TRACE

Transition Region and Coronal Explorer (TRACE) was a NASA heliophysics and solar observatory designed to investigate the connections between fine-scale magnetic fields and the associated plasma structures on the Sun by providing high resolution images and observation of the solar photosphere, the transition region, and the corona. A main focus of the TRACE instrument is the fine structure of coronal loops low in the solar atmosphere. TRACE is the fourth spacecraft in the Small Explorer program, launched on April 2, 1998, and obtained its last science image on 21 June 2010 23:56 UT.[6]

Transition Region and Coronal Explorer

Illustration of TRACE
Names	Explorer-73, SMEX-4
Mission type	Heliophysics
Operator	NASA / GSFC
COSPAR ID	1998-020A
SATCAT no.	25280
Website	trace.lmsal.com
Mission duration	Planned: 1 year Final: 12 years, 2 months and 19 days[1]
Spacecraft properties
Manufacturer	NASA / GSFC Lockheed Martin[2]
Launch mass	250 kg (551 lb)[2]
Dimensions	1.9 × 1.1 m (6.2 × 3.6 ft)[2]
Power	220 W[3]
Start of mission
Launch date	April 2, 1998, 02:43:23 UTC[4]
Rocket	Pegasus XL
Launch site	Stargazer, Vandenberg AFB
Contractor	Orbital Sciences
Entered service	April 20, 1998[2]
End of mission
Disposal	Decommissioned
Deactivated	21 June 2010
Orbital parameters
Reference system	Geocentric
Regime	Sun synchronous
Semi-major axis	6,914.2 km (4,296.3 mi)
Eccentricity	0.00267
Perigee altitude	517.6 km (321.6 mi)
Apogee altitude	554.5 km (344.6 mi)
Inclination	97.5325°
Period	95.3667 min
RAAN	89.297°
Argument of perigee	91.5219°
Mean anomaly	32.1161°
Mean motion	15.1 rev/day
Epoch	September 10, 2015, 19:19:29[5]
Revolution no.	95290
Main telescope
Name	TRACE Imaging Telescope
Type	Cassegrain[2]
Diameter	30 cm (12 in)[2]
Focal length	8.66 m (28.4 ft)[2]
Wavelengths	Ultraviolet and extreme ultraviolet[2]
Resolution	1 arcsec[2]
Small Explorer program

The satellite was built by NASA's Goddard Space Flight Center. Its telescope was constructed by a consortium led by Lockheed Martin's Advanced Technology Center. The optics were designed and built to a state-of-the-art surface finish by the Smithsonian Astrophysical Observatory (SAO). The telescope has a 30 cm (12 in) aperture and 1024×1024 CCD detector giving an 8.5 arc minute field of view. The telescope is designed to take correlated images in a range of wavelengths from visible light through the Lyman alpha line to far ultraviolet. The different wavelength passbands correspond to plasma emission temperatures from 4,000 to 4,000,000 K. The optics use a special multilayer technique to focus the difficult-to-reflect EUV light; the technique was first used for solar imaging in the late 1980s and 1990s, notably by the MSSTA and NIXT sounding rocket payloads.

Image gallery

• 
  TRACE image of some typical million Kelvin loops
• 
  Image of a sunspot taken by TRACE
• 
  TRACE mosaic of the full-disk Sun

References

1. "TRACE science mission terminated". Lockheed Martin Solar and Astrophysics Lab. June 21, 2010. Retrieved September 13, 2015.
2. Rumerman, Judy A. (2009). NASA Historical Data Book, Volume VII: NASA Launch Systems, Space Transportation/Human Spaceflight, and Space Science 1989-1998 (PDF). NASA History Series. NASA. pp. 812–813. ISBN 978-0-16-080501-1. SP-2009-4012.
3. "TRACE". National Space Science Data Center. NASA. Retrieved September 13, 2015.
4. "TRACE - Trajectory Details". National Space Science Data Center. NASA. Retrieved September 13, 2015.
5. "TRACE - Orbit". Heavens Above. September 10, 2015. Retrieved September 10, 2015.
6. "Transition Region and Coronal Explorer". Lockheed Martin Solar and Astrophysics Lab.

External links

Media related to TRACE at Wikimedia Commons

• TRACE website by Lockheed Martin
• TRACE Data Center by Lockheed Martin
• TRACE website (archived) by NASA's Goddard Space Flight Center