Submillimeter Wave Astronomy Satellite

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SWAS (Explorer 74)
SWAS (Explorer 74)
Type: Space telescope
Country: United StatesUnited States United States
Operator: National Aeronautics and Space AdministrationNASA NASA
COSPAR-ID : 1998-071A
Mission dates
Dimensions: 288 kg
Begin: December 6, 1998, 00:57 UTC
Starting place: Point Arguello WADZ
Launcher: Pegasus-XL F25
Status: in orbit
Orbit data
Rotation time : 97.6 min
Orbit inclination : 69.9 °
Apogee height :  651 km
Perigee height :  638 km

Submillimeter Wave Astronomy Satellite (SWAS) is a space telescope that extracts spectra of interstellar matter in the submillimeter range . The aim of SWAS is to investigate the chemical composition and condition of interstellar gas clouds in the star formation regions of our Milky Way .

construction

SWAS has a relatively small telescope with an elliptical primary mirror measuring 71 × 55 cm. By observing molecules such as water and molecular oxygen, it was possible to achieve results that can not be achieved with large ground-based radio telescopes , since these are hindered by the earth's atmosphere. Due to the design, SWAS only observes the following spectral lines:

  • Water (H 2 O) at 556.936 GHz
  • molecular oxygen (O 2 ) at 487.249 GHz
  • neutral carbon (CI) at 492.161 GHz
  • the carbon monoxide isotope ( 13 CO) at 550.927 GHz and
  • the water isotope (H 2 18 O) at 548,676 GHz.

The spatial resolution is about 4 arc minutes. SWAS is a small explorer project of NASA in cooperation with American research institutes and the University of Cologne.

begin

The launch took place with an aircraft-based Pegasus XL rocket. The L-1011 carrier aircraft took off on December 5, 1998 at 23:58 UTC from Vandenberg Air Force Base , California, and disengaged the rocket an hour later over the Pacific in the Point Arguello Western Air Drop Zone . According to local time it was December 5th, according to UTC it was already December 6th. A start attempt two days earlier had been canceled due to software problems in the dropping area.

Deep Impact Measurement Campaign

To protect the environment, SWAS was switched off on July 21, 2004. The satellite was reactivated on June 5, 2005 to observe comet Tempel 1 , which was hit by part of the Deep Impact spacecraft on July 4 . The observations continued until September 1, 2005. Contrary to expectations, the released matter hardly contained any water vapor.

Web links

Individual evidence

  1. ↑ SWAS - orbit data in the NSSDCA Master Catalog, accessed on September 27, 2012 (English).
  2. ↑ Frank Bensch et al: SWAS Observations of Comet 9P / Tempel 1 and Deep Impact. (PDF) In: Proceedings IAU Symposium No. 231, 2005. International Astronomical Union, March 21, 2006, pp. 489-490 , accessed September 27, 2012 (English).