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- NASA\u2019s Europa Clipper spacecraft<\/strong> zipped past Mars in March 2025, using the planet\u2019s gravity to build up speed on its way to Jupiter\u2019s icy moon Europa.<\/li>\n
- Mission scientists used the flyby to test Europa\u2019s radar instrument<\/strong>, which will allow the craft to peer below Europa\u2019s thick icy crust.<\/li>\n
- The test was a success,<\/strong> with a radar image of Mars\u2019 surface proving that the instrument is working as intended.<\/li>\n<\/ul>\n
NASA published this original article on August 1, 2025. Edits by EarthSky.<\/p>\n
Europa Clipper successfully tests radar during Mars flyby<\/h3>\n
As it soared past Mars in March 2025, NASA\u2019s Europa Clipper conducted a critical radar test that had been impossible to accomplish on Earth. Now that mission scientists have studied the full stream of data, they can declare success: the radar performed just as expected, bouncing and receiving signals off the region around Mars\u2019 equator without a hitch. <\/p>\n
Called REASON (Radar for Europa Assessment and Sounding: Ocean to Near-surface), Europa Clipper\u2019s radar instrument will \u201csee\u201d into Europa\u2019s icy shell, which may have pockets of water inside. The radar may even be able to detect the ocean beneath the shell of Jupiter\u2019s 4th-largest moon.<\/p>\n
Don Blankenship, principal investigator of the radar instrument, said: <\/p>\n
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We got everything out of the flyby that we dreamed. The goal was to determine the radar\u2019s readiness for the Europa mission, and it worked. Every part of the instrument proved itself to do exactly what we intended.<\/p>\n<\/blockquote>\n
![\"Silhouette](\"https:\/\/earthsky.org\/upl\/2024\/10\/Europa-clipper-deploying-instruments-november-2024.jpg\")
This artist\u2019s concept of Europa Clipper shows the spacecraft silhouetted against Europa\u2019s surface, with its long radar antennas \u2013 seen at the lower edge of the solar panels \u2013 fully deployed. The antennas are key components of the spacecraft\u2019s radar instrument, called REASON. Image via NASA\/ JPL-Caltech.<\/figcaption><\/figure>\n Europa Clipper\u2019s unusual radar system<\/h3>\n
Europa Clipper radar will help scientists understand how the ice may capture materials from the ocean and transfer them to the surface of the moon. Above ground, the instrument will help to study elements of Europa\u2019s topography, such as ridges, so scientists can examine how they relate to features that REASON images beneath the surface.<\/p>\n
Europa Clipper has an unusual radar setup for an interplanetary spacecraft: REASON uses two pairs of slender antennas that jut out from the solar arrays, spanning a distance of about 58 feet (17.7 meters). Those arrays themselves are huge \u2013 from tip to tip, the size of a basketball court \u2013 so they can catch as much light as possible at Europa, which gets about 1\/25 as much sunlight as Earth.<\/p>\n
The instrument team conducted all the testing that was possible prior to the spacecraft\u2019s launch from NASA\u2019s Kennedy Space Center in Florida on October 14, 2024. During development, engineers at the agency\u2019s Jet Propulsion Laboratory in Southern California even took the work outdoors, using open-air towers on a plateau above JPL to stretch out and test engineering models of the instrument\u2019s spindly high-frequency and more compact very-high-frequency antennas.<\/p>\n
But once the actual flight hardware was built, it needed to be kept sterile and could be tested only in an enclosed area. Engineers used the giant High Bay 1 clean room at JPL, where the spacecraft was assembled, to test the instrument piece by piece. To test the \u201cecho,\u201d or the bounceback of REASON\u2019s signals, however, they\u2019d have needed a chamber about 250 feet (76 meters) long, nearly 3\/4 the length of a football field.<\/p>\n
Europa Clipper flew past Mars in March<\/h3>\n
The mission\u2019s primary goal in flying by Mars on March 1, less than five months after launch, was to use the planet\u2019s gravitational pull to reshape the spacecraft\u2019s trajectory. But it also presented opportunities to calibrate the spacecraft\u2019s infrared camera and perform a dry run of the radar instrument over terrain NASA scientists have been studying for decades.<\/p>\n
As Europa Clipper zipped by the volcanic plains of the red planet \u2013 starting at 3,100 miles (5,000 kilometers) down to 550 miles (885 kilometers) above the surface \u2013 REASON sent and received radio waves for about 40 minutes. In comparison, at Europa the instrument will operate as close as 16 miles (26 kilometers) from the moon\u2019s surface.<\/p>\n
A successful test<\/h3>\n
All told, engineers were able to collect 60 gigabytes of rich data from the instrument. Almost immediately, they could tell REASON was working well. The flight team scheduled the full dataset to download, starting in mid-May. Scientists relished the opportunity over the next couple of months to examine the information in detail and compare notes.<\/p>\n
Trina Ray, Europa Clipper deputy science manager, said: <\/p>\n
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The engineers were excited that their test worked so perfectly. All of us who had worked so hard to make this test happen \u2013 and the scientists seeing the data for the first time \u2013 were ecstatic, saying, \u2018Oh, look at this! Oh, look at that!\u2019 Now, the science team is getting a head start on learning how to process the data and understand the instrument\u2019s behavior compared to models. They are exercising those muscles just like they will out at Europa.<\/p>\n<\/blockquote>\n
Europa Clipper will reach the icy moon in 2030. Its 1.8-billion-mile-journey (2.9 billion kilometers) includes one more gravity assist \u2013 this time using Earth \u2013 in 2026.<\/p>\n
Bottom line: Europa Clipper tested its radar during a Mars flyby in March 2025. The newly announced results show the instrument is working as hoped.<\/p>\n
Via NASA<\/p>\n
Read more: Europa Clipper en route and all systems go<\/p>\n
<\/div>\n
\n - Mission scientists used the flyby to test Europa\u2019s radar instrument<\/strong>, which will allow the craft to peer below Europa\u2019s thick icy crust.<\/li>\n