A mission to gather samples of the wind flowing from the Sun and a mission to fly by three near-Earth comets have been selected as the next flights in NASA's Discovery Program of lower-cost, highly focused scientific spacecraft.
The Genesis mission is designed to collect samples of the charged particles in the solar wind and return them to Earth laboratories for detailed analysis. It is led by Dr. Donald Burnett from the California Institute of Technology, Pasadena, CA, at a total cost to NASA of $216 million. Due for launch in January 2001, it will return the samples of isotopes of oxygen, nitrogen, the noble gases, and other elements to an airborne capture in the Utah desert in August 2003. Such data are crucial for improving theories about the origin of the Sun and the planets, which formed from the same primordial dust cloud.
The Comet Nucleus Tour (CONTOUR) will take images and comparative spectral maps of at least three comet nuclei and analyze the dust flowing from them. CONTOUR is led by Dr. Joseph Veverka of Cornell University, Ithaca, NY, at a total cost to NASA of $154 million. It is scheduled for launch in July 2002, with its first comet flyby to occur in November 2003. This flyby of Comet Encke at a distance of about 60 miles (100 kilometers) will be followed by similar encounters with Comet Schwassmann-Wachmann- 3 in June 2006 and Comet d'Arrest in August 2008.
"This was a very difficult selection, given the first-class science proposed by all five teams," said Dr. Wesley Huntress, Associate Administrator for Space Science at NASA Headquarters, Washington. "We picked two based on our distribution of resources and the excellent fit of the timetables for these missions with other robotic space science explorers. Genesis will give us a sample of the Sun as we are preparing to receive samples of a comet and asteroid from other missions. Meanwhile, CONTOUR will help us better understand the breadth of the 'family' of comets, which are believed to be quite individual in their properties."
The selection of these missions is the second step of a two- step process. In the first step, NASA selected five proposals in April 1997 for detailed four-month feasibility studies. Funded by NASA at $350,000 each, these studies focused on cost, management and technical plans, including small business involvement and educational outreach.
The selected proposals were among 34 proposals originally submitted to NASA in December 1996, in response to a Discovery Announcement of Opportunity (AO) issued on September 20, 1996. As stated in the AO, the initial cost estimates were allowed to grow by a maximum of 20 percent between the April selection and the detailed final proposals.
The investigations proposed in response to this announcement (AO-96-OSS-02) were required to address the goals and objectives of the Office of Space Science's Solar System Exploration theme or the search for extrasolar planetary systems element of the Astronomical Search for Origins and Planetary Systems theme. A selected mission was required to be ready for launch no later than September 30, 2002, within the Discovery Program's cost cap of $280 million total per mission, including development, launch and operations.
CONTOUR and Genesis follow four previously selected NASA Discovery missions. The Near Earth Asteroid Rendezvous (NEAR) spacecraft was launched in February 1996 and returned sharp images of the asteroid Mathilde from a distant flyby in June of this year, on its way to orbit the asteroid Eros in early 1999. The Mars Pathfinder lander, carrying a small robotic rover named Sojourner, landed successfully on the surface of Mars on July 4, and since has returned hundreds of images and thousands of measurements of the Martian environment.
The Lunar Prospector orbiter mission to map the Moon's composition and gravity field is scheduled for launch in January 1998, and the Stardust mission is designed to gather dust from Comet Wild-2 in 2004 and return it to Earth, following a planned February 1999 launch.