Stratospheric Observatory for Infrared Astronomy

from Wikipedia, the free encyclopedia
First SOFIA flight on April 26, 2007
KAO and SOFIA, Ames Research Center 2008
The main mirror before the coating
SOFIA in flight with the telescope door open (December 18, 2009)
The telescope in the fuselage of the aircraft
SOFIA conducts a night test flight over California (in HD).

The Stratospheric Observatory for Infrared Astronomy ( English Stratospheric Observatory For Infrared Astronomy , SOFIA ) is a flying telescope , which the NASA in cooperation with the German Center for Aerospace (DLR) for Infrared Astronomy has developed. For this, a reflector telescope was installed on board a converted Boeing 747SP (short long-haul version) with the registration number N747NA . SOFIA has been in use since November 30, 2010.

description

SOFIA is designed for a service life of 20 years. The aircraft is operated by NASA's DAOF ( Dryden Aircraft Operations Facility ) in Palmdale , California. On three to four nights a week, up to eight hours should be observed from a height of 12 to 14 kilometers. Once a year SOFIA should be stationed at Stuttgart Airport in Germany for two weeks. SOFIA replaced the Kuiper Airborne Observatory (KAO), which was in use from 1974 to 1995.

Infrared telescopes that are mounted on airplanes fly above the troposphere , which absorbs a large part of the infrared radiation. Maintenance costs are lower and improved technology can be retrofitted more easily than in telescopic satellites. In addition, the service life for aircraft-mounted telescopes is 20 years, whereas the liquid helium supply for cooling is exhausted after a few years for telescope satellites .

The cooperation between NASA and DLR was contractually extended for a further 4 years until 2020 on June 2, 2016 - at the status of 250 10-hour observation flights. In 2018 research results are to be evaluated [out of date] in order to decide on a further extension within the time frame of 2030.

Course of the missions

The first test flight with the telescope door open took place in December 2009, the first test flight with the use of the telescope, the so-called " first light ", on May 26, 2010.

The first scientific observation flight was carried out from November 30th to December 1st, 2010. SOFIA started from NASA Dryden Aircraft Operations Facility in Palmdale, California and carried out observations at heights of about 13 km with the infrared camera ( FORCAST - Faint Object InfraRed-CAmera for the SOFIA Telescope ). The aim of the observation was the constellation Orion . Full functionality was planned for 2014; around 160 missions with around 1000 hours of observation should then be carried out annually.

On March 4, 2014, after budget cuts, NASA announced that it would no longer be able to raise any further financial resources for the SOFIA project and that it would mothball the aircraft in 2015 if no partner would pay the costs. The then chairman of the DLR Board of Management, Johann-Dietrich Wörner , was "dismayed and annoyed" by NASA's decision. After NASA got its budget for this project approved, the German-American project could be continued.

In the summer of 2015, SOFIA was stationed in New Zealand in order to be able to observe a star occultation of the dwarf planet Pluto at the end of June 2015 . Such occultations are relatively rare and in this case it was able to provide special information for the Pluto probe New Horizons , which flew past this dwarf planet almost two weeks later .

At the end of 2015, NASA then summarized the results:

  • Exploring Pluto
  • Promotion of young scientists
  • Clues as to where the earth's water originates
  • A connection between supernovae and the formation of planets
  • The first exoplanet observed by SOFIA

SOFIA has been on its fourth scientific mission since February 3, 2016. On June 6, 2016, SOFIA (after 2013 and 2015) landed again in Christchurch , NZ, in order to complete 25 observation flights from there by July 20. For the first time in New Zealand, in addition to GREAT (German Receiver for Astronomy at Terahertz Frequencies), an improved version of the instrument is also flying: upGREAT contains 14 more sensitive sensors instead of one. The aim is to map the occurrence of atomic oxygen in the Magellanic Clouds. For the first time in the southern hemisphere, this is also German FIFI-LS (Field-Imaging Far-Infrared Line Spectrometer), which is supposed to map several chemical elements more quickly and over a broader frequency spectrum, for example in star formation regions. The US-American instrument FORCAST (Faint Object InfraRedCAmera for the SOFIA Telescope) analyzed dust disks around young stars and elsewhere in a shorter-wave range than FIFI-LS in a planned 9 missions. The schedule was for SOFIA to return to Palmdale on July 25th to complete 40 more science flights from California from mid-August to the end of 2016 after servicing the aircraft and telescope.

