That is the antenna that can transmit again the primary close-up pictures 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 way of a week-long check marketing campaign on the Compact Antenna Check Vary, a part of the Company’s ESTEC technical centre within the Netherlands.
The CATR’s metallic partitions isolate exterior radio alerts whereas its foam-spike-lined inside absorbs radio alerts to forestall reflections and reproduce the empty void of area. 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 quantity we want, with the Low Acquire Antenna as backup for low knowledge fee emergency communications” explains Hera antenna engineer Victoria Iza.
Hera system engineer Paolo Concari provides: “Coupled with an revolutionary deep-space transponder, this antenna may also carry out science in its personal proper. Doppler shifting in its alerts 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 nicely, the antenna sign might want to stay secure over time, which implies the antenna itself has to take care of 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 secure 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 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.”
Positioned 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 area – for added safety towards the latter, the antenna shall be flown coated in a Kapton-Germanium sunshield that gives thermal isolation whereas radio waves can nonetheless go by way of 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 test 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 in addition its tightly centered directivity – it’s a very narrowly centered beam with low facet lobes. Our check alerts cross lower than 2 m from our antenna to the Excessive Acquire Antenna throughout the chamber however our specialist software program can rework the alerts as if they’re travelling throughout huge distances.”
The Excessive Acquire Antenna boosts its sign greater than 4000-fold to achieve Earth, centered all the way down to solely half a level, in order that all the spacecraft will transfer so as to line up with its homeworld.
“It’s a unbelievable feeling to see flight {hardware} take form like this,” concludes Paolo. “And all concerned did an awesome job in making it occur on time, to fulfill our launch schedule in October 2024.”
