Credits: NASA/JPL-Caltech and NSF/AUI/GBO
The near-Earth object was thought to pose a slight risk of impacting Earth in 2068, but now radar observations have ruled that out.
After its discovery in 2004, asteroid 99942 Apophis had been identified as one of the most hazardous asteroids that could impact Earth. But that impact assessment changed as astronomers tracked Apophis and its orbit became better determined.
Now, the results from a new radar observation campaign combined with precise orbit analysis have helped astronomers conclude that there is no risk of Apophis impacting our planet for at least a century.
Estimated to be about 1,100 feet (340 meters) across, Apophis quickly gained notoriety as an asteroid that could pose a serious threat to Earth when astronomers predicted that it would come uncomfortably close in 2029. Thanks to additional observations of the near-Earth object (NEO), the risk of an impact in 2029 was later ruled out, as was the potential impact risk posed by another close approach in 2036. Until this month, however, a small chance of impact in 2068 still remained.
When Apophis made a distant flyby of Earth around March 5, astronomers took the opportunity to use powerful radar observations to refine the estimate of its orbit around the Sun with extreme precision, enabling them to confidently rule out any impact risk in 2068 and long after.
“A 2068 impact is not in the realm of possibility anymore, and our calculations don’t show any impact risk for at least the next 100 years,” said Davide Farnocchia of NASA’s Center for Near-Earth Object Studies (CNEOS), which is managed by NASA’s Jet Propulsion Laboratory in Southern California. “With the support of recent optical observations and additional radar observations, the uncertainty in Apophis’ orbit has collapsed from hundreds of kilometers to just a handful of kilometers when projected to 2029. This greatly improved knowledge of its position in 2029 provides more certainty of its future motion, so we can now remove Apophis from the risk list.”
Farnocchia was referring to the Sentry Impact Risk Table. Maintained by CNEOS, the table keeps tabs on the few asteroids whose orbits take them so close to Earth that an impact can’t be ruled out. With the recent findings, the Risk Table no longer includes Apophis.
Relying on optical telescopes and ground-based radar to help characterize every known near-Earth object’s orbit to improve long-term hazard assessments, CNEOS computes high-precision orbits in support of NASA’s Planetary Defense Coordination Office.
Science Opportunity
To arrive at the latest Apophis calculations, astronomers turned to the 70-meter (230-foot) radio antenna at the Deep Space Network’s Goldstone Deep Space Communications Complex near Barstow, California, to precisely track Apophis’ motion. “Although Apophis made a recent close approach with Earth, it was still nearly 10.6 million miles [17 million kilometers] away. Even so, we were able to acquire incredibly precise information about its distance to an accuracy of about 150 meters [490 feet],” said JPL scientist Marina Brozovic, who led the radar campaign. “This campaign not only helped us rule out any impact risk, it set us up for a wonderful science opportunity.”
Goldstone also worked in a collaboration with the 100-meter (330-foot) Green Bank Telescope in West Virginia in order to enable imaging of Apophis; Goldstone was transmitting while Green Bank was receiving – a “bistatic” experiment that doubled the strength of the received signal.
Although the radar imagery of Apophis appears pixelated, the images have a resolution of 38.75 meters (127 feet) per pixel, “which is a remarkable resolution, considering the asteroid was 17 million kilometers away, or about 44 times the Earth-Moon distance,” added Brozovic. “If we had binoculars as powerful as this radar, we would be able to sit in Los Angeles and read a dinner menu at a restaurant in New York.”
As the radar team further analyzes their data, they also hope to learn more about the asteroid’s shape. Previous radar observations have suggested that Apophis has a “bilobed,” or peanutlike, appearance. This is a relatively common shape among the near-Earth asteroids larger than 660 feet (200 meters) in diameter; at least one in six have two lobes.
Astronomers are also working to develop a better understanding of the asteroid’s rotation rate and the axis it spins around (known as its spin state). That knowledge will enable them to determine the orientation the asteroid will have with Earth as it encounters our planet’s gravitational field in 2029, which could change that spin state and even cause “asteroid quakes.”
