The National Aeronautics and Space Administration's (NASA) DART mission has captured rare images of the Earth before it makes its fateful journey of smashing into an asteroid's moon. The DART mission uses an impactor spacecraft and a reconnaissance satellite developed by the Italian Space Agency (Agenzia Spaziale Italiana) that will send photographs of the mission back to Earth. As part of a test run for tomorrow's impact, the monitoring CubeSat beamed back a rare image of Earth from a distance of roughly 11 million kilometers.
NASA's DART Mission On Its Way To Hit Asteroid Moon Millions Of Kilometers Away From Earth
The DART mission and the CubeSat were launched on a SpaceX Falcon 9 rocket late last year, and tomorrow's event will make the rare opportunity for NASA to test out the system as the asteroid passes its closest approach to Earth for the next few decades. Its impactor spacecraft and the satellite were launched together, and the imaging spacecraft separated from the impact spacecraft earlier this month as the pair reached their destination.
The imaging spacecraft is officially dubbed as LICIACube, and it features two optical cameras. These will capture the asteroid's surface, and more importantly, document the impactor spacecraft's collision with the asteroid system's moon.
According to NASA, the target asteroid system is called the Didymos asteroid system and it features the primary asteroid Didymos and its moonlet asteroid Dimorphos. The agency's estimates suggest that the moonlet asteroid weighs 5 billion kilograms, and the impact spacecraft will weigh around 570 kilograms at the time of impact.
Both these cameras were tested earlier this week prior to the impact event tomorrow, with one of them capturing an image of the Earth and the other capturing an image of the Pleiades star cluster.
NASA will evaluate whether the mission was a success or not by determining if the moonlet asteroid's orbit around the primary asteroid changed. The agency will do this by looking at the asteroid through telescopes located on Earth, and this is a key reason why late September has been chosen as the date for impact as less distance between Earth and the asteroid system will help the telescope imagery.
Four hours prior to impact, the spacecraft will become fully autonomous while ground controllers will retain the ability to manually command it. The autonomy is essential as the time lag between communicating with the spacecraft, and the fact that it will be traveling at 14,000 miles per hour at the time of impact make controlling it manually tricky.
The impact spacecraft uses twelve hydrazine thrusters for propulsion, and NASA's mission systems engineer for the DART mission Ms. Elena Adams explained during a media teleconference that:
Three minutes prior to impact, two minutes prior to impact, it is 42 pixels in size and you're moving extremely fast and at that point, you cannot send any commands in. So your system has to be very very precise in how it's controlling the spacecraft, what information we're taking in from all the different sensors on the spacecraft, in addition to the telescope itself.
An hour before impact, the spacecraft will reorient itself to Dimorphus instead of Didymos, and the moonlet will be visible only as a small pixel on the camera. Each image has a two and a half second latency, 38 seconds to travel and up to eight seconds for processing - implying that an image received on the ground is roughly 45 seconds late.
The mission will also let NASA analyze the surface of the asteroid, and determine how different surface types respond to impact. Not all asteroid surfaces are solid, as low density often gives them a fluid-like feeling.
Prior to launching the spacecraft, NASA tested it extensively on the ground, using Jupiter's moons to mimic the asteroid system to train the spacecraft's navigation system. The algorithms powering this system are similar to those used in missiles. The agency will also compare the effects of the kinetic impact from the DART experiments with the results of its simulations on the ground to check the validity of its physics.
NASA will start its coverage of the DART mission at 6 pm Eastern Time tomorrow, with impact targetted for 7:14 pm.
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