ESA’s Hera spacecraft closes in on the asteroid NASA struck
Hera has returned an image that shows the smaller asteroid Dimorphos as a separate object. Detailed pictures are due later this year as the probe moves closer.
Key points
- ESA's Hera spacecraft imaged the Didymos system on 18 October from about 1,280 kilometres away
- Dimorphos appeared separate from its larger companion for the first time
- Hera's speed relative to the asteroids was cut to 20 metres per second
- Detailed images of Dimorphos are scheduled for release on 25 November
- NASA's 2022 DART impact shortened Dimorphos's orbit by roughly 33 minutes, more than predicted
The European Space Agency’s Hera spacecraft has sent back an image showing the smaller asteroid Dimorphos as a separate object, according to ScienceDaily. The picture was taken on the evening of 18 October, when the probe was about 1,280 kilometres from its targets. The asteroid pair is currently roughly 197 million kilometres from Earth.
The image was captured with a black-and-white Asteroid Framing Camera. Until then, the system appeared as a single point of light. Dimorphos currently covers only about one pixel, yet it is clearly apart from its larger partner.
Slowing down for the approach
Earlier in October, Hera fired its thrusters twice, with one week between the burns. Those manoeuvres reduced its speed relative to the asteroids to 20 metres per second. That gave mission controllers more room to manage the final stage of the approach.
Both bodies are small by everyday standards, yet they are substantial objects. Dimorphos is about 151 metres across, roughly the size of the Great Pyramid of Giza. Didymos, its bigger companion, measures around 780 metres in diameter, which is just under the height of Dubai’s Burj Khalifa, currently the tallest building on the planet.
Dimorphos orbits Didymos at an average distance of only 1.15 kilometres. It moves at about 18 centimetres per second. Mission manager Ian Carnelli said the team can now see the double asteroid system for the first time through the spacecraft’s own cameras, and that views will sharpen as Hera gets closer. Detailed pictures of Dimorphos are scheduled for release on 25 November.
Why the asteroid pair matters
Hera’s arrival gives scientists a chance to study the aftermath of NASA’s Double Asteroid Redirection Test, known as DART. On 26 September 2022, that spacecraft struck Dimorphos at about 6.1 kilometres per second. The collision sent debris thousands of kilometres out, reaching up to 10,000 kilometres, and shortened the asteroid’s path around Didymos by roughly 33 minutes.
The test showed that a spacecraft can deliberately alter the path of an asteroid. That result could matter for protecting Earth from future threats. However, the change in the orbit was much larger than computer simulations had predicted, and scientists are still working out why.
A closer investigation ahead
The probe will spend the months ahead examining the spot where the 2022 collision took place, a study the team refers to as a crash site investigation. Equipped with several research tools, the craft will observe the asteroid and the area around it. Two small CubeSats, each roughly shoebox-sized, will also be deployed to gather data from nearer range. Landing operations may later be part of the work.
Researchers do not yet know whether the impact left a crater or significantly changed the overall shape of Dimorphos. Scientists still lack exact readings of the rock’s makeup, interior layout and weight, which are needed to explain why the impact was so effective. Those answers could help improve predictions for future deflection attempts.
Following the mission
Members of the public can follow the journey through the Hera Space Companion. The interactive platform is linked to the mission and is designed to make this first planetary defence mission of the European Space Agency easier to access. It is described as more than a conventional AI chatbot.
Frequently asked questions
What did the Hera spacecraft image show?
Hera took an image on the evening of 18 October that shows the smaller asteroid Dimorphos as a separate object. Before this, the Didymos system appeared as a single dot.
What happened when NASAu0026#039;s DART spacecraft hit Dimorphos?
On 26 September 2022, DART struck Dimorphos at about 6.1 kilometres per second. The impact shortened the asteroidu0026#039;s orbit around Didymos by roughly 33 minutes, a larger change than simulations had predicted.
When will detailed images of Dimorphos be released?
Detailed images of Dimorphos are scheduled for release on 25 November, according to the mission team. Sharper views are also expected as Hera moves closer.
Sources
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