TIM FURNISS / LONDON
NASA prepares for first trip since 1970s and keeps threatened Pluto mission hopes alive
NASA has approved the Messenger $256 million Mercury Surface Space Environment Geochemistry and Ranging mission, for launch in March 2004.
The US agency has also chosen two science-industry groups to produce, under a $450,000 three-month feasibility study contract, detailed concepts for a Pluto-Kuiper Belt (PKB) mission to be launched from 2004.
Messenger - the seventh in the Discovery series of missions - will be the first spacecraft to go to Mercury since the Mariner 10 in 1974-75. Equipped with seven scientific instruments, including a camera, its purpose will be to map the entire surface for the first time when it reaches the innermost planet in the solar system in April 2009. Mariner 10 surveyed about half of Mercury.
The Messenger spacecraft will be built by Johns Hopkins Applied Physics Laboratory (APL), which will also manage the mission.
Messenger's five-year flight to Mercury will incorporate two fly-bys of Venus and two of Mercury.
Orbiting 57 million km (35.4 million miles) from the Sun, the Messenger spacecraft will need to be protected by a sunshield made of ceramic material, similar to the Space Shuttle's heatshield tiles.
The moon-like, cratered Mercury is the densest planet in the solar system, with a core of iron. Some parts of its surface endure temperatures up to 470 million°C, while ice appears to form in some craters near the poles.
The two concept teams working on the PKB Pluto mission are the University of Colorado-led Pluto and Outer Solar System Explorer (POSSE), and the Southwest Research Institute-led New Horizons: Shedding Light on Frontier Worlds.
The POSSE team will include NASA's Jet Propulsion Laboratory, Lockheed Martin Astronautics and Ball Aerospace, while the New Horizons project team involves APL, NASA's Goddard Space Flight Center and Ball Aerospace.
The teams were selected from five submitting proposals to NASA in April following a mission announcement of opportunity by the space agency in an attempt to save the PKB mission after budget cuts. The PKB is not yet funded, but the US Congress has requested NASA to keep the project afloat while attempts are made to provide funds from the fiscal year 2002 budget.
With a 2004 launch, the PKB craft would reach Pluto, the most distant planet in the solar system, and its geostationary-orbiting moon Charon in about 2020.
If the mission does not launch by 2006, however, the opportunity of using gravity-assist fly-bys of Jupiter to alter the flight path and quicken the journey will be lost. A later mission will take much longer to reach Pluto, by which time the planet will be moving towards its furthest point from the sun and will be totally frozen over.
Pluto is the only unexplored planet in the solar system. The PKB will carry a suite of remote sensing instruments including an imager to study the planet's geology, morphology, surface composition and atmosphere.
Source: Flight International
