The magical thinking behind it:
This mission requires more magical thinking than a leprechaun trying to predict the track of a flock of flying unicorns on their annual migration.
MPCV employs a heat shield designed for lunar return and its CM is ~20% (thousands of pounds) overweight for its parachutes. But we’re going to equip MPCV with an even heavier heat shield for Mars return and magically it will be capable of a safe Earth landing?
There’s practically no element of the ISS ECLSS that lasts more than a year. But magically every component will remain operating for 17 months in a new vehicle when applied to a Mars flyby mission?
ASAP is warning about the lack of an ECLSS shakedown on MPCV before sending astronauts around the Moon for a few days. But magically we’re going to decide that the ASAP membership are all wimps of the highest order and decide to risk astronaut lives for 17 months on the first shakedown of the MPCV ECLSS?
At best, SLS is scheduled to have an upper stage capable of launching this mission a half decade after the mission’s 2021 window closes. And magically that half decade of development is going to be accelerated by more than a decade?
Congress can’t find funding to perform testing like AA-2 or to finish development like MPCV ECLSS in a timely fashion, and the White House is wrapped around the axle of ARM. But magically billions of dollars of federal funding are going to appear in a timely manner to develop a new ECLSS, a new hab module, a new heat shield, and a new upper stage for this mission?
If Tito really wants to see this happen, he has to give up on getting NASA to pay for it, and for it to happen with NASA hardware. He needs to sit down with SpaceX and Bigelow.
Its easy to have magical thinking when everyone involved knows it will never happen. Its just an excuse to keep the pork flowing until the next administration comes into office and sends NASA off into some other direction.
What is the value of a manned flyby? It’s “spam in a can” of the worst kind. Except it’s multi-billion dollar spam in a can which exposes the crew to serious risks for no benefit. I hope that SpaceX is able to develop their MCT fast enough to shut down these silly fantasies and put SLS where it belongs, in the junkyard.
I think the SLS Mars flyby is quite doable if we change our astronaut selection criteria. There are a lot of people we could send who are under three feet tall. Verne Troyer (Mini-Me) is only 31 inches. For such small astronauts there would be a relative doubling of the diameter of the Orion, and of course an eight-fold increase in its relative pressurized volume. That could eliminate the need for a separate habitat section and its attendant mass, along with greatly reducing the amount of consumables required.
Capital idea George!
I should also point out that, given the stated intention of Tito and the other Inspiration Mars folks to defray at least part of the mission’s expenses with sales of media rights, shows featuring Little People have an established multi-year track record of drawing passable ratings. And the Little People on these shows weren’t even zooming around in outer space! If earthbound Little People doing ordinary stuff are already ready for primetime, then Little People floating around, weightless, on the way to Mars and Venus should be a cinch to draw big numbers in the overnights and sweeps. More bucks for Little Buck Rogers!
Heheh, now there’s some high-tech dwarf tossing!
I suspect you could strip a lot of weigh out of the capsule if you removed two of the seats and restricted the crew size to two. If you only need the capsule for the last few hours, you could likely strip even more.
You could strip everything unnecessary out and cram it into the hab before you ditch it. l also think 1,000 of that 5,000lbs is in the service module and should not effect the re-entry mass.
The Heat Shield may not be as bad a problem as you think.
If the Heat Shield design on MPCV is an ablator, it should be designed to burn down to an “End Mass
or Thickness”. So while it would be heavier at the start, it should be the same mass at the end.
Now, how risky is that approach and designing that ablator, well, I don’t even want to guess.
“If Tito really wants to see this happen”
The proposals look good and they sound good to anyone but the alpha nerds that are capable and knowledgeable enough to find the significant technical flaws that will prevent it from ever happening. And that should be your answer right there. Smoke and mirrors.
I see no technical reason it can’t be done Wodun, just not for the costs and the mass budget Tito is proposing.
You can’t lock two people in a phone booth for a year and a half. You need room and you need redundancy.
Rad issue? Personally, I think it’s overblown.
http://www.scientificamerican.com/article/radioactive-omission-where/
“just not for the costs and the mass budget Tito is proposing.”
Exactly. This is all just PR.
“Rad issue? Personally, I think it’s overblown.”
It can’t be that overblown if you need to take those kinds of pharmaceuticals to mitigate it. 🙂
The reason this mission is being proposed has nothing to do with plausibility, and everything to do with politics.
