 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
Studying the Sun's Radiation
Solar radiation is the dominant energy source for our solar system the Earth, planets, and minor bodies such as planetary moons, comets, asteroids, and dust. In the case of the Earth and planets, this radiation fuels the chemical and dynamical processes of the atmospheres, and any variations in solar radiation will change the atmosphere's structure, temperature, and composition. It is little wonder that studies of the planets and of the Earth require precise and accurate knowledge of both the intensity of solar radiation and the amount by which it varies. The Sun's radiation spans the color spectrum from very energetic x-rays, through the visible, and out to the infrared. The careful measurement of the Sun is indeed challenging because our atmosphere strongly absorbs and scatters the light. For this reason no accurate measurements could be made until special instruments could be sent above the atmosphere in order to make the observations from space.
 The Upper Atmosphere Research Satellite (UARS) Photo courtesy of NASA/JPL/Caltech |
Side by Side with NASA
The University of Colorado at Boulder's Upper Air Laboratory (the predecessor of LASP) made some of the very first observations of the Sun from space in the 1950s. In 1972 a LASP rocket instrument was launched to provide a solar measurement to accompany observations being made of the moon by Apollo 17. The data obtained on this first rocket achieved a new level of accuracy, and they were soon widely used by scientists trying to understand the chemistry of our stratosphere the atmospheric layer where the ozone lies. Interest in these solar measurements was intensified when the threat to ozone in the stratosphere was first postulated in 1974. NASA encouraged LASP to expand the solar program and the frequency of rocket observations increased. LASP was awarded a contract to develop its own small satellite, the Solar Mesosphere Explorer (SME), specifically designed to study atmospheric ozone and changes it was undergoing. One of the SME instruments was a small spectrometer to study and record solar radiation.SME was extremely successful, providing both atmospheric and solar observations for almost eight and a half years. Meanwhile another NASA mission, the Upper Atmosphere Research Satellite (UARS), was being formulated to provide even more specific and detailed ozone research. NASA selected LASP to provide one of the 10 scientific instruments on UARS - quite naturally, LASP contributed an instrument that measured solar radiation. It was called the Solar Stellar Irradiance Comparison Experiment (SOLSTICE). This device has the unique capability of observing stars with the same set of optics and detectors used for the solar observations. Because this stellar calibration uses the stars as reference standards, any similar solar measurements in the future can be compared back to today's UARS observations.
UARS was launched in 1991 and an additional 10 years of solar data has since been accumulated to add to the earlier SME observations. In fact, the LASP observations now span a time period of more than 20 years with only a small gap from 1989 to 1991. Shortly after the launch of UARS, LASP was selected to develop a new instrument to extend the spectral range of the irradiance program to very shortest wavelengths - the extreme ultraviolet and x-rays. This radiation is especially important to the upper layers of the Earth's atmosphere. The LASP instrument, the Solar Extreme ultraviolet Experiment (SEE) was successfully launched in December 2001 on NASA's Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics (TIMED) Explorer Mission.
 | The Spectral Irradiance Monitor (SIM), one of LASP's five instruments on SORCE. Image courtesy of Goeffry Wheeler |
Our Future with the Sun
LASP is now in the midst of a major program providing five instruments and a small spacecraft as elements of NASA's Earth Observing System. This Solar Radiation and Climate Experiment (SORCE) launched Jan 25, 2003 and will operate for five years. This is just the beginning, for LASP is now being considered for a follow-on SORCE mission to operate from 2006 to 2011. LASP has also been selected to build similar instruments for the National Polar Orbiting Environmental Satellite System (NPOESS) that will operate for an additional 15 years. All of these programs combined - past, present, and future - indicate that LASP will continue to be active measuring solar radiation and improving our understanding of the Sun.Going to the SORCE
NASA's present and future Earth Observing Program is built around a number of satellite missions studying all elements of our environment. As part of the Earth Observing System (EOS), NASA has selected LASP to develop and operate a small satellite solely dedicated to the measurement of solar radiation. This mission is called the Solar Radiation and Climate Experiment (SORCE) and carries five instruments to study all aspects of solar radience, covering all wavelengths from the ultraviolet to the near infrared. LASP has complete management reponsibility for this mission, and has set the science goals, developed and built the instruments, purchased a spacecraft from an industrial partner, and will operate the satellite for a period of five years after its launch Jan 25, 2003.-
Scientific Objectives of the Solar/Terrestrial Program:
- Know the amount of solar radiation arriving at the top of our atmosphere and its variability over all time scales.
- Understand how the varying solar irradiance energizes the terrestrial environment.
- Understand processes occurring at the sun that give rise to variations in its radiance.
- Understand the flow and confinement of energetic particles within the terrestrial environment.
- Understand how these particles and fields impart energy and disturbance to the earth.
- Understand how variations in the fields and particles surrounding the earth can disrupt our technical infrastructure, including power systems, communication networks, and operational satellites.
Related LASP Projects:
 | |
 | |
 | |
 | |
 |
|
 |
|
 | |
