As a NASA spacecraft whizzed away from Earth at 40,265 mph, it took a brief moment to look over its robotic shoulder at how far it's traveled.
Psyche, a mission and orbiter named after its space destination, is traveling to a metal-rich asteroid that orbits the sun between Mars and Jupiter in the main asteroid belt. While the spacecraft won't reach the asteroid Psyche until 2029, it is already more than 180 million miles away — a distance double the stretch between Earth and the sun.
The new image, which shows Earth along with an even smaller point of light coming from the moon, harkens back to Carl Sagan's famous Pale Blue Dot image, a shot the Voyager 1 spacecraft took in 1990 on its way out of the solar system. That historic photo has come to represent the vastness of space and humanity's humble place within it.
The purpose of this new image taken in July, presented below, was to test the spacecraft cameras' ability to capture relatively dim objects, whose light is actually reflected sunlight, just like the Psyche asteroid. Other dots in the frame are stars sparkling from the constellation Aries.
"We are up and running, and everything is working well," Bob Mase, the mission’s NASA project manager, said in a statement.
That the orbiter's instruments and systems are operating as expected comes as a relief for the space agency. In April, engineers paused the spacecraft's four electric thrusters to investigate a surprising drop in pressure. They discovered that a faulty valve that manages the flow of xenon fuel to the engines was to blame.
Fortunately, the orbiter has another fuel line. After the team switched to using the backup, the spacecraft was able to resume firing its thrusters.
The spacecraft is headed to Psyche because scientists believe it is made of the same stuff found in metallic planet cores, like Earth's. It's most likely battered from many violent ancient collisions. Asteroids are the rocky rubble left over from the formation of the solar system about 4.6 billion years ago. Studying this asteroid may provide researchers with clues about what's in our own planet's core and how the rocky planets orbiting the sun formed.
That's important, scientists say, because it's impossible to get to Earth's core, roughly 1,800 miles below the surface, due to its extreme heat and pressure level. The most cutting-edge drilling instruments, which reach a maximum of 7.5 miles down, haven't gone anywhere close to that deep underground. Arizona State University is leading the mission for NASA.
Psyche is a potato-shaped asteroid, stretching 173 miles long and 144 miles wide, while being 117 miles thick. No one has seen the giant rock up close — the radar observations are pixelated — so scientists won't know what it looks like until the orbiter arrives.
Though the spacecraft is already quite far from home, the journey will take much longer. Its next major milestone will be a flyby of Mars in May 2026 to get a propulsion boost from the Red Planet's gravity.
The team will likely take more sightseeing images to continue testing the cameras along the way.
"We’re sort of collecting solar system ‘trading cards’ from these different bodies," said Jim Bell, Arizona State's imager instrument lead for the mission, in a statement, "and running them through our calibration pipeline to make sure we’re getting the right answers."
