Nasa is ready with a sci-fi plot and it will play out for real

In 1998, two Hollywood sci-fi flicks — Armageddon and Deep Impact — enthralled us with magnificent plots: Nasa dispatches a crew to blow up an asteroid that is on a collision course with earth, with a potential to wipe away humanity. The protagonists carry out the mission successfully and save the planet from catastrophe.

Who knew that Nasa would manifest a somewhat similar mission in reality just under 25 years after the movies were released.

Nasa’s upcoming DART (Double Asteroid Redirection Test) mission, albeit an uncrewed one, has all the ingredients of any sci-fi thriller.

The rogue rocks

Asteroids are leftover rocky rubble from the days the solar system was forming. Millions of these small rocky masses occupy the space between Mars and Jupiter, orbiting around the sun tied to Jupiter’s gravity. Some asteroids cross paths with the earth’s orbit (near-earth asteroids) and have the potential to crash into us, posing a threat to our survival. History is rife with such asteroid attacks.

Currently, there is no asteroid threat to us in 100 years; however, only 40 per cent of such dangerous rocks have been identified. Hence scientists constantly peer into space, watching out for probable hazardous asteroid candidates heading our way in future. Moreover, scientists also want to get asteroid samples for analysis as they hold vital clues to our origins.

In 2013, Nasa formed the Asteroid Redirect Mission (ARM) with the primary goal to ‘identify, capture and relocate an asteroid to a stable orbit around the moon’. In addition, ARM received funds for testing new technologies to help us defend against future collisions from these rogue rocks and divert them away from earth orbits.

65803 Didymos is a 780-m long asteroid some 6 million km away from us. The space rock has a 160-m long companion rock called Dimorphos, orbiting around the parent like a moonlet. The gravitationally coupled space rocks form an asteroid binary system orbiting the sun in tandem. Dimorphos is the type of space rock that poses a hazard to earth. The mission will be a first of its kind where humanity will be attempting to change the path of a space object.

The daring plot

Initially, under the ARM initiative, Nasa proposed to send a spacecraft to Didymos fitted with robotic clasps and arms. The probe was to land on Dimorphos, scoop up a boulder from the moonlet’s rubble and lift off. Then, clasping the boulder in the robotic arm, the spacecraft would travel to the moon and set it in a safe redirected orbit around the moon.
Later, a crewed mission would leave earth to the moon and rendezvous with the asteroid-spacecraft. Then, astronauts would walk over to the boulder, collect samples, and return to earth for analysis.

However, this daring mission was aborted in 2017 and toned down to the current DART mission to test planetary defence mechanism technologies.

Under this project, on November 23, SpaceX’s Falcon 9 rocket will lift off from the Vandenberg Spaceforce Base, California, carrying the Double Asteroid Redirection Test (DART) spacecraft with it. The target of the mission: intercept and park close to Didymos in space and relay its observations to earth. Then, deploy DART on a suicidal manoeuvre to crash into Dimorphos. The aim is to nudge the moonlet slightly off its course.

In action

The nose-dive of DART will be testing the kinetic impact technology. DART will intercept Dimorphos after travelling for 11 million km, aided by two gravity assists. At the target, the spacecraft will ram into the asteroid at a relative speed of 6.6 km per second. The impact is expected to alter the course of Dimorphos around its parent rock, Didymos. The impact will change the moonlet’s velocity by a fraction of one per cent. However, this minute change will alter its orbital period by several minutes — enough for telescopes to make their observations.

If successful, this technology will find use under the planetary defence mechanism to mitigate future hazardous asteroids. Purportedly, when asteroids come hurtling towards us, these impactor probes will be launched to self-navigate, intercept and crash into the asteroids in space and to eliminate the threat.

Nasa is also testing its advanced ion thruster propulsion system, NEXT-C in this mission. In a first, solar-powered propulsion systems will be used to fire the engines using the electrostatic acceleration of the propellent ions.

The NEXT-C engines will impart higher thrust and efficiency, improving the performance manifold. Nasa says: “These propelling systems will be of immense utility for future crewed missions to Mars and beyond when humans have to travel far longer distances in space for several months.”

The overseers

Piggybacking on DART is Italy’s CubeSat LICIACube (Light Italian CubeSat for Imaging of Asteroids) — a shoebox-sized instrument that will disengage from DART ten days before the impact.

The CubeSat will record the impact event and the ejecta (material ejected due to impact from the moonlet’s surface) and the impact site back to earth.

A year later, the European Space Agency will send another spacecraft Hera to Didymos to perform in-depth observations of the impact site on Dimorphos.

Apart from the ion thrusters and self-navigation systems, DART is equipped with a lone high-resolution imager called DRACO (Didymos Reconnaissance and Asteroid Camera for Optical navigation). DRACO will help cruise the spacecraft on its journey, identify and engage with the target, and take a picture every second till its last breath.

Once proven, the technologies of this mission will leap-frog future crewed missions that will use these advanced engines and navigation systems.

We are living in exciting times, witnessing these fantastic events. So, keep an eye on this space for a ringside view as the events unfurl.