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Well, I guess I'll have to go back and defend Mars Direct yet again.
1) The assumption that a crew of four CANNOT accomplish the goals of an initial mission is flawed. Two scientists on Mars for 18 months in constant consultation with scientists on Earth and a ton (literallyl) of equipment can do a great deal of usefull work.
2) I think Mars Direct (as initially designed) is workable. Sure, it allows little margin for mass growth, but who is to say that mass would inevitably surge?
3) Mars Semi-Direct (as initially designed) is CERTAINLY workable given its more generous mass budget. The three launch variety that is.
4) If the Ares booster as designed isn't big enough. Just build a bigger one. A booster utilizing four SRBs, and five RS-68s in the first stage has been estimated to be capable of 450,000 to 500,000 lbs. to LEO. This is CERTAINLY enough lift capacity to launch the original Mars Direct. MOST CERTAINLY enough to do the mission using Semi-Direct.
5) There is no reason such a large booster need "break the budget" when it comes to development. It requires no new engine development which is one of the driving costs of larger boosters.
6) Politically, seven launches for each mission is a nonstarter.
REGARDLESS of what advantages it has, seven launches makes the mission look hideously complicated and excessively costly.
Back to the original thread topic now.
An interim measure might be to cancel usage of two of the three orbiters. Use only the one that is in the best condition (Endeavour probably). Use the other two for parts (and new lawn ornaments) That gives us one orbiter still to use on occasion for vital missions (such as Hubble repair) and for the OCCASIONAL trip to ISS (just to keep our oar in for a few years).
Use the last shuttle for a maximum of three missions per year.
Six launches (seven if you use a CEV to deliver the crew to the Mars vehicle in orbit) is still way too many.
Why not just build a huge booster? Large boosters are nothing new for NASA. There were designed variants of the Saturn V that could put up to 1 million pound (500 tons) into LEO.
One of the major points of Mars Direct was "no orbital assembly"
Because, thats SEVEN launches within a probable one month time frame at most in order to get everything in orbit for the window to open for a trajectory to Mars.
Unless you want six separate pieces of ONE mission orbiting the Earth for months until you decided tro start connecting them.
Bottom line. More launches. More risks. More costs.
Yes GCN, I DO DISAGREE with NASA.
I'm in agreement with the guy who wrote "Lost In Space:The Rise and Fall of NASA" that after Dr. Robert Zubrin presented Mars Direct to Nasa that NASA DELIEBERATELY set out to make the mission architecture far more complicated to avoid encouraging a manned Mars mission from becoming their primary mission.
I believe NASA officials are terrified of being ordered to undertake a manned Mars mission because it would probably be the end of the station and shuttle programs.
The Nasa staff is old. They don't want to rock the bot just a few years before retirement.
GCN, your mission architecture makes alot of sense.
From the MARS end of it.
From the Earth, Kennedy Space Center end of it though. It makes NO sense whatsoever.
You're talking about, for a mars mission SEVEN thats SEVEN launches from Earth. Thats SEVEN assemblies in the VAB.
Thats SEVEN trips by Hans or Franz to the launch pad.
SEvEN on pad fuelings, checkouts, countdowns, and launchings.
FOUR in space rendevous.
No way.
Three launches from KSC for each Mars mission.
Or none at all.
Thats the way it goes.
Sorry GCN,
Your proposal is attractive, but there is no way NASA will ever be authorized to do a Mars program that takes SIX launches per mission.
Three maybe (Mars semi-direct) two preferably.
Launches from Earth are when the most things can go wrong with the program. You've got to minimize them if at all possible.
If that means putting together a 500,000 lb. to LEO capability booster, then so be it.
Its my understanding GCN, that the NTR third stage that would be integrated into Mars Direct utilized one of the smallest NTR engines proposed and that it wouldn't be ignited until well after reaching orbit.
Now back to Mars Direct, I understand you in regards as to what you see in the inefficiency of sending the entire ERV to Mars surface.
But I think the inefficiency is more than balanced by having the entire ERV apparatus on the Martian surface, accessible to the astronauts, who if they found some kind of damage or mechanical fault would have a realistic chance at repairing or bypassing the damage.
This is opposed to Semi-Direct (NASA Reference Mission) in which you are parking the Mars Transfer Vehicle in orbit and hoping nothing goes wrong in the two years or so before you need it.
As for reusability.
You've got to be kidding.
Even if we launch larger Mars Missions with longer stay times to build a base, the launch rate is still going to be something like once every 2 years.
That launch rate does not justify reusability.
If Earth orbital mission don't justfiy reusability, then manned Mars missions most certainly do not.
Oh I'm all for NTR engines GCN. NEPs and eventually fusion engines as well.
But I do think Dr. Zubrins worries that such a development program would bring too much criticism to a manned Mars program early on were valid.
WERE valid.
I'm not sure now. Ever since the 2001 California energy crisis, Americans seem somewhat more accepting of nuclear power.
