Are We Safe from Doomsday Asteroids?

May 20, 2023
May 20, 2023 Hal Jordan

Are We Safe from Doomsday Asteroids?

A comprehensive analysis conducted by astronomers has provided reassurance that Earth is unlikely to be struck by large asteroids for at least the next 1,000 years. However, this conclusion should not lead to immediate relief, as the examination primarily focused on near-Earth objects (NEOs) with a width of at least 0.6 miles (1 kilometer), leaving room for potential impacts from smaller yet still hazardous asteroids.

The research team based their study on the positions and orbits of known NEOs, as recorded by the NASA-funded Minor Planet Center at the Smithsonian Astrophysical Observatory (SAO). They placed particular emphasis on objects larger than 1 kilometer, aiming to rank them according to their risk of collision over a longer timeframe of 1,000 years—a more extensive analysis than usual. Davide Farnocchia, an astrophysicist at NASA’s Jet Propulsion Laboratory (JPL) in Southern California and co-author of the study, explained their approach to Space.com, stating, “Our focus was on the objects larger than 1 kilometer, and we tried to rank them in terms of their associated risk of impact over 1,000 years, which is a longer time span than we usually analyze.”

Scientists worldwide, including those at NASA’s Center for Near-Earth Object Studies (CNEOS), have been diligently monitoring NEOs for years, with the primary objective of identifying any potential threats to human civilization. The catastrophic extinction event that wiped out the non-avian dinosaurs and approximately 75% of Earth’s species resulted from the impact of an asteroid roughly 6 miles wide (10 kilometers) around 66 million years ago. Therefore, tracking NEOs and assessing their risk is crucial.

According to NASA, approximately 95% of NEOs with a diameter of at least 3,300 feet (1 kilometer), which approach within 30 million miles (50 million kilometers) of Earth, have been identified thus far. CNEOS maintains the Sentry Risk Table, a system that calculates the probability of these asteroids colliding with our planet over the next century by tracking their orbits. Study co-author Farnocchia emphasized, “Thanks to the Sentry impact monitoring system, we already know that none of the large NEOs that have been discovered so far has any risk of impacting Earth over the next 100 years. We also know that none of the smaller objects already discovered is of concern in terms of impact hazard over the next 100 years.”

However, Farnocchia and his team sought to expand our understanding of potential asteroid impacts far beyond the century timeframe. Their objective was to gather similar information for the next 1,000 years, focusing on the larger celestial bodies near Earth. Farnocchia explained their selection criteria, stating, “We focused on objects of the 0.62 miles, or 3,300 feet (1 kilometer), range and larger because they are the ones that have the potential to cause global-scale damage if they were to reach the Earth.”

Understanding the importance of size in asteroid tracking The Global Challenges Foundation estimates that asteroids wider than 0.62 miles (1 kilometer) possess the capability to inflict global-scale damage, potentially disrupting human civilization and even threatening the existence of our species. In an asteroid impact exercise conducted in April, NASA scientists, led by Paul Chodas, the manager of NASA’s Near Earth Object (NEO) Program Office, approximated that such an impact could release around 100,000 megatons of energy, equivalent to the force of 6.6 million Hiroshima nuclear detonations, each of which carried the explosive energy of 15,000 tons of TNT.

Fortunately, large asteroid impacts are infrequent, and the time between such strikes decreases as the diameter of the asteroids increases. According to NASA researchers in April, asteroids with diameters of at least 3,300 feet (1 kilometer) are estimated to collide with the Earth approximately once every 700,000 years. Even more catastrophic events involving 3-mile-wide (5 km) asteroids are predicted to occur only once every 30 million years.

“A 1-kilometer asteroid impact would likely lead to significant cooling on Earth due to debris expelled into the atmosphere, blocking sunlight. This would result in the decline of vegetation, crop failure, and subsequent mass starvation and famine,” explained Farnocchia.

He further added, “There is no known object that poses this threat for the next 1,000 years, although we should continue to monitor the evolution of certain asteroid orbits.”

To improve their predictions, Farnocchia and the team utilized a novel approach to model asteroid orbits, focusing on the points where these space rocks come closest to Earth. This allowed them to extend their impact risk assessments far into the future.

“For a significant number of these objects over 3,300 feet (1 km) in size, we observed that their orbital paths were far enough from that of Earth, even over long time spans,” Farnocchia explained. “Therefore, although the position along the orbit may become uncertain over time, we know that the asteroid cannot reach Earth.”

