Planetary Defense Plans for Asteroids Form

Concepts for communicating the risks and managing the threat of asteroid impacts will be considered by the United Nations following an expert working group meeting in Colorado.

The Near-Earth Object (NEO) media/risk meeting came within days of a 300-meter (984-ft.)-plus-dia. asteroid passing between the Earth and the Moon on Nov 8, and as NASA closed on additional congressional funding of more than $20 million for an ongoing survey mission aimed at finding objects posing a potential collision threat.

Although acknowledged as a statistically rare, low-probability event, asteroid impacts are seen as potential global catastrophes. Now, with 1,265 asteroids currently listed as potentially hazardous to Earth and with around 100 or more new potential impacts currently being flagged each month by the NASA Jet Propulsion Laboratory’s automated collision-monitoring Sentry system, the threat is being taken increasingly seriously by governments and space agencies.

According to NASA, as of Nov 3 8,421 NEOs have been discovered, of which 830 are asteroids with a diameter of approximately 1 km or larger. A NEO is an asteroid or a comet with an orbit close to that of Earth in which the perihelion (or nearest point to the Sun) is less than 1.3 astronomical units (1.3 times the distance from the Earth to the Sun). Potentially hazardous NEOs are 500 ft. or so in diameter and follow orbital paths that come within 4.65 million mi. (7.48 million km) of Earth.

The meeting, held at University of Colorado’s Laboratory for Atmospheric and Space Physics, was organized by the Secure World Foundation and aimed at a draft report for the U.N. Action Team 14 working group on NEOs. The team forms part of the U.N.’s Committee on the Peaceful Uses of Outer Space Scientific and Technical Subcommittee, and will present guidance to the U.N. working group at a NEO-mitigation meeting in Vienna, in February 2012.

Following a review in June next year, final recommendations will form the blueprint for possible U.N. action from 2013 onward. The working group is studying setting up an information, analysis and warning network (IAWN) to coordinate data about NEO detection, orbit analysis, impact prediction and notifications. The Colorado meeting was focused on IAWN communications, including protocols used by similar warning nets dealing with natural disasters such as hurricanes and tsunamis, as well as improving public education on the NEO phenomenon.

Parallel work is underway to set up a NEO Mission Planning and Operations Group (MPOG) that will coordinate international space agencies on the planning and conduct of missions to threatening asteroids. The MPOG will be modelled on the inter-space agency group established to monitor space debris.

The conference included discussion of communication strategies for events ranging from those with almost no warning such as the TC3 asteroid which exploded over southern Sudan in 2008 less than 21 hr. after being detected, to decades-long scenarios such as the Apophis asteroid which could potentially impact Earth in 2036.

In particular, the meeting focused on effective ways of communicating the reality of threats and evacuation notices to predicted impact zones in short-term warning scenarios. For longer-term threats, the group weighed the geopolitical implications of potential mitigation strategies involving speeding up or slowing down an asteroid. By altering an asteroid’s speed, its trajectory could be altered to either miss the Earth altogether or be deflected toward less-populated areas. Such choices inevitably involve increasing the risk to certain nations and regions, while decreasing it for others, raising enormous policy questions.

Social scientists, invited to advise the group, called for transparent debate from agencies over both warnings and mitigation strategies. Dennis Mileti, director emeritus of University of Colorado’s National Hazards Center, warned “the biggest issue will not be panic but getting them to take your NEO warning seriously. Human beings need to dichotomize risk. That’s how they decide to do something about it or not. Don’t try and explain your science to the public.”

Former Apollo astronaut and asteroid awareness trailblazer Russell Schweickart warned greater efforts and survey systems are needed. “We have many more objects that will be discovered. We’re not running out of objects, we’re running out of capability of our telescopes.” While roughly 94% of the largest NEOs are believed to have been located, “there are 60% still not detected in the 300-meter or so size,” said Schweickart, who is co-founder and past chairman of the B612 Foundation dedicated to protecting Earth from asteroid strikes. Detection numbers are even lower for smaller NEOs between 100 and 300 meters in diameter with only 10% of the estimated population accounted for, while for the smallest ones – like the approximately 50-meter asteroid that airburst over Tunguska, Siberia, in 1908 – we’re below 1% of total objects discovered. When it comes to objects that can do serious damage we’re nowhere near a full inventory yet,” he added.

NASA NEO Observations Program Executive Manager Lindley Johnson said securing allocated NEO funding is “critical to continuation of our existing survey programs like the radars for instance, and to do sorely needed upgrades for the Arecibo (radio telescope) in particular – that has suffered from a lack of funding over the years.” Johnson added money will also support analysis “to determine what the next generation survey should be.”

Options include new land-based telescope projects like the Atlas (Asteroid Terrestrial-impact Last Alert System) and Large Synoptic Survey Telescope as well as space-based systems. These could include hosted payload-type concepts in which a staring array would be mounted on the “backside of a commercial payload,” scanning as it orbits the Earth. Such schemes are less capable than a dedicated survey telescope, but much more affordable. “We really need to ferret out the best solution,” said Johnson.

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