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I agree that we need an interim heavy lifter that can be built with minimal modifications as soon as possible. Energia is a possible solution, but the infratructure has deteriorated so much that SDV might be cheaper because most of the components are in production. Perhaps the Delta or Atlas 5-meter payload shroud could even be used (with minor modifications) on the SDV to reduce costs for commercial and non-manned payloads. Adding a 5th segment to the SRBs would also be a growth option with minimal development cost.
If a manned Mars program has a launch rate similar to Apollo, it would justify using an interim heavy lifter (like an SDV) instead of a new design. But a few Mars Direct-type missions should be viewed as a foot in the door that might call for more frequent launches and a true big dumb booster. After all, a permanent base will need to be re-supplied. The more supplies, the better.
Both Ares and Vulkan would require considerable new development because the cores of those boosters were not designed for an axially-mounted payload. My belief is that the money to redesign these existing launchers would be better spent towards an entirely new design that eliminates the flaws inherent in the older designs. Yes, we would be spending more money to build something new. But this is a long-term investment in our future that offers room for new growth.
There have been numerous debates raging in this forum about building a shuttle-derived vehicle or reviving the moribund Energia to launch a Mars mission. While both these options are viable for a crash-program for getting to Mars, an all-new heavy lifter is needed for sustained exploration of space.
Both the shuttle stack and Energia were optimized for launching a laterally-mounted, 90 tonne spaceplane. This is not the way to maximize your payload. Starting from a clean slate of paper, the rocket designers would draft something where the engines, payload, and propellant were all in a straight line. The SDV and Energia would have to be redesigned and re-stressed to meet this payload configuration. And the SDV has the disadvantage of having its engines off-center and gimballing to match the thrust vector.
Strap-on boosters are also a problem in the event that one engine should fail. We've seen how bad an SRB failure would be. An LRB failure would cause a loss of control in the vehicle. It would be better to have just one first stage, like on the Saturn V, but perhaps dropping some booster engines on the way to orbit like the Atlas.
My "ideal" HLLV would look much like the Saturn V, except that the rocket would have only two stages. The first stage would first run on Kerosene, then drop its four booster engines and run on Hydrogen for the sustainer engines. The second stage would send the payload to the Moon, Mars, or an asteroid. Heavier but cheaper tankage would be used, making this rocket truly a "big dumb booster."
If OSP i built before 2008, it will not have wings.
Early on in the program, Boeing has promoted an upscale version of the X-37 as their OSP. But the X-37 will not fly in orbit until 2006. Do they expect two years to be sufficient for building an enlarged, man-rated version?
That's why Boeing is also planning on an Apollo-like capsule. It remains to be seen what the new Lockheed-Northrop team will come up with.
Most of the Mars missions that have called for nuclear power have specified using the SP-100, a 100 kW reactor.
This poll would be more accurate if it was "semi-ballistic re-entry" versus "lifting re-entry." A lifting body has little or no wing area, but it behaves much like a winged craft.
I was surprised to learn that the encapsulated ejection seats for the Hermes space plane were designed for use at Mach 6 and 100,000 feet. Truly incredible, and hopefully they can be put to use in OSP.
To meet NASA's new requirement for crew escape, it is probably required that the vehicle have some sort of titanium cabin that will survive a Columbia-type descent until it reaches ejection speed and altitude, at which point the crew will punch out. These systems will make the vehicle heavier, but a crew of only four should give engineers some leeway to design a robust crew escape system.
Still unsettled is whether the booster rocket will use solid boosters. The small solids used on the EELVs are more dependable than the large segmented solids on Titan and Shuttle, but they're still not totally dependable. Still, it may be necessary to use solid boosters to avoid the expense of launching the craft atop an expensive Delta IV heavy.
I totally agree that it's easier to re-use vehicles that operate only in the space environment. Vehicles that must return to earth must have heavier structures and heat shields to survive re-entry. The problem with re-using lunar shuttles and other vehicles of that nature is building the infrastructure to refuel, inspect, and repair them.
The bill insists on using the earth-moon libration points as a gateway to lunar orbit, and views lunar orbit as a gateway o the moon. I feel that the specifics of an earth-moon transportation system should be left to the project engineers, but overall I agree with the spirit of the bill.
There is no doubt that America needs a clear goal for space exploration. The question in my ind is whether the Lampson bill as written is the best way of achieving a goal. The bill's insistence on reusability would have easily killed any mission from cost and technical standpoints. I think that NASA should be re-focused on exploration of space beyond earth orbit, and the role of the space station should be modified to fit into this grand picture. Mars, moon, and asteroid exploration will be important parts of this plan, but they should not be linked to each other lest a problem with one program kill the others. NASA should also share the responsibilities of exploration with private industry and academia so the taxpayers won't have to foot the entire bill for this grand exploration projects.
