Jupiter Observed With SOFIA
The Stratospheric Observatory for Infrared Astronomy, or SOFIA, completed the telescope characterization and "first light" mission between sunset May 25 and sunrise May 26.
"First light" is a term astronomers use to describe the first viewing with a new telescope. The airborne observatory obtained its first in-flight celestial observations with a crew that included 10 scientists, engineers and technicians from NASA, the Universities Space Research Association, the German SOFIA Institute and Cornell University, Ithaca, N.Y.
"This culminates over a decade of work by many, many people on SOFIA and it represents the first time light has gone through the optical path to a science instrument in flight," said Bob Meyer, SOFIA program manager.
The highly modified Boeing 747SP with the high-tech telescope, which is based at the Dryden Aircraft Operations facility in Palmdale, completed the tasks during a nearly eight-hour mission.
"We've retired many of the threats and much of the risk with this telescope-characterization and first-light flight. This was a major accomplishment in terms of understanding the quality of our observations, for example the amount of image stability, or shaking, with airflow over the telescope. Though improvements can be made, we exceeded expectations," Meyer added.
The NASA 747SP performed well and the telescope's milestone was a reflection on its manufacturers, he said.
"The German-designed-and-built telescope has really worked well. It represents some of the great German engineering that we have come to appreciate over the years," Meyer said.
Scientists are processing the data gathered with the 2.5-meter telescope and Cornell University's Faint Object infrared Camera for the SOFIA Telescope, also known as the FORCAST. The FORCAST is unique in that it records energy coming from space at infrared wavelengths between 5 and 40 microns - most of which cannot be seen by ground-based telescopes due to blockage by water vapor in Earth's atmosphere.
With the key flight complete, Meyer said, upgrading the on-board mission control and communication systems for improved integration of the science instrument and control of the telescope is next.
Other short-term goals will include ensuring that all the flying observatory's systems are operational; verification and validation tests of new software and systems; improving the telescope's stability while it is pointed at an object; and overall efficiency and effectiveness of the observatory, he said.
Also key will be expanding the range at which the telescope can "see" celestial objects as the aircraft flies and preparing for the first science missions with the SOFIA by winter. A first flight with the FORCAST instrument and a second with the German Receiver for Astronomy at Terahetz Frequencies instrument, which will allow scientists to view images in three different infrared wavelengths, are planned for coming months.
Meyer anticipates it will take more than two years before routine science flights, which will occur at a rate of three or more missions a week, can begin.
Before that can happen, a number of items will be checked off the list, including a process called commissioning of the science instruments. During that process, tests on the ground and in the air define and confirm the instruments' exact characteristics, to enable future observers to know what capabilities are available and what data can be obtained with each, Meyer said.
From a flight hardware and maintenance standpoint, there also are a few items on the to-do list.
For example, the door to the telescope has become stuck in flight during past tests. A new procedure was approved to allow for the software to be reset in flight to facilitate proper operation, Meyer said. Previously, the aircraft was required to land in order for the software to be reset.
The door's reliability is expected to improve with the new procedure, and upgrades to the door system are planned, he said. In addition, science operations May 26 called for the door to be opened and closed only once, where during flight test the door was opened and closed up to 30 times per flight.
Teams members also are working to resolve an anticipated problem before it impacts science flights, Meyer said. The SOFIA aircraft is among the few 1970s-vintage "SP" 747s still in operation, meaning it will become increasingly difficult to find spare parts.
NASA purchased an SP model that is no longer being flown from a source in Arizona, where parts unique to the SPs that are airworthy or can be refurbished are being catalogued for potential use. Program officials anticipate that the SOFIA will be operated for as many as another 20 years, Meyer said. Another change planned for the near future is a partial upgrade from dials and switches to an electronic, or partial glass, cockpit.
Meyer praised the Ames team involved in the work on the cavity in the SP where the telescope is housed. "The work was phenomenal," he said.
And NASA's 25 years of experience flying the Kuiper Airborne Observatory at Ames Research Center, Moffett Field, Calif., have made valuable contributions to the SOFIA program and will continue doing so as science missions begin.
"Lessons learned in the design of the opening itself - the port to look through - were applied to SOFIA; we benefited from the operational lessons learned from KAO. They had mission-planning software in place and they had a lot of tools they used for mission planning in terms of where targets would be and how to calculate headings. That software has been improved upon and we're reaping the benefit of a lot of the work done on the Kuiper," he said.
Another feature to be added based on the KAO is the capability to pre-cool the telescope and cavity on the ground prior to flight. This will allow science observations to be made earlier in the mission, rather than using a portion of the flight to cool the telescope with the cold atmosphere aloft.
Meyer also acknowledged the reason he feels the program is a success: "We have a very talented group of people who have taken on the challenges and resolved them."
By Jay levine