If an asteroid gained sentience and set a course for Earth, could it choose a time like the holidays to catch humans off guard? Well, that’s not going to work: someone is monitoring the space for incoming objects, festive or not.
Kelly Fast manages the Near-Earth Object Observing Program at NASA’s Planetary Defense Coordination Office, which funds observing teams at US institutions using telescopes located around the world. And yes, he told me, researchers monitor the night sky even when most of the country has a day off.
Fast and I discuss the schedule and the daily work to keep the planet safe from asteroids.
Our conversation has been condensed and edited for clarity.
Caroline Mimbs-Nyce: When we talk about looking for asteroids or near-Earth objects, what does that mean?
Quick Kelly: They are astronomers using telescopes. What they are looking for are objects that look like stars but are moving relative to those background stars. And then they report those observations.
It has several telescopes, such as the Catalina Sky Survey at the University of Arizona and the Pan-STARRS at the University of Hawaii, which NASA funds to search for near-Earth asteroids. They do that survey every night, or every night they can. Things like the weather or a full moon can be a problem. But that’s why it’s good to have several telescopes, because someone can always be watching, even if the sky is cloudy in one place.
New: Is the full moon too bright?
Fast: Right. It just makes the sky shine. And so if you’re looking for weaker objects, it overwhelms them. But only the area of the sky around the full moon is a problem.
We have a network of telescopes making that search effort. And they all report their observations of moving objects to the Minor Planet Center, which is funded by NASA but is the internationally recognized repository for positional measurements of natural objects and small bodies of all kinds, not just near-Earth asteroids. Everyone reports their measurements there. And if there is something that is not already associated with an object that is already known, then it is put in the NEO confirmation page at Minor Planet Center.
Other astronomers can go and look there and see what needs additional observations. It’s one thing to have seen something that might be a new asteroid discovery, but if you don’t get enough information about it, enough positions to be able to calculate an orbit and figure out where it will be in the future, then that doesn’t help you much.
New: When you identify something, could it also be falling space junk?
Fast: Or, actually, orbiting space junk. Or operational satellites. But that is removed as much as possible based on what is available in the public catalogs. Also, they often move at different speeds.
It is up to the Minor Planet Center to make that determination, because they take those observations and determine an orbit from them. And from that they can say, Oh, this is in orbit around the sun. This is not a satellite in Earth orbit..
New: How close is “near Earth”?
Fast: The definition of a near-Earth asteroid is any asteroid with an orbit that brings it closer to about one-third the distance from the sun to Earth. But not all near-Earth asteroids actually come close to Earth’s orbit. And so, there’s a subset that we’d really like to keep an eye on, that if we were going to be in the same place at the same time as Earth one day, we’d want to know ahead of time.
NASA also funds the Center for Near-Earth Object Studies at the Jet Propulsion Laboratory. They look at all that data in the Minor Planet Center and do a precision orbit determination into the future to see if anything could pose a long-term impact threat to Earth. The goal is to find something that might pose a threat years or decades in advance.
New: It looks like we have a bit of lead time to figure out where they’re going and where they might enter on Earth.
Fast: That is certainly the goal. But there is always the possibility that something could be discovered in the short term. But probably very small. You can see most large objects much farther away, perhaps many orbits ahead of time. But it can happen. In fact, we had an impactor just a few weeks ago.
Fast: Well, we are talking about very small. The good thing about our atmosphere is that it does a good job of breaking up small objects. You just see a nice shooting star or a ball of fire. That happens all the time.
Technically, an asteroid, as defined by the International Astronomical Union, is a natural object more than one meter in size. Our atmosphere handles objects of that size very easily. The one we had a few weeks ago, 2022 WJ1, was discovered in space before impact. And that’s only happened, like, six times before, where an object was discovered in space and linked to an actual fireball seen in Earth’s atmosphere. One of them, a few years ago, was in New Year’s Day. The universe doesn’t care that we have vacations.
I know you were interested in knowing who is on call during the holidays. The good thing is that he is not just a person; there are teams of people and many automated systems that determine the orbit and then flag if there is anything that should be an alert.
If you read about the object just a few weeks ago, that’s exactly what happened. A telescope reported the data. Minor Planet Center put it on the confirmation page. And later the scout system, which was developed by the Center for the Study of Near-Earth Objects at the Jet Propulsion Laboratory, flagged it and said this has a chance of impacting. Then more observations were taken and the region of impact was reduced. And then there was the fireball, a good exercise in the system.
New: You said we’ve only had six that we’ve been able to connect with the fireball in the atmosphere? Are there others who escape?
Kelly: Well, these objects are very small, just a couple of meters in size, and they’re not the ones NASA is tasked with trying to discover, and they’re certainly not the ones we should be warning people about. We ended up treating it as an exercise. It is not that others escape. They are served by the atmosphere anyway.
We would certainly want to warn about something much bigger. In the case of the Chelyabinsk impact in Russia in 2013, it was a much larger object, probably about 20 meters in size. But it came from the direction of the sun, from the daytime sky. So it wasn’t something you could warn about in advance. And it wasn’t one that knew many orbits ahead of time. And that was one that got everyone, because there was no way to see it.
New: So are there still surprises in your business?
Fast: Right. Congress has tasked NASA with finding these objects, specifically near-Earth asteroids 140 meters in size or larger, a size that can have regional consequences if one hits Earth. Obviously, NASA wants to find objects of any size that can hit Earth, but this is the task given to it by Congress.
NASA has been looking for ways to speed up the discovery of near-Earth asteroids, because we keep finding objects that size and larger. And people who model the asteroid population can say that there are more out there that we haven’t found. So, NASA is working on a mission to help speed up the discovery of near-Earth asteroids. and it’s called Near-Earth Object Surveyor. It is a space telescope that works in the infrared and is designed very specifically to search for near-Earth asteroids. It would be able to look into parts of the sky closer to the direction of the sun, for example, than ground-based telescopes can.
It will be a very powerful way to speed up the discovery of these objects. We may find that none of them pose an impact threat. And that would be fabulous. And maybe we find that one could pose a threat, and it’s years in the future, and that would give time to learn more about it, maybe plan, if necessary, a diversion mission. The goal is not to be in a sticky situation, but to have the luxury of time.
New: How much can humans do? Are asteroids a solvable problem for humanity?
Fast: An asteroid impact is the only natural disaster that could be prevented because humanity can do something.
the dart [Double Asteroid Redirection Test] mission [during which NASA flew a spacecraft into an asteroid and changed its orbit] it was fabulous, because that was just a test just to prove it. it’s physics. If you want to deflect an asteroid, the easiest way is to hit it and change its speed so that it changes its orbit. This was on a very small scale and was done in a test situation with a binary asteroid, because it was simply changing the orbit of one asteroid around another. It was very successful. We can use this data to help inform, should we ever need to design a larger mission. That was a huge milestone, to go from just doing the math on how you could deflect an asteroid to an actual mission test.
As for large or multi-kilometre near-Earth asteroids that would have global consequences, we are not so concerned about them, because most of that population has been discovered. And so that population understands itself much better. At the other end of the spectrum, as I mentioned, are these small asteroids a couple of meters long that don’t make it to the ground intact.
It is that intermediate range that would have no global consequences, but could still cause serious regional damage. So, we are working on that population. How do you eat an elephant? One bite at a time.