Which asteroid poses the greatest threat to Earth in the next 1,000 years? According to the team’s investigation, the asteroid that presents the highest risk of impacting Earth in the next millennium is asteroid 7482 (1994 PC1). This stony asteroid, estimated to have a diameter of approximately 3,600 feet (1.1 km), passed within 1.2 million miles (1.9 million km) of Earth in 2022. The team calculated that it has a probability of approximately 0.0151% of coming within one Earth-moon distance over the next 1,000 years, making it about 10 times more likely to impact compared to the next riskiest asteroid in this category, 20236 (1998 BZ7), which has a 0.001% chance of approaching closer to us than the moon. (The average distance between the moon and Earth is about 239,000 miles or 384,600 km.)

However, it’s important to note that the team’s findings do not provide a complete assurance for Earth’s safety. The study primarily focuses on larger objects and does not cover smaller asteroids, some of which still have the potential to cause significant damage.

During a hypothetical asteroid impact exercise led by Chodas and other NASA scientists, it was stated that an asteroid approximately 1,000 feet (300 m) in diameter could cause devastation on a continental scale, releasing up to 2,000 megatons of energy upon impact. That’s 133,000 times the estimated energy released by the bomb that devastated Hiroshima.

An impact from an asteroid just 2,000 feet (600 m) in diameter would approach the scale of a global catastrophe, releasing as much as 20,000 megatons of energy. This demonstrates that a doubling in asteroid diameter corresponds to roughly a tenfold increase in impact energy.

“For other objects, their orbital paths can be close to that of Earth, so we cannot completely rule out a collision in the next 1,000 years,” Farnocchia cautioned. “Nevertheless, a collision with such large objects remains highly unlikely, and our findings can assist in prioritizing the tracking of these larger objects in the future.”

Reference:

Asteroid impact – The Global Challenges Foundation – Globalchallenges.org

Asteroid that killed the dinosaurs: Likely origin and what we know about the famous space rock – Space.com

CNEOS – NASA

Medium-Size Asteroid Strike Could Unleash a Mini Ice Age – Space.com

NASA’s Jet Propulsion Laboratory (JPL): Facts & Information – Space.com

Sentry: Earth Impact Monitoring – NASA

What are asteroids? – Space.com

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THIS WEEK IN STAR TREK HISTORY

20 May
1936Anthony Zerbe is born.
1958Matt McCoy and Jane Wiedlin are born.
1960John Billingsley is born.

21 May
1933Richard Libertini is born.
1940Booker Bradshaw is born.
1966Nichelle Nichols is contracted to play Lieutenant Uhura, only three days before filming begins on the first regular Star Trek episode, “The Corbomite Maneuver“.
1986David Ajala is born.

22 May
1930A. Conan Doyle dies.
1939Paul Winfield is born.
1961Ann Cusack is born.
1995Yadira Guevara-Prip is born.
2022Gregory Jein dies.

23 May
1921James Blish is born.
1929Marvin Chomsky is born.
1933Joan Collins is born.
1942Alex Henteloff is born.
1957Iona Morris is born.
1966H. Jon Benjamin is born.
1967Patrick Barnitt is born.
1994TNG: “All Good Things…” airs. Series finale.
2001Harry Townes dies.
2001VOY: “Endgame” airs. Series finale.
2012 – Ashes of James Doohan released into Earth’s orbit by SpaceX’s Falcon-9 rocket.

24 May
1960Doug Jones is born.
1963Michael Chabon is born.
1966 – Cameras roll on TOS: “The Corbomite Maneuver“, the first regular production episode of Star Trek. The first scene filmed is Kirk and McCoy‘s conversation in sickbay. Among the scenes filmed today is scene 21, where Janice Rand, in Kirk’s quarters, lays out a clean uniform for the captain. The scene is deleted from the episode’s final edit.
1978Barry Atwater dies.
1996John Abbott dies.
2018Jerry Maren dies.

25 May
1990Vic Tayback dies.

26 May
1964Lenny Kravitz is born.
1970Fabio Passaro is born.
1980Franz Bachelin dies.
2001Anne Haney dies.
2020Richard Herd and Anthony James die.

TODAY’S HUMOR

The United Federation Starfleet Blog is written by Fleet Captain Hal Jordan and is published every Friday. Join in the discussion! Engage with us on Discord at: discord.io/ufstarfleet

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