A NASA mission will soon reveal the well-kept secrets of
a mysterious region situated 40 to 110 miles (about 60 to 180
kilometers) above the Earth called the Mesosphere and Lower
Thermosphere/Ionosphere (MLTI), where electrical currents
surge and auroras cast an eerie glow over the Northern and
Southern hemispheres.
The Thermosphere, Ionosphere, Mesosphere, Energetics and
Dynamics (TIMED) mission will uncover the mysteries of this
region by producing the very first set of comprehensive,
global measurements of the MLTI.
TIMED is scheduled to launch Dec. 7 aboard a Delta II rocket
from the Western Range of Vandenberg Air Force Base, Calif.,
during a launch window that extends from 9:58 a.m. to 10:18
a.m. EST (6:58 a.m. to 7:18 a.m. PST).
Studying the MLTI was nearly impossible until now.
Conventional airplanes and balloons cannot reach this high
altitude, and it is too low for direct satellite measurements.
Satellites traveling at orbital speeds encounter enough
particles to burn up, and sub-orbital rockets are limited to
studying just one specific area before falling back to Earth
after only a few minutes.
This first in a series of six Solar Terrestrial Probes will
study the MLTI region from a very high location — a 388-mile
(approximately 625-kilometer) circular orbit around the Earth.
TIMED will “share” its launch vehicle with an oceanography
mission called Jason-1.
“It is imperative that we learn more about the dynamics of the
MLTI because the Sun’s energy often has profound effects on
the areas directly above and below this region,” said Sam Yee,
TIMED project scientist at The Johns Hopkins University
Applied Physics Laboratory (JHU/APL) in Laurel, Md. “With
TIMED, scientists will be able to develop better predictive
models of space weather’s effects on communications, satellite
tracking, spacecraft lifetimes and degradation of spacecraft
materials.”
TIMED will gather data on the MLTI using four instruments:
* Global Ultraviolet Imager (GUVI). GUVI is an ultraviolet
spectrograph designed to measure the composition and
temperature profiles of the MLTI region, as well as its
auroral energy inputs.
* Solar Extreme Ultraviolet Experiment (SEE). This instrument
will observe solar ultraviolet irradiance (the primary energy
that is deposited into the MLTI region). SEE will determine
how much this energy varies and how it affects the atmosphere
and changes its composition.
* TIMED Doppler Interferometer (TIDI). TIDI will measure
winds and temperature of the MLTI, determining wind speed and
direction by examining minuscule changes in the color of light
emitted from chemical constituents in the atmosphere.
* Sounding of the Atmosphere using Broadband Emission
Radiometry (SABER). This multi-channel infrared radiometer
will measure a wide range of infrared light emitted by the
atmosphere at several altitudes.
A unique feature of the TIMED mission is its interdisciplinary
approach. The four instrument Principal Investigators, or PIs,
will have direct control of their instruments and experiments
from the Payload Operations Centers at JHU/APL; NASA Langley
Research Center, Hampton, Va.; the University of Colorado,
Boulder; and the University of Michigan, Ann Arbor. Each PI
institution will send daily commands to the TIMED Mission
Operations Center located at JHU/APL, where instructions for
the instruments and spacecraft will be gathered and uplinked
daily to the TIMED spacecraft. Six interdisciplinary
investigators participating in the TIMED mission will analyze
and interpret data acquired by the instrument PIs throughout
the mission.
NASA and the National Science Foundation are jointly
sponsoring a program that will enable the TIMED spacecraft
team to closely collaborate with other scientific community
members studying the MLTI. The program takes advantage of the
synergy between ground- and space-based instruments and of the
scientific contributions made by data assimilation and
modeling. One of the most significant contributions of the
collaborative investigators’ program will be to provide
ground-based data complementary to that provided by the TIMED
spacecraft.
The TIMED mission cost of $193 million includes the
spacecraft, instrument payload, and launch vehicle. An
additional $42 million has been reserved for data analysis and
ground/mission operations. The Solar Terrestrial Probes
Program Office at NASA’s Goddard Space Flight Center,
Greenbelt, Md., manages the TIMED mission for the Office of
Space Science, Washington. JHU/APL designed, built and will
operate the spacecraft and lead the science effort for NASA
during the mission.
Detailed information about the TIMED mission and other Solar
Terrestrial Probe missions is available at:
http://stp.gsfc.nasa.gov/missions/timed/timed.htm
Detailed information about the TIMED spacecraft and
instruments, interdisciplinary approach and mission operations
is at:
