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| Re: House Panel Resists Changes in NASA Space Program (501343) | |||
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Re: House Panel Resists Changes in NASA Space Program |
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Posted by WillD on Wed Sep 23 00:40:10 2009, in response to Re: House Panel Resists Changes in NASA Space Program, posted by GP38/R42 Chris on Tue Sep 22 22:28:32 2009. When is the shuttle set to stop running?The current last mission for the Space Shuttle is planned to be STS-133, which will be Discovery's last flight and will fly on September 16th 2010. Within a year we may have the entire shuttle fleet retired. If there are issues with STS-134 then there is a Launch On Notice rescue flight to pick up the crew, which will be STS-135. NASA's replacement for the Space Shuttle is the Orion capsule, which is not too different from the Apollo capsule. The Orion capsule is planned to be boosted by the Ares I rocket. The Shuttle's LEO role will in part also be replaced by the SpaceX Dragon capsule and the Orbital Science Corporation's Cygnus capsule. Both of those result from NASA's commercial space contract to fly supplies as part of the COTS-C contract. Now NASA is moving on to the COTS-D contract, and SpaceX appears set to do manned flights to the ISS with their booster and their capsule by 2014. That rocket will be composed of a 5 segment version of the solid rocket motor whose 4 segment version currently provides a bit less than half of the takeoff thrust of the Shuttle. It will use a pair of J-2X engines based on the rocket engines used in the 2nd and 3rd stages of the Saturn V in the second stage. The 5 segment SRB from the first stage will be recoverable, just as the current 4 seg boosters are. So far it seems unlikely the Ares I will make it past the development stage. It has severe problems with thrust oscillations, weight to orbit, and has very little margin for growth.  The Shuttle's cargo role is set to be supplanted by the Ares V very heavy lift booster. It will use a modified external tank 10 meters in diameter (the current ET is 8.4 meters in diameter), with six RS-68 liquid rockets -currently the most powerful liquid rocket engines the US produces- in conjunction with the 5.5 segment boosters being developed for the Ares I. The upper stage will use either one or two of the same J-2X boosters planned for the Ares I. It is planned to place 188 metric tons into low earth orbit, but I believe that isn't into a circular orbit. If left in that orbit without additional thrusting it would reenter on the next closest approach to the Earth. There are serious questions as to whether the RS-68s will be a viable engine for the extreme thermal conditions that will exist at the base of the Ares V on takeoff. The RS-68 is designed to slowly disintigrate throughout flight, and with six of them and two SRBs it is possible they'd be destroyed before the first stage is jettisoned. The Ares V will also require a complete change in launch infrastructure at Kennedy Space Center to accomodate the greater weight, height, and different requirements for servicing. Worst of all the two shuttle launch pads would need to be dedicated, one for the Ares I crew launch vehicle, and one for the Ares V cargo launch vehicle. It is also possible that they will be required to dedicate Vehicle Assembly Bays to each launcher, thereby halving its capacity. But then with the Ares I unlikely to fly before 2015 (with the Augustine committee estimating it will not occur before 2017) we are facing a 5 to 7 year down period in manned NASA spaceflight. NASA will not be able to justify retaining its manpower at the Cape during that downtime, so it will be forced to lay off thousands of workers. The same is true of the Michoud Assembly Facility in Louisiana, where the External Tanks are produced, and the Thiokol plant in Utah where the SRBs are built. These layoffs will represent a major loss in operational knowledge about spaceflight. It was with these difficulties in mind that the Obama administration initiated the Human Space Flight Committee. It is more popularly known as the Augustine Committee after the committee's leader, Norman R. Augustine, a former head of Lockheed Martin. They were asked to develop a number of alternatives to the current plan while also assessing the budgetary situation of the NASA human spaceflight program in view of its stated goal of returning to the Moon and landing on Mars. Among the alternatives being considered are an Ares V Lite rocket which would replace the Ares I crew launch vehicle with a slightly downgraded heavy lift booster. This would introduce commonality between the crew and cargo launchers, but would also bring the Ares V's RS-68 base heating problems to the crewed launcher, and may be complete overkill for simply launching an Orion capsule to the ISS. Lockheed Martin and Boeing's consortium, United Launch Alliance, which has a near-monopoly on US expendable launchers with their Evolved Expendable Launch Vehicles, the Atlas V and Delta IVH, is floating their own concept. They would use a new larger upper stage and an increased number of first stage engines to expand the capability of their boosters to create a slightly less-than-heavy lift capability from what is now a medium lift booster family. They would use a number of launches to place the Orion capsule, the lunar lander, the earth departure stage, and the fuel for the EDS into low Earth orbit. This breaks with NASA's current two launch architecture and potentially creates an opportunity for mission failures in assembling everything in LEO.  