Ramon Lopez/WASHINGTON DCTim Furniss/LONDON
The additional $750 million NASA has been given over the next five years to help develop technologies for the next generation of re-usable launch vehicles (RLV) should instead be used for further upgrades of the four Space Shuttle orbiters, says Russ Turner, Boeing's vice-president for re-usable space systems.
Turner believes an upgraded Space Shuttle fleet could fly until at least 2020. He hopes that NASA will make "an objective comparison of capabilities and costs and conclude that it needs to continue investing in the Shuttle".
One RLV under study is the proposed VentureStar, which would be derived from the $1 billion NASA/Lockheed Martin X-33 suborbital RLV technology demonstrator. The VentureStar could fly as an unmanned RLV by 2004, says Lockheed Martin.
Turner, however, believes that a combination of Shuttle upgrades and new development is the answer. "The US Government needs to let the private sector develop VentureStar for commercial applications while US tax dollars are spent to upgrade the Shuttle," the Boeing executive concludes. Boeing's Rocketdyne division provides the aerospike engines for the X-33 and could play a major role in any VentureStar project.
The Space Shuttle fleet is already being modernised at a cost of $280 million, Turner points out. The Atlantis is being fitted with a Multifunction Electronic Display Subsystem (MEDS) made by Honeywell, which is similar to the glass cockpit installed in the Boeing 777.
The Atlantis and the other three orbiters (the Columbia, Discovery and Endeavour) will also be equipped with global positioning system navigation and new thermal protection system tiles that are 10 times more durable than those used at present, says Turner.
If NASA were to invest $2 billion in the VentureStar, the money would come out of the Shuttle budget, meaning no more upgrades, even though updates could represent the most cost-effective route, considering the proven record of the Shuttle and the technical uncertainty of some future programmes.
Phase III upgrades would include an improved auxiliary power unit, improved fuel cells, new avionics and electro-mechanical actuators for main engines.
A Phase IV upgrade would represent the most radical change to the Shuttle so far - the replacement of the Shuttle's twin solid rocket boosters with a twin-liquid, winged fly-back booster system. This hardware change would reduce annual operating costs by up to $400 million, estimates Boeing.
Turner says it will cost an estimated $1 billion to complete the Phase III/IV modifications on the four Shuttle orbiters, while the VentureStar programme could cost as much as $5 billion.
"This Shuttle upgrade programme is a bargain," Turner concludes. Each Space Shuttle has so far made an average of 22 flights and although each is certified for 100 missions, Turner believes that 150 may be achievable "-since the orbiters are showing no signs of fatigue".
Turner's comments illustrate the Shuttle conundrum facing NASA. The answer may seem simple, however, as the Shuttle is the only planned crewed vehicle for the foreseeable future. If the VentureStar is developed, it will not be crewed, says Lockheed Martin.
The Shuttle Columbia is rolled out to the launch pad for its STS90 Neurolab mission on 16 April
In the initial publicity surrounding Lockheed Martin's X-33/VentureStar proposal, it was seen as a replacement for the Shuttle. Lockheed Martin now says that VentureStar vehicles, if developed, will be used only as RLV systems under the company's investment. A man-rated vehicle would require another programme.
NASA will have to decide whether to continue to rely on the Shuttle as the primary method for human access to space or switch to a future manned version of a commercial RLV, such as a Mk2 VentureStar. Given the current climate, funding of such a vehicle is uncertain and its method of taking humans into space would be fundamentally different.
The original idea for the VentureStar was to provide transportation along the lines of unmanned cargo. Passengers - there would be no flightcrew - would be carried in a transportable container in the VentureStar's cargo bay. Who would fund the "crew transfer module" is open to question. A manned version would unlikely to be available until about 2010.
The future of the VentureStar in the long term depends on raising enormous private investment. In the short term, it depends more on the success of the X-33 sub-orbital technology demonstrator flights.
NASA is providing $941 million and Lockheed $212 million for the X-33 programme, which will see the first flight of the vehicle from a site close to Edwards AFB, California in July 1999. The X-33 is 19m long and has a wingspan of 20m. Fifteen demonstration flights are planned in a 15-month period under the NASA contract. Among the aims of the flights is to reach speeds of Mach 15 and altitudes of 260,000ft (80,000m).
Future trends will almost certainly revolve around whether commercial versions of the US Air Force Evolved Expendable Launch Vehicle (EELV) boosters are considered to be sufficient for future unmanned launch needs.
A $2 billion EELV contract will be awarded jointly in June to Boeing and Lockheed Martin to develop a range of small, medium and large launchers, capable of reducing launch costs by as much as 50% (or $20-$50 million). In the commercial market, where launcher availability, rather than cost, is a prime factor, the philosophy has always been "if it ain't broke, don't fix it" when it comes to proposals for fundamentally new launch methods, such as RLVs.
The uncertain future direction of human spaceflight and RLVs is indicated by another issue: commercialising Shuttle operations is a key objective for United Space Alliance, which operates the Shuttle for NASA. NASA and Boeing are studying an advanced upper stage which could make the vehicle competitive against RLVs.
Source: Flight International
