Planetary Defense Exercise Uses Apophis as Hazardous Asteroid Stand-In
Over 100 participants from 18 countries – including NASA scientists and the agency’s NEOWISE mission – took part in the international exercise.
PASADENA, Calif. (NASA PR) — Watching the skies for large asteroids that could pose a hazard to the Earth is a global endeavor. So, to test their operational readiness, the international planetary defense community will sometimes use a real asteroid’s close approach as a mock encounter with a “new” potentially hazardous asteroid. The lessons learned could limit, or even prevent, global devastation should the scenario play out for real in the future.
To that end, more than 100 astronomers from around the world participated in an exercise last year in which a large, known, and potentially hazardous asteroid was essentially removed from the planetary defense-monitoring database to see whether it could be properly detected anew. Not only was the object “discovered” during the exercise, its chances of hitting Earth were continually reassessed as it was tracked, and the possibility of impact was ruled out.
Coordinated by the International Asteroid Warning Network (IAWN) and NASA’s Planetary Defense Coordination Office (PDCO), the exercise confirmed that, from initial detection to follow-up characterization, the international planetary defense community can act swiftly to identify and assess the hazard posed by a new near-Earth asteroid discovery. The results of the exercise are detailed in a study published in the Planetary Science Journal on Tuesday, May 31.
The exercise focused on the real asteroid Apophis. For a short while after its discovery in 2004, Apophis was assessed to have a significant chance of impacting Earth in 2029 or later. But based on tracking measurements taken during several close approaches since the asteroid’s discovery, astronomers have refined Apophis’ orbit and now know that it poses no impact hazard whatsoever for 100 years or more. Scientific observations of Apophis’ most recent close approach, which occurred between December 2020 and March 2021, were used by the planetary defense community for this exercise.
“This real-world scientific input stress-tested the entire planetary defense response chain, from initial detection to orbit determination to measuring the asteroid’s physical characteristics and even determining if, and where, it might hit Earth,” said Vishnu Reddy, associate professor at the University of Arizona’s Lunar and Planetary Laboratory in Tucson, who led the campaign.
Tracking a ‘New’ Target
Astronomers knew Apophis would approach Earth in early December 2020. But to make the exercise more realistic, the Minor Planet Center (MPC) – the internationally recognized clearinghouse for the position measurements of small celestial bodies – pretended that it was an unknown asteroid by preventing the new observations of Apophis from being connected with previous observations of it. When the asteroid approached, astronomical surveys had no prior record of Apophis.
On Dec. 4, 2020, as the asteroid started to brighten, the NASA-funded Catalina Sky Survey in Arizona made the first detection and reported the object’s astrometry (its position in the sky) to the Minor Planet Center. Because there was no prior record of Apophis for the purpose of this exercise, the asteroid was logged as a brand-new detection. Other detections followed from the Hawaii-based, NASA-funded Asteroid Terrestrial-impact Last Alert System (ATLAS) and Panoramic Survey Telescope and Rapid Response System (Pan-STARRS).
As Apophis drifted into the field of view of NASA’s Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) mission, the MPC linked its observations with those made by ground-based survey telescopes to show the asteroid’s motion through the sky. On Dec. 23, the MPC announced the discovery of a “new” near-Earth asteroid. Exercise participants quickly gathered additional measurements to assess its orbit and whether it could impact Earth.
“Even though we knew that, in reality, Apophis was not impacting Earth in 2029, starting from square one – with only a few days of astrometric data from survey telescopes – there were large uncertainties in the object’s orbit that theoretically allowed an impact that year,” said Davide Farnocchia, a navigation engineer at NASA’s Jet Propulsion Laboratory in Southern California, who led the orbital determination calculations for JPL’s Center for Near Earth Object Studies (CNEOS).
During the asteroid’s March 2021 close approach, JPL astronomers used NASA’s 230-foot (70-meter) Goldstone Solar System Radar in California to image and precisely measure the asteroid’s velocity and distance. These observations, combined with measurements from other observatories, enabled astronomers to refine Apophis’ orbit and rule out a 2029 impact for the purpose of the exercise. (Beyond the exercise, they also were able to rule out any chance of impact for 100 years or more.)
