against with Aldrin's idea are the hyperbolic cyclers.  Cute in principle, a pain in reality.  You'd need several of these mini-stations to shuttle crew since neither Mars or Earth perfectly align, meaning when the cycler completes an orbit neither Earth or Mars will always meet it at its orbital perihelion and aphelion.  Since the crew vehicles need to launch into a Martian trajectory anyway, there's no propulsive gain - indeed you need more fuel to ensure you rendezvous with an interplanetary hotel.  Skip the hotel and just make a better 'mobile home' i.e. Deep Space Habitat, otherwise focus the hardware on landers and surface bases (Lunar or Martian).

What I do like are Aldrin's ideas for landers.  There's the recognition of aerocapture as an enabling technology for crew, cargo, Phobos, and Mars landers.  All incoming landers brake with the atmosphere and either meet with Phobos or reenter and land on the next pass.  This seems an interesting swerve away from NASA's SEP preaching.  Furthermore, little was spoken of needing SEP (which probably would annoy Bolden and the ARM people a touch).  I find the ascent/return vehicles strange and vague, but I could respect the idea of converting a crew capsule (Orion cited no less) into a (crude) rover; I think Orion would make a better ascent stage than a rover...but perhaps feasible.

All together, Aldrin seems almost as grandiose as Van Braun was 50+ years ago, albeit with a touch more focus on the actual targets...which I approve of.  It needs to be simplified; for example I doubt 3 sets of bases either could or would be funded; for the Moonbases there may be a loophole through the international community otherwise choices must be made; for Phobos I'd suggest prospecting visits rather than full bases.  Tighten the goals a little further just as you focus a lens to get a better view.

[redliox]

That cycler looks like it would take a few SLS flights to put it together, although on the plus side the DSH portion looks like either an inflatable or an SLS-derived module.  I will say it looks more feasible than the titanic cyclers suggested in the '80s under SEI.  Could a simpler version, consisting of just the SEP and DSP portions, be launched on a single SLS?

[NovaSilisko]

I do enjoy the cycler concept. You only need to impart that energy to the habitat once, then from there all you need to do is impart it to the crew vehicles, and supplies. SEP makes it even better, as you can much more easily do the required trajectory corrections to keep it on the right cyclic path.

[mike robel]

Buzz wrote a book about his concept.

[redliox]

I do enjoy the cycler concept. You only need to impart that energy to the habitat once, then from there all you need to do is impart it to the crew vehicles, and supplies. SEP makes it even better, as you can much more easily do the required trajectory corrections to keep it on the right cyclic path.

The disadvantage is all spacecraft that have to rendezvous with it need to be traveling fast enough to get to Mars anyway.  Nice for more living space, but if you miss it and don't have enough fuel to correct you're stuck in your capsule for 6 months.  I remember first reading about the idea when I was about 10, but when I began to understand the painful logistics the nostalgia and admiration for cyclers evaporated.

[gbaikie]

I do enjoy the cycler concept. You only need to impart that energy to the habitat once, then from there all you need to do is impart it to the crew vehicles, and supplies. SEP makes it even better, as you can much more easily do the required trajectory corrections to keep it on the right cyclic path.

The disadvantage is all spacecraft that have to rendezvous with it need to be traveling fast enough to get to Mars anyway.  Nice for more living space, but if you miss it and don't have enough fuel to correct you're stuck in your capsule for 6 months.  I remember first reading about the idea when I was about 10, but when I began to understand the painful logistics the nostalgia and admiration for cyclers evaporated.

If spacecraft missing reaching the cycler, one allow for the cycler to docking with stranded spacecraft.

So cycler could already have a earth return vehicle, docked to it before one sends a spacecraft to it.
And any spacecraft missing reaching the cycler, could have an "abort option" which is to send the return vehicle from Cycler to the stranded spacecraft and bring crew back to the cycler.

And/or Cycler has Ion Tugs, they could disconnect and retrieve the stranded spacecraft. Or both- get crew to cycler as quickly as possible, and one also gets the stranded spacecraft to the Cycler [so it can refueled to depart the cycler to go to Mars]. So what abort options depend upon would be if stranded spacecraft just lacks rocket fuel or crippled and unusable for some other reason.

A important aspect of Cycler is it has extra rocket fuel- or it's a fuel depot with lots of living space.

