NASA Forms New Planetary Defense Office To Manage Asteroid Threats (cnn.com)

An anonymous reader writes: NASA has set up a new Planetary Defense Coordination Office to detect and track near-Earth objects. CNN reports: "The department, which includes the position of Planetary Defense Officer, is managed by the Planetary Science Division of the Science Mission Directorate at NASA Headquarters in Washington DC. And its mission includes the early detection of potentially hazardous objects (PHOs) — asteroids and comets which get within 0.05 Astronomical Units of Earth's orbit around the sun (7.5 million kilometers) and are large enough, greater than around 30 — 50 meters (98 — 164 feet), to reach the Earth's surface." Bruce Willis had no comment on his level of involvement in the new agency.

Comments

Could we be certain enough

[presidenteloco]

of impact of a really dangerous one

in time to expend a lot of money on an active defense launch?
(e.g. a launch of an ION thruster which would sit on the object and when at correct orientation, would fire to push it slowly into a safe trajectory)

1. The farther out the object is, the less certain the prediction of Earth impact is.
but
2. The object has to be quite far out for active defense to work.

Has anyone run the numbers on this?

We seem to have a lot of trouble investing in EFFECTIVE levels of action on a certain unnamed problem that science is, say 97% certain is going to affect us.

Assuming we had built one just in case,
wouuld we send a $100 billion defense system out on a 1% chance of asteroid impact?
10%? 50%? 90%? 97%? How about a 1/1000 chance? or 1/1000,000 chance of catastrophic impact?

Re:A good start

[Rei]

The tiny stuff could be nuked easily enough, but the really big stuff would just create a lot of really big (and now somewhat radioactive) rubble to carpet-bomb whatever place gets the impact.

This is a common myth. The reality is that simulations show that nuclear weapons can readily both deflect large asteroids without destroying them, or alternatively destroy them into bits too small to pose a threat and with too much momentum to reform into a large impactor. And even if that wasn't the case, there's also significant dispute among experts to the popularly repeated concept that a bunch of small pieces are worse than one big piece, as smaller pieces come in at varying time and thus spread out the heat load, ejecta load, etc, experience more burnup, produce much less powerful tsunamis that don't "echo" around the Earth as much, etc.

There's really no other option that has the sort of combination of A) near term technology, B) little lead time to deploy, C) minimal lead time required for effective deflection, D) low odds of failure, and E) capability of deflecting very large objects with small payloads - nuclear detonation, whether via standoff deflection or explosive disassembly, in is better than all or almost all competitors in every single category (kinetic impactors are slightly better in some categories but provide orders of magnitude less deflection capability for a given payload size)