The DSCOVR satellite, launched this week on the private rocket Falcon 9, will provide a whole-Earth view of our planet that hasn’t been seen since the last Apollo moon mission in 1972. It’s a view we need to remember.
DSCOVR, which stands for Deep Space Climate Observatory, has a dual purpose: to study the Earth from afar, and be an early-warning beacon for solar storms that could disrupt our communication technology.
To do that, it will be placed in a very special position called L1, a Lagrange point, where the gravity of the sun and the Earth balance each other. A spacecraft parked there will remain there, following the Earth through space, while always remaining between the Earth and the sun.
From that vantage point of more than a million kilometres out, the spacecraft will have a view of the entire Earth, fully lit by the sun, from a distance.
This view has not been seen by humans since the crew of Apollo 17, the last mission to the moon, caught a full-Earth view on their way out.
That image has since become the poster child for the environmental movement. It’s rather poetic that this view includes Africa, the origin of humanity, in the centre of the frame. That’s quite an accomplishment, looking back from a vantage point halfway to the moon on the place where our ancestors first stood upright about six million years ago.
DSCOVR will have a similar view of the Earth, but since it will be out there 24/7, the Earth will turn under it. We will see all sides of our planet and should even be able to assemble those images into a time-lapse movie of the Earth turning in space.
This has only been done once before, in 1990, when the Galileo spacecraft swung by the Earth to get a gravitational assist for a trip to Jupiter. During its fly-by, a series of images were taken every five minutes, then put together into a stunning movie showing a partial rotation. DSCOVR images will be far superior to that.
By the way, astronauts on the International Space Station do not get this view today, because they are only 400 km up, which is too close to see the whole planet. To get their perspective, take a globe and place it against your forehead and the bridge of your nose, then try to see the whole thing. It can’t be done.
Space station astronauts are also circling the globe every hour-and-a-half, so they do see their own motion out the window, but they don’t actually see the Earth itself rotate.
Of course, there is more to the DSCOVR mission than just getting pretty pictures of our planet. The satellite will measure the energy balance of the Earth, which compares how much we take in from the sun and how much is reflected back into space.
It will also keep track of atmospheric activity, such as aerosols, ozone, moisture, etc. - with all the data to be made publicly available.
And from its position between the sun and the Earth, DSCOVR will intercept coronal mass ejections from the sun and provide a 15- to 60-minute warning time to operators of satellite companies, power utilities, even airliners flying over the North Pole, that potentially damaging electromagnetic effects are on the way.
While the scientific information will be a valuable contribution to our understanding of the Earth as a whole, perhaps that view of our small blue ball floating in the blackness in a vast, hostile universe will be a constant reminder that this little orb is all we have.
A whole Earth picture is also a picture of ourselves … all of us. We know we are changing the face of the planet like badly behaved children.
Now, we have a chance to heed a scolding that might be given by a parent: “Look at yourselves!”