NASA’s DART mission to redirect a non-threatening asteroid is set to launch later this week. Here’s what you need to know about this historic deep-space test and how “kinetic impactors” could eventually protect our civilisation from an asteroid apocalypse.
1. This is NASA’s first planetary defence test mission
The Double Asteroid Redirection Test (DART) is NASA’s first attempt to deliberately alter the orbital characteristics of a distant celestial body. Built by the Johns Hopkins Applied Physics Laboratory, the car-sized DART spacecraft will attempt to alter the speed of Dimorphos — a tiny asteroid — by smashing right into it. This asteroid is junior member of a binary asteroid system known as Didymos. DART will not survive, but that’s ok; NASA is testing the technologies required to prevent a potentially dangerous asteroid from smashing into Earth.
2. You can watch the launch live
A SpaceX Falcon 9 will deliver DART to space. The rocket is scheduled to blast off from Vandenberg Space Force Base in California at 5:21 p.m. AEDT on November 24. A livestream of the launch will be available at NASA’s website and the NASA app, or you can watch it at the feed provided below. Coverage will begin at 4:30 p.m. AEDT.
3. There’s no risk to Earth
When DART arrives at Didymos in 11 months, the spacecraft will be 11 million km from Earth, according to NASA. Didymos, which is Greek for “twin,” measures 780 metres in diameter, while Dimorphos, which is Greek for “two forms,” measures 160 metres in diameter, which is just shy of two football fields long. The moonlet, also known as Didymoon, is in orbit around Didymos, circling it once every 11.9 hours.
To be crystal clear, neither Didymos or Dimorphos pose a risk to Earth. They don’t present a risk now, nor will they after the redirection test. NASA chose this particular system as it was deemed ideal for test purposes. The smash-up “will change the speed of the moonlet in its orbit around the main body by a fraction of one per cent, but this will change the orbital period of the moonlet by several minutes — enough to be observed and measured using telescopes on Earth,” as NASA explained.
As it stands, no known asteroid the size of Dimorphos or larger has a significant chance of hitting Earth within the next 100 years. The concern, however, has to do with potentially hazardous objects that suddenly appear out of the blue. Such was the scenario in this year’s asteroid impact simulation, in which participants were told of a fictional 140-metre-wide asteroid with a 100% chance of hitting Earth in just six months. This left them very little time to react and prepare. Asteroids of this size would inflict serious damage across a 200-kilometre-wide radius should they hit Earth.
4. The mission will test a bunch of new technologies
Once in space, DART will deploy its Roll Out Solar Arrays (ROSA) which it will use to power NASA’s Evolutionary Xenon Thruster (NEXT). ROSA’s high-efficiency solar cells and reflective concentrators will provide three times more power than conventional solar arrays, while NEXT — a cutting edge solar-powered propulsion system — could represent a new class of engine technology. Both the solar panels and the ion thruster will be demonstrated during the mission, and DART is not wholly dependent on these systems to reach Didymos.
DART will be equipped with a lone scientific instrument named Didymos Reconnaissance and Asteroid Camera for Optical navigation, or DRACO for short. The camera will perform double duty, however, capturing images of the binary pair and providing support for the spacecraft’s autonomous optical navigation system.
5. DART will reach its target in late 2022
The autonomous targeting system is called SMART Nav, and it will allow DART to distinguish between Didymos and Dimorphos and then set a course directly towards the latter. Moving at 24,140 km per hour, the 620 kg spacecraft will smash into the moonlet in late September 2022.
Excitingly, DART is bringing a companion spacecraft along for the ride: a cubesat named LICIACube. Developed by the Italian Space Agency, this spacecraft will separate from DART 10 days before impact and capture images of the encounter, which it will do with two cameras named LUKE and LEIA. LICIACube will then transmit these images back to Earth, so we should be able to see DART’s destruction in gory detail.
6. Effects of the ‘kinetic impactor’ will be detected from Earth
The European Space Agency will track DART’s progress using its Estrack Network, which includes dish antennas at Malargüe, Argentina, and New Norcia, Australia. Using an “ultra-precise deep-space navigation technique” called Delta-DOR, mission controllers will calculate DART’s position to a few hundred meters.
NASA says “ground-based telescopes and planetary radar” will be used to “measure the change in momentum imparted to the moonlet,” specifically changes in Dimorphos’s orbit around Didymos. Again, this should be a minor adjustment, and the system won’t suddenly pose a threat to Earth.
7. A follow-up mission will investigate the scene from up-close
Ground stations should get a good bead on changes made to the binary system, but we’ll really know for sure once the joint NASA-ESA HERA mission gets underway.
With an expected launch in 2024, the HERA spacecraft is scheduled to arrive at Didymos in January 2027. Once at the scene of the crime, HERA will inspect the system from up-close, measuring the effects of the impact and gathering images of Dimorphos’s new crater.
8. It takes a village to smash a spacecraft into an asteroid
Many people from a lot of different teams are involved in this $US308 (A$426) million mission. NASA partners from the U.S. includes NASA Goddard Space Flight Centre, Johnson Space Centre, Langley Research Centre, Glenn Research Centre, Marshall Space Flight Centre, Kennedy Space Centre, Launch Services Program, Jet Propulsion Laboratory, SpaceX, Aerojet Rocketdyne, Lawrence Livermore National Laboratory, Auburn University, University of Colorado, Johns Hopkins University, Lowell Observatory, University of Maryland, New Mexico Tech with Magdalena Ridge Observatory, Northern Arizona University, and Planetary Science Institute. International partners include the European Space Agency and the Italian Space Agency.
9. DART could forever alter our relationship with space
This is, in my humble estimation, one of the most important missions in the entire history of space exploration. Learning about our solar system and searching for signs of life are obviously very important, but developing the capacity to prevent an asteroid from smashing into Earth would be a massive accomplishment, as it could someday save us from potential extinction. DART is a small but very important step in this direction.
DART is also important in that it’s our first foray into solar system re-engineering. The Anthropocene, the ongoing human-caused geological epoch, will eventually trickle into space, as we tweak the orbits of asteroids, mine celestial bodies for valuable resources, terraform dead planets, and possibly even seek to extend the life of our Sun. But first things first — let’s give Dimorphos a tiny shove and take it from there.