Support Structure Project for the Constellation-X Mirrors

Mirror Support Home

Statement of Work

The goal of our project is to investigate and design one or more possible restraint/support structures that will prevent the mirrors aboard Constellation-X from failing during launch. We would like to do so in such a way that the final position of the mirrors is accurate and we will report the extent to which we were able to do so in the final report. We will also stay within the constraints set by GSFC (Goddard Space and Flight Center).

 

Background

X-ray telescopes will be used on the NASA Constellation-X mission to image stellar phenomena invisible to optical telescopes, such as black holes, galaxy formation, Universe evolution, etc. Unlike a typical optical telescope, which requires two mirrors for directing and focusing a beam, X-ray telescopes require many shells of mirrors, as they must be bent at grazing angles. The mirror module of an X-ray telescope requires over 200 shells of concentric mirrors, each made of glass approximately .4mm thick to achieve angular resolutions of 12.5 seconds; they are very fragile, and any deforming or breaking of the mirror causes failure in the telescope. The X-Ray mirror team is therefore responsible for creating a support structure that will protect the mirrors from failing under launch conditions.

We focus on two major launch environment concerns to address this goal. One concern is that during this stage, mirrors will be subjected to up to 15g acceleration, causing considerable strain to the glass mirrors. To correct for this problem, the team will perform a thorough stress analysis of various support materials appropriate for space conditions, as well as simulate how their attachment to the mirrors may alleviate the stress. The other major cause of failure during launch is mirror resonance; a pressure oscillation may cause the mirrors to vibrate constructively until the energy compounds to the point of failure. Typically, pressure frequencies under launch conditions are 50 Hz or less. Therefore, a vibration analysis must be preformed to produce the support structure that will maximize resonant frequency increase. On completion of these two analyses, the team will propose designs for a support structure capable of withstanding launch conditions without failure.