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SPACE SCIENCE

observe Dimorphos using ground-based deflecting an asteroid. Because LICIACube doesn’t carry a large antenna, images will be
telescopes to confirm that DART’s downlinked to Earth one by one in the coming weeks.
impact altered the asteroid’s orbit “DART’s success provides a significant addition to the essential toolbox we must
around Didymos. Researchers expect have to protect Earth from a devastating impact by an asteroid,” said Lindley Johnson,
the impact to shorten Dimorphos’ orbit NASA’s planetary defense officer. “This demonstrates we are no longer powerless to
by about 1%, or roughly ten minutes; prevent this type of natural disaster. Coupled with enhanced capabilities to accelerate
precisely measuring how much the finding the remaining hazardous asteroid population by our next planetary defense
asteroid was deflected is one of the mission, the near-earth object (NEO) surveyor, a DART successor, could provide what
primary purposes of the full-scale test. we need to save the day.”
“Planetary defence is a globally With the asteroid pair within 11 million kilometres of Earth, a global team is
unifying effort that affects everyone using dozens of telescopes stationed around the world and in space to observe the
living on Earth,” said Thomas asteroid system. Over the coming weeks, they will characterise the ejecta produced
Zurbuchen, associate administrator for and precisely measure Dimorphos’ orbital change to determine how effectively DART
the Science Mission Directorate at NASA deflected the asteroid. The results will help validate and improve scientific computer
headquarters in Washington. “Now models critical to predicting the effectiveness of this technique as a reliable method for
we know we can aim a spacecraft with asteroid deflection.
the precision needed to impact even a “This first-of-its-kind mission required incredible preparation and precision, and the
small body in space. Just a small change team exceeded expectations on all counts,” said APL director Ralph Semmel. “Beyond
in its speed is all we need to make a the truly exciting success of the technology demonstration, capabilities based on DART
significant difference in the path an could one day be used to change the course of an asteroid to protect our planet and
asteroid travels.” preserve life on Earth as we know it.”
The spacecraft’s sole instrument, Roughly four years from now, the European Space Agency’s Hera project will
the Didymos reconnaissance and conduct detailed surveys of both Dimorphos and Didymos, with a particular focus on
asteroid camera for optical navigation the crater left by DART’s collision and a precise measurement of Dimorphos’ mass. n
(DRACO), together with a sophisticated
guidance, navigation and control system For more information about DART visit: https://www.nasa.gov/dart
that works in tandem with small-body
manoeuvering autonomous real time Image credits: NASA/Johns Hopkins APL/Steve Gribben
navigation (SMART Nav) algorithms,
enabled DART to identify and Asteroids are large rocky objects that orbit the Sun, while meteorites are solid pieces of
distinguish between the two asteroids, debris from a comet, asteroid or meteoroid that originate in the outer space and survive
targeting the smaller body. their passage through the atmosphere to land on the surface of a planet. In other words,
These systems guided the 570 the difference between asteroid and meteorite is all in the naming.
kilogram box-shaped spacecraft through South Africa has a meteorite claim, or was it an asteroid after all?
the final 90,000 kilometres of space
into Dimorphos, intentionally crashing Tswaing meteorite crater
into it at roughly 22,530 kilometres Some 220 000 years ago, a meteorite half a soccer field in diameter, travelling at 4 000
per hour to slightly slow the asteroid’s kilometres per hour, hit what is now the Gauteng province of South Africa, exploding with
orbital speed. DRACO’s final images, the impact of 100 atomic bombs. The result was the Tswaing meteorite crater, just over one
obtained by the spacecraft seconds kilometre in diameter, now a spectacular natural wonder with a salt lake at its heart.
before impact, revealed the surface of The crater is one of around 170 impact craters in the world and one of four known
Dimorphos in close-up detail. impact craters in South Africa. What is special about Tswaing is that firstly, it is one of the
Fifteen days before impact, DART’s best preserved meteorite craters in the world, and secondly, that it’s very accessible – you
CubeSat companion Light Italian can walk down into the crater, taking in its quiet beauty.
CubeSat for Imaging of Asteroids At the point of impact, the immediate area up to three kilometres around the crater,
(LICIACube), provided by the Italian all life forms and rock, as well as the meteorite itself, would have vaporised. A broader area
Space Agency, deployed from the of 1 000 square kilometres would have
spacecraft to capture images of DART’s been flattened. A gigantic air blast of up
to 1 000 kilometres per hour would have
impact and of the asteroid’s resulting added to the destruction.
cloud of ejected matter. In tandem These days the whole site is covered
with the images returned by DRACO, in dense bushveld, and walking along the
LICIACube’s images are intended to trail on the rim, you’ll look down into this
provide a view of the collision’s effects marvellous phenomenon, with the small
to help researchers better characterise 100-metre diameter lake at its centre.
the effectiveness of kinetic impact in

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