New Satellite Can Capture Entire Dayside Earth


Teiko Yakobson

The first satellite capable of watching the entire diurnal side of Earth continuously launched into space last Friday. This satellite, which is called Deep-Space Climate Observatory, is the result of Scripps Institution of Oceanography researcher Francisco Valero’s 17-year-long mission to generate comprehensive observational data about the earth’s energy budget, which could possibly provide valuable insight into the rate of change of the Earth’s climate.

Unlike current satellites that can only look at a single point on Earth once per day, DSCOVR has a camera that can sweep across an entire hemisphere — from the North Pole to the South Pole ¬— which will allow researchers to compare conditions in different regions simultaneously. Furthermore, it is able to survey regions for a long period of time, from sunrise to sunset.

Valero told the UCSD Guardian that DSCOVR’s data is valuable because it will convey a complete picture of places on Earth throughout the day.

“Usually, satellites that orbit the Earth have temporal problems because [they go] around the Earth, so you see all the points [on Earth] once during the day and once at night,” Valero said. “You see one point, and then, in order to see it again, you have to wait 24 hours. With DSCOVR, you will continuously see all [of] the [Earth’s] points from sunrise to sunset… so the data is far more complete.”

DSCOVR’s camera, called the Earth Polychromatic Imaging Camera, will capture a comprehensive image of the Earth in four million pixels and then use the spectral channels to break down atmospheric composition and other quantities important for climate analysis. Data from EPIC will also support research in ozone dynamics and aerosol chemistry, leading to important speculations of how aerosols — small particles in the atmosphere — are currently contributing to climate change.

The two main phenomena that DSCOVR will measure are the solar energy that hits the earth and the amount of infrared radiation that it reflects back into space. These components together determine the earth’s energy budget and, consequently, the state of our climate. If the amount of light energy absorbed by Earth equals the amount reflected, then the budget is considered balanced, which means our climate is not changing. If there is more energy absorbed than reflected, then the budget is positive and our climate is warming. Conversely, a negative energy budget would mean the planet is cooling.

DSCOVR’s location plays a significant factor in its novelty. This is the first satellite to be secured at the Larange-1 point — a special position in space about 1 1/2 million kilometers away — where DSCOVR can remain in between the sun and Earth during its entire orbit. By matching its angular velocity to the earth’s, DSCOVR will have a continuous view of Earth as it is irradiated by the sun.

Ideally, Valero hopes to launch a second satellite at the Larange-2 point, which is similar to L-1 in that it would also cause a satellite to orbit at the same pace as Earth but on the opposite side. Using Earth to shield it from the sun, an L-2 satellite would only view the nighttime hemisphere, but, when combined with DSCOVR, the scope of the two satellites would cover the entire Earth.

“We would be able to observe the whole planet, minute by minute,” Valero said. “This is the first step in a completely new approach for Earth observation.”

For now, Valero says he will continue to plan the team’s research until data from DSCOVR begins to come through in about four to five months. The satellite will start to operate in about 110 days when it reaches its destination.

“It takes a long time for the satellite to get there,” Valero said. “All we can do now is keep our fingers crossed.”