WS More or Less: Avoiding Asteroids

Episode Summary

Executive Summary: The episode examines whether humanity is really at risk from a surprise asteroid impact and finds the danger is falling as detection improves. NASA scientist Steve Chesley explains new warning systems, current cataloguing of large near-Earth objects, and a planned deflection test mission. The show also checks the real-world plausibility of Armageddon, concluding the film is wildly dramatic but not wholly impossible in principle.

Main Topics: Asteroid detection is improving (Priority: 5/5): NASA’s SCOUT warning system is scanning telescope data to flag potentially hazardous objects sooner and more reliably than before. How many dangerous asteroids are already known (Priority: 5/5): The discussion focuses on large asteroids over one kilometre wide, which are easier to detect and are now mostly catalogued. How likely is a surprise Armageddon-style impact? (Priority: 4/5): The programme asks whether a civilization-threatening asteroid could still appear with little warning, and concludes this is very unlikely. Planetary defence by asteroid deflection (Priority: 5/5): NASA and ESA’s planned AIDA mission is presented as a real test of whether spacecraft impact could alter an asteroid’s path. Could Armageddon happen in real life? (Priority: 3/5): The show revisits the film’s premise, including drilling and nuking an asteroid, and tests the science behind it. Training astronauts vs drillers (Priority: 2/5): The episode investigates Ben Affleck’s criticism of the film’s logic about whether drillers could be trained faster than astronauts could learn drilling.

Key Arguments: New observational systems are making asteroid detection more effective, reducing the chance of an unwarned impact. Large asteroids are easier to find than smaller ones, and NASA says it has catalogued about 95% of objects larger than a kilometre. The remaining unknown kilometre-scale objects are so rare that their impact timescales are tens of millions of years, making them a low immediate threat. A sudden, days-away discovery of a truly catastrophic asteroid is not the most likely scenario; decades of warning are more probable. The most plausible defence strategy is kinetic impact: sending a spacecraft to knock an asteroid off course. AIDA would provide the first measured demonstration that an asteroid’s orbit can be changed intentionally. The film Armageddon is scientifically shaky, especially the assumption that oil drillers are easier to convert into astronauts than vice versa, but the episode could not verify the training claim definitively.

Data Points: Asteroid 2016 UR36 size: About 10 metres in diameter - A recently detected asteroid used to illustrate SCOUT’s warning capabilities 2016 UR36 close approach distance: 1.3 times the Earth-Moon distance - Its Halloween flyby distance 2016 UR36 discovery lead time: About five days earlier - It was found shortly before its close approach Catalogue completeness for >1 km asteroids: About 95% - NASA’s estimate of how many kilometre-scale near-Earth objects are known and monitored Impact timescale for large asteroids: About 1 million to 10 million years - How often large asteroids hit Earth in general Impact timescale for missing 5% of >1 km asteroids: Many tens of millions of years - Estimated risk from the still-undiscovered kilometre-scale asteroids AIDA mission test date: October 2022 - Planned timing mentioned for the asteroid deflection demonstration Astronaut training: Usually 2 years general + 2 years mission-specific - Typical astronaut preparation described in the comparison with drillers Exception to astronaut training: 1 year - An example from the 1980s when a teacher received only a year’s training for a mission

Pivotal Quotes: "we're continuing to drive that down to zero" — Steve Chesley: Describing NASA’s efforts to reduce the risk of an unwarned large asteroid impact "It's calculated that there are 18 days until the asteroid strikes" — Armageddon clip: The film’s dramatic countdown premise "the entire premise of the movie was predicated on the idea that it's easier to teach oil drillers to be astronauts than it is to teach astronauts to drill a hole in the ground" — Ben Affleck: His criticism of the logic behind Armageddon

Implications: Listeners are left with reassurance that asteroid risk is being steadily reduced, not ignored. Real planetary defence is moving toward practical deflection methods, while Hollywood-style last-minute rescues remain highly unlikely.