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SOFIA eNewsletter for Scientists
Recent SOFIA Accomplishments
Telescope Operation and Integration into Aircraft

v 9 January 13, 2004

This eNewsletter is intended for the scientific community. If you would like to receive our quarterly newsletter, please contact SOFIA@usra.edu

All major components of the telescope, excepting the secondary and tertiary mirrors, have now been installed in the SOFIA aircraft (see Figures 1 and 2). In addition, all control and support equipment is now in place and has been shown to function correctly. A major milestone was reached in November when the 1.2 meter spherical hydrostatic bearing was successfully used to float the ten-ton SOFIA telescope on 50 atmospheres of oil pressure. At that point the telescope could be moved easily by one person. The telescope servo control system was closed around the electronic fiber optic gyros in early December. All three tracker cameras were successfully operated in mid December. By placing fixed laser spots on the ceiling of the hangar, the SOFIA team was able to image the spots in the 6 degree wide field camera (Figure 3). Although these spots were slightly out of focus, the team was able to demonstrate inertial tracking of the telescope with the correct direction and rate. Within the next few months, the following additional checks will be made:

1) Non-inertial tracking using the fixed laser spots
2) Tests of the secondary alignment, focus and chopping mechanism
3) Alignments of the all telescope optics
4) End to end star test with the CCD camera HIPO

Figure 1: The SOFIA telescope, looking through the cavity opening. The 2.7 meter primary mirror is under the red cover. The wide field camera, with its aluminum cover, is on the telescope headring at the 8 o'clock position. The plastic wrap temporarily protects areas of the metering structure painted with Ball IR black paint.

Figure 2: The SOFIA telescope from within the interior of the B747SP aircraft. The bearing sphere (not visible) is inside the structure centered on the white bulkhead. Instruments are mounted on the far end of the Nasmyth tube, presently foil covered.

Click on images for close-up view

Figure 3: Wide field image of two laser spots projected on the hangar roof.
Verification of the inertial tracking and camera orientation were obtained from a set of similar images.

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