It's a difficult decision: With about $300 million to spend, should NASA buy a spacecraft that could find Earth- sized planets around nearby stars? What about a mission that could peer deep inside Jupiter's gaseous atmosphere? Or should the agency go with a mission to orbit the two largest asteroids in the solar system?
The answer to that question will have to wait about a year. In the first step of a two-step process, NASA's Office of Space Science selected three proposals for detailed study as candidates for the next mission in the agency's Discovery Program of lower cost, highly focused, rapid-development scientific spacecraft.
"The diversity of science represented in these three mission proposals is outstanding. NASA will have its hands full picking only one for flight," said Dr. Jay Bergstralh, acting Director of Solar System Exploration at NASA Headquarters, Washington, D.C.
The selected proposals were judged to have the best science value among 26 proposals submitted to NASA last August. Each selected team will receive $450,000 to conduct a four-month implementation-feasibility study focused on cost, management and technical plans, including educational outreach and small business involvement.
Following detailed mission concept studies, NASA intends to select one of the three proposals late in 2001 for full development. The mission should be launched around 2005 or 2006.
NASA has also decided to fund American participation in a mission to Mars being flown by another nation. In this "Mission of Opportunity" NASA will contribute to seismology, meteorology and geodesy (to measure the size and shape of the planet) experiments on the French-led NetLander Mission, scheduled for launch in 2007. The Mission of Opportunity team will receive $250,000 to conduct its feasibility study.
The selected Discovery and Mission of Opportunity proposals are:
* The Kepler mission is a space telescope specifically designed to detect Earth-sized planets around stars in the Sun's neighborhood of the galaxy. By monitoring 100,000 stars over a four-year mission, Kepler could detect up to 500 Earth- sized planets and up to 1,000 Jupiter-sized planets. Dr. William Borucki of NASA's Ames Research Center at Moffet Field, Calif., would lead Kepler at a total cost to NASA of $286 million.
* The Interior Structure and Internal Dynamical Evolution of Jupiter (INSIDE Jupiter) mission is a Jupiter orbiter designed to observe and measure processes occurring within the Jovian magnetosphere and atmosphere. INSIDE Jupiter would determine the internal structure of the planet by obtaining high-resolution maps of the magnetic and gravity fields. Dr. Edward J. Smith of NASA's Jet Propulsion Laboratory in Pasadena, Calif., would lead INSIDE Jupiter at a total cost to NASA of $296 million.
* The Dawn mission intends to orbit Vesta and Ceres, two of the largest asteroids in the solar system. According to current theories, the very different properties of Vesta and Ceres are the result of the asteroids being formed and evolving in different parts of the solar system. By observing both asteroids with the same set of instruments, Dawn would probe the early solar system as well as determine in detail the properties of each asteroid. Dr. Christopher T. Russell of the University of California at Los Angeles would lead Dawn at a total cost to NASA of $271 million.
* A U.S. contribution to the French-led NetLander mission will add unique capabilities to each of the four landers and the orbiter which comprise the mission. In 2007, NetLander will create the first science network on Mars to study the planet's internal structure. The American contribution includes short period seismometers and wind sensors on the landers, and a high-resolution geodesy instrument on the orbiter. Dr. W. Bruce Banerdt of the Jet Propulsion Laboratory will lead the U.S. contribution to NetLander at a total cost to NASA of $35 million.
The Discovery Program is designed to provide frequent, low-cost access to space for planetary missions and missions to search for planets around other stars. The selected science missions must be ready for launch before September 30, 2006, within the Discovery Program's cap on each mission's cost to NASA of $299 million.
The Discovery Program is managed at JPL, a division of the California Institute of Technology in Pasadena, for NASA's Office of Space Science, Washington, D.C. More information on the Discovery Program is available at: http://discovery.nasa.gov/index.cfml .