Maarg Manthan · Topic 12.24

NASA’s Asteroid Impact and Deflection Assessment Mission

Science & Technology › Space Technology and ISRO · Topic 12.24

The Asteroid Impact and Deflection Assessment, AIDA, is a joint plan of NASA and the European Space Agency to test whether a spacecraft can change the path of an asteroid. Its first part is NASA's Double Asteroid Redirection Test, DART, launched on 24 November 2021, which on 26 September 2022 crashed at about 6.1 kilometres per second into Dimorphos, a small moon about 160 metres wide that orbits the larger asteroid Didymos. The impact shortened the orbit of Dimorphos around Didymos by about 32 minutes, from 11 hours 55 minutes to about 11 hours 23 minutes, showing that a kinetic impactor can deflect an asteroid. The second part is ESA's Hera mission, launched in October 2024, which will study the crater and the asteroid pair in detail.

5 min read · UPSC Prelims · Science & Technology · Space Technology and ISRO

At a Glance

DART launched 24 November 2021
Impact 26 September 2022
Target Dimorphos, moon of Didymos
Orbit change About 32 minutes
Follow-up ESA Hera, 2024 launch
Exam link UPSC Prelims, Science & Technology: Space Technology and ISRO

Where Does It Fit?

This topic follows the account of air-breathing engines. It looks at space missions aimed at protecting Earth from impacts by near-Earth asteroids, which is also a theme of disaster preparedness. Previous topic: Air-Breathing Propulsion System. Next topic: Hyperspectral Imaging Satellite and Water Propulsion System in CubeSats.

What Happened in the DART Mission?

Item	Details
Purpose	To test a kinetic impactor, a fast spacecraft hitting an asteroid, as a method of planetary defence
Target	Dimorphos, about 160 m wide, orbiting Didymos, about 780 m wide. Neither asteroid threatened Earth
Launch	24 November 2021 on a SpaceX Falcon 9 from Vandenberg
Impact	26 September 2022 at about 6.1 km per second, about 11 million km from Earth
Spacecraft	About 570 kg, with a camera called DRACO and autonomous navigation system called SMART Nav
Cubesat	LICIACube, a small Italian satellite released before impact, took images of the aftermath
Result	Orbital period of Dimorphos reduced by about 32 minutes, more than 25 times the minimum success target of 73 seconds

Why Does Planetary Defence Matter?

Near-Earth objects: asteroids and comets whose orbits bring them close to Earth. Over 30,000 near-Earth asteroids are known
Impact risk: large impacts are rare but would be catastrophic. The Chicxulub impact about 66 million years ago is linked with the extinction of the dinosaurs
Chelyabinsk: a 20 m asteroid exploded over Russia in 2013, injuring over a thousand people
Early warning: detection, tracking and orbit prediction are the first requirement
Deflection methods: kinetic impactor, gravity tractor, nuclear option for large bodies and laser ablation
Hera: ESA’s spacecraft to measure the mass of Dimorphos, the crater and the change of the asteroid, expected to arrive in late 2026
Planetary Defence Coordination Office: NASA’s office for tracking threats
International cooperation: the UN-endorsed International Asteroid Warning Network and Space Mission Planning Advisory Group coordinate warnings

What Else Should You Remember?

AIDA: the joint NASA and ESA concept with DART as the impactor and Hera as the observer
Didymos: Greek for twin, a near-Earth asteroid with a small moon
Momentum transfer: debris thrown out by the impact adds extra push, so the change was larger than from the spacecraft’s momentum alone
Rubble pile: observations suggest Dimorphos is a loose pile of rubble, not a solid rock
Planetary Society: non-profit groups also support detection
NEO Surveyor: a NASA infrared space telescope planned to find hazardous asteroids
Apophis: a 340 m asteroid that will pass very close to Earth on 13 April 2029, to be studied by missions such as OSIRIS-APEX
Sample missions: Bennu and Ryugu samples show the makeup of asteroids, as in Cassini Mission to Saturn and OSIRIS-REx Mission to Asteroid Bennu
India: ISRO has a planetary defence programme and is part of the international groups on asteroid warnings. It plans a mission to Apophis. Check the current plan
ISRO NETRA: the same tracking system for debris also supports watching asteroids in future
Legal frame: the Outer Space Treaty requires states to avoid harmful contamination, and no law yet covers who may deflect an asteroid
Cost: DART cost around 300 million dollars, small compared with the damage of an impact
Torino scale: a scale from 0 to 10 used to rate the impact hazard of a near-Earth object, where 0 means no hazard
Detection surveys: telescopes on the ground, such as Pan-STARRS and Catalina, find most new near-Earth asteroids, and the Vera Rubin Observatory adds many more
Warning time: a deflection by kinetic impactor needs years of warning because a tiny push early becomes a large shift later
Gravity tractor: a heavy spacecraft hovering near an asteroid slowly pulls it with its own gravity, a gentle method for small changes

