NASA’s DART mission has a sequel. How Europe’s HERA will explore an asteroid impact aftermath.

The European Hera mission will comply with NASA’s DART asteroid-deflecting spacecraft to the binary space rock Didymos and element the aftermath of DART’s collision with the smaller of the 2 asteroids, Dimorphos. It will even try to peek contained in the asteroid duo in a scientific first. 

According to the European Space Agency’s (ESA) unique plans, Hera would have witnessed DART‘s suicidal encounter with Didymos’ moon Dimorphos in 2022 firsthand. But preliminary hesitation amongst ESA’s member states led to funding delays. As a outcome, this investigator spacecraft will solely arrive on the scene greater than two years after the cataclysmic impact. The “dust” will have settled at that time, and astronomers will have recognized from Earth-based observations whether or not DART achieved its purpose of altering Dimorphos’ orbit across the bigger Didymos. 

What else will be there for Hera to be taught? Surprisingly, fairly a lot. Astronomers know little or no about Didymos and its moon Dimorphos. And the knowledge Hera will collect will assist researchers finetune a attainable future mission that will purpose to deflect an asteroid on a collision course with Earth. 

Related: If an asteroid really threatened the Earth, what would a planetary defense mission look like?

“Hera is currently on track to launch in October, 2024,” Michael Kueppers, Hera challenge scientist at ESA, advised “It will arrive in late 2026 or early 2027. Although we originally wanted to observe the impact directly, there are certain advantages to arriving later. We will be able to see the final outcome, which may be the most relevant point from the planetary defence point of view.”

Before it rams into Dimorphos, DART will {photograph} the 2 asteroids with its single instrument, the high-resolution DRACO (Didymos Reconnaissance and Asteroid Camera for Optical Navigation) digicam. Ten days earlier than its demise, the spacecraft will launch a cubesat that will stand in for the delayed Hera and take primary photos of the impact’s speedy aftermath. Hera will then comply with with a extra superior suite of devices that will enable it to investigate intimately the result of the crash, in addition to the construction of Didymos and Dimorphos and their chemical composition.

Rubble pile or stable block? 

“Right now, we know quite well how the two asteroids orbit each other and how they together orbit the sun,” mentioned Kueppers. “We know that the larger Didymos is about 800 meters [2,600 feet] across and the smaller Dimorphos about 170 meters [560 feet] across. But we don’t know their shapes, we don’t know the mass of Dimorphos and we have no information about their composition and chemistry.”

Astronomers assume that the bigger Didymos shouldn’t be a single stable block of stone however reasonably what they name a “rubble pile,” a conglomeration of boulders and pebbles loosely held collectively by gravity. The similar could also be true for Dimorphos. What occurs in the course of the impact relies upon to a massive diploma on these unknowns. A rubble pile will reply in a different way in comparison with a stable block of rock. It may crumble into a variety of fragments that may then fly away on their separate trajectories.

The energy and chemical composition of the fabric will decide how a lot of the vitality delivered by DART the asteroid absorbs. Scientists, for instance, do not know how a lot materials will be stirred up from the floor of Dimorphos by the DART impact, which could have an effect on how a lot the impact adjustments the asteroid’s orbit. 

“The more detail we learn, the better we will be able to scale up the mission to achieve a desired outcome if it was ever needed one day to protect Earth,” Kueppers mentioned. “We would need to be better able to much better predict the outcome of such an impact if it’s ever needed in a real case.”

First look inside 

Some of essentially the most attention-grabbing measurements of the Hera mission would possibly come not from the Hera spacecraft immediately however from two cubesats that will journey to Didymos aboard Hera. One of those cubesats, known as Juventas, will carry a novel radar instrument which will allow it to analyse the inside of the 2 asteroids. If profitable, this is able to be a scientific first, mentioned Kueppers.

“The cubesat carries a radar instrument that will send radio waves into the asteroids and measure the reflection,” mentioned Kueppers. “These waves will penetrate the asteroids and reveal the subsurface structure.”

The second cubesat, known as APEX (for Asteroid Prospection Explorer) will measure the crater created by the DART impact utilizing optical and infrared imagers. 

Both cubesats will orbit the 2 space rocks at a nearer distance than the mothership and will try to land on Dimorphos on the finish of their missions. 


With the mud settled and Dimorphos recovered from the orbit-altering impact, Hera and its companions will have a a lot clearer view of the newly born crater than they’d have within the direct aftermath of the collision.  

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Yet, the crater will be contemporary. Much more energizing than all the different craters beforehand studied by astronomers, a lot of which had been born in violent asteroid impacts thousands and thousands of years in the past. 

“We have many craters on the moon and asteroids in the solar system,” Kueppers mentioned. “But this is a unique case where we can investigate a crater where we know exactly the properties of the impacting object. That will help us to significantly advance our understanding of the physics of cratering and the scaling of craters, which is a valuable piece of information for both, science and planetary defense.”

Follow Tereza Pultarova on Twitter @TerezaPultarova. Follow us on Twitter @Spacedotcom and on Facebook

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