In 2022 NASA’s DART spacecraft made history, and changed the Solar System forever, by impacting the Dimorphos asteroid and measurably shifting its orbit around the larger Didymos asteroid. In the process a plume of debris was thrown out into space.
The latest modelling, available on the preprint server arXiv and accepted for publication in the September volume of The Planetary Science Journal, shows how small meteoroids from that debris could eventually reach both Mars and Earth – potentially in an observable (although quite safe) manner.
In its latest test of readiness for space, ESA’s Hera spacecraft for planetary defence is being operated for around three weeks in hard vacuum, while being subjected to the same temperature profiles it will experience during its journey to the Didymos binary asteroid system.
The 1.6 × 1.6 × 1.7 m spacecraft was slid inside the 4.5-m diameter, 11.8-m long Phenix thermal vacuum chamber at ESA’s ESTEC Test Centre in the Netherlands.
“You’re always a bit nervous when your baby gets moved about,” remarks Ian Carnelli, overseeing Hera for ESA. “Right now it’s being shut into a dark airless box for weeks on end, but we have confidence it will perform well.”
Hera can be seen receded into the rectangular ‘thermal tent’ within Phenix. The six copper walls of this internal box can be heated up to 100°C or cooled via piped liquid nitrogen down to –190°C, all independently from each other.
Then, after the main door of the stainless steel Phenix chamber was slid shut, the air within the chamber was pumped out during a lengthy 20 hours process down to approximately one billionth of outside atmospheric pressure. This will allow the Hera team from ESA, European Test Services operating the Test Centre and Hera manufacturer OHB to test the spacecraft’s thermal behaviour as the temperature changes around it.
Space is a place where it is possible to be hot and cold at the same time if one part of your spacecraft is in sunlight and another is in shade. And because there is no air, there is no conduction or convection to lose heat from your spacecraft. Instead thermal experts employ insulation and radiators to keep the body of a spacecraft within carefully chosen temperature limits. In general spacecraft electronics – just like their human makers – work best at room temperature.
“We already have detailed models of the spacecraft’s thermal behaviour, and this spacecraft-level thermal vacuum test lets us correlate these models with reality,” explains Hera’s Product Assurance and Safety manager, Heli Greus.
“More than 400 thermal sensors have been placed in and around Hera to give us precise knowledge of what is going on, and the test is being supervised on a 24/7 basis in case anything anomalous occurs. The spacecraft is now being put through a series of ‘cold plateaus’ and ‘hot plateaus’ representative of its mission, which will allow us to test the thermal limits of each specific unit aboard.”
Hera is Europe’s contribution to an international planetary defence experiment. Following the DART mission’s impact with the Dimorphos asteroid in 2022 – modifying its orbit and sending a plume of debris thousands of kilometres out into space – Hera will return to Dimorphos to perform a close-up survey of the crater left by DART. The mission will also measure Dimorphos’ mass and make-up, along with that of the larger Didymos asteroid that Dimorphos orbits around. Hera is due for launch in October 2024.
The ESTEC Test Centre in the Netherlands is the largest facility of its kind in Europe, providing a complete suite of equipment for all aspects of satellite testing under a single roof.
2023’s highlight was the highly anticipated launch of Juice, Europe’s Jupiter Icy Moon Explorer. The Juice spacecraft was placed on course to Jupiter on the second-to-last Ariane 5 launch vehicle in April. After an eight-year journey, Juice will begin observing the giant gas planet and its three large ocean-bearing moons – Ganymede, Calisto and Europa.
The Euclid space telescope was launched in July with the aim of unravelling the enigmas of ‘dark matter’ and ‘dark energy’. Euclid’s first images were released in November, revealing razor-sharp astronomical images with detail never before seen by a telescope across such a large patch of the sky.
After almost five years in space, ESA’s Aeolus wind mission was retired. This trailblazing mission was tasked with observing wind patterns from space thereby improving weather forecasts and climate models.. Aeolus data and technology will have an important role to play in the accuracy of future weather forecasting. On 28 July, it burned up in an assisted re-entry – the first assisted re-entry by a mission which was not designed to do so.
As space debris becomes an increasingly serious issue, ESA is determined to search for solutions. Together with its commercial and institutional partners, ESA has developed the ‘Zero Debris Charter’, launched this year. By signing the Charter, space entities worldwide can register their intent to work together towards the sustainable use of Earth’s orbital environment.
Earlier in in 2023, MTG-I1, the first of the Meteosat Third Generation missions, sent back its first images. The satellite was launched in 2022 and carries two instruments: a flexible combined imager and a lighting imager. Both instruments performed beyond expectation and a stunning combined image from both was revealed.
