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150MT is so that hard, the Ares-V hits 130MT and its the biggest practical rocket to build without serious new infrastructure and having to start from scratch. And razor thin margins are a plan for disaster! What happens if the mission winds up absolutely needing 160MT? You can't make MarsDirect any smaller!
But even then, suppose it does work, MarsDirect will never be good for anything except direct flights with small payloads or crews and no option for growth or upgrades. I also think that the baseline MarsDirect is a bad deal as far as what science you get for the amount of trouble.
I disagree.
As a followup to the basic Apollo program Von Braun had plans for upgrades to the Saturn V that would carry up to 250 tons to LEO and I believe were compatible with the existing KSC facilities.
And once you get a manned program to Mars going with regular flights every 26 months........THEN you find ways to upgrade the amount of men and material delivered to the surface.
You don't try to solve every problem and contingency before even the first flight is made.
Otherwise, we'll never get a manned mission to Mars.
I'm appalled at what I see as the steady growth in complexity of NASAs planning. Larger crews. More launches. Several in space rendevous.
I can't get over someones idiotic reasoning that a mission would have to carry at least TWO surgeons. Why? If one needs surgery, the other surgeon can operate on him.
I still think that the basic Mars Direct is the way to go.
Four man crew. Direct Earth to Mars flight. Direct Mars to Earth return.
Even if to get the necessary mass means you have to build a 150 ton to LEO capacity booster (not that hard to do) and cut the safety margins razor thin.
I think manned spaceflight could use some danger and excitement anyway.
Is NASA likely to stick with the six man mission rather than the four man that Dr. Robert Zubrin originally envisioned?
Finally got to revisit this, Football season is finally over so I have alot more spare time.
I was wondering. If the sleeping quarters of a rotating interplanetary spacecraft as I'm envisioning here were kept at 1G, then how much additional exercise would the crew have to do to prevent bone mass loss given they would be spending at least say 10 hours or so under the influence of 1G?
I know the return to the moon architecture is the CEV and lunar landing being launched separately, docking in orbit, then going to the moon.
But I don't recall what the last version of the manned Mars mission architecture looks like?
Last I heard it was basically Mars Semi-Direct with six launches.
Three launches orbiting the Earth Return Vehicle, Mars Ascent Vehicle, and the Mars Hab that functions as the mission module on the outbound trip and on Mars surface.
These three vehicles are supposed to dock with three nuclear powered upper stage launched separately into Earth orbit.
I can't remember that ever being updated.
What is the latest?
Me? Hmmmm... as far as more-or-less present propulsion goes, you have basically three options:
-Gas Core Nuclear Rocket (GCNR)
~3000-5000sec ISP
~Uses Hydrogen for propellant
~No special fuel tank required
~Fuel tank is still bulky
~Engine is relatively light weight
~Uses small amounts of nuclear fuel-Nuclear Salt Water Rocket (NSWR)
~10,000sec ISP(?)
~Uses water laced with Uranium for fuel
~Requires special neutron-absorbing fuel tank
~Fuel tank is compact
~Uses lots of nuclear fuel
~Engine requires heavy blast shield/pusher plate
~Would only require a fuel heater-VASIMR (Variable specific impulse magnetoplasmic rocket)
~10,000sec ISP
~Uses Hydrogen for propellant, consumes no Uranium
~Bulky fuel tank
~Only moderate thrust, bad maneuver/departure
~Requires massively powerful but light nuclear reactor
~Generates lots of excess electricity when not firing
~Engine itself is heavy due to magnets, cooling
~Questionable reliability due to complexity
~Generates powerful magnetic field, may shield the shipNeither engine really has sufficent performance for a trip to all the outer planets with a single load of fuel, but if refueling at each destination were employed then you could do it in a reasonable time frame provided you didn't stay at each destination too long. The ship would retain enough fuel for an abort back to Earth at all times.
Which engine you use depends, a GCNR or VASIMR engine would need to break down water into Hydrogen and liquify it but would have to lug little Uranium and its performance is so-so for this kind of a trip (GCNR lower efficiency, VASIMR lower thrust). An NSWR engine has much more kick to it and would only need liquid water, but refueling at each stop would be less effective due to the mass of Uranium salt required, so its a trade off.
For this duration of a mission, a ship full or partially spinning would probably be a must. Perhaps a combination of RLV and Ares-V class flights:
Ares rockets bringing up the "engineering" section, the manned "core" section, and the workshop/storage/instrument section. It would also launch two chemical-fueled landers.
