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NASA: blowing up asteroids and planetary defence

  • Publish Date: Posted 12 days ago
  • Author: James Kenealey
As part of its programme of research, development and exploration, NASA is embarking on two huge missions involving the study of asteroids.

Firstly, NASA has announced it is to attempt to alter the course of an asteroid in our solar system as a test of our planetary defence potential.

Similar to the plot of the 1998 film Armageddon starring Bruce Willis, the mission will assess the possibility of diverting an incoming asteroid from a potential collision course with Earth... because actually, there are some things we do wanna miss, and an extinction-level event like the one that wiped the dinosaurs out 66 million years ago is one of them.

How will this work?

Launching on November 23rd, 2021, the mission will attempt to hit an asteroid hard enough to change its course. The plan is not to destroy the asteroid, rather use a plan called the kinetic impactor technique to shoot a spacecraft into the surface. This kinetic energy will push the asteroid and change its momentum and hence its direction.

The Double Asteroid Redirection Test (DART) will be heading for a binary asteroid called Didymos. This is made up of a large asteroid (780 meters in diameter) and a smaller orbiting ‘moonlet’ of around 160m in diameter. The initial target is this smaller moonlet, and the DART craft will crash into the surface at a speed of around 15,000mph. The spacecraft will be destroyed, and the asteroid will lose a fraction of a percent of its velocity. This doesn’t sound like much, but that fraction of a percent will change the orbital period around the larger asteroid by several minutes.

The pair of asteroids has been chosen because they will be passing within seven million miles of Earth, meaning the effects of the impact will be able to be observed from Earth. Another craft, the Light Italian CubeSat for Imagine Asteroids (LICIACube) will attempt to fly close to the action for another view.

Tom Statler, a programme scientist at Nasa, said:

"This is our first full-scale attempt to demonstrate that we can change the motion of an asteroid in space, potentially as a way of defending Earth against the hazard of asteroid impacts. We're going to demonstrate one technology to cause that deflection that, someday, if we need to, we might use to prevent an asteroid from hitting the Earth. We certainly hope that we will never have to deploy an asteroid deflector, but we want to do the test now.”

Is the threat of an asteroid impact imminent?

NASA has long been monitoring every single known ‘near-Earth’ asteroid. The definition of near-Earth is asteroids that come within 1.3 astronomical units (1.3 times the distance between the Earth and the sun) of the planet. Currently, it is believed that none of the tracked asteroids pose a direct threat to the planet within the next 100 years.

A longer-term mission

NASA aren’t just planning on shooting asteroids. Before DART takes to the skies, they are also readying on the launch of Lucy, the next asteroid-bound mission that will attempt to make a landing on the surface.

Aiming for a launch window which begins on October 16th, the spacecraft, powered by an Atlas V rocket designed by Lockheed Martin, will be making a 12-year journey to the outer solar system where it is intended that it will visit numerous ancient ‘Trojan’ asteroids that orbit in the same path as Jupiter. The mission is intended to allow scientists to further study the building blocks of the solar system and the early universe, as asteroids are essentially leftover pieces from the formation of the solar system. The makeup of these can reveal a lot to scientists about how the system came to exist.

Across a dozen years, Lucy will visit at least eight different asteroids and revisiting Earth orbit to pick up gravity assists to increase speed.

Lucy will be loaded with instruments. These include a long-range reconnaissance imager for high-resolution images, a thermal emission spectrometer and a high-gain antenna to determine the mass of each asteroid.

Lucy is named after the 3.2-million-year-old humanoid skeleton that was found in 1974. Thought to be a keystone in understanding human evolution, NASA has drawn inspiration from this in naming the mission that is set to be a keystone in understanding the beginnings of the solar system. Four of the seven ‘Trojan’ targets are pairs, which will allow Lucy to study both in the same run.

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