Transition Region and Coronal Explorer (TRACE)
Artist's illustration of TRACE in orbit
||2 April 1998 UT
||Vandenberg Air Force Base
||1998 - 2010
||white light (170 to 1000 nm)
UV (~121.6/155/~160/~170 nm)
EUV (17.1/19.5/28.4 nm)
||30 cm (aperture)
TRACE (Transition Region And Coronal Explorer) was a NASA space telescope 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 and transition region to the corona. A main focus of the TRACE instrument is the fine structure of coronal loops low in the solar atmosphere. TRACE is a SMEX or SMall EXplorer mission, launched in 1998 and obtaining its last science image in 2010.
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 for the period, by the Smithsonian Astrophysical Observatory (SAO) in Cambridge MA. TRACE was launched in April 1998 on a Pegasus rocket, has a 30 cm aperture and 1024 x 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.