[FishInferno]

Buzz wrote a book about his concept.

And a good book it is too!  Although I am more a fan of Elon Musk's plan than Aldrin's, mainly because I don't want to wait until 2040 to put a man on Mars

[KelvinZero]

The disadvantage is all spacecraft that have to rendezvous with it need to be traveling fast enough to get to Mars anyway.  Nice for more living space, but if you miss it and don't have enough fuel to correct you're stuck in your capsule for 6 months.  I remember first reading about the idea when I was about 10, but when I began to understand the painful logistics the nostalgia and admiration for cyclers evaporated.

Not hitting your target is probably always not a good thing for BEO space missions*, but you probably would have less time to recover if in just a small capsule. Perhaps it should always carry enough to survive. With a cycler you might be able to perform a rescue since it must also have motive power. It might also have a back up capsule that could be sent out. This design seemed to have two.

A bigger problem for me is that my understanding is that cyclers are not free but take quite a bit of thrust to keep them on the right orbit. If they were entirely free you could build them up to be an entire space hotel with arbitrary levels of redundancy.. or if you could just keep the thrust down to a level manageable by a solar sail or mini-magnetosphere.

Another problem is that you need two, one for the trip there and one back I believe.
(edit: I couldn't spot this in the video though.. saw something about returning three of six crew from Phobos, which sounds odd. Surely if you have 6 crew you want the ability to return them in a single mission?)

*On that subject, does anyone know if trajectories to Mars are planned so that if at any time during the burn to leave earth is aborted, you are still on a trajectory back to earth? I once noticed that (ignoring the influence of earth and mars themselves) you could put a bunch of orbits through a single point on earth's orbit with ever higher excentricity, and every single one would also intersect earth's orbit a year later. With a series of SEP propelled depots on these orbits you could get to Mars rapidly and efficiently even on hypergolics.

[QuantumG]

Has Elon musk published an official plan for Mars missions equivalent to the level of the Project Aldrin-Purdue Plan?  I know he has ambitions for Mars, but I'm unaware of anything for Mars that is published or peer reviewed at a mission level. 

Nah. He's been saying for a few years now that the unveiling of MCT would include such a thing, but we're still waiting with baited breath.

[FishInferno]

Has Elon musk published an official plan for Mars missions equivalent to the level of the Project Aldrin-Purdue Plan?  I know he has ambitions for Mars, but I'm unaware of anything for Mars that is published or peer reviewed at a mission level. 

Nah. He's been saying for a few years now that the unveiling of MCT would include such a thing, but we're still waiting with baited breath.

He says they will release their plans by the end of 2015

[QuantumG]

Has Elon musk published an official plan for Mars missions equivalent to the level of the Project Aldrin-Purdue Plan?  I know he has ambitions for Mars, but I'm unaware of anything for Mars that is published or peer reviewed at a mission level. 

Nah. He's been saying for a few years now that the unveiling of MCT would include such a thing, but we're still waiting with baited breath.

He says they will release their plans by the end of 2015

He said that for 2014 too.

[Hanelyp]

Not hitting your target is probably always not a good thing for BEO space missions*, but you probably would have less time to recover if in just a small capsule. Perhaps it should always carry enough to survive. With a cycler you might be able to perform a rescue since it must also have motive power. It might also have a back up capsule that could be sent out. This design seemed to have two.

Rendezvous with a cycler is a matter of reaching it's orbit in phase.  Exactly where in that orbit you meet up isn't critical.  Of course the more precisely you can plan your departure the faster you can meet up with less delta-V.

A bigger problem for me is that my understanding is that cyclers are not free but take quite a bit of thrust to keep them on the right orbit. If they were entirely free you could build them up to be an entire space hotel with arbitrary levels of redundancy.. or if you could just keep the thrust down to a level manageable by a solar sail or mini-magnetosphere.

I've see cycler concepts based on near resonant orbits using gravity assist to make the needed phasing adjustments.  Ideally only a small delta-V is needed for the cycler itself to make minor corrections.  The difficulty is the delta-V needed to rendezvous at each end.

*On that subject, does anyone know if trajectories to Mars are planned so that if at any time during the burn to leave earth is aborted, you are still on a trajectory back to earth? I once noticed that (ignoring the influence of earth and mars themselves) you could put a bunch of orbits through a single point on earth's orbit with ever higher excentricity, and every single one would also intersect earth's orbit a year later.

