TRACE

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Transition Region and Coronal Explorer
Transition Region and Coronal Explorer satellite
NamesExplorer-73
SMEX-4
TRACE
Mission typeHeliophysics
OperatorNASA / GSFC
COSPAR ID1998-020A Edit this at Wikidata
SATCAT no.25280
Websitetrace.lmsal.com
Mission duration1 year (planned)
12 years, 2 months and 19 days (achieved) [1]
Spacecraft properties
SpacecraftExplorer LXXIII
Spacecraft typeTransition Region and Coronal Explorer
BusTRACE
ManufacturerGoddard Space Flight Center
Launch mass250 kg (550 lb)
Dimensions1.9 × 1.1 m (6 ft 3 in × 3 ft 7 in)
Power220 watts
Start of mission
Launch date2 April 1998, 02:42:39
Pegasus XL (F21)
Launch siteVandenberg, Stargazer
ContractorOrbital Sciences Corporation
Entered service20 April 1998
End of mission
Deactivated21 June 2010, 23:56 UTC
Last contact21 June 2010
Orbital parameters
Reference systemGeocentric orbit[2]
RegimeSun-synchronous orbit
Perigee altitude520.0 km (323.1 mi)
Apogee altitude547.2 km (340.0 mi)
Inclination97.84°
Period95.48 minutes
Instruments
TRACE Imaging Telescope

TRACE mission patch
Fast Auroral Snapshot Explorer (Explorer 70) (SMEX-2)
Submillimeter Wave Astronomy Satellite (Explorer 74) (SMEX-3) →
 
Explorer program

Transition Region and Coronal Explorer (TRACE, or Explorer 73, SMEX-4) was a

Small Explorer program, launched on 2 April 1998, and obtained its last science image on 21 June 2010, at 23:56 UTC.[3]

Mission

The Transition Region and Coronal Explorer (TRACE) is a NASA small explorer mission designed to examine the three-dimensional magnetic structures which emerge through the Sun's photosphere (the visible surface of the Sun) and define both the geometry and dynamics of the upper solar atmosphere (the transition region and corona). Its primary science objectives are to: (1) follow the evolution of magnetic field structures from the solar interior to the corona; (2) investigate the mechanisms of the heating of the outer solar atmosphere; and, (3) determine the triggers and onset of solar flares and mass ejections. TRACE is a single-instrument, three-axis stabilized spacecraft. The spacecraft attitude control system (ACS) utilizes three magnetic-torquer coils, a digital Sun sensor, six coarse Sun sensors, a three-axis magnetometer, four reaction wheels, and three two-axis inertial gyros to maintain pointing. In science mode the spacecraft uses an instrument-provided guide telescope as a fine guidance sensor to provide a pointing accuracy of less than 5 arcseconds. Power is provided to the spacecraft through the use of four panels of gallium arsenide (GaAs) solar cells with a total area of 2 m2 (22 sq ft). The solar array actually produces power of around 220 watts, 85 W of which is used each orbit by the spacecraft and 35 W of which is used by the instrument each orbit. The remaining power is used for operational and decontamination heating of the spacecraft and telescope. A 9 A-hour nickel–cadmium battery (NiCd) provides energy during time when the spacecraft is in the Earth's shadow. Communications are provided via a 5 W S-band transponder, providing up to 2.25 Mbit/s downlink data transmission and 2 kbit/s uplink. Data are transmitted up to six times daily. Data are stored on-board using a solid-state recorder capable of holding up to 300 MB. The command and data handling system uses a 32-bit 80386/80387 processor.[4]

Spacecraft

The satellite was built by NASA's

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 extreme ultraviolet (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.

Experiment

TRACE Imaging Telescope

The telescope is of

SWATH, a small explorer developed for the U.S. Air Force, and NIXT, a set of rocket flights flown by the Smithsonian Astrophysical Observatory (SAO) five times between 1983 and 1993. Many of the designs and some of the space flight hardware from the MDI instrument on Solar and Heliospheric Observatory
(SoHO) was also used.

Image gallery

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

See also

  • Explorer program

References

  1. ^ "TRACE science mission terminated". Lockheed Martin Solar and Astrophysics Lab. 21 June 2010. Archived from the original on 7 February 2016. Retrieved 13 September 2015.
  2. ^ "Trajectory: TRACE (1998-020A)". NASA. 28 October 2021. Retrieved 29 November 2021. Public Domain This article incorporates text from this source, which is in the public domain.
  3. ^ "Transition Region and Coronal Explorer". Lockheed Martin Solar and Astrophysics Lab.
  4. ^ "Display: TRACE (1998-020A)". NASA. 28 October 2021. Retrieved 29 November 2021. Public Domain This article incorporates text from this source, which is in the public domain.

External links

Media related to TRACE at Wikimedia Commons

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