Last July, a once-in-a-lifetime event happened. Not the good kind; the football-field-sized-asteroid near-miss kind. And that near miss is the catalyst for a renewed effort from NASA to detect more dangerous space-rocks that might threaten Earth.
Last summer’s near-miss asteroid was named 2019 OK, and it passed within about 77,000 km (48,000 miles) of Earth. It managed to slip past all of our detection methods and came within 0.19 lunar distances to Earth. In astronomical terms, that is remarkably close.
We only had 24 hours notice that the asteroid was coming, thanks to a small telescope in Brazil that spotted it. That near miss has sparked a renewed conversation on planetary defense and on NASA’s role in it.
It also left people wondering how this could happen.
Most of our asteroid detection telescopes are here on Earth, where weather and atmospheric conditions can limit detections. They also mostly rely on visible light. When 2019 OK was on its way to its near-miss with Earth, the brightness of the Moon made it difficult to see. That, combined with bad weather and the slow speed of the object, meant that we just didn’t see it.
Obviously, Earth needs better detection systems if the bright Moon prevented us from seeing a potentially dangerous asteroid. Luckily for us, scientists already knew that, and the work to build a better asteroid detector has been ongoing. In fact, Congress requested in 1998 an asteroid detection system that would spot 90% of the near-Earth asteroids measuring 1 km across in ten years. That was prompted by the media frenzy around asteroid NEO 1997 XF11.
That original goal has been exceeded, and in 2005 Congress set a new goal: to find 90 percent of the NEOs down to the much smaller size of 140 meters (450 feet), and to do so by the year 2020.
The NeoWISE spacecraft has done much of the heavy lifting. NeoWISE was just the new name given to the WISE (Wide-field Infrared Survey Explorer.) WISE’s mission ended in 2011 when its coolant ran out.
WISE was then reactivated in 2013 and named NeoWISE. NeoWISE used its infrared capabilities to spot asteroids from Earth orbit. It was successful, and it discovered about 34,000 new asteroids, including 135 Near Earth Objects (NEOs.) NeoWISE is still operating.
But even NeoWISE missed 2019 OK, and this near miss has got people working on the problem. The solution is two-fold:
- We need a space-based system to find asteroids.
- We need a system that detects infrared.
In NASA emails released due to an access to information request from Buzzfeed, you can see the frustration that NASA feels about 2019 OK and all the issues surrounding it.
In one email, Paul Chodas of NASA’s Jet Propulstion Laboratory wrote “This object slipped through a whole series of our capture nets. I wonder how many times this situation has happened without the asteroid being discovered at all.”
NEOCam (Near Earth Object Camera) has been in the works ever since Congress set the new goal in 2005 of detecting 140 meter asteroids. But it keeps getting bogged down by bureaucracy. Since it’s a planetary defense mission, not a science mission, it keeps getting passed over by other missions in NASA’s Discovery Program.
It’s been stuck in the design and technology phase for years. It’s never been killed, it’s just kind of been sitting there, while proponents argue for its completion and launch.
In June 2019, the National Academies of Sciences, Engineering, and Medicine issued a statement acknowledging the problem: “Recommendation: Missions meeting high-priority planetary defense objectives should not be required to compete against missions meeting high-priority science objectives.” That may have been a breakthrough moment.
Now it looks like NEOCam may finally move ahead, and we may have asteroid 2019 OK to thank for that. Nothing motivates like fear.
On September 23rd, NASA committed to a new asteroid hunting spacecraft. Though they didn’t specifically commit to NEOCam, many people have been advocating for that system, and its design is already established. It could be ready by 2025 if it receives the required funding: between $500 and $600 million.
A presentation from Thomas Zurbuchen, Associate Administrator Science Mission Directorate, provided some detail.
NASA’s calling this new asteroid-hunting spacecraft the Neo Surveillance Mission. It’ll sit in a Sun-Earth L1 halo orbit. From that vantage point, it’ll be free of the blind spots and deficiencies of a ground-based system. Using a 50 cm infrared sensor, it would find 65% of undiscovered PHAs >140 m in 5 years (goal: 90% in 10 years.)
A system that detects infrared will be more effective than a visible light system because some asteroids are too dark to be detected in visible light. But they all emit infrared because of the energy they receive from the Sun. Typically, a sensitive infrared scope needs to be cryogenically cooled to operate, but out at LaGrange Point 1, it’s cold enough without cooling. All it will need is a sun shield, much like the James Webb Space Telescope will use.
If the funding is put in place, and if NASA commits to it, NEOCam could be in operation before too long. It’s under the umbrella of the Planetary Defense Coordination Office (PDCO) which is also working on the Double Asteroid Redirection Test (DART) mission. But DART is eating up PDCO’s budget. DART will be launched in 2021 and its mission cost $313 million. Unless Congress finds a bunch of new money, NEOCam will have to wait until after that.
After all the wrangling, and administrative and bureaucratic maneuvering, NEOCam, or a mission very similar to it, may finally make it out of its extended design phase. It better, because asteroid impacts are a serious threat.
Remember the Chelyabinsk meteor? It exploded over Chelyabinsk Russia in 2013, and caused quite a bit of damage, and quite a few injuries. It slipped by undetected. What if it had been larger? What if 2019 OK had taken a slightly different course?
“This one did sneak up on us and it is an interesting story on the limitations of our current survey network,” said Lindley Johnson, NASA’s planetary defense officer in a July 26 email.
And in a news release sent out weeks after 2019 OK’s flyby, NASA said, “If 2019 OK had entered and disrupted in Earth’s atmosphere over land, the blast wave could have created localized devastation to an area roughly 50 miles across.”
- NASA Presentation: Planetary Defense Strategy
- Space Policy Online: SPACE-BASED INFRARED TELESCOPE FOR PLANETARY DEFENSE GETS BOOST FROM NATIONAL ACADEMIES
- Buzzfeed: A “Sneaky” Asteroid Narrowly Missed Earth This Summer. Internal Emails Show How NASA Scientists Totally Missed It.
- CalTech: NEOCam: Finding Asteroids Before They Find Us
- NASA Press Release: Twenty Years of Tracking Near-Earth Objects