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SOFIA eNewsletter for Scientists

v10 September, 2004

I am pleased to announce three major milestones in the SOFIA program since the last newsletter in January 04. First, in April, the SOFIA Aircraft successfully passed an FAA proof-pressure test in Waco, TX. The aircraft modifier, L3 Communications Integrated Systems, pressurized the fuselage to a differential pressure 1.3 times that which will be experienced at cruising altitude. At the time of maximum pressure almost one million pounds of force was exerted on the bulkhead that supports the SOFIA telescope. The second milestone occurred this summer, when the SOFIA telescope was integrated into the aircraft and successfully tested. The tests included the first observations of stars through the entire optics system using the observatory’s guide cameras and the first light occultation photometer HIPO (High-speed Photometer for Occultations; Ted Dunham, Lowell Observatory, PI). Some of the results of this test are described below. This successful testing effort was the result of the combined work of many members of the SOFIA team, including NASA, DLR, USRA, L3, the HIPO team and MAN and KT (German telescope contractors). Finally, in July, DLR, the German aerospace agency supporting SOFIA, announced that the University of Stuttgart will run the Deutsches SOFIA Institut (DSI) that will support the German contribution to the SOFIA program during operations. This contribution will include telescope support personnel, scientists, aircraft fuel, aircraft engine maintenance and telescope spare parts. The DSI will also be responsible for the solicitation and selection of German telescope time proposals. Below, detailed descriptions and images of our milestones have been put together by our Education and Public Outreach Director, Dana Backman.

Regards,

Eric Becklin, SOFIA Chief Scientist

SOFIA telescope sees its first stars, August - September 2004

On August, 18 2004, SOFIA was towed out of its hangar and the telescope was pointed at the sky. For the very first time, light from a celestial source, in this case the star Polaris, passed through the SOFIA telescope and was detected by the HIPO instrument (High-speed Imaging Photometer for Occultations; Ted Dunham, Lowell Observatory,PI) which was bolted to the science instrument flange at the telescope focal plane.

Tests were repeated a few days later after adjustments were made to optimize the alignment of the telescope optics. The resulting images are described below and can be viewed at this URL:

http://sofia.arc.nasa.gov/News/news_2004/08-19-04_OnSky/08-19-04_OnSky.html

(1) The exterior and interior of the aircraft during the tests plus a pdf file containing the NASA-Ames press release regarding the on-sky tests.

(2) An image of Polaris as seen by HIPO through the SOFIA optics. The FWHM of the image is 2-3 arcsec.

(3) A contour plot of a region of the image centered on Polaris.

(4) A Shack-Hartmann test image corresponding to the Polaris image used to measure the wavefront tilts across telescope entrance pupil.

(5) A plot of tracking data taken with HIPO showing better than 0.8 arcsec RMS tracking.

(6) HIPO, and its proud crew of designers and builders from Lowell Observatory.

Excerpts from e-mail messages to the SOFIA team from USRA Chief Engineer Pat Waddell and NASA SOFIA Deputy Chief Engineer Kaiser Adeni respectively at the start and end of the on-sky tests can also be found at the following URL:

http://www.sofia.usra.edu/Science/newsletter/2004/2004_v10/email_excerpts.html

SOFIA Aircraft Proof-pressure Test, April 2004

This was a significant event in verifying the integrity of the aircraft's structural modifications as well as the Telescope Assembly's capacity to support cabin pressure. In many ways it was the most significant structural loading case for the Observatory. In addition to passing the test, the aircraft was thoroughly instrumented with strain gages allowing us to begin the process of validating the analytical Finite Element Model that was developed for the structural design development.

More information and images can be found at this URL:

http://sofia.arc.nasa.gov/News/news_2004/04-21-04_PressureTest.html

DSI (German SOFIA Institute) to be at the University of Stuttgart

The University of Stuttgart was successful in its bid to be the home of the German operations center for SOFIA. More information can be found at this URL:

http://sofia.arc.nasa.gov/News/news_2004/07-06-04_Univ_Stuttgart/07-06-04_stuttgart.html

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Page Last Updated: December 21, 2004