NASA's DART Mission Live: Get live updates as NASA's DART spacecraft crashes into the asteroid Dimorphos. (Illustration credit: NASA) Double Asteroid Redirection Test (DART) Mission Live Updates: NASA’s DART (Double Asteroid Redirection Test) spacecraft is scheduled to collide with the asteroid Dimorphos at approximately 7.14 PM EDT on September 26 (4.44 AM IST on September 27). The mission will be the first to test a “kinetic impactor” method of planetary defence, which involves changing the trajectory of asteroids that threaten Earth by crashing a high-speed spacecraft into it.
Data obtained from DART’s crash will be compared to the data from various computer simulations run by scientists to ascertain whether this kinetic impactor method will remain a viable option in case of an actual threatening asteroid. Scientists don’t yet know the exact mass of Dimorphos but it is estimated to be around five billion kilograms. The DART spacecraft weighs around 600 kilograms.
NASA’s livestream of the DART mission will start at 6 PM EDT on September 26 (3.30 AM IST on September 27. You can watch it on NASA TV, NASA’s mobile app, its YouTube channel or through the window above. You can read live updates below.
NASA’s DART spacecraft will use a “kinetic impactor” method for deflecting the asteroid Dimorphos. The space agency is using this method because it is the simplest and most technologically mature method available to defend our planet against asteroids. In case an actual asteroid poses a threat to the Earth, we only need to either delay or hasten its intersection with Earth’s orbit by seven minutes. This is because the Earth takes about seven minutes to travel the distance of its diameter. So if an asteroid arrives seven minutes late or early, it will miss our planet completely.
Scientists don’t yet know the exact mass of Dimorphos but it is estimated to be around five billion kilograms. Meanwhile, the DART spacecraft will weigh about 570 kilograms when it crashes into the asteroid. Nancy Chabot, DART coordination lead at NASA compared the collision to a “golf cart crashing into the great pyramid,” during a press conference on September 12.
The crash is intended to be a “small nudge” that will change the position of the asteroid ever so slightly. In the event of an asteroid that actually poses a threat to Earth, this collision will have to happen years ahead of time. Over the years, the small change in position will add up to a large deviation.
There is no known asteroid that presents a significant risk of impact on Earth in the next 100 years. But there is a 1 in 714 chance that an asteroid called 2009 FD will impact the Earth in 2185. This means that the chance of impact is close to 0.2 per cent. NASA’s Jet Propulsion Laboratory’s Center for NEO (near-Earth object) maintains a Sentry Impact Risk Table, which is updated continuously as new asteroids are discovered and known asteroids are better observed.
ATLAS (Asteroid Terrestrial-impact Last Alert System) is a NASA-funded asteroid detection system operated by the Institute for Astronomy at the University of Hawai’i. It is capable of searching the entire sky every 24 hours for near-Earth objects that pose a potential threat to the planet. It consists of four telescopes—one each in Haleakalā and Maunaloa in Hawai’i, and two more in South Africa and Chile.
In a single exposure, each of the four ATLAS telescopes can image a part of the sky that is 100 times larger than the full moon. When it is daytime in Hawai’i, the two telescopes located at Sutherland Observing Station in South Africa and El Sauce Observatory in Chile will allow ATLAS to observe the night sky.
The DART spacecraft is not alone on its journey. On September 11, LICIACube, a CubeSat built by the Italian Space agency, separated from the spacecraft. LICIACube is programmed to document the effects of DART’s impact while also capturing images of the asteroid surface and images of the debris ejected due to the collision.
LICIACube has two optical cameras—LUKE (LICIACube Unit Key Explorer) and LEIA (LICIACube Explorer Imaging for Asteroid). Three minutes after DART’s collision, LICIACube will fly past Dimorphos to confirm the spacecraft impact, observe the evolution of the ejected plume and potentially even capture images of the newly-formed impact crater.
During the last four hours before the crash, the DART spacecraft will go into the terminal phase where it will operate completely autonomously. It will target Didymos till around 50 minutes before impact. Then, it will manoeuvre by a quarter of a degree in terms of field of view to put itself on course for collision with Dimorphos.
“That is a very ‘sweaty’ time for us. The spacecraft is so far away that it takes 38 seconds for one-way communication. It will be travelling at a speed of 6 kilometres per second. It is going at a speed that will cover the distance between DC and Philadelphia in about 40 seconds,” explained Evan Smith, deputy mission systems engineer for DART, during a NASA press conference on September 12.
The rapid spin of Didymos suggests that Dimorphos may have formed because of a process known as rotational fission, where material is shed from an asteroid due to fast rotation. Scientists think that Didymos started spinning fast and fast because infrared light was emitted unevenly from its Sun-warmed surface, which would have resulted in a twisting force.
This process could have gained enough momentum over millions of years to release material from the surface. This material could have then gathered to become Dimorphos. While this is a sound theory, other possibilities of formation have not been conclusively ruled out.
While the DART spacecraft was on its way to the planned encounter with the Didymos system, its DRACO instrument captured thousands of images of stars and other cosmic objects, including the image of Jupiter below.
To test the spacecraft’s SMART Nav system, the DART mission team pointed the DRACO imager at Jupiter. DRACO detected and targeted Jupiter’s moon Europa, similar to how it is expected to visually separate Dimorphos from the larger Didymos. Until that test, all SMART Nav systems tests were done via simulations performed on the ground.
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“We are not aware of a single object right now threatening the earth in the next 100 years. But I guarantee you that there will eventually be one. We can deduce that from the geological records of our planet and even data from the Moon. We want to test the technology now so that it is ready in case we ever need it,” said Thomas Zurbuchen, the associate administrator for the Science Mission Directorate at NASA, during a press conference on September 12.
The DART spacecraft lifted off from Space Launch Complex 4E at the Vandenberg Space Force Base in California atop a SpaceX Falcon 9 rocket at 1.21 AM ET (10.51 AM IST) on November 24, 2021.
Image credit: NASA/Bill Ingalls
The asteroid Didymos and the small moonlet Dimorphos make up a binary asteroid system. Didymos is about 780 metres in diameter while Dimorphos is about 160 metres in diameter. Didymos is shaped like a spinning top and has a raised ridge running along its equator, which is a common shape among binary asteroids. But not much is known about Dimorphos except that it appears to be somewhat elongated.
The binary asteroid system poses no threat to Earth but it occasionally approaches relatively close to our planet. According to NASA, it passed only 0.0487 astronomical units away from our planet in 2003. One astronomical is the distance between the Sun and the Earth.
The DART spacecraft has only one instrument on board—DRACO or the Didymos Reconnaissance and Asteroid Camera for Optical navigation. Not only will this high-resolution camera capture images of Didymos and Dimorphos, but it will also be supporting DART’s autonomous guidance system that will take over about one hour before the planned collision.