The RLVs, probably two-stage spaceplane, would deliver:
-the fuel tanks, or just water in NSWR
-bolt together ring compartments, unfurnished
-two pressurized tunnels connected to the "core"
-supplies, furnishings, space suits, tools, and probes
-airlock (if seperate from workshop)
-emergency reentry vehicle (in case Earth capture fails)
-uranium for NSWR, or radiators for VASIMR
-water collection equipment for refuelingThe engineering section, containing the engine, power reactor, and fuel condenser (in GCNR & VASIMR) would be mated end-to-end with the "core" module and finally the workshop/storage/etc. The core itself would be heavily radiation shielded and contain the command equipment/life support/etc and ports for the ring tunnels and ancilliary modules. The workshop/storage section would contain the science & surface gear as well as docking facilities for the landers.
The ring would have thin, fairly small spaces probably little larger than a train car to minimize the mass as it will have to be fairly wide to negate the coriolis force to any degree. I envision a crew of six to eight each with their own cabin (with extra rad-hardend bed)/office, some laboratory spaces, galley and so on. Since the ring will be wide for the coriolois force, it will probably have excess volume where bulk foodstuffs would be kept.
In the event of a solar storm or when traveling through Jupiters' radiation belts, the crew would have to stay in the heavily shielded core section for the duration probably, but the ship could perhaps spend most of its time on the outermost Gallilean moon that resides outside these belts.
The ship itself will be capable of landing tail-first, which should be easy on slow turning moons with low gravity, in which case the ring will stop its roation probably and landers parking nearby until the ship reenters orbit. It will land to make gathering up water for refueling easier and skip having to shuttle it back and forth from the mother ship. The VASIMR's magnetic field is kinda attractive though.
You sure know your stuff.
I've got to print that out.
Well, then its a good thing nobody is going to suggest using mostly expendable ships in the "long run."
In the short run though, before we are ready to do anything more than exploration and "beach head" building, smaller mostly expendable vehicles make good sense.
So-called "comprihensive systems" with "all the spacefaring nations" is a Star Trek pipe dream. We'll never get along politically enough nor engineering wise enough. There is no one-size-fits-all solution, that the best way to get to the Moon and Mars with and without a base are different, and since a large "comprihensive" system takes a much bigger commitment than the smaller one, which makes it more likely travel to these places will actually start.
GEO orbit is way too high, there are presently no practical alternatives to chemical rockets to get into orbit, and so you want to rely on these as little as you can versus more efficient engines (ion, nuclear thermal, etc). This means the lower the orbit the better, plus you can't aerobrake into GEO.
Why will building a space station make travel much easier? You still need the same amount of rocket fuel, which is the real problem. The issue is where you get the fuel from, that if all or at least a majority of the propellant needed for landing and return is made from the destinations, then you save huge amounts in launch costs.
Just building a space station doesn't give you this, so the first priority should instead be to build fuel depots on Moon/Mars. One we have these, and we are ready to do more than explore the inner solar system, then we can talk about reuseable launch vehicles and space stations, but not before.
Interesting GCN.
You know a great deal about propulsion systems.
If you were called on to design an interplanetary spacescraft to take a dozen or so astronauts to multiple planets in a single multi year mission........what do you think you would end up designing?
I wonder if some kind of downsized and cheaper version of JIMO might be possible?
Perhaps with chemical propulsion, aerobraking at Jupiter, and using large RTGs to run a smaller suite of instruments.
Its been six months.
Any new information on either of these possible projects?
The half billion dollars is still better spent on a replacement.
Whenever I hear that I think of NASA scientists being so unconcerned with Skylab being destroyed because "we'll have a bigger and better space station in orbit before long".
It took more than 30 years.
If the current Ares is too small for Mars Direct just do one of two things.
1) Build a bigger booster. Not hard. Just a matter of funding.
2) Go Mars Semi-Direct. Use three Ares launches to send the necessary equipment and crew for each Mars mission.
No show stoppers.
Given its retrograde orbit around Neptune and geysers on the surface, Triton is probably the most interesting.
Can I assume you are not going to turn Jupiter into a Star?
I had not planned to.
I haven't gotten back to this in awhile.
But I decided to add tension to the book by having a major Earth wide military conflict break out while the ship is at Callisto.