Earth observation is key to keeping our planet and the population as a whole, safe. Today, monitoring earthquakes, forest fires or flooding from space already helps to coordinate rescue response but the data can also be used to better understand phenomena such as climate change and support the IPCC climate reports.
Last year, NASA’s Dart mission impacted on a small moonlet of the asteroid Didymos, changing its course. We’ll soon be launching ESA’s Hera spacecraft to collect data on the aftermath of this collision. The Hera spacecraft was integrated and underwent testing this year in ESA ESTEC’s test centre in the Netherlands.
2023 also saw the first hardware tests for the second generation of Galileo satellites but even more importantly the Galileo High Accuracy Service was launched in January. This new service delivers centimetre accuracy from space further cementing Galileo’s reputation as the most accurate satellite navigation system in the world.
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At some point, statistically speaking, a large asteroid will impact Earth. Whether that’s tomorrow, in ten years, or a problem for our descendants, ESA is getting prepared.
As part of the world’s first test of asteroid deflection, ESA’s Hera mission will perform a detailed post-impact survey of Dimorphos – the 160-metre asteroid struck, and successfully deflected, by NASA’s DART spacecraft.
Hera will soon study the aftermath. Launching in October 2024, Hera will turn this grand-scale experiment into a well-understood and hopefully repeatable planetary defence technique.
But before Hera and its two CubeSats fly, they’re rigorously tested at ESA’s ESTEC test centre in Noordwijk, the Netherlands. From the force and noise of the rocket take-off to the sustained vacuum and temperature extremes of deep space, all aspects of Hera’s functioning are checked before they begin their journey, alone in space.
Credits: ESA – European Space Agency
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We are Europe’s gateway to space. Our mission is to shape the development of Europe’s space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe and the world. Check out https://www.esa.int/ to get up to speed on everything space related.
Hera is complete. ESA’s asteroid mission for planetary defence was built and prepared in two halves, but now, through a painstaking operation, they have been mated together to make a single spacecraft, ready for full-scale testing of its readiness for space.
The mating took place at OHB Bremen in Germany, with Hera’s Core Module raised more than 3 m above its Propulsion Module then gradually and carefully slotted into place, over a three-hour period. The modules had been placed in cages to ensure their correct alignment relative to each other down to a few tenths of a millimetre.
Hera’s Propulsion Module incorporates its propellant tanks – housed within a central titanium cylinder, the ‘backbone’ of the spacecraft – along with piping and thrusters, which will have the job of hauling the mission across deep space for more than two years, then to manoeuvre around the Dimorphos and Didymos asteroids.
Meanwhile Hera’s Core Module can be thought of as the brains of the mission, hosting its onboard computer, mission systems and instruments.
Once the tip of the Propulsion Module cylinder met the top deck of the Core Module the mating was complete. Then an initial test bolt was inserted to check the alignment was entirely correct in advance of the two modules being fully bolted together.
The combined Hera spacecraft is scheduled to go through a test campaign to assess its readiness for spaceflight, along with the two CubeSats it will carry aboard, in preparation for its October 2024 lift-off.
Credits: ESA – European Space Agency Footage: ESA / OHB
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We are Europe’s gateway to space. Our mission is to shape the development of Europe’s space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe and the world. Check out https://www.esa.int/ to get up to speed on everything space related.
The night of 26 September 2022 will make space history – as the moment when @NASA’s DART spacecraft impacts the Dimorphos asteroid in an attempt to divert its course – humankind’s first planetary defence test. Next, in 2024, ESA launches its Hera spacecraft to investigate the post-impact asteroid. In fact, Hera is not one spacecraft but three: it carries with it ESA’s first deep-space CubeSats to make extra observations of its target.
With the Hera mission, ESA is assuming even greater responsibility for protecting our planet and ensuring that Europe plays a leading role in the common effort to tackle asteroid risks.
In this video, Ian Carnelli, Hera mission manager, and members of the Hera team, reflect on the DART impact and introduce Hera and its Milani and Juventas CubeSats.
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We are Europe’s gateway to space. Our mission is to shape the development of Europe’s space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe and the world. Check out https://www.esa.int/ to get up to speed on everything space related.
All eyes are looking up as @NASA intentionally crashes the 550 kg DART spacecraft into an orbiting asteroid at high speed. Our Estrack network of ground stations, Europe’s ‘eyes on the sky’, will be particularly focused on the humanmade impactor, keeping track as it closes in on the 160-metre-wide moving target in the world’s first test of asteroid deflection.
We are Europe’s gateway to space. Our mission is to shape the development of Europe’s space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe and the world. Check out https://www.esa.int/ to get up to speed on everything space related.
