(ORDO NEWS) — One of the main instruments of the Europa Clipper, which is being prepared for flight, received the “first light” – this is the name for the first inclusion of the instrument in operating mode.
The E-THEMIS infrared camera took a panorama of Tempe, Arizona as a performance test. The interplanetary probe’s “cosmic eye” captured the earth’s urban landscape two years before the start of the mission and a full eight years before arriving in the Jupiter system.
The problem with testing spacecraft nodes on Earth is not just the difficulty of simulating their operating conditions during a mission. The fact is that local factors are almost more dangerous for precision equipment than all sorts of horrors of interplanetary space like galactic rays and micrometeorites.
Terrestrial microbes and dust can get on the equipment and create a risk of its failure before the guaranteed period of operation. And the life-giving oxygen in the atmosphere has the mean property of oxidizing all materials in a row, which for precision parts easily turns into tolerance violations due to changes in surface properties.
In general, in order to test their offspring in “combat” conditions before the start, employees of the Arizona State University ( ASU ) first developed a mobile clean room-laboratory for several months.
When the test bench was ready, an E-THEMIS ( Europa Thermal Emission Imaging System ) infrared camera was placed in it and raised to the roof of one of the buildings on the ASU campus in Tempe. From there, you have a great view, so you can check the operation of a scientific instrument, capturing a highly detailed urban landscape.
On the example of the panorama of the city center, the engineers made sure that the camera provides the required image detail and has the necessary resolution in different temperature ranges. However, this does not mean that the tool is ready.
Next , E-THEMIS needs to be calibrated, because it will take pictures of objects heated not to 25 degrees Celsius (Arizona has a warm winter), but much colder.
E-THEMIS temperature measurement accuracy targets – an error of no more than 2.2 degrees in the infrared radiation range of 14-28 nanometers (the average value is approximately 130 kelvins). In other parts of the spectrum to which the camera is sensitive, errors should be even smaller: two degrees for 7-14 nanometers (220 Kelvin) and one degree for 28-70 nanometers (90 Kelvin and below).
The maximum theoretical resolution of images should reach 5×22 meters per pixel from a distance of 25 kilometers. Actual detail will depend on the range of the IR spectrum used at the time of the survey and the height of the probe’s flight over Europa’s surface.
The goal of the Europa Clipper mission is to determine whether Jupiter’s moon Europa is fit for life. After a launch scheduled for 2024, the probe will begin its journey to the gas giant, which will end in 2030. The device will not go into orbit around its main research object: it is too dangerous, since Europa is located in Jupiter’s radiation belt.
With great difficulty, an automatic interplanetary station will be able to survive under such conditions for more than six months (the direct scientific mission, according to the plan, should last three and a half years).
Instead, studying the icy planet-like object Europa Clipper will be flybys at varying distances from its surface. The closest one is just 25 kilometers above the surface, the probe can even catch frozen droplets of water ejected through cracks in the ice.
This will make it possible to obtain data on the composition of the ocean on Europa without the need to launch a lander with a drill in the arsenal. Most of the flights will take place at an altitude of about two and a half thousand kilometers, the device itself will remain in orbit around Jupiter.
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