The Times - UK (2021-11-25)

the times | Thursday November 25 2021 29

News

Nasa embarked on a journey towards
its first planetary defence test yesterday
when it launched a blockbuster mission
to knock an asteroid off track, 6.8 mil-
lion miles from Earth.
The $330 million Double Asteroid
Redirect (Dart) mission, which will
demonstrate technology designed to
protect the planet from catastrophic
asteroid impacts, lifted off from Van-
denberg space force base, California, at
6.20am GMT on a Falcon 9 rocket.
“Lift-off of Falcon 9 and Dart, with
Nasa’s first planetary defence test to

Lift off for Nasa’s Armageddon asteroid mission

intentionally crash into an asteroid,”

Nasa announced. The spacecraft will

spend the next ten months travelling to

a binary asteroid system consisting of

Didymos, a 2,560ft (780m) rock, and its

smaller asteroid satellite, Dimorphos.

Neither is a threat to Earth.

Next September the spacecraft will

slam into Dimorphos at 15,000mph to

assess the extent to which the kinetic

impact affects the asteroid’s speed and

trajectory. Shifting an asteroid’s

dynamics by a minute fraction could be

enough to divert it from a collision

course with Earth.

Bill Nelson, the head of Nasa,

described the mission as “something of

a replay” of the 1998 film Armageddon,

in which Nasa sends a team of hastily

recruited heroes to save the planet from

an asteroid the size of Texas. Bruce

Willis, the lead actor, declined an invi-

tation from Nasa to attend the launch.

It is estimated that about 25,000

asteroids measuring 459ft or more orbit

near Earth. Last month an asteroid

came within 1,860 miles of Earth, but

with a diameter of just 6ft it would prob-

ably have burnt up in the atmosphere.

Only two other asteroids are known to

have come closer — the 2020 QG aster-

oid, roughly the size of a car, flew 1,830

miles above the Indian Ocean last

August. In November last year a tiny as-

teroid, the 2020 VT4, flew by a few hun-

dred miles away on Friday the 13th.

Nancy Chabot, chief planetary scien-

tist at Johns Hopkins University’s

applied physics laboratory — a lead sci-

entist for the Dart mission — said: “Sort

of a kilometre and up are the size that

you worry about for global extinction

events — dinosaur killers, if you will,

and I’m happy to say that we’ve found

the majority of those asteroids... none

of those are on a collision course with

the Earth. We’re tracking them, so glob-

al extinction events like the dinosaurs

are not in our future. But these few

100m-size ones, we’ve only found less

than half of the population actually. So

we are still looking... planetary defence

isn’t just about deflecting asteroids, it’s

also finding all the asteroids, figuring

out where they are, characterising

them, keeping track of them.”

Dart’s impact with Dimorphos,

likened by Chabot to “a small golf cart

running into a great pyramid”, will be

observed using ground-based

telescopes and space assets including

the Hubble space telescope, as well as a

tiny satellite that will be released by

Dart ten days before the crash.

Jacqui Goddard Miami

Dimorphos

Impact:

Sept-Oct, 2022

Dart collides with

the asteroid

Dimorphos at high

speed

Burj

Khalifa

830m

Ten days before

impact the

spacecraft will

deploy a small

CubeSat to follow

behind and record

the aftermath of

the intervention

Current orbit

The collision

alters the speed of

Dimorphos, and

diverts the asteroid’s

course by a fraction

of a degree

Didymos

Target:

Dimorphos Dart

CubeSat

5

New orbit

ASTEROID ATTACK

Nasa image of Dart spacecraft as it

separates from the Falcon 9 second stage

Yesterday, 6.20am

SpaceX Falcon 9

rocket containing

Double Asteroid

Redirection Test (Dart)

takes off from the

Vandenberg Space

Force Base in

California

Earth

1

2

3

4

Asteroids to scale

Dart separates

from launch

vehicle and

deploys solar

arrays for

propulsion

Eiffel

To w e r

321m

Dimorphos

Dart 163m

19m

Dart

Didymos

780m

(diameter)

Reusable booster

A