Editor’s Note: An earlier version of this story stated that it has not been possible to capture images of the entire sunlit side of Earth since Apollo 17 astronauts captured the iconic Blue Marble photograph in 1972. In fact, other satellites—including Galileo, the Lunar Reconnaissance Orbiter, and geostationary weather satellites including GOES—have captured full-disc views of Earth since then.
The journey has been a long one for the Deep Space Climate Observatory (DSCOVR). Once known as Triana, the satellite was conceived in 1998 to provide continuous views of Earth, to monitor the solar wind, and to measure fluctuations in Earth’s albedo. The mission was put on hold in 2001, and the partly-built satellite ended up in storage for several years with an uncertain future. In 2008, the National Oceanic and Atmospheric Administration (NOAA), NASA, and the U.S. Air Force decided to refurbish and update the spacecraft for launch.
On February 11, 2015, DSCOVR was finally lofted into space by a SpaceX Falcon 9 rocket. After journey of about 1.6 million kilometers (1 million miles) to the L1 Lagrange Point, the satellite and its Earth Polychromatic Imaging Camera (EPIC) has returned its first view of the entire sunlit side of Earth. At L1—four times farther than the orbit of the Moon—the gravitational pull of the Sun and Earth cancel out, providing a stable orbit and a continuous view of Earth. The image above was made by combining information from EPIC’s red, green, and blue bands. (Bands are narrow regions of the electromagnetic spectrum to which a remote sensing instrument responds. When EPIC collects data, it takes a series of 10 images at different bands—from ultraviolet to near infrared.)
This first public image shows the effects of sunlight scattered by air molecules, giving the disk a characteristic bluish tint. The EPIC team is developing data processing techniques that will emphasize land features and remove this atmospheric effect. Once the instrument begins regular data acquisition, new images will be available every day, 12 to 36 hours after they are acquired by EPIC. These images will be posted to a dedicated web page by autumn 2015. Data from EPIC will be used to measure ozone and aerosol levels in Earth’s atmosphere, as well as cloud height, vegetation properties, and the ultraviolet reflectivity of Earth. NASA will use this data for a number of Earth science applications, including dust and volcanic ash maps of the entire planet.
“This first DSCOVR image of our planet demonstrates the unique and important benefits of Earth observation from space,” said NASA Administrator Charles Bolden. “As a former astronaut who’s been privileged to view the Earth from orbit, I want everyone to be able to see and appreciate our planet as an integrated, interacting system.”
Image courtesy of the DSCOVR EPIC team. Caption by Rob Gutro and Adam Voiland.