3 results found.
... Science Frontiers ONLINE No. 94: Jul-Aug 1994 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects The shattering of 951 gaspra 951 Gaspra is an irregular asteroid with an average radius of 6.1 kilometers. Located at the inner edge of the main asteroid belt between Mars and Jupiter, Gaspra is believed to be composed mainly of olivine, pyroxene, and nickel-iron. Shape model of Gaspra showing the locations of the grooves. On October 29, 1991, the Galileo spacecraft swept past 951 Gaspra at a distance of 1600 kilometers, snapping photographs as it went. J. Veverka et al report below on what the photos showed: "We report the discovery of grooves in Galileo high-resolution images of Gaspra. These features, previously seen only on Mars' satellite Phobos, are most likely related to severe impacts. Grooves on Gaspra occur as linear and pitted depressions, typically 100-200 m wide, 0.8 to 2.5 km long, and 10-20 m deep. Most occur in two major groups, one of which trends approximately parallel to the asteroid's long axis, but is offset by some 15 , the other is approximately perpendicular to this trend. The first of these directions falls along a family of planes which parallel three extensive flat facets identified by Thomas et al. The occurrence of grooves on Gaspra is consistent with other indications (irregular shape, cratering record) that this asteroid has evolved through a violent collisional history." (Veverka, J., et al ...
Terms matched: 1 - Score: 254 - 15 May 2017 - URL: /sf094/sf094a05.htm
... Science Frontiers ONLINE No. 86: Mar-Apr 1993 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Cosmic Snowballs And Magnetic Asteroids The genesis of a cosmic "dust bunny". The nebulous meteor of July 29, 1970, as observed over Dover, England. The great diversity of the debris swirling around the solar system is making life difficult for scientists trying to reconstruct solar-system history. At the high end of the density spectrum, we now have an asteroid that seems to be mostly metal (probably iron). This is the asteroid Gaspra, some 13 kilometers across, that the Galileo spacecraft encountered in August 1992 on its way to Jupiter. Scientists had not expected Galileo's magnetometer to flicker as it passed Gaspra at a distance of 1600 kilometers -- but it did. In fact, considering the inverse square law and Gaspra's small size, it was a magnetic wallop. Thus, Gaspra is the first known magnetic asteroid; and it is probably mostly metal. (Kerr, Richard A.; "Magnetic Ripple Hints Gaspra Is Metallic," Science, 259: 176, 1993.) At the low end of the density spectrum, we now find that Pluto's moon, Charon, and some of Saturn's moons have very low densities (1 .2 -1 .4 ), meaning they are probably mostly water ice. Such density figures come from direct observation of these objects' volumes combined with mass estimates from their orbital dynamics. (Crosswell, Ken; " ...
Terms matched: 1 - Score: 52 - 15 May 2017 - URL: /sf086/sf086a04.htm
... Science Frontiers ONLINE No. 94: Jul-Aug 1994 Other pages Home Page Science Frontiers Online All Issues Last Issue Next Issue Sourcebook Project Sourcebook Subjects Contents Archaeology Earth's oldest paved road Music and theories of everything Astronomy First you don't see it; then you don't don't see it Beware the ides of june -- and the rest of the month, too! The shattering of 951 gaspra Biology LACRIMA MORTIS: THE TEAR OF DEATH Cancer: a precambrian legacy? Horse sense? Those strange antarctic fishes Our genes aren't us! Geology The incorruptibility of the ganges Geophysics Flat-plate hail Mystery radio bursts Plane weirdness made plain An offset solar halo of 28 ...
Terms matched: 1 - Score: 15 - 15 May 2017 - URL: /sf094/index.htm
