- Speculation that asteroids were similar to the moons of Mars persisted throughout the 1970s and 1980s.
- Asteroids are now calculated to have broken from larger "parent asteroids."
- In November 1991, Gaspra became the first asteroid photographed up close:
- The picture was returned to Earth by the Galileo spacecraft.
- Galileo was 16,000 km or 10,000 miles from the asteroid.
- Prior to this flight, Gaspra was an obscure asteroid in the main belt.
- Galileo's path was chosen to make an encounter with the asteroid.
- Gaspra became the focus once astronomer's knew that Galileo would obtain data from close range.
- Spectra obtained of Gaspra from the Mauna Kea Observatory in Hawaii aided in the course adjustments of Galileo.
- Features indicative of olivine and pyroxene type minerals suggested that Gaspra had once melted.
- Gaspra may well have been a mantle-fragment of a larger asteroid.
- Gaspra's rotation was determined to be 7 hours by the spectra.
- The dimensions for Gaspra were established at 20 x 12 x 11 km (12 x 7.5 x 7 miles).
- Photographs of Gaspra also revealed fewer craters than consistent with 4-billion-year-old surfaces of many bodies.