TRACE
Encyclopedia
TRACE 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 loop
s 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 passband
s 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.
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
space telescope
Space observatory
A space observatory is any instrument in outer space which is used for observation of distant planets, galaxies, and other outer space objects...
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
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
photosphere
Photosphere
The photosphere of an astronomical object is the region from which externally received light originates. The term itself is derived from Ancient Greek roots, φῶς, φωτός/phos, photos meaning "light" and σφαῖρα/sphaira meaning "sphere", in reference to the fact that it is a spheric surface perceived...
and transition region to the corona
Corona
A corona is a type of plasma "atmosphere" of the Sun or other celestial body, extending millions of kilometers into space, most easily seen during a total solar eclipse, but also observable in a coronagraph...
. A main focus of the TRACE instrument is the fine structure of coronal loop
Coronal loop
Coronal loops form the basic structure of the lower corona and transition region of the Sun. These highly structured and elegant loops are a direct consequence of the twisted solar magnetic flux within the solar body. The population of coronal loops can be directly linked with the solar cycle; it...
s 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
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....
was built by NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
'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
Charge-coupled device
A charge-coupled device is a device for the movement of electrical charge, usually from within the device to an area where the charge can be manipulated, for example conversion into a digital value. This is achieved by "shifting" the signals between stages within the device one at a time...
detector giving an 8.5 arc minute field of view
Field of view
The field of view is the extent of the observable world that is seen at any given moment....
. The telescope is designed to take correlated images in a range of wavelengths from visible light, through the Lyman alpha line to far ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
. The different wavelength passband
Passband
A passband is the range of frequencies or wavelengths that can pass through a filter without being attenuated.A bandpass filtered signal , is known as a bandpass signal, as opposed to a baseband signal....
s correspond to plasma
Plasma (physics)
In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...
emission temperatures from 4,000 to 4,000,000 K
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...
. The optics use a special multilayer technique to focus the difficult-to-reflect EUV
Extreme ultraviolet
Extreme Ultraviolet radiation is high-energy ultraviolet radiation, generally defined to be electromagnetic radiation in the part of the electromagnetic spectrum spanning wavelengths from 120 nm down to 10 nm, and therefore having photons with energies from 10 eV up to 124 eV...
light; the technique was first used for solar imaging in the late 1980s and 1990s, notably by the MSSTA
MSSTA
The Multi-spectral solar telescope array, or MSSTA, was a sounding rocket payload built by Professor A.B.C. Walker, Jr. at Stanford University in the 1990s to test EUV/XUV imaging of the Sun using normal incidence EUV-reflective multilayer optics...
and NIXT
NIXT
The NIXT, or Normal Incidence X-ray Telescope, was a sounding rocket payload flown in the 1990s by Professor Leon Golub of the Smithsonian Astrophysical Observatory, to prototype normal-incidence optical designs in extreme ultraviolet solar imaging...
sounding rocket payloads.