It gives SLS/Orion what it currently lacks; a “wow” mission to justify its existence. Sure, SLS and Orion can’t do it, but it’s politically convenient to pretend that they can.
Nature abhors a vacuum. In the absence of any real mission for SLS, many people will cast about with cool PowerPoint missions. It’s more indication, as if anybody needed it, that the lack of serious payloads for serious missions means SLS is truly a rocket to nowhere. After EM-1, will the remaining SLS launchers end up as museum pieces like the last Saturns, never flown?
This mission is nonsense. The asteroid mission at least prototypes technologies required for long term manned habitation of space. This one is useless.
NASA needs to spend less resources on launchers and more on payloads.
In my conversations with some of the principals, I have learned that the earth entry velocity for the Mars-Venus flyby is one of the biggest selling points. They were worried about being able to handle the Mars only entry, but the Venus mission is well within Orion capability.
Any idea what the reentry speed would be? I can’t seem to find it anywhere.
> Any idea what the reentry speed would be?
A little over 14 km/s, nominally 14.2 .
http://www.aiaa.org/uploadedFiles/About-AIAA/Press-Room/Key_Speeches-Reports-and-Presentations/2013_Key_Speeches/Inspiration-Mars-FISO-Presentation2013-04-03.pdf
Thanks Egad, but that’s for the 2017 launch window (And that 14.2kps is well over Orion’s planned lunar-return velocity capacity of 11kps)
What I can’t find is the 2121 proposed trajectory reentry speed. It’s a different trajectory as it’s a Venus flyby as well, and gets a grav assist from Venus, and then does a flyby of Mars. Inspiration Mars 2017, on the other hand, didn’t encounter Venus.
What I’m trying to figure out is how a lower reentry speed than the 2017 mission profile’s is even possible? I simply cannot see how the vehicle can gain (compared to the 2017 course) kinetic energy from a grav assist AND have a lower reentry velocity.
Does it gain speed from Venus or just get its trajectory altered? It could potentially get its trajectory altered and lose speed too depending on which side of the planet it approaches, the leading or the trailing and the distance it passes.
@M Puckett
The trajectory, *assuming it’s being shown accurately* is for an overtaking approach to Venus, so it’d be getting a grav assist. How much depends on a the exact trajectory, speed, and approach distance, but it’d have to get some.
Perhaps they’re just ignoring this issue the way they are the launch vehicle and life support issues. 🙂
I thought the Ames Trajectory Browser would give Earth-Mars-Venus-Earth trajectories. Maybe it does, but it’s my own lack of skill leading to it not doing so:
http://trajbrowser.arc.nasa.gov/traj_browser.php
Just curious what people think: If they ever do build SLS, and assuming that there isn’t a much cheaper Falcon Heavy in operation, what would stop space colonizers from hiring SLS to just keep bringing a whole lot of rocket fuel and other useful materials up there to a depot or such? I mean, is the incredible cost of one SLS mission because it only flies once a year or something and even then no one has a mission? Or could you bring the cost way down just by finding something useful for it to do more frequently? Once they have it developed, could they fly it often if someone wanted it to?
There are no conditions in which SLS would ever be affordable to anyone except a (foolish) government.
The constraint on flight rate is production capacity for SLS components. My understanding is that the Michoud plant can only turn out two SLS first stages per year. Even if cost-free payloads could somehow be found, the variable costs for SLS are in the high hundreds of millions. With the pro-rata cost of R&D added in, total cost per mission is in the billions.
Remember you do not have a stream lined, commercial, launch process but a launch process dictated by “how many jobs does this mean for my district?” “Wait, I think my district should be represented at the launch also” etc etc etc .. So even though it will only launch once per year, you are going to pay that army for a full year to stand around until the next launch and create some make work for them to keep busy until that next launch.
If all they are doing is making things up for PR purposes, why not use a plan that could actually work? Afraid someone might call their bluff?
Wodun… my guess is that the reason they aren’t going with a plan that could actually work is they can’t. There is no such plan that SLS can actually do that has the “wow” factor they’re looking for. The closest they can come is towing a pebble (tiny asteroid smaller than the vehicle) to lunar orbit so SLS/Orion can send a crew to it.
So, as there’s no mission that SLS can actually do that meets their criteria, the logical step, from their POV, is to pretend an impossible one is possible.