NASA Downplays Threat of Asteroid 2011 AG5 Impact in 2040

NASA released a workshop report today that downplays the risk to Earth of Asteroid 2011 AG5, saying that it “will fly safely past and not impact Earth in 2040.”   Asteroid 2011 AG5 is one of a subset of Near Earth Objects (NEOs) classified as Potentially Hazardous Asteroids (PHAs).

The agency acknowledges, however, that more observations are needed in the years ahead to be doubly sure that analysis is correct.  A key event will occur — or not — in February 2023 when the asteroid is 1.1 million miles from Earth.   If it passes through a very small “keyhole” in space at that time, Earth’s gravity could be just enough to modify its trajectory such that an impact with Earth might be possible on February 5, 2040. 

The keyhole is 227 miles wide.   Lindley Johnson, program executive for NASA’s Near Earth Object (NEO) observation program, said: “Given our current understanding of this asteroid’s orbit, there is only a very remote chance of this keyhole passage even occurring.”

Today’s press release provides a link to a JPL website where four related documents are posted, including a “consensus summary” of the May 29, 2012 workshop.   The links to the four documents are a little hard to find so are provided here:

• JPL Report on 2011 AG5
• Executive Summary of JPL Report on 2011 AG5
• Consensus Summary for the Goddard Workshop held on May 29, 2012
• Lindley Johnson’s slides presented at the Goddard Workshop

The one page consensus summary of the workshop does not list the participants.  Shown as bullet-points, it states that there is only a 0.2 percent chance of the asteroid passing through the keyhole in 2023, and also only a 0.2 percent change of it impacting Earth in 2040.

The 140-meter diameter asteroid was discovered in January 2011 and is currently located in the daytime sky and cannot be observed with Earth-based telescopes.  Observations can be made in the fall of 2013 and again in 2015-2020.  Data from those observations will allow scientists to better predict its path.

Should the unlikely occur and it turns out the asteroid is on a collision course with Earth after all, the workshop concluded that “numerous viable deflection mission options are available.”   For example, “an impactor spacecraft could be an effective means.”  If that approach is chosen, “[i]t is desirable to also have a rendezvous spacecraft on station at the asteroid at least a few months” in advance and it could be “equipped with a gravity tractor” as a backup.