Incidentally, GCN, I'm very familiar with your concerns about the inadequacies of basic Mars Direct.
With NTR engines, the amount of mass landed on Mars using Mars Direct would increase by something like 50%.
Thus, do you see NTR as making basic Mars Direct (two launches, direct to Mars, direct back, four astronauts) viable again?
As I'm sure you're aware, Dr. Zubrins Mars Direct is modifiable to incorporate NTR engines as soon as available.
No offense GCN but your obsession with nuclear thermal engines makes you sound like Stanley Borowski.
If the Russians want to continue building and flying Soyuz capsules for the manned missions to orbit, lets just do that.
Lets be honest, most ISS missions were planned to be 4 month tours. Thats three manned launches per year.
Double that, and its still only six manned launches per year.
That kind of launch rate will NEVER justify a reusable shuttle system.
Just one note. Max Faget did try to get a major shuttle redesign post Challenger.
Replacing the SRBs with dual F-1 engined liquid fueled boosters.
Moving the SSMEs to the base of the External Tank.
Basically, converting the shuttle stack into Energyia/Buran.
Don't know if this would've helped the shuttle system but it couldn't have hurt.
You know whats really ironic?
The shuttle disaster that Michael Collins and numerous others have feared for decades, a main engine explosion, is the one that hasn't even happened yet!
An engine explosion that takes out the other two engines and probably causes the entire aft end of the orbiter to disintergrate...might never happen.
Or it could happen the very first return to flight mission.
I just can't see what people who work at NASA expect. Do they REALLY think they can keep flying orbiters, year after year after year after year after year....?
Or is it a case of "Just keep flying the shuttle until I can take retirement"?
I was reading the book "Lost In Space", about the rise and fall of NASA and what struck me was this:
How much better it would be for NASA if the President simply ordered the Space Transportation System canceled. With Discovery, Atlantis, and Endeavour mothballed and put on display somewhere.
Currently, NASA clings to the shuttle program and by extension ISS like a man who can't swim with only one buoy within 1,000 miles.
Some observations:
1) We could still send astronauts and modules to ISS by simply paying the Russians to do it. We'd still have people aboard ISS and this would allow us to keep up our committments to ISS as well as paying the Russians still.
2) There would be a mad scramble in NASA and the Aerospace industry to find uses for remaining shuttle tech.
The only logical solution would be Mars Direct or Mars Direct derived long duration lunar missions as both could use SRBs and modified ETs for their launch vehicles.
3) NASA has tended to do better when challenged politically.
When Congress balked in the late 1960s at funding the "Grand Tour" space probes to the outer planets, NASA simply designed a slightly less capable set of probes that proved to work brilliantly (Voyager I & II) as well as a set of precursors (Pioneer 10 & 11) .
When the Reagan Administration canceled the Venus Orbiting Imagine Radar (VOIR), NASA responded by cobbling together Magellan which performed well.
Anyone think canceling the shuttle progam immedately is a good idea?
I've about settled on a "Super Ares" design with four, 5 segment SRBs along with 5 RS-68s on the base of a heavily modified External tank and a single RS-68 upper stage.
I've heard that the LEO capability would be something like 475,000 lbs. and payload delivered to the Mars surface would be something like 75,000 to 80,000 lbs.
I believe that is large enough for an Earth Return Vehicle supporting a five man crew adequately.
What would it cost? Probably on the order of 10 billion dollars. Spread over five years thats only about 2 billion a year. With each production model booster of around 1 billion dollars. Given you need an average of one booster built per year for Mars Direct, that is all well within NASAs current 14 billion a year budget.
Personally, I would plan on two "Super Ares" boosters per year so you could also launch long duration lunar flights and boost extremely large space station segments to LEO.
What I'm saying is that any bodily trauma bad enough to justify transfusion would probably not be survivable on Mars anyway.
With the exception of amputations of course.
After all, Lord Nelson had his injured arm amputated in a tiny rowboat rocking violently back and forth.
What would be the crew and cargo capacity of the mini-shuttle you mention?
4 person and no cargo at all, not even carry-on luggage. If an astronaut wants to bring personal items (like a toothbrush) the mass budget is 185 pounds for body weight plus luggage. One or more seats could be replaced with a duffle bag of cargo, strapped to the floor bolts that held the seat. Mass of bag plus cargo equal to one astronaut body weight, ACES suit, plus seat. Instead of a seat or duffle bag, it could carry a frame to hold science drawers for/from the science module of ISS.
I"d have preferred something that could carry a crew of five and perhaps at least 1,000 lbs. of cargo.
What distance must you get from the sun that radiation hazards from solar flares diminish considerably?
I think trying to plan for a "permanent presence" on Mars would be a fatal error in getting congressional funding for a manned Mars program.
A fair chunk on Congress would get rid of the manned space program altogether.
Many in Congress, seeing people talk about a "permanent presence" on Mars will see any approval of an initial manned landing as the "camels nose under the tent".
