News reports of hurricanes forming and predictions about storm paths are familiar occurrences. Less familiar are reports about solar wind and magnetic fields from the sun which can also have an impact for life on Earth.
The Deep Space Climate Observatory, known as DSCOVR, is a mission lead by the National Oceanic and Atmospheric Administration, or NOAA, in partnership with NASA and the U.S. Air Force, with a primary task to collect measurements to enable space weather forecasting by NOAA.
The DSCOVR satellite is planned for launch in January 2015 from Cape Canaveral Air Force Station's Space Launch Complex in Florida. In addition to the space weather instruments, NASA is providing two Earth-observing instruments on the spacecraft, the Earth Polychromatic Imaging Camera, or EPIC, and the National Institute of Standards and Technology Advanced Radiometer, or NISTAR.
DSCOVR will make unique space measurements from the first sun-Earth Lagrange point, known as L1. This L1 vantage point offers a continuous view of the entire sunlit half of Earth in a “snapshot,” as opposed to other Earth-observing satellites situated closer to Earth that capture an image strip that is later “stitched” together to form a global view.
The L1 point is on the direct line between Earth and the sun located 1.5 million kilometers (930,000 miles) sunward from Earth, and is a neutral gravity point between Earth and the sun. The spacecraft will be orbiting this point in a six-month orbit with a spacecraft-Earth-sun angle.
The sun continuously emits a solar wind and magnetic fields. A solar explosion in the form of bursts of plasma and increased magnetic fields released into space is known as a coronal mass ejection, or CME. “A CME is many times larger than Earth, and will pass over the satellite, allowing scientists to determine the magnetic field and the strength of the resulting geomagnetic storm that will ensue,” said Douglas Biesecker, NOAA’s DSCOVR program scientist, based out of the National Weather Service’s Space Weather Prediction Center in Boulder, Colorado.
Space weather has demonstrated the potential to disrupt major public infrastructure systems, including power grids, telecommunications and GPS. The DSCOVR solar wind observations collected by the solar wind plasma sensor and magnetometer would provide a 15-60 minute lead time for geomagnetic storm warnings. DSCOVR will succeed NASA's Advanced Composition Explorer’s role in supporting solar wind alerts and warnings from NOAA.
DSCOVR also offers advantages for observing Earth. “With DSCOVR, we will be able to see the whole sunlit disc of Earth all the time,” said Adam Szabo, NASA’s DSCOVR project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
The NASA EPIC instrument takes images of Earth in ten narrowband channels, from ultraviolet to near infrared. At the L1 position, EPIC is able to view the entire sunlit face of the Earth from sunrise to sunset. This viewing angle will provide a unique perspective, and will be used in science applications to measure global ozone levels and aerosol properties, cloud height over land and ocean, vegetation properties and ultraviolet reflectivity of the Earth. The data from EPIC will be used by NASA for a number of Earth science studies including dust and volcanic ash maps of the entire Earth.
As part of EPIC data processing, a true color Earth image will be produced about every two hours. This information will be publicly available through NASA Langley Research Center in Hampton, Virginia, approximately 24 hours after the images are acquired.
The other DSCOVR NASA instrument NISTAR is a cavity radiometer designed to measure the reflected and emitted energy in four broadband channels (between 0.2 and 100 micron) from the entire sunlit face of Earth. This measurement is intended to improve understanding of the effects of changes in Earth's radiation budget caused by human activities and natural phenomena.
The information from NISTAR can be used for climate science applications. NISTAR will measure the amount of reflected sunlight and the thermal radiation of Earth in the direction towards the sun. These quantities are key ingredients of current climate models.
DSCOVR (formerly known as Triana) was originally conceived in the late 1990s as a NASA Earth science mission that would provide a near continuous view of Earth and measure Earth’s albedo. In 2001, Triana was suspended and the satellite was stored in a clean environment at NASA’s Goddard Space Flight Center.
NOAA funded NASA to remove DSCOVR from storage and test it in 2008. The same year, the Committee on Space Environmental Sensor Mitigation Options (an interagency assessment requested by the White House Office of Science and Technology Policy) determined that DSCOVR was the optimal solution for meeting NOAA and U.S. Air Force space weather requirements.
NOAA is responsible for the DSCOVR mission, providing program management, spacecraft operation and distribution of all mission data. NOAA funded NASA to refurbish the spacecraft, recalibrate the space weather sensors, prepare the spacecraft for launch; develop the ground systems and operations; and provide technical management of the space segment.
For more information about DSCOVR please visit: http://www.nesdis.noaa.gov/DSCOVR/