When the original requirements for OSP came out, it was inevitably compared to the HL-20 (which was resurrected early in the design stage) and the X-20. The reason for this is because the X-20 was the logical next step between the small capsules of the 1960s and the large shuttle of the 1980s. However, the boobs who ran the DoD in the early '60s (McNamara and Harold Brown, specifically) felt that the X-20 had to posess a military mission to be justified. Hence, the X-20 was cancelled in favor of the more cost-effective MOL. But the X-20 should have been saved, merely refocused as a technology development program. Had the X-20 been flown, engineers would have posessed realistic expectations regarding the shuttle regarding its maintenance, materials, propulsion, and operations.
In the year 2003, we're looking back and realizing how ignorant we are in terms of ability to build a reusable spacecraft. That's why a Dyna-Soar inspired solution has become so appealing to engineers. Build the small spaceplane first, and a bigger shuttle-class vehicle will follow.
I think the supporters of winged or lifting body vehicles were handed a victory by the Level 2 requirements, because it is easier to punch out of a glider than a semi-ballistic capsule (although the Vostok astronauts were required due to design to eject.) However, capsules are more resistant to failure during re-entry, so ejection seats might not be necessary for a capsule. A capsule would be better off using the re-inforced crew compartment.
It is interesting to note some of the level II requirements for OSP, as released on Sep. 23. One of the requirements is that both crew abort and crew escape be possible. Abort consists of saving the crew and vehicle, while escape is defined as saving the crew while losing the vehicle. Interestingly, it is suggested that a reinforced crew cabin that could survive the loss of vehicle is an alternative to ejection seats or capsules. The final Columbia report makes a small reference to such an idea as a retrofit to the space shuttle, as it was determined that Columbia's crew module descended around 75,000 feet before the stresses became too much for its heat-weakened structure. It should also be noted that crew members sitting in a reclined position (such as the X-38 seating arrangement) would not be able to eject using conventional seats. Because mass will be an important consideration, the reinfoced cabin may be a better idea for the OSP than my personal favorite, the encapsulated ejection seat.
If the ablative covering was attached to a metal shield that fit over the capsule, it shouldn't be too hard to jettison the shield just before landing and then replace it before re-flight. A hot structure would be needed on the other areas of the capsule to prevent a burn-through.
It's not an easy feat. A white ablative was developed for the X-15 that could be stripped off and reapplied between flights. However, this ablative could not handle the heat generated at Mach 6.7, and the airframe was damaged.
The basic Gemini weighed 2.6 tonnes, the baseline USAF Big Gemini weighed 15.6 tonnes. Much heavier versions of Big G were also planned, making use of larger Titan and Saturn rockets to deliver more cargo.
It's not such a nutty idea. No human has ever been to GEO before, so I'd like to do it for the sake of adventure. With a two-man Gemini, the large SDV still seems like overkill (without having done any calculations on what it would take to put Gemini or Big G in GEO.) The second-stage motor would need a fairing over the nozzle to cut down on drag.
Thus far, ISS has been a tremendous waste. At this rate, NASA & co. will have spent far more time assembling it that using it for science. COntrast this with the space station plans that Von Braun and other had in the late '60s. Before 1980, an uprated Saturn V was to launch a twelve-man space station that replaced the drag-producing solar panels of the ISS with a nuclear reactor. Even Skylab, an 84-ton station launched by the standard Saturn V, had the same amount of internal volume as the ISS.
Boeing hired Lockheed Martin employees from the Atlas V project. These employees then gave Boeing proprietary documents on the Atlas V that should have stayed at LockMart. The Air Force responded by reversing many of the launch contracts that had been granted to Boeing. Overall, the picture at Boeing's Launch Services isn't too rosy--they already pulled out of commercial launches, and the Air Force launches they counted on just aren't there anymore.
Perhaps it's better for us, as space enthusiasts, that the bring-back capacity of OSP is so limited. The need to return more science hardware justifies more OSP launches. More launches also means more money to the aerospace industry, hence more jobs in California and other states.
With the space shuttle economic model, the bulk of the launch costs are fixed, and the incrimental cost of adding more missions is low. I would expect this to be different with OSP on an EELV, because it's more expensive to replace the entire rocket than it is to replace the fuel tank and rebuild the SRBs. Still, much of the EELV cost must be fixed, so it should not be too expensive to increase the flight rate. And after the sanctions slapped down on Boeing for its scandalous behavior in the EELV competition, I would expect Boeing to favor any decision that would increase their Delta IV launch rate.
