OK, whose rocket just hit the moon?

You know you’re living in the space age when a rocket hits the moon, and the industry as a whole points to the sky and, like an angry teacher holding up a paper airplane, asks, “Who launched this?!” Really, that’s what happened this week when an unidentified rocket stage (!) slammed into the lunar surface, forming a new and interesting crater and we all wonder how it is possible not to know what happened.

The short version of this story is that skywatchers directed by Bill Gray months followed an object that, based on their calculations, would soon hit the moon. It was clearly a piece of rocket waste (missiles produce a lot of waste), but no one stepped up to say “yes, that’s ours, sorry about that.”

Based on their observations and discussions, these amateur object trackers (though certainly not lacking in expertise) determined that it was most likely a 2015 SpaceX launch. NASA decided it was more likely to launch from China in 2014. China denies this is the case, saying the launch vehicle in question was burned upon return.

Maybe they are telling the truth; maybe they don’t want to be responsible for the first completely accidental moon impact in history. Other spacecraft hit the moon, but it was either intentional or part of a failed landing (in other words, the impact was intentional, just a little harder than expected) — not just a quirky piece of space junk.

Maybe we’ll never know, and really, that’s the weirdest thing of all. With hundreds of terrestrial telescopes and radars, space-based sensor networks and cameras pointing in all directions – and that’s just the space surveillance we know! – it seems amazing that an entire rocket stage managed to stay in orbit for six or seven years and eventually make it all the way to the moon, without being identified.

Animation by Tony Dunn showing the mysterious object (green) in orbit, eventually impacting on its originally estimated date in March. Image Credits: Tony Dunn

I thought someone was with LeoLabs, who has built a new network of debris-tracking radars around the world, may have some insight. Darren McKnight, senior technical fellow there, had the following answers to my questions.

How is it possible that we did not know the identity and trajectory of such a large and relatively recently launched object?

Tracking decayed objects in the cislunar’s orbit probably isn’t a high priority for government sensors when they can spend that time observing satellites or space junk closer to Earth. However, tracking and monitoring operational satellites in orbit around the cislunar is critical to strategic intelligence as it is new high-ground.

Would such confusion be possible for an object launched now?

Yes, this could now happen again, as the technology used by the US government to track space objects has not changed in many years.

Are more of these “mysterious objects” likely to have an impact here and there in the coming years?

It’s possible that such an accidental lunar attack could happen again in the future, depending on how many missions put rocket bodies into those orbits and given enough time (years or decades). But events like this should generally remain extremely rare.

And as Bill Gray points out in his article:

… High-altitude clutter didn’t matter to anyone outside of asteroid studies, and even we weren’t too concerned about it. These types of objects are not tracked by the US Space Force; they (usually) use radar, which is “near-sighted”: it can track 10cm across objects in low orbits, but can’t see large rocket stages like this one when they’re as far away as the moon. You need telescopes for that.

Strange as it may seem (to me anyway), orbits are only calculated by me in my spare time for these types of objects.

It’s remarkable in a way, but as anyone in the space surveillance world will tell you, there’s a lot up there to look at and choose your targets. An object the size of a rocket halfway through the moon is not easy or easy to get a good picture of.

Perhaps our best clue to the object’s identity is the crater it left behind when it impacted. The impact site was imaged shortly afterwards and has a curious double O shape: two overlapping craters, one 18 meters wide and the other 16 meters. Here’s the before and after:

“The double crater was unexpected and may indicate that the rocket body had large masses at each end. Usually, a spent rocket has mass concentrated at the motor end; the rest of the rocket stage consists mainly of an empty fuel tank,” NASA’s Mark Robinson wrote .

While it’s an enticing mystery, the truth is that there doesn’t seem to be much reason to devote serious resources to figuring it out. Stranger things happen in space than a piece of a rocket that flies off at exactly the angle and speed needed to eventually hit the moon. And as far as we know, there is someone who is very well aware of what this strange double-ended piece of space junk is, but prefers to keep it quiet.

#rocket #hit #moon

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