Yes, there is a continuum of orbits through a single point, in a given plane, with the same period.  But I believe planning your burn so your path is confined to such a set of orbits will use a lot more delta-V, and is otherwise constraining for when you depart for a destination.  Better to have a fault tolerant thruster array and margin of propellant.

[R7]

9) Return crew members from the surface of Mars via transfer to one or more Phobos bases... then back to Earth

Is the BA330 based crew return thingie launching from Phobos supposed to catch up with a cycler or travel to Earth as is? Just wondering what the Bigelow module is there for if former and the point of cyclers if latter.

[KelvinZero]

(1) I've see cycler concepts based on near resonant orbits using gravity assist to make the needed phasing adjustments.  Ideally only a small delta-V is needed for the cycler itself to make minor corrections.  The difficulty is the delta-V needed to rendezvous at each end.
...
(2) Yes, there is a continuum of orbits through a single point, in a given plane, with the same period.  But I believe planning your burn so your path is confined to such a set of orbits will use a lot more delta-V, and is otherwise constraining for when you depart for a destination.  Better to have a fault tolerant thruster array and margin of propellant.

I thought I had read different for (1) but can't find a reference. Im not convinced about the second. That inspiration Mars thing discusses a 501 day free return orbit as if it is a rare thing so there might be a more fundamental issue.. and the fact you apparently cannot always throw yourself at mars on a free return to earth is also why I am dubious of (1) being free.

[Hanelyp]

KelvinZero, free return doesn't fit what you described.  If the departure burn is aborted early it leaves you in an orbit that may not return to the planet of departure in short order.  But if the burn putting you on a free return trajectory is completed you will return to the planet of departure with no more than minor course correction.  The point of return may be elsewhere on that planet's orbit.

[KelvinZero]

KelvinZero, free return doesn't fit what you described.  If the departure burn is aborted early it leaves you in an orbit that may not return to the planet of departure in short order.  But if the burn putting you on a free return trajectory is completed you will return to the planet of departure with no more than minor course correction.  The point of return may be elsewhere on that planet's orbit.

That was my point. The 501 orbit (at a simplistic level of argument) is inferior in multiple ways: it takes longer, you do not get free return at any point, it is only rarely available.. but I don't hear other options even being mentioned.

My conclusion is that the simplistic argument for my 365 day orbit probably has more fundamental issues than inferior delta-v. I can't argue higher than that level so I can only really trust published solutions where someone else has done all the work and other people have reviewed it. No doubt someone has, somewhere.

[UberNobody]

Regardless of the pros/cons of cyclers, they are semi-permanent pieces of infrastructure in space.  The battle for long term funding is much easier when part of it is maintaining infrastructure.  Just look at ISS.  That funding stability is the secret sauce in Buzz's plan.  Once you get that, a Mars base is a lot closer to reality. 

Now that I think about it, a reusable SEP spacecraft qualifies as infrastructure as well.  Maybe that is the reason NASA is focusing on it.  Not because of its technical advantages (which are debatable), but because of the funding stability it brings.

We love to debate the technical merit of different plans, but we rarely look at what works best when ever changing government leadership is involved.

[UberNobody]

For some reason Congress does not want to buy a new car when it comes to going to Mars.  They insist on reducing costs but still want to use the old car.  I call this the "Six Sigma Syndrome".

So I would say that 'maintaining infrastructure' is ultimately going to be the enemy of doing something new and is risky/less stable.

Infrastructure is a double edged sword.  It maintains funding, but keeps you from doing anything new.  Right now, a big part of why we aren't going beyond LEO is because of the ISS and Shuttle infrastructure, both on the ground and in space.  We've sunk something like $150B into ISS, so choosing to deorbit it early is about as difficult as closing a NASA center (pretty much impossible).

Using serious infrastructure in a Mars plan, if done right (and you can get to that point), could prevent an Apollo style situation where everything is cut back and then canceled.

But of course, when you have a determined Billionaire as your leader, you don't have to worry about all that.

Buzz agrees with me that SpaceX is leading the charge right now when it comes to Mars.  I mean, hopefully NASA will get the green light on a real Mars mission, but our best hope currently lies with Mr. Musk.  Let's see how far he can take us