An existential threat

 

From aviationweek.com

NASA Ramps Up Efforts To Protect Earth From Space Impact Threats

Mark Carreau

April 21, 2023

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HOUSTON—With the success of the Double Asteroid Redirection Test (DART) and launch of the Near Earth Object (NEO) Surveyor on its agenda, NASA has devised a 10-year strategy for advancing efforts to protect the Earth from a devastating encounter with a Near Earth asteroid or comet.

The April 18 release of the 46-page “NASA Planetary Defense Strategy and Action Plan” follows the April 3 White House Office of Science and Technology Policy’s 38-page “National Preparedness Strategy and Action Plan for Near-Earth Object Hazards and Planetary Defense.” These documents are intended to signal an effort to better organize and coordinate a protection strategy, updated from 2018.

Each of the reports is focused on enhancing the detection, characterization and responses to impact threats as well as improving coordination among government agencies and international cooperation. Concerns are focused on asteroids and comets that orbit the Sun and come within 30 million mi. of the Earth’s orbital path.

The objects of concern are Near Earth Objects (NEOs) that range in diameter from 10 m (33 ft.) to more than 10,000 m.

“The release of this strategy steps up NASA’s intentions for the next 10 years to ensure the agency works both nationally and internationally to protect our planet for the benefit of all,” notes Lindley Johnson, who leads NASA’s Planetary Defense Coordination Office (PDCO).

The cadence of impact threats to the Earth range from once in a decade for the smallest object to once per 100 million years for the largest recognized in the two reports. The corresponding damage ranges from detonation in the atmosphere with enough acoustic energy for widespread structural damage across the landscape below to global devastation and mass extinctions.

An example of a smaller impact occurred over Chelyabinsk, Russia, on Feb. 15, 2013. Undetected, the object was estimated at just more than 50 ft. in diameter and detonated at an altitude of 14 mi., shattering windows across a 200-mi.2 region and injuring more than 1,600 people.

It was an estimated 66 million years ago that an asteroid more than 6 mi. in diameter struck the Yucatan Peninsula in Mexico, triggering a global tsunami and long-term climate changes that were linked to the extinction of dinosaurs and much of the life on Earth.

Fortunately, the more numerous the objects that pose an impact threat, the smaller they are. But that renders them more difficult to detect. NEOs 460 ft. across, of which there are estimated to be 25,000, are calculated to be capable of unleashing 300-megaton blasts leading to regional devastation and mass human casualties, the PDCO says.

On Sept. 26, 2022, NASA achieved a milestone in efforts to address the threat as the DART spacecraft reached Dimorphos, a 530-ft. asteroid moonlet almost 7 million mi. from Earth, to demonstrate a kinetic-impact strategy for diverting an NEO on a course to strike the Earth. Dimorphos was not selected because it posed an actual threat, but rather because it and its larger parent asteroid, Didymos, could be observed from Earth before and after the encounter to assess the effectiveness of a kinetic impact. The White House report called it a success.

The earliest possible detection of NEO threats, however, with follow-up tracking and characterization, is critical to implementing the most effective defensive strategies, the two reports says.

Funding has been a challenge, the NASA report acknowledges. Currently budgeted at $138 million for 2023, NASA is seeking $251 million for 2024, with an increase to $400 million projected for 2026 and a decrease to $79 million by 2028.

In 2005, the George E. Brown Near-Earth Object Survey Act was signed into law. It designated NASA as the nation’s planetary defense lead and directed the agency to discover and catalogue at least 90% of NEOs at least 140 m in diameter by 2020.

The goal has proven elusive, and it is currently NASA’s goal to find at least two-thirds of NEOs 140 m or larger within five years of launching the NEO Surveyor. It is a $1.2 billion infrared space telescope to be positioned at the Sun-Earth Lagrange Point 1, nearly 1 million mi. from Earth in the Sun’s direction.

Though facing cost and schedule challenges that could affect the development and scheduling of other NASA science missions, the NEO Surveyor is planned for launch no later than June 2028.

The updated White House planetary defense strategy is focused on six goals over the next decade:

•Enhancing NEO detection, tracking and characterization capabilities.

•Improving NEO modeling, prediction and information integration.

•Further developing NEO reconnaissance, deflection and disruption technologies to hasten a threat response.

•Increasing international cooperation on NEO preparedness.

•Strengthening and routinely exercising NEO impact emergency procedures and action protocols to be shared with the public and the international community.

•Improving U.S. management of planetary defense with enhanced interagency collaboration.

NASA’s follow-up defense strategy and action plan lists eight responsive agency objectives:

•Enhancing NEO detection, tracking and characterization capabilities.

•Improving coordination on NEO modeling, prediction and information integration.

•Developing technologies for NEO reconnaissance, deflection and disruption missions.

•Increasing contributions to international cooperation on NEO preparation.

•Coordinating with the Federal Emergency Management Agency and other agencies to strengthen and routinely exercise NEO impact emergency procedures and action protocols.

•Improving contributions to ongoing interagency coordination on planetary defense.

•Improving the organization of the agency’s planetary defense activities.

•Enhancing related strategic communications.