On April 13, 2029, the asteroid Apophis will pass less than 20,000 miles (32,000 kilometers) from our planet’s surface – closer than the distance of geosynchronous satellites. During that 2029 close approach, Apophis will be visible to observers on the ground in the Eastern Hemisphere without the aid of a telescope or binoculars. It’s also an unprecedented opportunity for astronomers to get a close-up view of a solar system relic that is now just a scientific curiosity and not an immediate hazard to our planet.
“When I started working with asteroids after college, Apophis was the poster child for hazardous asteroids,” said Farnocchia. “There’s a certain sense of satisfaction to see it removed from the risk list, and we’re looking forward to the science we might uncover during its close approach in 2029.”
If NASA Analysis says that Earth Is safe From an Asteroid catastrophe for 100-plus years, then it could be appropriate to be rather worried about safety in the near future.
Only from asteroid Apophis!!
While predicting the orbit of an asteroid 100 years into the future is difficult, the precision of the calculations out that far are relatively well known and acknowledged. Predicting future climate is orders of magnitude more difficult, while the precision of such calculations is basically unknown and swept under the rug.
“IF” we all servive the RNA pandemic, technology or ( Mr. E . Musk ) will send it on its way , 2068 ? Our local wiz kid ( 6
.years old ) says.he wiil build a tow truck
As NASA often is wrong, time to worry ? 😀
Praise the Lord, one less thing to worry about.
Astrologically 20,000 miles is less than an RCH. One small step closer and it would mean a giant disaster for mankind.
I meant to say astronomically. Coffee deficient.
In the intervening 100+ years, how many comets, asteroids and other space detriment will it meet along the way? How much will those impacts cause it’s flight/trajectory to vary? We may have more to worry about than NASA thinks.
Reading a menu in NY from LA? I understand their point about what the setup allows them to do, but does it really take curve of the earth into consideration? If so, WOW!
Maybe they consulted with Gavin Schmidt on this ? Perhaps NASA can adjust the curvature of the earth.
it encounters our planet’s gravitational field
Say what?
Close enough for government work.
The Earth’s gravity will change the asteriod’s orbit. So how solid is that 2068 prediction of another miss?
Their prediction has taken that into account. Of course, this depends on how accurate their estimate of the asteroid’s mass is and the exact distance to Earth as it passes by. No doubt there will be numerous measurements of the actual distance and effect on the asteroid’s orbit in 2029 which will allow them to increase the precision of their longer term predictions.
In astronomical terms, 340 meters across is just ever so tiny.
In addition to your mask, nose mask, and face shield,
just wear a bicycle helmet, that’s all.
Please try to keep up on The Science, David. It’s uninformed cavalier comments like this that put us all at greater risk. There should be a nose mask, then a paper mask, then an N95 mask, then a smoke hood, then a face shield, then a motorcycle helmet. It wouldn’t hurt to add a bicycle helmet outside the motorcycle helmet, though. (For extra protection against asteroid fragments).
Of course, that’s if you’re fully vaccinated. If not, then you should also add a plexiglas shield between yourself and the Zoom camera, adjust your tinfoil hat, and remain inside your Faraday cage and isolation bubble at all times. (Except while attending an Antifa riot of course).
While I appreciate your sentiment, try telling that to the remains of 80 million trees around Tunguska:
https://en.wikipedia.org/wiki/Tunguska_event
from above link:
“Studies have yielded different estimates of the meteoroid’s size, in the order of 50 to 190 metres (160 to 620 feet), depending on whether the body entered with a low or high speed”
So, 1/2 this space rock diameter. And continuing:
“It is estimated that the shock wave from the air burst would have measured 5.0 on the Richter magnitude scale, and estimates of its energy have ranged from 3–30 megatons of TNT (13–126 petajoules). An explosion of this magnitude would be capable of destroying a large metropolitan area.”
What would the energy of the 340 meter diameter rock be?
We are pretty close to having detected and plotted all space rocks “nearby” which are crossing earth’s orbit which 1000 meter in diameter or larger. But this about NEOs {Near Earth Objects} not things such a longer duration objects like comets.
