A method was developed for in-orbit measurement of the relative pointing of spectrometer channels, and the relationship between the spectrometer channels and the spacecraft coordinate system. In this innovation, individual scans of the Moon, from the three channels, were used to determine the position of the center of the Moon, with respect to channel-specific coordinates. Comparing the coordinates of the center of the Moon, obtained from individual channels, yields the relative pointing between the channels. Comparing the coordinates of the center of the Moon in one of the channels with the Moon ephemerides and with the spacecraft coordinate measurement, using the onboard star tracker, yields the relative orientation of the channel optical axes with respect to the spacecraft coordinates.

This work was done by Alex Abramovici and Harold R. Pollock of Caltech for NASA’s Jet Propulsion Laboratory. For more information, contact This email address is being protected from spambots. You need JavaScript enabled to view it.. NPO-47526

NASA Tech Briefs Magazine

This article first appeared in the May, 2011 issue of NASA Tech Briefs Magazine.

Read more articles from this issue here.

Read more articles from the archives here.