Telescope in space needed to spot asteroids hurtling toward Earth, report says
By MARK HARPER | The News-Journal, Daytona Beach, Fla. | Published: July 10, 2019
(Tribune News Service) — Asteroids and comets are orbiting toward Earth, and a new National Academy of Sciences report notes the United States is nowhere near the objective set in 2005 to detect 90% of them by next year.
You know the scenario: An Earth-bound asteroid threatens all humanity but not before Bruce Willis armed with a hydrogen bomb can stop it. But before wandering down the well-worn path of "Armageddon" jokes, consider what one local scientist, Terry Oswalt of Embry-Riddle Aeronautical University, says about the prospect of such an event occurring.
"It's right in the middle of all the statistical risks that people like the insurance industry compute," Oswalt said. "It's a rare but widespread event. It's like the difference between a single-car accident and an airplane crash."
A rarer event, but more people are involved in the latter.
As they come in all shapes and sizes, the NASA scientists charged with tracking the most potentially calamitous "NEOs" — or near-Earth objects, as they're called — have discovered nearly 2,000 larger than 1 kilometer (or about three-fifths of a mile in diameter). Those are big enough to kill "many millions," having global effects.
But only about one-third of the estimated 24,000 NEOs larger than 140 meters have been catalogued. Those are asteroids large enough to cause regional or national destruction, and they're worth our attention, Oswalt and others argue.
In fact, improved asteroid tracking should be a top priority of the U.S. space program, a new poll suggests.
The Associated Press reported Thursday that a poll it conducted with the NORC Center for Public Affairs Research showed asteroid and comet monitoring should be the U.S. space program's top objective, even over explorations to the moon and Mars, searching for extra-terrestrial life and establishing a military presence in space.
New telescope sought
The academies — some of the most distinguished scientists in the United States acting as non-governmental "advisers to the nation — is recommending a space-based, infrared telescope working in conjunction with the Earth-based telescopes already dedicated to the task of tracking masses hurtling toward us.
Several telescopes in the United States and elsewhere have been used in the search for NEOs, including the Spacewatch at Kitt Peak National Observatory in Arizona, Space Surveillance Telescope at White Sands Missile Range, New Mexico, which is being relocated to Western Australia.
To better detect asteroids, NASA commissioned the academies to evaluate the strengths and limitations of space-based infrared and visible wavelength telescopes.
"A dedicated, space-based infrared telescope, working in conjunction with current ground-based telescopes would greatly improve data collection and detection efficiency," a summary of the academies' report states. It calls such a telescope "necessary" to meeting the 90-percent inventory goal.
That goal, the George E. Brown Jr., Near-Earth Object Survey Act, defines as potentially hazardous asteroids that are 140 meters in diameter — larger than Niagara Falls but smaller than the Eiffel Tower.
A cooled infrared telescope in space has demonstrated the best way to accurately estimate the size of asteroids. The report states the cost of such a telescope is in the range of $480 million to $850 million.
A $600 million telescope capable of meeting the goal within 15 years is "comparable to many other NASA discovery class missions," according to Henry Melosh, distinguished professor of earth, atmospheric and planetary science/physics at Purdue University. He chaired the academies' report.
The finding makes sense to Oswalt, professor of engineering physics and chair of physical sciences at Embry-Riddle.
"It's not a big investment relative the the cost of other things related to space," he said. "If it isn't too much, you should do something about it before it comes to hit you in the face."
Dinosaurs 'didn't have a clue'
Oswalt, who has a doctor of philosophy in astronomy degree from the Ohio State University, has spent some time observing NEOs and has a collection of pieces of asteroids that have struck Earth.
The rocks serve as reminders that the risks of asteroids are real. Just six years ago, a 20-meter (or 65-foot asteroid moving at 12 miles per second struck the atmosphere, exploding about 20 miles above Chelyabinsk, Russia. Its shock wave broke windows and knocked down structures.
"I think that the apprehension of danger from an asteroid impact has become much stronger since the 2013 Chelyabinsk fireball and airblast," Melosh said in an email. "While that event did not kill anyone, it did send about 1,000 people to hospitals and images of the damage caused by the event are widely known.
"That, combined with the modern consensus that the dinosaurs were wiped out by a much larger asteroid impact, has made the possibility of serious damage from asteroid impacts much more plausible to the general public," Melosh said.
The academies' report notes that 66 million years ago, an asteroid with a diameter between 7 and 9 miles wide struck the Yucatan Peninsula, resulting in climate change that led to the extinction of dinosaurs and "more than 75 percent of all nonavian life on Earth," the academies' report states.
"Such devastating impacts are fortunately rare, but our highly interconnected modern society may be vulnerable to much smaller impacts," the report states, adding that even a 1-kilometer (0.62 miles) wide object could "trigger earthquakes, tsunamis and other secondary effects — such as climate change sufficient to cause global crop failures for several years — that extend far beyond the immediate impact area."
Oswalt argues that with investment in an infrared, space-based telescope, much more can be known and developed to avoid catastrophe.
"We don't want to be like the T-Rex," Oswalt said, "the dinosaurs that didn't have a clue that the thing falling from the sky 65 million years ago, the object the better part of a mile across ... would bring the equivalent of a nuclear winter and block out sunlight for several years, collapsing the food chain."
Because humans have landed probes onto the surface of asteroids, there is a belief that scientists can engineer an NEO off course enough to miss a collision with Earth.
"The actual probability of such an impact is still small, but the potential number of fatalities from even a moderate size impact is so large that the threat seems worth consideration," Melosh said. "Asteroid impacts, unlike most other natural hazards, are predictable years in advance and can potentially be averted with modern technology."
Terry Oswalt, professor of Physics at Embry-Riddle Aeronautical University, with his collection of pieces of asteroids that have hit the earth.