Though astronomers have indirectly detected thousands of exoplanets, they are just starting to get fuzzy pictures of the orbs themselves. But what can they learn from just a few pixels of light? It turns out that the Deep Space Climate Observatory (DSCOVR), a space-weather satellite with a controversial past, is answering those questions right now, says Stephen Kane, an exoplanet scientist at San Francisco State University in California. "We can get a significant advance preview of what those data will look like, because we now have a satellite that is staring directly at Earth."
Those observations are in jeopardy, however, with news today that the proposed budget of U.S. President Donald Trump seeks to kill Earth-facing instruments on DSCOVR years before the mission ends. It would be a setback for exoplanet research, Kane says. "We're enormously disappointed to hear this news."
Perched between the gravitational pull of the sun and Earth, DSCOVR, which was launched in 2015, primarily serves as a space-weather buoy, giving advance notice of inbound solar storms. But it also has two instruments that peer back at Earth and capture the entire planet with the aim of detecting long-term trends in the planet's balance of incoming and outgoing energy, along with long-term shifts in its clouds, aerosols, and ozone.
Several years ago, Kane realized this steady drip of iconic whole-Earth images would be a boon to exoplanet research. His team has taken these shots and degraded them to one pixel—the type of information that a telescope might someday obtain for an Earth-sized exoplanet. From those extremely limited data, they have still been able to tease out Earth's 24-hour rotational rate and the tilt of its spin axis. But this is preliminary, Kane says. "Our results still need a couple years of DSCOVR to fully encapsulate them."
This is work that couldn't have happened before the spacecraft went up, he adds. Stitching together Earth images captured from lower orbits makes it hard to degrade the image, and a long time series is necessary to learn anything about how atmospheric dynamics could be captured by a pixel.
So why would the administration seek to disable part of a mission in the middle of its prime? Republicans have long held a grudge against DSCOVR, which started out several decades ago as the brainchild of Vice President Al Gore, who hoped to stream back live video of Earth to inspire public support for environmental policies. Republicans derided it as "GoreSat," and, under former President George W. Bush, the unfinished spacecraft sat mothballed for years.
President Barack Obama revived the mission, aiming it primarily at space weather, with two Earth-observing instruments along for the ride. Research based on these data, and its use in tracking vegetation, cloud height, and reflectivity, among other factors, has only begun to come out. This research is intrinsically valuable on its own, Kane says. "DSCOVR is continuously monitoring Earth in a way it's never been done before."
NASA spends only $1.2 million a year operating the satellite’s Earth-facing instruments, as DSCOVR's primary costs, for its sun-facing space weather instruments, lie with the National Oceanic and Atmospheric Administration. "This is a silly thing to cut," said Casey Dreier, director of space policy at the Planetary Society, based in Pasadena, California, on Twitter.
The ultimate fate of DSCOVR and its data rests, of course, not with the Trump administration but appropriators in Congress. And Kane hopes they can look past DSCOVR's polarized origins and see not just its real-world benefits, but those that are out of this world. When astronomers get their picture of a distant pale blue dot, after all, they will want to know whether they’re staring at another Earth.