How the Hera asteroid mission will phone home

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

The 1.13-m diameter Excessive Acquire Antenna of ESA’s Hera mission went by means of a week-long take a look at marketing campaign on the Compact Antenna Take a look at Vary, a part of the Company’s ESTEC technical middle within the Netherlands.

The CATR’s metallic partitions isolate exterior radio alerts whereas its foam-spike-lined inside take up radio signals to stop reflections and reproduce the empty void of space. Every take a look at 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 Acquire Antenna can be a essential a part of our mission—it will likely be our sole technique of receiving knowledge and sending instructions with the amount we’d like, with the Low Acquire Antenna as backup for low knowledge price emergency communications,” explains Hera antenna engineer Victoria Iza.

Hera system engineer Paolo Concari provides, “Coupled with an progressive deep-space transponder, this antenna may even carry out science in its personal proper. Doppler shifting in its alerts resulting from slight shifts in Hera’s velocity because the spacecraft orbits Dimorphos shall 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 implies the antenna itself has to keep up its geometrical form very exactly.”

The Excessive Acquire Antenna was manufactured by HPS in Germany and Romania. The corporate was checking that the antenna’s CATR take a look at efficiency met mission necessities, evaluating the outcomes to simulated radio frequency knowledge.

“The antenna reflector is manufactured from carbon fiber, which makes it very steady and proof against temperature extremes and normal 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 is able to function 1.5 million km from Earth. However Hera’s antenna might want to cowl a lot higher distances nonetheless than Euclid, transmitting and receiving throughout so far as over 400 million km.”

Situated on the outside of the spacecraft, the Excessive Acquire 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 shall be flown lined in a Kapton-Germanium sunshield that gives thermal isolation whereas radio waves can nonetheless move by means of it.

So, as a subsequent step, the antenna will endure 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, to be able to verify that this environmental testing did nothing to degrade its radio-frequency efficiency.

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

The Excessive Acquire Antenna boosts its sign greater than 4,000-fold to succeed in Earth, targeted all the way down to solely half a level, in order that all the spacecraft will transfer to be able to line up with its dwelling world.

“It is a incredible 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.”