Editing Galileo project (section)

===951 Gaspra===
[[File:951 Gaspra.jpg|[[951 Gaspra]] (enhanced colorization)|thumb|right|alt=Potato-shaped asteroid]]
Two months after entering the [[asteroid belt]], ''Galileo'' performed the first asteroid encounter by a spacecraft.{{sfn|Meltzer|2007|pp=161–164}} ''Galileo'' passed [[951 Gaspra]], an [[S-type asteroid]], at a distance of {{convert|1604|km|mi|abbr=on}} at 22:37&nbsp;UTC on October 29, 1991, at a relative speed of about {{convert|8|km/s|mi/s|sp=us}}.<ref name="PDS"/> Fifty-seven images of Gaspra were taken with the SSI, covering about 80 percent of the asteroid.{{sfn|Veverka|Belton|Klaasen|Chapman|1994|p=2}} Without the HGA, the bit rate was only about 40 bit/s, so an image took up to 60 hours to transmit back to Earth. The ''Galileo'' project was able to secure 80 hours of Canberra's 70-meter dish time between 7 and 14 November 1991,{{sfn|Veverka|Belton|Klaasen|Chapman|1994|p=7}} but most of images taken, including low-resolution images of more of the surface, were not transmitted to Earth until November 1992.{{sfn|Meltzer|2007|pp=161–164}}

The imagery revealed a cratered and irregular body, measuring about {{convert|19|by|12|by|11|km|mi|sp=us}}.{{sfn|Veverka|Belton|Klaasen|Chapman|1994|p=2}} Its shape was not remarkable for an asteroid of its size.{{sfn|Veverka|Belton|Klaasen|Chapman|1994|p=8}} Measurements were taken using the NIMS to indicate the asteroid's composition and physical properties.{{sfn|Granahan|2011|pp=265–272}} While Gaspra has plenty of small craters—over 600 of them ranging in size from {{convert|100|to|500|m|sp=us}}—it lacks large ones, hinting at a relatively recent origin,{{sfn|Meltzer|2007|pp=161–164}} although it is possible that some of the depressions were eroded craters. Several relatively flat planar areas were found, suggesting that Gaspra was formed from another body by a collision.{{sfn|Veverka|Belton|Klaasen|Chapman|1994|p=8}} Measurements of the solar wind in the vicinity of the asteroid showed it changing direction a few hundred kilometers from Gaspra, which hinted that Gaspra might have a magnetic field, but this was not certain.{{sfn|Meltzer|2007|pp=161–164}}