How to save the Earth from as­ter­oid Ar­maged­don (Bruce Wil­lis op­tional)

Guru Magazine - - LIFE -

De­spite the lack of a cur­rent threat, there are a num­ber of tech­niques for im­pact mit­i­ga­tion that have been pro­posed. Some are in­ge­nious while oth­ers are more than a lit­tle im­prac­ti­cal! NASA’s ver­dict is that our only fea­si­ble op­tion at the mo­ment would be to nuke the as­ter­oid. Here’s the low­down on some of the more in­ter­est­ing tech­niques that have been pro­posed.

Use a ‘trac­tor beam’:

A ‘grav­ity trac­tor’ is a space­craft that po­si­tions it­self near to an as­ter­oid to cre­ate a con­stant grav­i­ta­tional force upon it in an at­tempt to change the as­ter­oid’s or­bit, and so avert disas­ter. Termed a ’slow-push-pull grav­ity trac­tor’, it could be very ef­fec­tive for small as­teroids that are decades away from im­pact. How­ever, this method is im­prac­ti­cal be­cause it needs a mis­sion lead time of over ten years.

Hit it re­ally hard:

The ‘ki­netic im­pact’ strat­egy crashes an enor­mous space­ship into the as­ter­oid at colos­sal speed (over 11,000 miles per hour!) Such an im­pact should change the as­ter­oid’s ve­loc­ity and or­bit and so save the world. Ki­netic im­pact could pro­tect the Earth from mod­er­ately sized as­teroids (sev­eral hun­dred me­tres to 1km in di­am­e­ter). The ki­netic method is rel­a­tively ro­bust, and has even been tested in space as part of NASA’s deep im­pact mis­sion in 2006. How­ever, hit­ting small as­teroids at high speed could be rather tricky and a warn­ing time of forty years would be needed to de­flect an as­ter­oid of 1km di­am­e­ter.

Nuke it:

Nu­clear ex­plo­sions have been pro­posed to elim­i­nate as­ter­oid threats by de­struc­tion or by knock­ing it off course. A ‘stand­off’ or ‘im­pact burst’ would heat the as­ter­oid’s sur­face on one side, forc­ing it to travel in the op­po­site di­rec­tion. This is the pre­ferred nu­clear method, as there would be no need to fly along­side the as­ter­oid at a low speed and the as­ter­oid’s com­po­si­tion doesn’t mat­ter. Al­ter­na­tively, a sur­face or near-sur­face ex­plo­sion could be at­tempted, but it would be tech­ni­cally more dif­fi­cult to hit an as­ter­oid dead-on. How­ever, this could be the only means to pre­vent an im­pact from a large as­ter­oid (greater than 1km in di­am­e­ter).

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