/trying to steer thread back on track/
In an audience with Dr. Mae Jemison, I asked her why there was such public disinterest in space. She replied by saying that the interest was there; people just needed to see some goal that the space program was working towards. The overwhelming public support to continue following the loss of Columbia only strengthened what she told me nearly three years ago. If we give the space program a lofty but realistic goal, the people will support it.
The goal is the problem. There are people like Sen. Brownback and Rep. DeLay who want to see NASA set a goal for itself, while Sean O'Keefe continues to stress the need for a "capabilities-oriented" program. Even if the DeLays win the argument, it's up in the air whether NASA will choose the moon, Mars, or asteroids as a goal. But Orbital Space Plane and ISS would be re-scoped in order to fit in with the grand scheme, and I dare say that ANY goal-oriented program will get us closer to Mars.
NASA isn't totally unwilling to use hardware that isn't made in the USA. The HL-20 was a refinement of Russia's BOR-4 lifting body. The core modules for ISS were designed for Mir-2. NASA's America-first mentality comes into play when it means preserving the jobs and the technical base of America's aerospace industry. Needless to say, Congress would rather spend money on creating manufacturing jobs in the US before they spend money on creating Russian or European or Japanese jobs.
The 9g deceleration and the off-course landing of Soyuz TMA-1 was due to a control problem. If the systems would have worked correctly, the Soyuz would have instead made a more manageable, 4g lifting re-entry. No capsule is immune to this problem; but its occurence on the Soyuz flight indicates a quality control issue.
It would be a fallacy for us to say that we don't need two capsules, and I'm certainly not saying that an American spacecraft would be better by default. What I am saying is that Soyuz is an old design that, despite the upgrades, was still configured for circumlunar flight and Salyut/Mir missions. A Big Gemini, with three times the crew of Soyuz, is better suited for the larger crews that ISS could handle in the future. Further, Big Gemini could be steered to a pinpoint landing at an airstrip and not require a recovery at sea or in the Russian wilderness
I happen to agree with Robert here, regarding "Shuttle-C" or whatever you want to call this shuttle-derived cargo rocket. The only point where our ideas differ is that I don't favor mounting a clutch of space shuttle main engines in a reusable pod. I feel that the shuttle aft thrust structure should be slightly modified to house three RS-68 engines. This would give our SDV more thrust, and eliminate the hassle & cost of refurbishing the SSMEs.
A shuttle-derived EELV would keep the shuttle's "standing army" employed, and it would restore a heavy-lift capability that vanished with the demise of Saturn V and Energia. If such a vehicle had been available, a space station with all the capabilities of ISS could have been launched in one try (This was the "Option C" that NASA and Russia discussed in 1993.) If this SDV could be upgraded to Saturn V-like levels of performance (through a laterally-mounted upper stage and longer SRBs,) a twelve-person, nuclear powered space station could have been launched (as von Braun and his supporters planned for the late 1970's.)
As far as reusability goes, the capsule might be cheaper if it's expendable. As long as it's more capable and reliable than Soyuz (more than three crew, no 9g ballistic re-entries,) it will be worth the cost. If reusablity is a key to the success of OSP, a lifting body becomes more viable because of its benign thermal profile. Even though the baseline HL-20 is too heavy to be launched on a single-core EELV, bear in mind that the baseline HL-20 was designed around a crew of two pilots+eight passengers. Scaling this back to two pilots + four passengers would allow the designers to scale the vehicle down and reduce the amount of thruster propellant and consumables.
The space station requires a lot of cargo to to come up and a lot of cargo to return to earth. Each Shuttle resupply mission brings 12.5 tonnes of water, rocket fuel, food, and scientific cargo. The European ATV (to fly in 2004) and Japan's planned HTV will carry roughly the same amount of cargo to the ISS (without a chance to return anything to earth, unlike the shuttle.) Further, the shuttle's OMS engines are used to re-boost the ISS. Although the same task can be done by Progress freighters, it makes fiscal sense to integrate this with the cargo mission.
Because the ISS currently lacks any vehicle that can deliver the 12.5 tonnes of cargo every three months, the crews have ben cut back to two. This will hopefully keep the ISS water budget balanced. But a shuttle or ATV will be necessay when the ISS crews grow to three and then to six.
The advantage of the shuttle (or a more durable replacement vehicle) over the ATV/HTV is the ability to RETURN cargo. ISS experiments are expensive. It also defeats the purpose of many experiments to let them burn up in the atmosphere when there. Many experiments, particularly those that deal with biology, must be returned to earth for future study.
There is really a need for three vehicles: a capsule to take humans to the ISS in the short term, and to be used on missions beyond the earth in the long term. A Starclipper-type vehicle must be built withinthe next ten or fifteen years to replace the shuttle. And a two-stage space plane with scramjets on the first stage can be developed within the next twenty to thirty years to deliver humans to more advanced space stations.