How the Hera asteroid mission will phone home

That is the antenna that can transmit again the primary close-up photographs of the distant Dimorphos asteroid since its orbit was shifted by a collision with NASA’s DART spacecraft.

The 1.13-m diameter Excessive Achieve Antenna of ESA’s Hera mission went via a week-long check marketing campaign on the Compact Antenna Check Vary, a part of the Company’s ESTEC technical heart within the Netherlands.

The CATR’s metallic partitions isolate exterior radio indicators whereas its foam-spike-lined inside soak up radio signals to forestall reflections and reproduce the empty void of space. Every check session took greater than 10 hours, with the antenna rotated a level at a time to construct up a 360 diploma image of the antenna’s detailed sign form.

“The Excessive Achieve Antenna is mostly a essential a part of our mission—it is going to be our sole technique of receiving information and sending instructions with the amount we’d like, with the Low Achieve Antenna as backup for low information charge emergency communications,” explains Hera antenna engineer Victoria Iza.

Hera system engineer Paolo Concari provides, “Coupled with an modern deep-space transponder, this antenna can even carry out science in its personal proper. Doppler shifting in its indicators on account of slight shifts in Hera’s velocity because the spacecraft orbits Dimorphos will probably be used to derive the mass and form of the asteroid. However for this radio science experiment to work nicely, the antenna sign might want to stay steady over time, which suggests the antenna itself has to take care of its geometrical form very exactly.”

The Excessive Achieve Antenna was manufactured by HPS in Germany and Romania. The corporate was checking that the antenna’s CATR check efficiency met mission necessities, evaluating the outcomes to simulated radio frequency information.

“The antenna reflector is manufactured from carbon fiber, which makes it very steady and immune to temperature extremes and common environmental stresses,” feedback Fulvio Triberti from HPS. “With a total mass of simply 7.5 kg, it’s a scaled up model of a smaller mannequin produced for ESA’s Euclid observatory, which can function 1.5 million km from Earth. However Hera’s antenna might want to cowl a lot larger distances nonetheless than Euclid, transmitting and receiving throughout so far as over 400 million km.”

Situated on the outside of the spacecraft, the Excessive Achieve Antenna is particularly inclined to accelerations throughout launch and the excessive and low temperatures skilled in space—for added safety in opposition to the latter, the antenna will probably be flown coated in a Kapton-Germanium sunshield that gives thermal isolation whereas radio waves can nonetheless move via it.

So, as a subsequent step, the antenna will bear vibration testing at IABG in Germany, to breed launch stresses, adopted by “thermal vacuum” testing at AAC in Austria, to simulate temperature extremes. Then the antenna will return to the CATR subsequent spring, so as to verify that this environmental testing did nothing to degrade its radio-frequency efficiency.

Antenna engineer Ines Barbary led the CATR check marketing campaign: “The problem for us has been the very excessive acquire of the antenna, and likewise its tightly centered directivity—it’s a very narrowly centered beam with low aspect lobes. Our check indicators cross lower than 2 m from our antenna to the Excessive Achieve Antenna throughout the chamber however our specialist software program can rework the indicators as if they’re touring throughout huge distances.”

The Excessive Achieve Antenna boosts its sign greater than 4,000-fold to succeed in Earth, centered right down to solely half a level, in order that all the spacecraft will transfer so as to line up with its dwelling world.

“It is a implausible feeling to see flight {hardware} take form like this,” concludes Paolo. “And all concerned did a terrific job in making it occur on time, to fulfill our launch schedule in October 2024.”