Not sure if this is a Delta IV or Atlas V, but it kinda looks like it. SpaceX is proposing to either adopt a ULA-like architecture with their EELV-class Falcon 9 booster, or to eventually develop a new all-liquid heavy lift booster similar in capability to the Saturn V. SpaceX has their own capsule design, the Dragon, which will replace the Space Shuttle for US crewed launches to the ISS by 2014 I believe. They are also looking to get in on space tourism in the near future. In theory the Falcon 9H could boost one of the Orion capsules into orbit.  Rocketplane Kistler was removed from COTS before their rocket even reached development, to be replaced by OSC. NASA Shuttle program manager John Shannon has floated another heavy lift concept called Sidemount, which is based on a number of plans which have been studied for years. The Sidemount uses a disposable booster that looks like a wingless shuttle with the same three liquid rockets mated to something that looks like the existing External tank and Solid Rocket Boosters. The Sidemount booster would be severely payload limited when compared to the Ares V, with around 80 metric tons to a circular low earth orbit, less than half of the Ares V's capability. The full shuttle derived vehicle will likely weigh more than 200 metric tons, so the External tank itself will require extensive rebuilding to deal with the different weight. On the other hand it'd be almost entirely compatible with the existing shuttle launch infrastructure. That having been said it is fairly non-upgradable, with a maximum payload fixed around 85 tons due to the off-center weight. There are also potential issues about using expensive Space Shuttle main engines in an expendable role. They also plan to jettison the massive payload fairing at a relatively low altitude, which potentially subjects the payload to undue thermal heating as the rocket may not have left the Earth's atmosphere at that point. Finally NASA's safety officials will be unlikely to approve astronauts again flying beside the external tank given the problems encountered with the Challenger and Columbia, even if they are flying in a capsule with a launch abort rocket system. Thus the Sidemount booster can replace the Ares V, but would be unlikely to replace the Ares I.  Finally a number of NASA engineers have developed a concept to return the Ares concept to its roots as a truly in-line Shuttle Derived launch vehicle maximizing the utilization of the existing facilities while increasing margins for growth. The current iteration of this plan is the Jupiter 130 and Jupiter 246. The J130 uses the existing 4 segment boosters and a modified 8.4 meter external tank with three SSMEs in the first stage. It will be capable of putting 60 metric tons into low earth orbit, which would include the Orion capsule and another 20 tons of payload. In theory the J130 could lift a pallet into orbit along with the Orion capsule which would act like a disposable version of the Space Shuttle's cargo bay. The possibility exists that the J130 would, like the Ares V Lite, be overkill for the ISS crew launches, but it could be ideal for other missions.  The Jupiter 130 (which stands for 1 stage, 3 single stage liquid rocket engines, zero upper stage rocket engines) can be developed into the Jupiter 246 heavy lift rocket by adding a fourth SSME to the first stage, and creating an upper stage with 6 RL-10B rockets from the proven Centaur upper stage. This rocket would be capable of boosting a moon flight by lofting a fully fueled upper stage to LEO without payload, then having another J246 launch a partially fueled upper stage with an Orion and Lunar Lander into LEO. The second upper stage would put the Orion and Lunar lander into LEO, where they would jettison it and dock with the fully fueled first upper stage. The fully fueled upper stage would serve as the Earth departure stage for the crew. The J246 could place 90 to 100 metric tons into orbit. But by incorporating improvements currently being developed for the Ares V payload could be increased to 120 metric tons by using the 5 segment SRBs, and the J-2X engine.  The big advantage of the Sidemount and DIRECT Jupiter launchers is that they can be readied quickly. NASA's current plans are dictated by the development time for the J-2X, the 5 segment booster, the RS-68B, and the 10 meter core for the Ares V, as well as the rebuilding of the Kennedy Space Center facilities for the new boosters. The Orion capsule may well be ready to fly by 2013 or 2014, but under the current plan may lack a booster before 2017 if the Augustine committee is correct. The Sidemount proponents claim they could fly the Orion capsule by 2014, with development of the new cargo carrier being the primary factor. The DIRECT team claims their Jupiter 130 rocket can fly by 2012, and that an extension of the Shuttle to 2012 would actually result in an overlap between the two launch systems. The Jupiter 246 would await the development of the upper stage, but the Jupiter 130 would suffice as a heavier-than-EELV booster still potentially capable of launching missions to the moon with a three-launch architecture. With the rapid development of the upper stage, which really only requires the assembly of various components and no real new development, the Jupiter 246 could in theory fly an Apollo 8-like lunar flyby before 2017, the 45th anniversary of Apollo 17, our last landing on the moon. If the lunar lander is given the proper priority we may even be capable of landing on the moon by 2019, the 50th anniversary of Apollo 11. Anyway, there you have it, a long drawn out list of the possibilities being considered by the Augstine Committee. I'm a fan of the in-line Shuttle Drived launch vehicles, be they a more rational Ares V, or the Jupiter family. |
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