posted 09-15-2019 10:41 AM               

Hera

Hera – named after the Greek goddess of marriage – is a candidate ESA mission that will be humankind's first probe to rendezvous with a binary asteroid system, a little understood class making up around 15% of all known asteroids.

Hera is the European contribution to an international double-spacecraft mission. NASA will first perform a kinetic impact on the smaller of the two bodies, then Hera will follow-up with a detailed post-impact survey that will turn this grand-scale experiment into a well-understood and repeatable planetary defense technique.

While doing so, Hera will also demonstrate multiple novel technologies, such as autonomous navigation around the asteroid – like modern driverless cars on Earth, and gather crucial scientific data, to help scientists and future mission planners better understand asteroid compositions and structures.

Due to launch in 2024, Hera would travel to a binary asteroid system – the Didymos pair of near-Earth asteroids. The 780 m-diameter mountain-sized main body is orbited by a 160 m moon, informally called "Didymoon," about the same size as the Great Pyramid of Giza.

This smaller body is Hera's focus: the spacecraft would perform high-resolution visual, laser and radio science mapping of the moon, which will be the smallest asteroid visited so far, to build detailed maps of its surface and interior structure.

By the time Hera reaches Didymos, in 2026, Didymoon will have achieved historic significance: the first object in the Solar System to have its orbit shifted by human effort in a measurable way.

The NASA mission called the Double Asteroid Redirection Test, or DART, is due to collide with it in 2022. The impact will lead to a change in the duration of Didymoon's orbit around the main body. But ground observatories will be watching from a minimum distance of 10 million km, and the immediate aftermath may well be hidden by an expected dust cloud. The observatories' measurements of Didymoon's altered orbit are expected to be stuck with a 10% residual uncertainty and the actual transferred momentum – that is, by how much was it deflected? – will not be measured directly, missing a vital piece of information: the mass of Didymoon and the crater shape.

By actually venturing to Didymoon, measuring its mass as well as its shifted orbit from up close and performing its own 'crash scene investigation' of the asteroid moon's impact crater and surrounding surface in great detail, Hera will hone our understanding of this grand-scale space experiment. Its data will allow, for the first time, the validation or refinement of numerical models of the impact process at asteroid scale, rendering this deflection technique for planetary defense ready for operational use if ever needed to safeguard our home world, Earth.

DART and Hera were conceived together as part of the international 'Asteroid Impact Deflection Assessment' experiment. The two missions are valuable individually, but if flown in concert their overall scientific and technological return is significantly boosted. They will contribute to the important and positive message that international cooperation is key for the achievement of a planetary defense initiative.

Hera, a further optimization of ESA's earlier Asteroid Impact Mission, is currently in Phase B1 of mission development in preparation to the Agency's Space19+ Council of Ministers at European Level in November 2019.

posted 10-06-2024 04:18 PM               

ESA's Hera asteroid mission encapsulated within its Falcon 9 launcher fairing in preparation to be attached to its launcher. The fairing features the patches of Hera and its CubeSats Milani and Juventas, plus the ESA logo. These images were acquired on 3 October 2024.

posted 10-07-2024 12:15 PM               

Planetary defense mission Hera heading for deflected asteroid

ESA's first planetary defense spacecraft has departed planet Earth. The Hera mission is headed to a unique target among the more than 1.3 million known asteroids in our Solar System – the only body to have had its orbit shifted by human action – to solve lingering mysteries associated with its deflection.

By sharpening scientific understanding of the 'kinetic impact' technique of asteroid deflection, Hera aims to make Earth safer. The mission is part of a broader ambition to turn terrestrial asteroid impacts into a fully avoidable class of natural disaster.

Developed as part of ESA's Space Safety programme and sharing technological heritage with the Agency's Rosetta comet hunter, Hera lifted off on a SpaceX Falcon 9 from Cape Canaveral Space Force Station in Florida, USA, on 7 October at 10:52 local time (16:52 CEST, 14:52 UTC) with its solar arrays deploying about one hour later.

