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Transition Region and Coronal Explorer
TRACE illustration (transparent bg).png
Illustration of TRACE
Names Explorer-73, SMEX-4
Mission type Heliophysics
Operator NASA / GSFC
COSPAR ID 1998-020A
SATCAT no. 25280
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 (1998-04-02UTC02:43:23Z) UTC[4]
Rocket Pegasus XL
Launch site Stargazer, Vandenberg AFB
Contractor Orbital Sciences
Entered service April 20, 1998[2]
Orbital parameters
Reference system Geocentric
Regime Sun synchronous
Semi-major axis 6,914.2 km (4,296.3 mi)
Eccentricity 0.00267
Perigee 517.6 km (321.6 mi)
Apogee 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]

TRACE logo.png


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 in 2010.[6]

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[edit]


  1. ^ "TRACE science mission terminated". Lockheed Martin Solar and Astrophysics Lab. June 21, 2010. Retrieved September 13, 2015. 
  2. ^ a b c d e f g h i 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[edit]

Media related to TRACE at Wikimedia Commons