Stardust
The first sample from a comet, and the surprise that it contained rock formed close to the Sun.
Key facts
- Agency
- NASA (United States)
- Type of mission
- Comet sample return
- Target
- Comet 81P/Wild 2
- Launched
- 7 February 1999
- Samples returned
- Thousands of comet dust grains in aerogel
- Status
- Completed 2011
Stardust flew through the cloud of dust around comet 81P/Wild 2 on 2 January 2004, passing about 240 kilometres from its nucleus. It held out a collector like a tennis racket, filled with aerogel, a glassy foam that is mostly empty space. Grains hitting it at about 6 kilometres per second burrowed in like bullets into soft snow, leaving carrot-shaped tracks with the particles at the end.
The capsule returned to Utah on 15 January 2006. At almost 12.9 kilometres per second it was the fastest re-entry of any human-made object at that time.
A surprise from the cold
Comets formed in the cold, outer Solar System, so scientists expected mostly fluffy, icy dust. Instead, many grains were high-temperature minerals such as olivine and pyroxene, and some looked like fragments of chondrules and of calcium-aluminium-rich inclusions, the oldest solids, which formed close to the young Sun. One CAI-like grain, nicknamed Inti, contains the rare mineral osbornite.
So material from the hot inner disc had been carried all the way out to where comets grew. The young Solar System was much more thoroughly mixed than anyone had thought.
The samples also contained glycine, the simplest amino acid, formed in space.
Interstellar dust
A second collector faced the stream of dust flowing through the Solar System from between the stars. Volunteers searching millions of microscope images helped find a handful of likely interstellar grains.
In 2011 the spacecraft also revisited comet Tempel 1 and photographed the crater made by Deep Impact.
Key dates
| Date | What happened |
|---|---|
| 7 February 1999 | Stardust launched on a Delta II rocket. |
| 2 November 2002 | Flew past the asteroid 5535 Annefrank. |
| 2 January 2004 | Flew through the coma of comet 81P/Wild 2 and collected dust. |
| 15 January 2006 | The sample capsule landed in Utah. |
| 14 February 2011 | Flew past comet Tempel 1 and imaged the Deep Impact crater. |
See where this mission fits among all the others in the mission timeline.
Did you know?
Aerogel is so light that a block the size of a person would weigh less than a kilogram.
Most of the comet grains Stardust caught are smaller than the width of a human hair.
Related pages
Comets connected with this mission: Comet Tempel 1, Comet Wild 2. See all comets.