And getting closer to detecting 1/2 km diameter or larger. And have detected lower percentage 1/3 km in diameter. And Tunguska size rocks are not close to having 1/2 them detected. And Tunguska might not have not been NEO. Again from link:”In 1983, astronomer Zdeněk Sekanina published a paper criticising the comet hypothesis. He pointed out that a body composed of cometary material, travelling through the atmosphere along such a shallow trajectory, ought to have disintegrated, whereas the Tunguska body apparently remained intact into the lower atmosphere. Sekanina also argued that the evidence pointed to a dense rocky object, probably of asteroidal origin. …
“They concluded with a probability of 83% that the object moved on an asteroidal path originating from the asteroid belt, rather than on a cometary one (probability of 17%)”
Comets aren’t NEO, and lot rocks aren’t NEO- objects which are in the asteroid belt is not a NEO. Hmm, wiki says:
“A near-Earth object (NEO) is any small Solar System body whose orbit brings it into proximity with Earth. By convention, a Solar System body is a NEO if its closest approach to the Sun (perihelion) is less than 1.3 astronomical units (AU).”
And by that definition most comets are NEO but for comets to “survive”/ exist, they have spend a lot of time beyond the frost line- or their surface volatiles evaporate- and frost line is at 5 AU or further- and asteroid belt is: “The asteroid belt lies between 2.2 and 3.2 astronomical units (AU) from our sun.” Or well within the frost line.
Or if object gets within 1.3, it could be interstellar object- which is really not what NEOs are, which are objects which remain close to Earth, generally have stayed in region for thousands of years- but one can say they are temporal if you talking about millions of years. In context of Tunguska, “comet” would be most of mass as volatiles- or at least something breaks apart easily like rubble pile space rock or dead comet.
That settles it then. If all the scientific evidence points to it being harmless, we must destroy capitalism and every vestige of Western civilization to avert this existential threat! To start with, everyone must be permanently locked down at a minimum. Then we should funnel around $100 trillion through our crony contributors to develop asteroid deflectors that will only work under limited weather conditions. It’s not perfect, but we must DO SOMETHING!
Correction: We must say we’re destroying capitalism while capitalists are paying us to say we’re destroying capitalism. Makes for a more lucrative story to tell students of voting age.
Just build a giant mask for the earth. Boom, protected. Easy peasey.
Perhaps we should vaccinate the asteroid,
It might make for a useful practice run to land a satellite on Apophis next time round and give it a slow but constant push off using solar sail or nuclear power to send it well out of its close passing orbit. Tempting to suggest it would be a useful way of getting rid of solar panels not doing much here – sarc.
So if they say no chance we can assume impact is imminent?! I may be getting cynical but that’s pretty much my feeling.
The most worrisome thing about all this…has anyway calculated the carbon footprint of this asteroid should it it??? Whichever country that got hit would then “own” the additional carbon and they might not be able to meet their carbon reduction goals. The horror.
From the article: “On April 13, 2029, the asteroid Apophis will pass less than 20,000 miles (32,000 kilometers) from our planet’s surface – closer than the distance of geosynchronous satellites.”
That’s pretty close!
So some years after achieving “declared carbon net neutral status” and at about the time the world realizes AGW was a total policy Potemkin Village, the big asteroid strikes. Is this a Michael Crichton story design?
If we know the orbit so well, why didn’t we have a probe or something sitting close by to study it? Seems like a wasted oppurtunity for all these NEOs not to get a technological hitchhiker while they are in the neighbourhood
“Reports that say that something hasn’t happened are always interesting to me, because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns—the ones we don’t know we don’t know. And if one looks throughout the history of our country and other free countries, it is the latter category that tends to be the difficult ones.”
— Donald Rumsfeld, February 12, 2002
After illuminating the asteroid with microwaves for months at a time, the team determined that it would have had no chance of impacting the Earth in this century. Unfortunately, the radiation pressure exerted by all of that radar scanning has put it on a course to to hit us next week.
Go to Costco and buy paper towels and toilet paper, everyone.