They will want a program they at least "think" they can cancel after a couple of manned missions.
That is one thing I like about Mars Direct. It holds out the possibility of a permanent base on Mars without making it an obvious goal for the initial program.
Why would you need a refuelable nuclear reactor?
Aren't the nuclear reactors being installed aboard Virginia class submarines capable of running "for the life of the boat" (that is 30 years)?
Could a smaller version of that type of reactor be built?
Even one that ran for 15 years without refueling would probably be worth the trouble on Mars wouldn't it?
What would be the crew and cargo capacity of the mini-shuttle you mention?
I think that once the crew reached Mars, having each donate a pint every two months or so would be practical and advisable.
Lets be honest though. I don't care if the crew has four or six, does anyone think that a surgical procedure severe enough to need a transfusion would be practical?
I can see a Mars crew performing an appendectomy. After all, the medical technicians aboard U.S. Navy submarines are theoretically capable of performing one if the sub can't return to surface for tactical reasons They might be able to deal with kidney stones and other painfull but handleable medical situations.
But I can't see them doing a transfusion.
I reason I mentioned artificial limbs is that even aboard Horatio Nelsons Royal Navy ships of the early 19th century amputations were done and crude "hooks" and "pegs" were fitted in place of arms and legs.
You'll notice I started with Mars Direct, tried to address what I perceive as weaknesses (ERV too small, and dropping it on Mars surface is a waste of fuel), and updating it with new technology developed in the last 14 years. What I ended up with is very similar to Mars Semi-Direct, except it uses the MAV as the TEI stage. That's what's called Mars Hybrid Direct, my preferred plan. Fuel saved by not dropping the ERV on Mars permits a larger return vehicle, no need for a larger booster. It also permits a reusable ITV, and can be easily assembled with medium lift launch vehicles like Delta IV Large. You can always build a bigger launch vehicle, but who's going to pay for it?
In Mars Hybrid Direct then, since all the fuel must be manufactured on the Mars surface, then the Mars Ascent Vehicle must hard dock with the Earth Return Vehicle and then use its engines to propel both back to Earth Orbit right?
Perhaps its a better plan. Who can say.
But for gods sake can't we all one or another just agree on a plan and lobby for it?
How big a crew? Can we all live with 5?
Conjunction flight plan? Can we live with that?
No more than three launches per mission? Can we live with that? Note, I'm not including the shuttle or crew return vehicle flight that takes the astronauts back down to Earth after the mission.
How much scientific equipment can we carry along? Can we do the job with one metric ton? Two metric tons? Three?
Whats the total mass of samples we wish to be able to return with?
I hope the time between the first manned Mars mission and the one to Callisto is considerably less than between the moon and Mars.
^So is it my understanding Robert that your preferred mission plan is Mars Semi-Direct rather than Mars Direct since if I read it right, you are advocating parking an unfueled vehicle in Martian orbit?
Or, are you advocating Mars Hybrid Direct in that you want all the return fuel manufactured on the surface?
Once again, I say this the original Mars Direct I believe is the best mission plan.
Now, you can want a more massive Earth Return Vehicle with greater room for mass growth.
You can want a six man instead of a four man crew.
If thats the case, why jack with the mission plans at all? Just build a larger booster in the first place?
I hate to use the metaphor, but when we talk about building a larger booster than the Ares, its not really rocket science. Its easily doable from an engineering standpoint.
It was mentioned somewhere once that a serious leg or arm injury on Mars during the 500 day stay there might require amputation.
If such an amputation was required, the crew member would be able to do far less work during the remainder of the mission. Greatly increasing the burden on the remaining crew members.
Might it be worth it to design and include four artificial limbs for possible use by the crew during the mission?
Two arms/hands-one for above the elbow amputations and one for below.
Two legs-one for above the knee amputation and one for below.
They might not be as advanced as what could be fitted on Earth, the emphasis would be on making them as easy as possible to use and attached and adjustable for the different members of the crew.
If they enabled an injured crewman to do nothing but basic housekeeping, they might be worth it.
David S.F. Portree has written such a book. I think the short title is "Humans to Mars" and it may still be available, for the cost of postage, from the government printing office.
I can't seem to find the book available anywhere.
Was it heavily illustrated?
I'm tempted to try to write a book myself. I have a list of some 18 different mission architectures that I've accumulated information on, including Mars Direct, Semi-Direct, Hybrid Direct, Nasa Reference Mission, Martin Marriettas Straight Arrow Approach, the "Split-Sprint" plan, Mars Visitor, and Mars 2000 and many many more.
But I"m not a writer. Beyond suggesting chapters and topics, I've never accomplished much beyond that.
And I"m certainly no engineer or scientist. Just a high school history teacher and unsuccessfull football coach.
I would enjoy seeing a book, heavily illustrated that detailed as many manned Mars mission plans and architectures over the years. Including early NASA plans and various Soviet and Russian concepts over the years.
I think such a book would be extremely interesting.