NEOWISE Homes In
Orbiting far above Earth’s atmosphere, NEOWISE provided infrared observations of Apophis that would be not have been possible from the ground because moisture in the Earth’s atmosphere absorbs light at these wavelengths.
“The independent infrared data collected from space greatly benefited the results from this exercise,” said Akash Satpathy, an undergraduate student who led a second paper with NEOWISE Principal Investigator Amy Mainzer at the University of Arizona, describing the results with inclusion of their data in the exercise. “NEOWISE was able to confirm Apophis’ rediscovery while also rapidly gathering valuable information that could be used in planetary defense assessments, such as its size, shape, and even clues as to its composition and surface properties.”
By better understanding the asteroid’s size, participating scientists at NASA’s Ames Research Center in Silicon Valley, California, could also estimate the impact energy that an asteroid like Apophis would deliver. And the participants simulated a swath of realistic impact locations on Earth’s surface that, in a real situation, would help disaster agencies with possible evacuation efforts.
“Seeing the planetary defense community come together during the latest close approach of Apophis was impressive,” said Michael Kelley, a program scientist with PDCO, within NASA’s Planetary Science Division at NASA Headquarters in Washington, who provided guidance to the exercise participants. “Even during a pandemic, when many of the exercise participants were forced to work remotely, we were able to detect, track, and learn more about a potential hazard with great efficiency. The exercise was a resounding success.”
Additional key planetary defense exercise working group leads included Jessie Dotson at NASA Ames, Nicholas Erasmus at the South African Astronomical Observatory, David Polishook at the Weizmann Institute in Israel, Joseph Masiero at Caltech-IPAC in Pasadena, and Lance Benner at JPL, a division of Caltech.
NEOWISE’s successor, the next-generation NEO Surveyor, is scheduled to launch no earlier than 2026 and will greatly expand the knowledge NEOWISE has amassed about the near-Earth asteroids that populate our solar system.
More information about CNEOS, asteroids, and near-Earth objects can be found at:
https://www.jpl.nasa.gov/asteroid-watch
For asteroid and comet news and updates, follow @AsteroidWatch on Twitter.
14 responses to “Planetary Defense Exercise Uses Apophis as Hazardous Asteroid Stand-In”
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It is ironic that Ronald Reagan once publicly entertained the notion of that old Outer Limits episode from the 60’s about Earth uniting against an alien threat. At the same time many scientists were entertaining it as a real possibility- that an impact from space had killed the dinosaurs.
Are we as stupid as the dinosaurs? A real question. What is the definition of intelligence?
If organizing and effecting action to ensure the survival of the species is included in that definition, then perhaps humans are not so “intelligent.” Aliens evaluating our civilization may have already written us off as too stupid to survive.
We could, within ten years with an Apollo type project, have a fleet of nuclear propelled and armed human-crewed Spaceships guarding planet Earth against impact threats. And it would not cost much more than….a new fleet of nuclear missile submarines. What is the DOD for anyway?
SLS could launch an intercept
https://www.engadget.com/20…
I would say the prerequisite for anything in space carrying nuclear devices is a human crew. I don’t think that is really negotiable.
In my view the best path is to move almost all nuclear weapons into deep space months away from Earth. Not much can be done about the lesser nuclear powers but the superpowers can and should get them off-world. And if you have fleets of “space boomers” on patrol they would always be ready to target an impact threat.
The best possible insurance for civilization, not only from an impact but also from an unintentional nuclear exchange. With only minutes to decide to “launch-on-warning” this has been the single biggest threat to humankind for over half a century.
The problem here, as is usually the case with grand schemes involving nuclear weapons, is perverse incentives that encourage cheating. In this case, the incentive is the ability to quickly strike a terrestrial opponent with weapons not sent to the deep space back of beyond but hidden for exactly this purpose. If all involved nations cheat to about the same extent, all one has done is substitute an only modestly lesser ghastly holocaust for a all-out one as a worst-case scenario should any aggressive nation’s trigger finger get itchy.