In 2016, the infrared telescope is expected to explore all astronomical objects such as planets, moons, asteroids and comets in our solar system. But also the exploration of emerging stars and planets, the exoplanets, the space between the stars and even closer active galaxies are on the agenda of this mission.

From September 16 to 20, 2019, SOFIA was stationed at Stuttgart Airport for the first time. On the night of September 18-19, she was to carry out her first research flight over Europe from there. [outdated]

The plane

The telescope is supported by a Boeing 747SP , which has a shorter fuselage, a higher maximum altitude and a greater range than the basic version 747-100 / 200. The Boeing 747SP can fly over 99 percent of the observations of disturbing water vapor at an altitude of 12 to 15 km. The selected machine with the registration number N747NA completed its maiden flight on April 25, 1977 as the 306th B747 built and was delivered shortly afterwards to its customer Pan Am . In May 1977, on the 50th anniversary of Charles Lindbergh's first solo flight across the Atlantic , his widow Anne Morrow Lindbergh christened the aircraft the Clipper Lindbergh . In February 1986 United Airlines took over the machine for which it flew until the end of 1995. NASA bought the B747 in 1997 and began rebuilding and test flights in Waco , Texas. A door has been cut into the fuselage behind the left wing, which is opened for operation to allow the telescope to look up. The telescope section is separated from the rest of the cabin by a pressure bulkhead , in which up to 15 scientists, technicians and observers work in addition to the three-person cockpit crew.

After rumors about the termination of the project in early 2006, NASA officially confirmed the continuation of the project in July 2006. The first flight after the conversion took place on April 26, 2007 in Waco. On May 21, 2007, Erik Lindbergh, a grandson of Charles Lindbergh , renamed the aircraft as Clipper Lindbergh . The base of the aircraft was relocated from the Dryden Flight Research Center to the Dryden Aircraft Operations Facility in Palmdale in January 2008 .

In 2014 Lufthansa Technik carried out a D-Check of the aircraft, during which the integrated telescope was also checked.

telescope

A Nasmyth telescope , manufactured by the German companies MAN Technologie AG and Kayser-Threde , is built into the rear fuselage area of ​​the B747SP , structurally a combination of a Newtonian telescope and a Cassegrain telescope . As with the latter, the rays are reflected by the convex secondary mirror in the direction of the primary mirror, but before reaching it, they are deflected to the side by a third, plane-ground mirror. The last section of the beam path with the focal point (Nasmyth focus) coincides with the tilt axis of the telescope and the longitudinal axis of the aircraft and is therefore stationary. The mirror telescope rotates in a circular bearing ring with a diameter of 1.2 m, which is hydrostatically sealed with oil and connected to the fuselage circumference by a pressure bulkhead in front of the telescopic sliding door and also takes the tube and ancillary units that are in front of the ring with it. The beam lasts in the direction of flight and passes through the measuring instruments mounted on the tube, which rotate with it.

The telescope, which is a dumbbell-shaped carbon fiber structure made of carbon fiber structure and is mounted in the middle to isolate vibrations, is connected via a belt loop reaching into a pit in the floor with various lines for energy, measurement, control, cooling and data. The lines run to a standing rack with the functions of supply and data processing.

Setting the correct right ascension is essentially based on the aircraft's corresponding heading, which typically flies approximately circular arc-shaped routes over the globe. The telescope can only be seen out of the aircraft on the port side (= left), controlled by a gear rim drive with 15–70 ° elevation, and is additionally fine-tuned by ± 3 ° with linear motors .

The operating altitude above the troposphere and a spectral range of the telescope from 0.3 µm to 1600 µm enable observations in a wide infrared range, which for ground-based observatories is only partially accessible in the infrared window due to absorption mainly from water vapor contained in the troposphere .

The main mirror has a diameter of 270 centimeters and an effective opening of 250 centimeters due to the shadowing (obstruction) of the two smaller mirrors. The telescope, with its frame, bearings and additional instruments, weighs around 17 tonnes and was installed in February 2004 after being transported by an Airbus Beluga aircraft and pointed into the sky for the first time on the night of August 19, 2004. The aircraft remained on the ground.

