TIM FURNISS /SPACEFLIGHT CORRESPONDENT
The shadow of the Columbia shuttle disaster still hangs over manned spaceflight
Unless China launches another astronaut earlier than expected, 2004 will be the quietest year in manned spaceflight since 1986. The current International Space Station (ISS) Expedition Crew will be replaced, but there are unlikely to be any Space Shuttle launches to the ISS, despite a scheduled return to flight in September, following 2003's Columbia shuttle disaster.
Highlights of the coming year will include launches of probes to a comet and the planet Mercury, the critical demonstration flight of the Ariane 5 ECA - its first flight failed in 2002 - and the maiden flight of Boeing's Delta IV Heavy booster.
The European Space Agency's (ESA) Rosetta comet probe is set for a late February launch on an Ariane 5G Plus booster from Kourou, French Guiana. Rosetta, which was delayed from January 2003 after the ECA launch failure, will be sent to a new destination, the comet 67P/Churyumov-Gerasimenko, with a rendezvous set for 2014.
NASA's Mercury Surface Space Environment Geochemistry and Ranging (Messenger) craft will be launched by a Delta II Heavy in May. Messenger will be only the second craft to explore Mercury, after Mariner 10 in 1973-4, and will be the first to orbit the solar system's innermost planet.
NASA also hopes that technical problems on the Gravity Probe B spacecraft, which have delayed the probe's launch seven times since April 2003, will be solved. The craft is designed to test Albert Einstein's general theory of relativity. It will measure how the Earth's presence warps space and time and how the planet's rotation drags space-time around with it. However, despite a launch scheduled for the second quarter of 2004, further delays are not ruled out.
Perhaps the most critical mission will be the mid-year launch of the Ariane 5 ECA booster, redesigned after its disastrous maiden flight failure with the loss of two operational commercial spacecraft in 2002. With the commercial launcher market becoming increasingly competitive, a success for Arianespace is essential. The ECA will be able to carry two communications satellites with a combined weight of 10,000kg (22,000lb) into geostationary transfer orbit.
Commercial launchers
The commercial launcher industry, including Arianespace, International Launch Services (ILS) and Sea Launch, is expected to make 20 launches, of which ILS will perform 10 with its Atlas and Proton boosters. Boeing's Delta IV Heavy booster will make its entry into space in July. With three common core stages strapped together, the launcher will make a demonstration flight with a dummy payload in preparation for Evolved Expendable Launch Vehicle missions for the US Air Force.
The Delta IV Heavy will take over from the Lockheed Martin Titan IV - which is scheduled for a launch, from Cape Canaveral, carrying a missile early warning monitoring satellite.
Another Titan IV is set to launch a National Reconnaissance Office satellite in December. In October a Pegasus XL will carry NASA's Demonstration for Autonomous Rendezvous Technology craft (DART), a spaceflight demonstrator aimed at testing technologies for the Orbital Space Plane to locate and rendezvous with the ISS.
The ISS is unlikely to be visited by the Space Shuttle in 2004, so there will have been no enlargement to the orbital base since the last construction mission in late 2002. The present crew will be relieved by a new two-man crew aboard a Soyuz in April, while unmanned Progress tankers will provide cargo.
Much work still needs to be completed before the date of the STS 113 Atlantis Return to Flight mission can be confirmed and already a second RTF mission, STS 121, has been scheduled before construction of the ISS can resume. As a result there may be just one manned space launch in 2004 (the ISS crew) with another ISS launch scheduled tentatively for later in the year.
Source: Flight International
