That is the antenna that may 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 Acquire Antenna of ESA’s Hera mission went via a week-long check marketing campaign on the Compact Antenna Test Range, a part of the Company’s ESTEC technical centre within the Netherlands.
The CATR’s metallic partitions isolate exterior radio indicators whereas its foam-spike-lined inside soak up radio indicators to stop reflections and reproduce the empty void of house. Every check session took greater than 10 hours at a time, 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 modern deep-space transponder, this antenna will even carry out science in its personal proper. Doppler shifting in its indicators because of 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 effectively, the antenna sign might want to stay steady over time, which suggests 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 check efficiency met mission necessities, evaluating the outcomes to simulated radio frequency knowledge.
“The antenna reflector is manufactured from carbon fibre, which makes it very steady and proof against temperature extremes and normal environmental stresses,” feedback Fulvio Triberti from HPS. “With a complete mass of simply 7.5 kg, it’s a scaled up model of a smaller mannequin produced for ESA’s Euclid’s observatory, which is able to function 1.5 million km from Earth. However Hera’s antenna might want to function over 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 very vulnerable to accelerations throughout launch and the excessive and low temperatures skilled in house – for added safety in opposition to the latter, the antenna shall be flown covered in a Kapton-Germanium sunshield that provides thermal isolation while radio waves can still pass through 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, with a purpose 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 achieve of the antenna, and likewise its tightly targeted directivity – it’s a very narrowly targeted beam with low facet lobes. Our check indicators cross lower than 2 m from our antenna to the Excessive Acquire Antenna throughout the chamber however our specialist software program can rework the indicators as if they’re travelling throughout huge distances.”
The Excessive Acquire Antenna boosts its sign greater than 4000-fold to achieve Earth, targeted all the way down to solely half a level, in order that the whole spacecraft will transfer with a purpose to line up with its homeworld.
“It’s a implausible feeling to see flight {hardware} take form like this,” concludes Paolo. “And all concerned did an amazing job in making it occur on time, to satisfy our launch schedule in October 2024.”