That does not, in my view, constitute an actual solution to the problem. Unless, of course, you think there is some infallible way to detect a secreted nuclear weapon hidden behind an arbitrarily large amount of shielding at a range of hundreds to thousands of miles. I don’t. Star Trek-ian “scanners,” worse luck, exist only in fiction.
A faster and far more economical solution to the nuclear war problem is to comprehensively defeat and disarm one’s aggressive opponents. Russia, for example, has recently chosen, quite unwisely, to embark on an act of conventionally-armed aggression which, it increasingly seems, will only accelerate its pre-existing rapid slide into economic, military and population oblivion.
The PRC may well go to pieces even sooner. It’s economy is in full melt-down mode and Putin’s little Ukrainian adventure has bollixed world food, energy and fertilizer supplies sufficiently that the PRC faces likely food shortages fairly soon with more serious shortfalls not far beyond.
Our best move is to use Starship to begin deploying, ASAP, a low-LEO constellation of anti-ASAT and anti-missile defenses sufficient to render it impossible for either Russia or the PRC to effectively threaten us with their nuclear arsenals. Then, we simply await the demise of both regimes, go in after each has fallen, and extract all of their nuclear “teeth” as well as any industrial capability to make more. I borrow the name of this plan from the late Pres. Reagan – “We win. They lose.” We can police up minor caches of nukes in other annoying places, such as Pakistan, North Korea and Iran, at our leisure.
Serial trolling me again. You sick twisted creep.
I’m writing about avoiding a nuclear holocaust, but – naturally – Gary thinks it’s all about him.
Before we send off a legion of Tom Corbetts in their nuclear battle cruisers to patrol the solar system for rogue rocks, we might better spend a tiny fraction of that amount actually inventorying the solar system and identifying potential threats as far in advance as we can. The 612 Foundation, for example, has recently developed a computational approach capable of post-processing astronomical image archives to identify previously unknown asteroids. With a comprehensive catalog in-hand, there are far less expensive and colorful ways to deal with actual rogue rocks than siccing Corbett and his mates on them.
Mocking and trivializing and citing an organization that prohibits use of the single most effective technique to deflect an impact threat. You read my comments and then write what you think will enrage me. Sadistic sociopathic behavior.
You are serial trolling me like you have for years. I blocked you and you were too lazy to bother doing it for awhile but your brother sociopath sejones started harassing me even though he was blocked and you followed his example.
F-ing sick twisted creep spacex fanboy.
No one is trying to deliberately enrage you, Gary. No one has too. You are an inveterate rage-aholic of a type so extreme as to make The Incredible Hulk seem laid-back and mellow. You will rage if we write anything.
Yes there are several potential ways of changing asteroid orbits that don’t violate treaties and put the world at risk of nuclear war. Worst case asteroid impact coming and I would still be quite nervous about several nations orbiting nukes. Would you be comfortable with Russian and Chinese putting a few hundred apiece in orbit? How about NK and Iran with a few dozen each?
The inventory would be the critical enabler for less dangerous methods of shifting orbits for exploitation or impact prevention. A small asteroid on a crossing orbit might be shifted to impact a dangerous one shifting that orbit out of the danger zone. Gravity tractors, solar sails, in situ rocket possibly solar thermal, asteroid beanstalk and several more are possibilities for less exciting orbital shifting.
Indeed, and shifting an asteroid’s orbit through active propulsion instead of nukes opens up the possibility of putting it where it can be useful, instead of just so much debris to either orbit endlessly around the sun, or burn up.
Avoids irradiation of the asteroid material you want to exploit as well.
You want to exploit “asteroid material” for profit so you don’t want to use nuclear weapons to keep it from hitting the Earth?
Idiotic!
I have never read anything that so clearly illustrates a mentality that worships money as the god of this world. No hope for you.
I think Gary just has an affinity for really big explosions.