Engineering topics

Ellison, S. L.

Publications and source records attributed to Ellison, S. L..

3 records

NASA NTRS2003

Hydrogen Concentrations on C-Class Asteroids Derived from Remote Sensing

We present spectroscopic observations of 16 asteroids from 1.9-3.6 microns collected from the United Kingdom Infrared Telescope (UKIRT) from 1996-2000. Of these 16 asteroids, 11 show some evidence of a 3 microns hydrated mineral absorption feature greater than 2(sigma) at 2.9 microns. Using relations first recognized for carbonaceous chondrite powders by Miyamoto and Zolensky and Sato et al., we have determined the hydrogen to silicon ratio for these asteroids and calculated their equivalent water contents, assuming all the hydrogen was in water. The asteroids split into 2 groups, roughly defined as equivalent water contents approx. greater than 7% (8 asteroids, all with 3 microns band depths approx. greater than 20%) and approx. greater than 3% for the remaining 8 asteroids. This latter group includes some asteroids for which a weak but statistically significant 3 microns band of non-zero depth exists. The G-class asteroids in the survey have higher water contents, consistent with CM chondrites. This strengthens the connection between CM chondrites and G asteroids that was proposed by Burbine. We find that the 0.7 microns and 3 microns band depths are correlated for the population of target objects.

Rivkin, A. S.↗

NASA NTRS2003

Hydrogen Concentrations on C-class Asteroids Derived from Remote Sensing

We present spectroscopic observations of 16 asteroids from 1.9-3.6 microns collected from the United Kingdom Infrared Telescope (UKIRT) from 1996-2000. Of these 16 asteroids, 11 show some evidence of a 3 micron hydrated mineral absorption feature greater than 2 sigma at 2.9 microns. Using relations first recognized for carbonaceous chondrite powders by Miyamoto and Zolensky (1994) and Sato et al. (1997), we have determined the hydrogen to silicon ratio for these asteroids and calculated their equivalent water contents, assuming all the hydrogen was in water. The asteroids split into 2 groups, roughly defined as equivalent water contents greater than approximately 7% (8 asteroids, all with 3 micron band depths greater than approximately 20%) and less than approximately 3% for the remaining 8 asteroids. This latter group includes some asteroids for which a weak but statistically significant 3 micron band of non-zero depth exists. The G-class asteroids in the survey have higher water contents, consistent with CM chondrites. This strengthens the connection between CM chondrites and G asteroids that was proposed by Burbine (1998). We find that the 0.7 micron and 3 micron band depths are correlated for the population of target objects.

Rivkin, A. S.↗

NASA NTRS2002

Hydrogen Concentrations on C-class Asteroids from Remote Sensing

We present spectroscopic observations of 16 asteroids from 1.9-3.6 microns, collected from the United Kingdom Infrared Telescope (UKIRT) from 1996-2000. Of these 16 asteroids, 11 show some evidence of a 3-micron hydrated mineral absorption feature greater than 2 sigma at 2.9 microns. Using relations first recognized for carbonaceous chondrite powders by Miyamoto and Zolensky (1994) and Sato et al. (1997), we have determined the hydrogen/silicon ratio for these asteroids and calculated their equivalent water contents, assuming all the hydrogen was in water. The asteroids split into two groups, roughly defined as equivalent water contents of greater than approx. 7% (eight asteroids) and less than approx. 3 % (the remaining eight asteroids). This latter group includes some asteroids for which there is a small but statistically significant 3-micron band of non-zero depth. The G-class asteroids in the survey have higher water contents, consistent with CM chondrites. This strengthens the connection between CM chondrites and G asteroids that was proposed by Burbine (1998). We find that the 0.7-micron and 3-micron band depths are correlated for the population of target objects.

Rivkin, A. S.↗