The semi-cylindrical window opening encompasses the upper half of an approximately four-meter-long fuselage section behind the wings and in front of the T-tail unit. The resulting constriction of the load-bearing fuselage to half the height required serious reinforcements. The window is partially or completely closed from the inside with a sliding door on a circular path and thus rainproof. In front of the front edge of the opening in the direction of flight there is a small inclined ramp in order to adequately repel the passing air flow and any solid objects such as birds and thus prevent them from entering.

The telescope is always accessible on the focus side. On the lens side, however, there is the low external pressure and around 210–230 K (−63 to −43 ° C) cold.

literature

  • Wendy Whiting-Dolci: Milestones in Airborne Astronomy: From the 1920's to the Present. AIAA, World Aviation Congress, Anaheim 1997, online , (PDF, 3 MB, accessed March 30, 2009).

Web links

Commons : Stratospheric Observatory for Infrared Astronomy  - Collection of images, videos and audio files

Individual evidence

  1. ↑ See also: Lear Jet Observatory - from 1967, received a second camera equipment in 1998.
  2. ↑ Telescope observes space from Jumbojet from Spiegel Online May 27, 2010, accessed May 27, 2010.
  3. ↑ Beth Hagenauer, JD Harrington: NASA Flight Tests Unique Jumbo Jet with Opening in Side: Plane's Airborne Telescope Will Be Used to Study Cosmos. NASA , December 18, 2009, accessed December 20, 2009 .
  4. ↑ SOFIA is making progress - German-language article on Raumfahrer.net from December 26, 2009, accessed May 27, 2010
  5. ↑ Successful first scientific flight of the flying observatory SOFIA , on dlr.de, December 1, 2010, accessed on April 18, 2019
  6. ↑ NASA-German SOFIA Observatory Completes First Science Flight ( Memento from April 3, 2012 in the Internet Archive ) sofia.usra.edu, December 1, accessed on December 4, 2010
  7. ^ SOFIA Image Gallery - Orion mid-IR image , accessed December 4, 2010
  8. ↑ SOFIA Completes Closed-Door Test Flights from January 16, 2008, accessed on May 27, 2010 (English)
  9. ↑ SOFIA sees the first starlight. In: Raumfahrer.net. May 26, 2010, accessed May 30, 2010 .
  10. ↑ Alexander Stirn: Telescope Sofia - NASA leaves the German space travel in the lurch. sueddeutsche.de, March 5, 2014, accessed on March 6, 2014 .
  11. ↑ Olaf Stampf : "It's all about the money" . In: Der Spiegel . No. 12 , March 18, 2014, ISSN  0038-7452 , p. 116 ( spiegel.de [accessed November 15, 2014]).
  12. ^ SOFIA in the Right Place at the Right Time for Pluto Observations. NASA, June 29, 2015, accessed February 22, 2016 .
  13. ↑ SOFIA Completes Busy Year, Highlights of 2015. NASA, December 28, 2015, accessed on February 22, 2016 (English).
  14. ↑ Down Under: SOFIA flying observatory with three instruments in New Zealand dlr.de, June 7, 2016, accessed October 6, 2016.
  15. ↑ SOFIA Begins Fourth Year of Observations Targeting Planets, Asteroids, Stars, Galaxies, and More. NASA, February 19, 2016, accessed February 22, 2016 .
  16. ↑ Research aircraft Sofia: Boeing 747 SP looks out from Stuttgart into the universe. In: aeroTELEGRAPH. September 17, 2019, accessed on September 19, 2019 (Swiss Standard German).
  17. ↑ Flying observatory SOFIA as a guest at Stuttgart airport uni-stuttgart.de
  18. ↑ a b Harald Zaun: Jumbo Phoenix from the Ashes. Telepolis, November 5, 2006, accessed May 27, 2010
  19. ↑ Air International, August 2009, p. 73
  20. ↑ DSI background material on the general overhaul in Hamburg dsi.uni-stuttgart.de; SOFIA's Heavy Maintenance Visit Time Lapse accessed November 15, 2014
  21. ↑ SOFIA data sheet (PDF; 87 kB) on dlr.de