The Deep Space Climate Observatory (also cleverly known as DSCOVR) is a spacecraft that sits a 1.6 million kilometres away from Earth, hovering between the sun and our planet. Its mission: to monitor space weather and send us an endless stream of interplanetary selfies. This is its first.
DSCOVR is hovering at a place known as Lagrange point 1. Lagrange points are the work of Joseph-Louis Lagrange, who realised that in any two-body planetary system, there are points of equilibrium, where an object can orbit with the same position between the two bodies. The points aren't perfectly stable, but with some minor thrusting, a spacecraft can keep on station.
Lagrange points in the Earth-Sun system. Picture: Andrew Moise/Creative Commons
L1, where DSCOVR is hanging out, is on a line between the Earth and the sun, about 1.6 million kilometres from Earth. That means DSCOVR will always be looking at the sunny side of the Earth, enabling it to take images on a variety of wavelengths every day. As well as looking damn pretty, these images can also help the National Oceanic and Atmospheric Administration forecast solar winds, a critical component of space weather.
As Buzz Aldrin also pointed out in a nostalgic blog post, DSCOVR is also an important test piece for the future (although it's worth noting that other spacecraft have used Langrange points before):
By matching Earth-Moon Lagrangian points with astronauts operating telerobotic hardware, this will allow the assembly of infrastructure on the lunar surface, carry out scientific research, scout out and unearth important resources, as well as help other nations establish their own "one small step" onto the Moon.
This capability is an innovative advance in redefining the word "exploration" -- and also is a powerful stepping stone to practice similar operations at Mars and its moons to establish a settlement on the planet Mars.