The automobile-sized Hera will carry out the first detailed survey of a 'binary' – or double-body – asteroid, 65803 Didymos, which is orbited by a smaller body, Dimorphos. Hera's main focus will be on the smaller of the two, whose orbit around the larger asteroid was changed by NASA's Double Asteroid Redirection Test (DART) mission, demonstrating asteroid deflection by kinetic impact, in 2022.

"Planetary defense is an inherently international endeavour, and I am really happy to see ESA's Hera spacecraft at the forefront of Europe's efforts to help protect Earth. Hera is a bold step in scaling up ESA's engagement in planetary defense," said ESA Director General Josef Aschbacher.

Hera will also perform challenging deep-space technology experiments including the deployment of twin shoebox-sized 'CubeSats' to fly closer to the target asteroid, manoeuvring in ultra-low gravity to acquire additional scientific data before eventually landing. The main spacecraft will also attempt 'self-driving' navigation around the asteroids based on visual tracking.

The mission's launch and journey into deep space is being overseen from ESA's European Space Operations Centre in Darmstadt, Germany.

"Hera is finally on its way to Didymos; today we are writing a new page of space history," said Hera mission manager Ian Carnelli. "This deep space mission took shape from contract signing to launch in only four years, a testimony to the hard work and dedication of the Hera team across ESA, European industry, science, and the Japanese space agency JAXA".

"But the underlying idea of a planetary defense mission based on one spacecraft impacting an asteroid with a second that gathers data goes back two decades, with a significant contribution made by the late Prof. Andrea Milani, a pioneer in asteroid risk monitoring whose name has been lent to one of Hera's two onboard CubeSats."

ESA, together with NASA and other partner agencies, maintains a watch on the sky to identify and track dangerous asteroids. But if an incoming body was spotted, what if anything could be done to stop it?

NASA's DART mission was created to help answer that question. On 26 September 2022, the DART spacecraft performed humankind's first asteroid deflection by intentionally crashing into Dimorphos, the Great-Pyramid-sized moonlet of the larger, mountain-sized asteroid Didymos, shifting its orbit.

Based on observations from Earth, DART succeeded in shrinking the orbit period of Dimorphos around Didymos by 33 minutes, nearly 5% of its original value, while also casting a plume of debris thousands of kilometres in space.

But many unknowns remain about the event, which scientists need to resolve in order to help turn this 'kinetic impact' method of asteroid deflection into a well understood and reliably repeatable planetary defense technique. How big was the crater left by DART's impact, or did the entire asteroid undergo reshaping? What is the mineralogy, structure and precise mass of Dimorphos?

With a cube-shaped main body measuring approximately 1.6 m across and flanked by twin 5-m solar wings, the Hera spacecraft is ESA's own contribution to this international planetary defense collaboration. Once it reaches the Didymos binary asteroid in two years' time, the mission will perform a close-up 'crash scene investigation' to gather all the missing knowledge needed.

"Hera's ability to closely study its asteroid target will be just what is needed for operational planetary defense," explains Richard Moissl, heading ESA's Planetary defense Office. "You can imagine a scenario where a reconnaissance mission is dispatched rapidly, to assess if any follow-up deflection action is needed. We should soon be practicing this again with our Ramses spacecraft, a proposed planetary defense mission to rendezvous with the Apophis asteroid during its close approach to Earth in 2029."

Around 100 European companies and institutes across 18 ESA Member States have been involved in developing the Hera mission. OHB System AG led the industrial consortium, including responsibility for the overall spacecraft design, development, assembly and testing.

Hera will perform the most detailed exploration yet of a binary asteroid system. Although binaries make up 15% of all known asteroids, none has ever been surveyed in detail. In addition, the Dimorphos asteroid is the smallest body yet visited by a space mission while Didymos is a fast spinner for its size, coming close to the limits of structural stability given its dimensions.

