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Aviation History
2003
2003 - 1756.PDF
Future of Fliqht _jPr India launches first satellite 1981 First US Space Shuttle orbital flight 1986 Space Shuttle Challenger 1992 First satellite retrieval, repair and redeployment (Intelsat VI by Shuttle) 1993 European Hermes spaceplane cancelled Sovi • • explodes during ascent Assembly of Soviet Mir space station begins (re enters 2001) 1988 Unmanned orbit test of iet Buran shuttle -1990 US Hubble Space Telescope deployed by Shuttle beyond 2020. The OSP, carried atop an expendable launch vehicle (ELV), is to enter service as a one-way crew return vehicle by 2010 or earlier, and as a two-way crew trans fer vehicle two years later. The revamped next-generation launch technology (NGLT) programme could lead to the first flight of a Shuttle replacement by 2015, but could also see NASA skip a generation and pursue development of a more advanced RLV that would enter service after 2020. All this seems a far ay from the vision of future spaceflight provided by Arthur C Clarke's and Stanley Kubrick's 1968 film 2001: A Space Odyssey. On the eve of the first manned landing on the moon, many believed it would be possible by the turn of century to have airliner-like launch vehicles flying commercially to massive space sta tions that would be linked by regular shuttle flights to thriving moonbases, but the tran sition from the expendable Saturn V to the reusable Shuttle proved more prolonged and expensive than anyone imagined. Today, the bulk of spaceflights, manned or unmanned, are launched on expend able boosters. ELVs have become more reli able over time but, while the latest vehicles are designed to reduce launch costs, expendable launchers remain an expensive way of getting into space. The lure of RLVs has been the promise of a significantly lower cost per kilogramme of payload, thanks to greater reusability and more air craft-like ground operations. But the road to full reusability has been a rocky one. NASA's first attempt at replacing the par tially reusable, and complex to operate, Shuttle was the Lockheed Martin X-33, a suborbital technology demonstrator for the 1998 International Space Station assembly begins 2001 First long-dura tion expedition crew occupies ISS '2003 Space Shuttle Columbia disintegrates during re entry planned VentureStar commercially devel oped and operated single-stage-to-orbit (SSTO) second-generation RLV. The X-33 proved ruinously over-ambitious technolog ically and was cancelled in 2001 before the demonstrator was completed, after techni cal problems led to schedule delays and cost overruns. NASA and its contractor team eventually spent almost $1.3 billion. Next-generation RLV The X-33 was superseded by the five-year, $4.8 billion Space Launch Initiative (SLI), the centrepiece of which was the develop ment of technology for a second-generation RLV. NASA's original goal was to decide on full-scale development of the RLV in 2005, leading to a first flight in 2010. Develop ment was to be funded by the US govern ment, but plans called for the second-gener ation RLV to be operated commercially. By late 2002, the three prime contractors working on SLI - Boeing, Lockheed Martin and Northrop Grumman - had selected their preferred vehicle concepts. All were two-stage-to-orbit (TSTO) designs, consid ered lower risk than an SSTO. But NASA and industry were becoming concerned over the potential development cost, while the need for a vehicle that would allow the ISS to be fully crewed was becoming criti cal, which led to the late-2002 revamp of the agency's space transport plan. Following the Columbia accident, con tinued work on a second-generation RLV under the NGLT programme has taken a back seat to NASA's efforts to return the Shuttle to flight and develop the OSP to support the ISS. The OSP has drawn criti cism as being too limited in its capability Future launch vehicles could climb to orbit on a beam of microwave energy as it will only be designed to carry four crew to and from the space station. Designs being considered range from an Apollo-type capsule to a small reusable spaceplane, launched atop a Boeing Delta IV or Lockheed Martin Atlas IV. To meet NASA's tight deadline, the OSP would be launched, initially unmanned, to dock with the ISS and act as a one-way lifeboat - a role now performed by the same Russian Soyuz TM craft that ferry crews to the station. Manned flights to the ISS are to begin two years later, and will require man-rating of the ELV/OSP combina tion. NASA plans to achieve this through the development of launch abort and crew escape systems for the OSP, rather than making major changes to the ELVs, which should have demonstrated their relia bility over about 10 years of flying by the time crew transfer flights are due to start. Critics of the OSP are concerned that NASA's near-term focus on supporting the ISS will delay development of a second- generation RLV to replace the Space Shuttle in the longer term. When the Shuttle returns to service, it is likely to be restricted to assembly and resupply flights to the ISS, aside from the occasional Hubble space telescope servicing mission. While ELVs including Europe's Ariane 5 can be used to fly cargo to the ISS, the Shuttle will be the only heavylift vehicle available to complete assembly and enable future expansion of the ISS. While NASA's NGLT programme could lead to a decision to start full-scale devel opment of a second-generation RLV as early as 2009, leading to a first flight - as an unmanned cargo vehicle - in 2015, most observers view this schedule as optimistic. Sceptics believe NASA could choose to bypass the conventional rocket-powered TSTO designs now being pursued in favour of a third-generation RLV that has an air- breathing hypersonic first stage. This would bring the US space agency more into line with its European and Japanese 30 8-14 JULY 2003 FLIGHT INTERNATIONAL www.flightinternational.com
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