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It is comforting to imagine that with space and ground-based telescopes pointed at the cosmos, we would be able to spot any dangerously sized asteroid heading towards us a mile away, with plenty of time to paint them white or detonate them.
But for every asteroid we see coming our way, there is a number we are missing until they fly forward.
And even for those we know well in advance, it can still be difficult to determine the true likelihood of a ground collision.
Asteroid 99942 Apophis is one such asteroid, whose orbit can pass a little too close to Earth for convenience.
Discovered in 2004, the 370-meter (1,210 ft) long rocky blob is on NASA’s Sentry List – a list of asteroids we should keep an eye on – and though scientists have erased any chance it will strike during its next close flyby. in 2029, they are not so sure that it will not bump into us in 2068 because it will come this way again.
While the risk of Apophis hitting Earth in 2068 is somewhere in the region of 1 in 150,000, an asteroid of that size would cause a larger explosion than an atomic bomb, so it’s best to double check the numbers.
And a presentation at the American Astronomical Society’s Division for Planetary Sciences virtual conference probably won’t get you any better night’s sleep.
Late last month, astronomer David Tholen from the University of Hawaii presented his research and that of his colleague Davide Farnocchia after observing the asteroid for three nights in January and one night in March.
They were able to obtain incredibly accurate information about the asteroid and were able to detect the Yarkovsky acceleration, which means that the asteroid radiates heat more strongly on its hemisphere exposed to the Sun than on its shadow side, which causes an asymmetrical thrust, slightly changing its orbit.
When working with that acceleration in the asteroid model, “it basically means that the 2068 impact scenario is still in play,” explains Tholen in his presentation.
“We have to monitor this asteroid very carefully – obviously the 2029 close approach is key.”
The April 2029 close approach will be very close (closer than close to some of our communications satellites) and offers scientists a very important opportunity to study Apophis in exceptionally high detail.
And with less than nine years to go, the Lunar and Planetary Institute held a virtual seminar earlier this month to try and get that ball rolling.
“Knowledge is the planet’s first line of defense and meeting Apophis in 2029 is an opportunity every thousand years,” says the Lunar and Planetary Institute.
“We have less than a decade to plan ground-based and possible in situ missions whose measurements can provide unprecedented detailed knowledge about the physical nature of Apophis as a prototype (child poster) example of potentially dangerous asteroids.”
If we’re lucky, we could get a Bennu-style mission to Apophis to explore the asteroid with a spacecraft, uncovering information that telescopes alone can’t hope to show us.
This asteroid “represents an excellent opportunity to prototype and demonstrate a fast-response near-orbit reconnaissance capability,” Brent Barbee, a University of Maryland aerospace engineer, explained at the conference, according to Gizmodo.
While Gizmodo’s George Dvorsky outlines some of the possibilities, we have yet to define what kind of scientific welcome mat we will give to Apophis.
Whether it’s a new spacecraft, a quick detour for OSIRIS-Rex or purely ground-based observations, we are about to learn a lot about our inconvenient neighbor and hopefully we can confirm once and for all whether Apophis is crashing in our place in the 2068. So, we can figure out what to do next.
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