Discovery Missions Under Consideration

Three missions were originally under consideration for selection as the fourth Discovery mission. These were the Stardust comet mission, the Suess-Urey solar wind mission, and the Venus Multi-Probe mission. After an evaluation of these missions the Stardust mission was chosen in November 1995. For more details on this mission, see the NSSDCA Stardust Page.

The Stardust Mission

[Stardust spacecraft]

Launch: 7 February 1999
Comet Rendezvous: December, 2003
Return to Earth: January, 2006

The Stardust mission is designed for a rendezvous with the active comet P/Wild 2, where it will collect material surrounding the comet. Stardust will then return to Earth with these samples, as well as samples of interstellar dust for scientific study. The mission will also measure the cometary coma in situ and take images of the comet. Passive aerogel collectors will be used to trap the samples of coma and interstellar dust. This material will provide our first sample of pristine cometary material, and increase our understanding of interstellar dust.

NSSDCA Stardust Page
Stardust Project Home Page
Comets and Asteroids Page
Comet Fact Sheet - including information on P/Wild 2

The Suess-Urey Mission

[Suess-Urey spacecraft]

Launch: August, 1999
Return to Earth: July, 2002

The Suess-Urey mission was not selected as a Discovery mission and will not be flown at this time. It was designed to fly beyond the Earth's magnetosphere to the L1 Sun-Earth libration point, where it would remain for 2 years, collecting samples of the solar wind. The samples would then be returned to Earth for analysis. Suess-Urey would also monitor the solar wind over this period. The spacecraft was to be equipped with cannisters holding ultra-clean foil, which would collect the solar particles. These samples of the Sun would allow improvements in our estimates of solar and nebular composition. The Suess-Urey mission was modified, reproposed, and selected under the name Genesis.

Genesis mission
Genesis and other candidates press release
NSSDCA Solar Home Page

The Venus Multiprobe Mission

[Venus Multi-Probe spacecraft]

Launch: May/June, 1999
Arrive at Venus: September, 1999

The Venus Multi-Probe Mission was not selected as a Discovery mission and will not be flown at this time. It was designed to deliver 16 small probes into the atmosphere of Venus to study the atmospheric dynamics. The probes would be dropped into various points in the atmosphere and fall slowly to the surface, making pressure and temperature measurements. The probe velocities would be tracked from Earth, giving wind profiles at many different points. The detailed temperature, pressure, and velocity information would give us a better understanding of the Venus atmospheric super-rotation and general circulation.

Venus Home Page - Links to Venus information
Venus Fact Sheet

Discovery Program
Discovery Press Release

Other Past, Current, and Future Planetary Missions
NSSDCA Planetary Science Home Page

Dr. David R. Williams,
NSSDCA, Mail Code 690.1
NASA Goddard Space Flight Center
Greenbelt, MD 20771

NASA Official: Dr. David R. Williams,
Last Updated: 30 December 2004, DRW