NASA Announces New Mission To Search for Asteroids

NASA Announces New Mission To Search for Asteroids

On the heels of an undetected asteroid making a close pass of Earth, the head of NASA’s science program announced today that the agency will begin a new mission to search for asteroids and comets, or Near Earth Objects (NEOs).  Speaking at an advisory committee meeting this morning, Thomas Zurbuchen said the agency will initiate a space-based NEO Surveillance Mission (NEOSM) to augment ground-based observations to detect and track asteroids.

Asteroids are rocks in space. There are millions of them and some come close to Earth.  Most pose no danger and, in fact, create delightful displays if they descend through the atmosphere as meteors.

Large asteroids can threaten the planet, however.  Called Potentially Hazardous Asteroids (PHAs), NASA has been charged by Congress to detect and track them since the 1990s, but ground-based telescopes can only see a small part of the sky. NEO-hunting scientists have argued for years that a telescope in space is needed whose sole purpose is to find asteroids.

Planetary defense — defending the Earth from asteroids and comets — took on new urgency in 2013 when a meteor exploded over Chelyabinsk, Russia. The accompanying sonic boom caused windows to shatter and more than 1,000 people were injured by flying glass.

Funding for NASA’s NEO search efforts grew and in 2016 the agency established a Planetary Defense Coordination Office (PDCO). The Obama White House released a NEO Preparedness Strategy in January 2017 and the Trump Administration put forward an Action Plan in June 2018.

PDCO’s funding is still quite modest, however, about $150 million per year, with little room for flight projects. Last year, it won approval to proceed with its first mission, the Double Asteroid Redirect Test (DART) that will demonstrate one method for altering an asteroid’s path, kinetic impact.

But the key is to find asteroids when they are still far enough away to be diverted.

The issue caught the interest of Congress two decades ago. In 1998, Congress directed NASA to detect, track, catalog, and characterize 90 percent of NEOs 1 kilometer or greater in diameter within 10 years.  NASA succeeded and in the 2005 George E. Brown Near Earth Object Survey Act, Congress then directed the agency do the same for NEOs 140 meters or more in diameter within 15 years.  That 15 years is up next year, but NASA is not close to achieving that goal because it is difficult to find NEOs that small.

The question is what ground- or space-based systems are needed to fulfill that requirement. NASA asked the National Academies to assess the alternatives.  The study, chaired by Jay Melosh of Purdue University and released three months ago, concluded that a space-based infrared telescope is the answer.

Just weeks after the report was released, a football-field size asteroid, 2019 OK, zoomed past Earth 65,000 kilometers away, one-fifth the distance to the Moon.  It had been detected only hours earlier by astronomers in Brazil.  The good news is that the orbit is now understood and it will not come this way again for another 200 years, but it was a close pass of a medium sized asteroid with virtually no warning.

Trajectory of asteroid 2019 OK as it passed by Earth on July 24-25, 2019. The asteroid moved right-to-left in this diagram, reaching its closest point to Earth at about 01:22 UTC on July 25, 2019. Credit: NASA-JPL Center for Near Earth Object Studies.

Paul Chodas, manager of NASA’s Center for Near-Earth Object Studies (CNEOS) at JPL, said an asteroid of this size, estimated at 60-130 meters, coming so close to Earth happens only twice a century.  If it had entered Earth’s atmosphere over land, the “blast wave could have created localized devastation to an area roughly 50 miles across,” JPL asserted.

Chodas added: “It is interesting to note that if a space-based infrared telescope has been on station and scanning the skies two years ago, it probably would have detected 2019 OK back then and this year’s close encounter would not have been a surprise.”

JPL has been working on such a mission for years, NEO Camera (NEOCam), but it never got the go-ahead to proceed into development. One reason is that it had to compete against science missions.  It is a planetary defense mission, not science.  NASA relies on Decadal Surveys from the National Academies of Sciences, Engineering, and Medicine to set scientific priorities, but NEO searches are not included in those reports.

Artist’s illustration of NEOCam. Credit: NASA-JPL Caltech

The 2019 National Academies report addressed that conflict.

The committee notes that NEOCam is primarily a planetary defense mission that has been forced to compete within NASA’s Discovery program against other proposals that have primarily scientific objectives. This has placed NEOCam and similar planetary defense-related missions at a competitive disadvantage.

Since “there is a bias against selection of planetary defense-focused missions,” they should not be forced to compete against missions meeting high-priority science objectives.

Amy Mainzer, Professor, Lunar & Planetary Laboratory (LPL), University of Arizona. Credit: LPL

Zurbuchen has come around to that way of thinking.  At a meeting of NASA’s Planetary Science Advisory Committee (PAC) today, he announced a plan to move forward with a space-based infrared telescope for asteroid detection even though he conceded that in the past his metric for approving new missions was science.

Zurbuchen calls it the NEO Surveillance Mission (NEOSM), but former NEOCam Principal Investigator Amy Mainzer told SpacePolicyOnline.com this afternoon via email that the mission is, indeed, NEOCam.  Mainzer recently left JPL and now is at the Lunar and Planetary Laboratory at the University of Arizona.

“Yes, this mission is what we proposed as NEOCam: It is a 50-cm telescope operating at thermal IR wavelengths, optimized for discovering, tracking, and characterizing potentially hazardous asteroids and comets. It directly responds to the National Academy report.”  — Amy Mainzer

Zurbuchen estimated the cost at $500-600 million with launch no earlier than FY2025, stressing that the actual launch date is dependent on funding.  Many details of how the project will be organized and led remain unclear, but he indicated the new mission will involve both JPL and Mainzer’s new home at the University of Arizona.  Mainzer is a member of PAC and during a Q&A after his presentation the two affirmed they will work together.

PDCO Director Lindley Johnson is scheduled to speak at PAC tomorrow morning and may provide more information.  He and Mainzer said at a media briefing in April that NEOCam could shorten the amount of time needed to meet the 2005 congressional requirement to find 90 percent of NEOs 140 meters or more in diameter from 30 years to 10 years.

Thomas Zurbuchen, NASA Associate Administrator, Science Mission Directorate. (NASA/Aubrey Gemignani)

Zurbuchen attributed his change of heart to a recognition that there is more than science involved, and many voices need to be heard and consensus reached.

Some of those voices are in Congress.

Not only did NASA’s asteroid-hunting effort originate in Congress, but NEOCam itself has support on Capitol Hill. The House Appropriations Committee (HAC) allocated $10 million for the NEOCam instrument in its report on the FY2019 Commerce-Justice-Science (CJS) appropriations bill that funds NASA.  The final version of the bill specified that it receive “no less” than FY2018.  For FY2020, HAC reiterated its support and recommended no less than FY2019. The House passed the bill in June.  The Senate Appropriations Committee will mark up the bill this week.

Another voice is that of NASA Administrator Jim Bridenstine who gave a keynote address at the sixth Planetary Defense Conference in April in order to dispel any “giggle factor” the topic may evoke. As for NEOCam, he noted that he had been asked about it at a recent congressional hearing and asserted “we are committed to doing that.”  Today Zurbuchen characterized Bridenstine as “passionate” about planetary defense.

The American public agrees, too. In a recent AP-NORC poll, monitoring asteroids and comets was at the top of the list of what the public thinks NASA should be working on, far more than sending astronauts back to the Moon or on to Mars.

Although Zurbuchen has christened the project with a new name, it appears NEOCam’s time has finally come.  When it will happen is dependent on funding, but at least it now has his support.

 

Correction: an earlier version of this article stated that DART would demonstrate the gravity tractor method of diverting an asteroid’s path, but it will demonstrate the kinetic impact method.

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