The Milani CubeSat, developed for ESA by Italian industry led by Tyvak International, will survey the mineral makeup of Dimorphos and its surrounding dust, while the Juventas CubeSat, produced by a Luxembourg-led consortium under GOMspace, will perform the first subsurface radar probe of an asteroid. Late in its six-month asteroid survey, Hera will also test out an experimental self-driving mode that will allow it to navigate around the asteroids autonomously based on monitoring of surface features.

ESA Hera mission scientist Michael Kueppers comments: "By the end of Hera's mission, the Didymos pair should become the best studied asteroids in history, helping to secure Earth from the threat of incoming asteroids."

Hera Principal Investigator Patrick Michel, Director of Research at CNRS / Observatoire de la Côte d'Azur, adds: "DART's impact was like the first episode in a cosmic adventure – a spectacular flash seen across space that left scientists with the question: what happened next?"

"Now Hera is on its way in the next episode, to turn the brief glimpses of the Didymos asteroids that the DART mission beamed back to us into a detailed survey, promising us fresh insights into the planetary collision process – which has been one of the primary mechanisms for creating the Solar System as we know it."

posted 10-14-2024 10:12 AM               

Hera's first images offer parting glimpse of Earth and Moon

ESA's Hera mission for planetary defence has taken its first images using three of the instruments that will be used to explore and study the asteroids Dimorphos and Didymos.

Above: Hera's Asteroid Framing Camera (AFC) captured this farewell image of Earth on 11 October from a distance of approximately 1.6 million km. (ESA)

Following a successful launch on 7 October 2024, Hera's instruments were switched on for the first time as part of the spacecraft's ongoing Near-Earth Commissioning Phase. On Thursday 10 October and Friday 11 October, Hera's asteroid deck, which houses the spacecraft's instruments, was pointed back towards our planet and three of its instruments captured their first images of Earth and the Moon from a distance of more than one million km.

[A] Asteroid Framing Camera, AFC

Above: Hera's first images (Asteroid Framing Camera) (ESA)

Hera's Asteroid Framing Camera (AFC) captured this farewell image of Earth (bottom left) and the Moon (centre) on 11 October from a distance of approximately 1.6 million km. Earth is oriented with north pointing upwards, with the Pacific Ocean illuminated by the Sun.

Incorporating two baffle-protected cameras for redundancy, each of Hera's two Asteroid Framing Cameras is a 1020x1020 monochrome visible light sensor. The cameras are used both for navigation and for scientific investigation and were produced by Jena-Optronik in Germany, based on its ASTROhead design.

[B] Thermal Infrared Imager, TIRI

Above: Hera's first images (Thermal Infrared Imager) (ESA)

Hera's Thermal Infrared Imager (TIRI) instrument captured this image of Earth and the Moon from a distance of approximately 1.4 million kilometres. Earth is in the centre of the image and oriented with north pointing upwards, showing the East coast of the USA and the Atlantic Ocean. The Moon is visible in the top right of the image.

TIRI will image the Dimorphos asteroid in the mid-infrared spectral region to chart the temperature on the asteroid's surface. By charting the 'thermal inertia' of surface regions – or how rapidly their temperature changes – physical properties such as roughness, particle size distribution and porosity can be deduced. TIRI was supplied by the Japan Aerospace Exploration Agency, JAXA, manufactured by Meisei Electric Co. Ltd. and inherited from the instrument onboard the agency's Hayabusa2 asteroid mission, with contributions from The Belgian Science Policy Office (BELSPO).

[D] HyperScout H

Above: Hera's first images (HyperScout H) (ESA)

Hera's HyperScout H instrument captured this false-colour image of Earth and the Moon from a distance of approximately 1.6 million kilometres. Earth (bottom right) is oriented with north pointing upwards, with the Pacific Ocean illuminated by the Sun. The Moon is visible in the top right of the image.

HyperScout H will observe the Dimorphos asteroid in a range of colours far beyond the limits of the human eye and help determine the asteroid's mineral makeup. The hyperspectral imager covers the 650–950 nm wavelength range, with colours coded so that blue represents the shortest wavelengths and red represents the longest. The shoebox-sized imaging spectrometer was provided by cosine remote sensing in the Netherlands.