I am writing a scenario for a game that I am a fan of. It involves an asteroid heading for impact with the Earth in 2027. This asteroid's initial diameter is about 1km, but it is slowly disintegrating (breaking apart into smaller pieces) due to the YORP effect. It is moving at ## Km/s.

After the asteroid has broken apart there is still a mass of rocks heading towards Earth. Instead of it being just a 1km asteroid hitting earth, it has now split up into several rocks with the largest (main part) being 300m in diameter.

Humanity detected the asteroid in 2021 and realise it is will hit the earth in 2027.

In the story, the humans lie to the world to cover up the fact that this asteroid is heading directly towards earth. Only in 2024 does news reach the public that the asteroid will hit Earth. This reasults in theories but no solutions to redirect the asteroid. In my scenario, the asteroid will hit the earth so these humans will ultimately fail to redirect the asteroid.

Info: The speed of the asteroid would be around 31 km/s (want it to be super fast to punch through atmosphere). Also this is just a bit more than the average speed of asteroids.

Question: I want my scenario, requiring the asteriod to hit Earth, to be believable. Given the trends in current technology, would it be possible to divert this asteroid between 2024 and 2027?

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    $\begingroup$ So this is no longer 1 km single asteroid - this is more like asteroid "buckshot" on a collision course with Earth? $\endgroup$
    – Alexander
    Jan 8, 2019 at 2:00
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    $\begingroup$ The YORP effect is generally about rotation and tumbling rather more than about breaking up (though admittedly splitting is not precluded). If the asteroid so unstable that it fragments...then perhaps it's really a comet? $\endgroup$
    – user535733
    Jan 8, 2019 at 2:53
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    $\begingroup$ Answer from USA GOV in June 2018: Currently 'Not really'...but there are some ideas that could be developed. $\endgroup$
    – user535733
    Jan 8, 2019 at 3:08
  • $\begingroup$ How far away is it (at any of these points in time) and at what velocity is it traveling? $\endgroup$ Jan 8, 2019 at 4:38
  • $\begingroup$ Welcome to Worldbuilding.SE. Stack Exchange uses a one-specific-question/one-best-answer model. I count 7 question marks and at least 4 separate questions. Please edit your question to reduce it to a single, specific question or risk closure. Thanks. $\endgroup$ Jan 8, 2019 at 5:02

1 Answer 1


Three years is ample time to send whatever you want to the asteroid cluster and deflect them away from the Earth.

Although, if the humans in your theory have similar technology than ours, that would mean the the asteroid is moving very slowly, which may not be realistic using the physics laws in our universe. We tend to detect inbound asteroid only months before they cross Earth's orbit, not nearly a decade prior.

Building a rocket takes about a year and a half, more or less, mostly depending on the particular requirements of the payload. That being said, given the ever increasing number of organizations, private or public, with the ability to send rockets into space, if there's a sense of urgency, they could requisition one of the rockets that are ready or nearly ready, and modify it to carry in orbit whatever they're going to send to meet the debris of the big asteroid. If they send a bunch of nuclear warheads, they don't even need to build them, just make modifications to make sure that they can keep working in space.

So, it could be just a few months after the news get public. Which is good, because the earlier you start, the easier it is to deflect the incoming object.

Keeping with your question, if they send bunch of nuclear warhead to destroy the fragments of the big asteroid, chances are that what will be left after the explosions would be small fragments that would be unable to do much damage, if at all, and burn upon entry in the atmosphere.

The explosions of the warhead themselves wouldn't be enough to render the fragments of the asteroids radioactive enough to pose any threat as there would be little waste, if any. On Earth, most of the radioactive waste created by a nuke is due to debris like leaves and twigs and dirt and so on. They get bathed in radiation when the bomb explode, then scattered throughout the area and high into the atmosphere due to the blast, the shockwave, and the mushroom cloud.

On as asteroid, there would be nothing of the sort that could become radioactive, and whatever rocky debris at the surface of the asteroid would disperse through space along the shockwave of the explosion.

For the asteroid to release radioactive waste when it impacts the Earth, it must either fall on a place where there is already radioactive material, such a nuclear energy facility, causing dispersal of the radioactive matter in the atmosphere, or be radioactive from the start. But, given the eons long trip that asteroid takes through space, it is unlikely that an asteroid could be very radioactive as most of the radioactive material into the asteroid would have decayed away and turned into non-radioactive material.

  • $\begingroup$ Thanks for replying. So I should most likely reduce the time before the asteroid was spotted? Maybe do it in the same year so that probes and rockets are unlikely to be used successfully in pushing the asteroid away? $\endgroup$ Jan 8, 2019 at 3:53
  • $\begingroup$ 6 months to a year max would be more believable, and make it nigh impossible to put up a mission to send anything up in time. $\endgroup$
    – Sava
    Jan 8, 2019 at 4:36
  • $\begingroup$ There is a BIG flaw in this answer. Most (all?) rockets in use now can get into earth orbit, but not beyond that. We'd need a rocket capable of earth escape velocity which is substantially more than orbit. $\endgroup$
    – Tim B
    Jan 8, 2019 at 15:38
  • $\begingroup$ @TimB I know, guess I wrote a bit too fast. Made a small modification to show that the rocket only carries the payload into orbit. $\endgroup$
    – Sava
    Jan 8, 2019 at 16:16
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    $\begingroup$ @Sava A 5 PJ explosion is 50% kinetic energy, 50% radiation and thermal energy. Without a medium of transmission (no atmosphere), the 2.5 PJ kinetic energy is mostly dissipated into space. Nuclear warheads will affect this asteroid about as much as that grasshopper hitting your windshield on the highway. $\endgroup$
    – pojo-guy
    Jan 9, 2019 at 4:35

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