Astronomers have captured an image of a SpaceX rocket segment that is set to smash into the moon next month.
The Falcon 9 rocket second stage has spent around seven years in space after having launched from Cape Canaveral, Florida, in February 2015, as part of a mission to deploy the National Oceanic and Atmospheric Administration's Deep Space Climate Observatory (DSCOVR) satellite.
After releasing the satellite, the second stage of the rocket had too little fuel to return to Earth and found itself in a somewhat chaotic orbit, influenced by the gravity of our planet and the moon.
Experts say it is now on a collision course with the moon.
Bill Gray—a creator of software that tracks near-Earth objects—has predicted in a blog post that the rocket stage, which weighs four metric tons, will very likely strike the far side of the moon near its equator on March 4, 2022, at a colossal speed of around 5,700 miles per hour.
On February 6, 2022, astronomers from the Virtual Telescope Project (VTP) snapped an image of the Falcon 9 rocket segment using a remotely operated 17-inch telescope named "Elena" that is located in Ceccano, Italy.
Astronomers took the image when the rocket segment was located around 186,000 miles away from Earth. VTP astronomer Gianluca Masi said the photo comes from a single 60-second exposure taken with Elena.
"The telescope tracked the apparent motion of the asteroid, so it looks like a sharp dot, with surrounding stars appearing slightly elongated," Masi said in a statement.
According to Masi, fluctuations in the rocket segment's brightness indicate that it is spinning fast.
News of the rocket segment's upcoming collision with the moon has prompted discussions about the increasing amount of space junk floating in the near-Earth space environment.
The U.S. Department of Defense is tracking more than 27,000 pieces of orbital debris, including old rocket parts and defunct satellites. But much more space debris, too small to track, is thought to exist.
Pieces of space debris travel at extremely high speeds, posing a threat to spacecraft in orbit due to the risk of collisions.
But, despite worries about the increasing quantity of space junk, experts told Newsweek that the upcoming collision of the SpaceX rocket segment with the moon shouldn't cause too much concern—for now at least.
"I've been asked [whether we should be concerned] and still haven't come up with any negative consequences, Gray told Newsweek. "Objects of this size or larger hit the moon fairly often, and usually at considerably greater speeds. This is a four-ton object hitting at 2.58 kilometers per second; impact speeds of 10-20 kilometers per second are common for asteroids hitting the moon."
"Some of the Apollo upper stages were deliberately aimed at the moon," Gray said. "The Apollo stages were somewhat larger than this one."
Moon Impacts Becoming More Common
Jonathan McDowell, an astronomer at the Harvard & Smithsonian Center for Astrophysics, also said we "don't need to be worried" at the moment.
But McDowell told Newsweek that "decades from now when lunar traffic is busier, we'll need to be more careful."
McDowell said most space debris is in much lower orbits than the Falcon 9 rocket segment and can't reach the moon.
"What's relevant here is the debris left in orbits that are as high as the moon. There's not much of that compared to lower orbit debris—but as activity involving the moon increases, that will start to change."
Gray said he would "not be surprised" if we see more space junk crashing into the moon in future.
"My hope is that the various space agencies decide that 'proper' disposal of this hardware is not difficult to do, and treat it accordingly.
He said that space junk in orbits as high as the Falcon 9 rocket segment has not been considered a problem by "pretty much anybody."
"I am, to my knowledge, the only person tracking high-orbiting junk."
Space junk in lower orbits is carefully tracked by the U.S. military and some other organizations, Gray said. "They want to avoid collisions with expensive spacecraft. They really don't care much about stuff this high up."
"I've been keeping track of such junk, mostly in my spare time, not because of concerns about safety or adding junk to the moon, but because the astronomers looking for asteroids that might hit the Earth find these objects and would like to know what they are and where they're going."
How to Dispose of Space Junk
Gray said there were better options for dealing with used spacecraft in high orbits than leaving them where they are, which may include deliberately crashing them into the moon.
"There are decent arguments in favor of lunar disposal, or disposal into solar orbit, or disposal in the middle of the Pacific Ocean or a similar, unoccupied area. Those are the three possibilities; just keeping them in Earth/lunar orbit is not likely to be a long-term solution."
"Any of the three options would effectively limit the potential danger—admittedly tiny—of high-altitude junk hitting a payload or occupied spacecraft. I slightly favor lunar disposal from my own viewpoint, but am mostly hoping that some thought is given in the future about where such junk goes, rather than leaving it to chance."
Gray said in some cases we could probably arrange for such spacecraft to pass the moon at a later date, pickup speed, and be ejected into orbit around the sun.
"If they hang around the Earth-moon system though, they'll probably hit something eventually. Directing them into the Earth's atmosphere would at least be acceptable." Gray said deliberately crashing high-altitude spacecraft into the moon may have some additional scientific benefits.
"The main advantage to a lunar impact is scientific. You make a crater that exposes fresh lunar soil from a meter or two down, and can conceivably examine that material and learn something about the moon's composition and geology in that spot. We don't often get a chance to dig that far below the surface of the moon."
But he added that the scientific benefits are "somewhat marginal" and that "SpaceX is catching much more criticism than I would have expected—and, in my opinion, undeservedly so, given that nobody else appears to have cared about this problem either."
McDowell, who thinks the best option would likely be to send such spacecraft into orbit around the sun, said it is "quite likely" that large pieces of space junk have crashed into the moon before without anyone noticing.
"There are about 50 objects over the past 60 years that were left in high orbit and not tracked afterwards and most of them should have shown up on recent asteroid searches if they were still there," he said.
"So, where are they? Most probably got kicked out into solar orbit, but likely some of them hit the moon without anyone noticing."
