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In its latest test of readiness for space, ESA\u2019s Hera spacecraft for planetary defence is being operated for around three weeks in hard vacuum, while being subjected to the same temperature profiles it will experience during its journey to the Didymos binary asteroid system.<\/p>\n
The 1.6 \u00d7 1.6 \u00d7 1.7 m spacecraft was slid inside the 4.5-m diameter, 11.8-m long Phenix thermal vacuum chamber at ESA\u2019s ESTEC Test Centre in the Netherlands.<\/p>\n
\u201cYou\u2019re always a bit nervous when your baby gets moved about,\u201d remarks Ian Carnelli, overseeing Hera for ESA. \u201cRight now it\u2019s being shut into a dark airless box for weeks on end, but we have confidence it will perform well.\u201d<\/p>\n
Hera can be seen receded into the rectangular \u2018thermal tent\u2019 within Phenix. The six copper walls of this internal box can be heated up to 100\u00b0C or cooled via piped liquid nitrogen down to \u2013190\u00b0C, all independently from each other.<\/p>\n
Then, after the main door of the stainless steel Phenix chamber was slid shut, the air within the chamber was pumped out during a lengthy 20 hours process down to approximately one billionth of outside atmospheric pressure. This will allow the Hera team from ESA, European Test Services\u00a0operating the Test Centre and Hera manufacturer OHB\u00a0to test the spacecraft\u2019s thermal behaviour as the temperature changes around it.<\/p>\n
Space is a place where it is possible to be hot and cold at the same time if one part of your spacecraft is in sunlight and another is in shade. And because there is no air, there is no conduction or convection to lose heat from your spacecraft. Instead thermal experts employ insulation and radiators to keep the body of a spacecraft within carefully chosen temperature limits. In general spacecraft electronics \u2013 just like their human makers \u2013 work best at room temperature.<\/p>\n
\u201cWe already have detailed models of the spacecraft\u2019s thermal behaviour, and this spacecraft-level thermal vacuum test lets us correlate these models with reality,\u201d explains Hera\u2019s Product Assurance and Safety manager, Heli Greus.<\/p>\n
\u201cMore than 400 thermal sensors have been placed in and around Hera to give us precise knowledge of what is going on, and the test is being supervised on a 24\/7 basis in case anything anomalous occurs. The spacecraft is now being put through a series of \u2018cold plateaus\u2019 and \u2018hot plateaus\u2019 representative of its mission, which will allow us to test the thermal limits of each specific unit aboard.\u201d<\/p>\n
Hera\u00a0is Europe\u2019s contribution to an international planetary defence experiment. Following the DART mission\u2019s impact with the Dimorphos asteroid in 2022 \u2013\u00a0modifying its orbit and sending a plume of debris thousands of kilometres out into space\u00a0\u2013 Hera will return to Dimorphos to perform a close-up survey of the crater left by DART. The mission will also measure Dimorphos\u2019 mass and make-up, along with that of the larger Didymos asteroid that Dimorphos orbits around. Hera is due for launch in October 2024.<\/p>\n
The\u00a0ESTEC Test Centre\u00a0in the Netherlands is the largest facility of its kind in Europe, providing a complete suite of equipment for all aspects of satellite testing under a single roof.<\/p>\n<\/p><\/div>\n<\/p><\/div>\n