The SORCE Satellite
To continue to monitor the Sun and to cut down on the uncertainty
of solar energy measurements, NASA launched the SORCE satellite on January 25, 2003.
The satellite flies at an altitude of 640 km in a
40-degree-inclination orbit around the Earth. On board SORCE are four
instruments that will greatly improve the accuracy of the measurements
of solar energy. All instruments take readings of the Sun during
each of the satellites 15 daily orbits. The information is
transmitted to ground stations at NASAs Wallops Flight Facility in
Virginia and a station in Santiago, Chile.
The SORCE satellite carries four instruments to
study the Sun. TIM, SIM, and SOLSTICE measure solar irradiance and the solar spectrum to help scientists understand
the Suns role in climate change. The XPS measures high-energy radiation from the Sun. (Image courtesy Solar Radiation and Climate Experiment Project)
Three of the four SORCE instruments will be of direct use to Earth
scientists. They are the Total Irradiance Monitor (TIM), the Spectral
Irradiance Monitor (SIM), and the Solar Stellar Irradiance Comparison
Experiment (SOLSTICE). TIM will accurately determine the TSI by
recording the sum of the energy from nearly all the Suns wavelengths.
SIM will measure upper portion of the ultraviolet spectrum (200400 nm), the full visible range, and the near infrared
up to 2000 nm. SOLSTICE will measure the full ultraviolet beginning at 100 nm, and
includes the lower half of the ultraviolet region of SIM (200-300 nm).
The 200300 nm portion of ultraviolet measured by both
SIM and SOLSTICE overlaps with UV-B (290320 nm)
which causes skin cancer, and is normally blocked from us by
the stratospheres ozone layer. (See Ultraviolet Radiation: How it Affects Life on Earth) Its readings will be of
primary importance to understanding the Suns impact on the
stratosphere. A fourth instrument, known as the Extreme Ultraviolet
Photometer System (XPS), will be of indirect use to Earth scientists.
The instrument will measure very high-energy ultraviolet radiation and
lower energy x-ray wavelengths. These readings should yield valuable
information about the Suns corona, solar events that impact satellite
communications, and the Suns effects on the very outermost layers of
the Earths atmosphere.
next: Total Irradiance Monitor (TIM)
back: Uncertainties in Solar Measurements
Solar Radiation and Climate Experiment (SORCE)
Earths Energy Balance
The Sun and Global Warming
Uncertainties in Solar Measurements
The SORCE Satellite
Total Irradiance Monitor (TIM)
Spectral Irradiance Monitor (SIM)
Solar Stellar Comparison Experiment (SOLSTICE)
Extreme Ultraviolet Photometer System (XPS)
Watching the Sun
Sunspots and the Solar Max
Clouds and Radiation
Why isnt Earth Hot as an Oven?
Reflected Solar Radiation
Outgoing Heat Radiation