Why Does It Matter for the Exam?

DART facts: date, target, result
Method: kinetic impactor
Follow-up: Hera
Current affairs link: Apophis and NEO surveys
Common errors: saying DART destroyed the asteroid or that Didymos was the target of impact

As an analytical point, DART showed that deflection works in principle. The practical need now is to find hazardous objects early, since deflection works best with years of warning.

Why Is This Topic Important?

Mission DART facts
Method Kinetic impactor
Defence Early detection

What Came Next?

The next topic covers a hyperspectral imaging satellite and water propulsion in CubeSats. Next topic: Hyperspectral Imaging Satellite and Water Propulsion System in CubeSats.

Key People and Terms

NEO Near-Earth object
Kinetic impactor Impact deflection
Dimorphos Asteroid moon
Didymos Larger asteroid
Hera ESA follow-up mission
Planetary defence Protecting Earth from impacts

Exam Corner

Points to Remember

DART launched: 24 November 2021.
Impact: 26 September 2022.
Orbit change: about 32 minutes.
Target: Dimorphos.
ESA follow-up: Hera.

Do Not Confuse With

DART and Hera NASA impactor versus ESA observer
Dimorphos and Didymos Moon versus main asteroid
Asteroid and comet Rock or metal versus ice and dust

Memory Hook

DART hits the little moon; thirty-two minutes shorter; Hera comes to look.

Mains Angle

Questions ask for mission facts and the idea of planetary defence. These points help.

Test Deflection proof
Need Detection
Cooperation Global warning network

A Question You May Face

An original practice question, not a past paper question.

“Discuss the significance of NASA’s DART mission for planetary defence and the international cooperation needed against asteroid threats.”

How to Answer

Mission DART result.
Method Kinetic impactor.
Need Detection.
Way Global network.

GS Relevance

Prelims: DART date, target, result, Hera, kinetic impactor. GS Paper 3: science and technology, space, disaster preparedness.

Frequently Asked Questions

What was the DART mission?

The Double Asteroid Redirection Test was a NASA mission launched on 24 November 2021 to test planetary defence. On 26 September 2022 the spacecraft hit the small asteroid Dimorphos, which orbits the larger asteroid Didymos, at about 6.1 kilometres per second, to see whether the impact could change the asteroid's orbit.

What was the result of the DART impact?

The impact shortened the orbit of Dimorphos around Didymos by about 32 minutes, from 11 hours 55 minutes to about 11 hours 23 minutes. This was far more than the 73 seconds set as the minimum for success, and it showed that a kinetic impactor can change the motion of an asteroid.

What is the Hera mission?

Hera is a mission of the European Space Agency, launched in October 2024, to visit the Didymos and Dimorphos asteroid pair after the DART impact. It will measure the mass of Dimorphos, study the crater made by DART and examine the asteroid's structure, so that the deflection method can be understood well.

What is a kinetic impactor?

A kinetic impactor is a spacecraft that deflects an asteroid by crashing into it at high speed and transferring momentum. Even a small change in speed, applied years in advance, can move the asteroid's path enough to miss the Earth. DART is the first full scale test of this method.

What are near-Earth objects?

Near-Earth objects are asteroids and comets whose orbits bring them within about 50 million kilometres of the Earth's orbit. Those larger than about 140 metres and passing close are called potentially hazardous. Space agencies find and track them with telescopes so that any impact threat can be predicted long in advance.

PYQ Practice — Statement Analysis

1 DART hit the asteroid Dimorphos on 26 September 2022.

True

A moon of Didymos.

2 DART destroyed the asteroid completely.

False

It only changed its orbit.

3 Hera is a mission of the European Space Agency.