Not one that would endanger the crew returning to Earth, but one that disrupts communications (conventional cruise missile attacks on Kennedy Space Center and Johnson Space Center) and rises tensions among the crew of which I have three international members. One from ESA, one from Russia, and a Japanese astronaut).
Finally, my book needs a catchy name.
Jellyfish do not chew their food.
After some misconversions between Imperial and Metric units, the explorers begin skipping like a flat stone across the top of Jupiter's atmosphere. Finally landing in the middle of the giant red spot. The giant jellyfish get an out of planet delicacy. Digesting the humans slowly to extract all the information, a Jupiter technological revolution is started.
Fortunately the Jupiter Jellyfish need high pressures to live and cannot invade Earth directly, but humanoids, remotely controlled, start to show up. Even the Earth Global Empire is suspected to be directly controlled from Jupiter. Hence the long delay between ideas from it's leader.
I really didn't consider the possibility of finding higher lifeforms to be likely.
Well, I'm a starry eyed optimist that hopes (and prays) that once we get away from LEO again that things will really start happening.
Radiation is much less an issue if you limit the crewed mission to Callisto and telerobotically explore the other moons and Jupiters atmosphere from there.
And yeah, the prestaging idea is a very sound and reasonable one.
My book about a mission to Jupiter envisions a mission launched around 2033. Not too many years after the first manned Mars missions.
I've read that using nuclear electric propulsion, it would take about 27 months to get to Jupiter.
Assuming 27 months there, and 27 months back, what would be the minimal stay time at Jupiter (on Callisto specifically)?
Also, I envision my mission as having 12 astronauts (6 flight crew, 6 science crew).
I also figured about 500 to 600 tons of spacecraft and crew delivered to Callisto.
Would this be enough?
and assuming 500 to 600 tons of spacecraft and crew delivered to Callisto by nuclear propulsion, how large would the spacecraft have to be leaving Earth orbit?
Note, the mission utilizes in situ resources on Callisto for both life support and fuel for the return trip.
Finally, my book needs a catchy name.
Help?
Bimodal Nuclear Rocket
VASIMR-Variable Specific Impulse Magnetoplasma Rocket-developed by Franklin Chang-Diaz and often mentioned for propelling a manned Mars mission
MPD-Magneto Plasma Dynamic
&
MTF- Magnetized Targeted Fusion
are four propulson concepts mentioned on the HOPE website (Human Outer Planets Exploration) that could potentially propel manned missions to Jupiter and beyond.
Which of these propulsion concepts is the closest to reality and which would be best in terms of payload and minimizing mission time?
I read somewhere that a lightweight "New Horizons" type mission has been proposed for Uranus.
And that a larger, far more elaborate nuclear powered orbiter mission to Neptune similar to the Jupiter Icy Moons Orbiter was in the planning stages.
Any substance to these?
Economic reasons will never get the public support the space program needs.
The American public has for two many decades heard about "billion dollar" missions and such that it won't happen.
We could be bringing back payloads of gold bars every mission and Americans still wouldn't believe that it was profitable.
The best things to push space exploration are probably tourism and nationalism.
We space advocates love to fill up the other forums here. Talk about technology, mission architectures, precursor missions, colonization, terraforming..............
all that.
But it seems to me that the Political Outreach forum is the one in desperate need of new ideas and thoughts. Because the political problems and obstacles are a greater challenge to space exploration than any of the technological ones.
Thoughts?
Lets send John Young.
Hes not dead yet is he?
Ah the cyclers...
Cyclers are elegant conceptually, but are never going to be practical.
First off, transit times are too long. If we want to have an interplanetary civilization, waiting months or years for a cycler to pass and many months more for it to transit is not going to work out.
The cycler doesn't, and I want to put this in big bold letters for emphasis, does not reduce the amount of fuel needed to get anywhere, only the size of vehicle required for manned transit. If the cycler is on a free-return trajectory, then your "little shuttles" have to be on a free-return trajectory too to dock with it.
Crew shuttles have one massive elephant-in-room problem too: if you fail to rendezvous with the cycler, and you don't have enough supplies to last the whole trip onboard (unlikly since its a little day-trip shuttle), then,
A: You are all going to die. Badly.
B: You have to carry along a MASSIVE amount of rocket fuel for a direct abort back to port.So, given the low speed and flexibility of a cycler, I don't think they make sense.
I agree about the Cyclers.
In the Cycler concept I see the reasons that NASA used to trumpet the shuttle program.
"Build this and costs will go down".
I didn't think that Quail hunters in Texas were required to wear orange vests.