NASA's twin ESCAPADE spacecraft have pulled off a maneuver no NASA mission has attempted. Each probe fired its engines during a close pass by Earth, using the planet's gravity to build speed toward Mars. The first burn happened on Nov. 7, and the second followed on Monday, Nov. 9. NASA says both went perfectly.
"No NASA mission has ever done this before," said Rob Lillis, a planetary and space physicist at the University of California, Berkeley and principal investigator of the ESCAPADE mission. "For most missions, it just isn't necessary."
Lillis is right that it's unusual. NASA's Mars missions typically launch inside a narrow window that opens only about every 26 months, when Earth and Mars line up favorably. ESCAPADE was built for the October 2024 window, but delays with Blue Origin's New Glenn rocket meant it missed that opening. Rather than wait for the next one this fall, mission planners designed a "loitering" path shaped like a kidney bean. The probes launched in November 2025 on the second-ever New Glenn flight and spent the year on that looping route.
The hard part came once the probes returned. Each had to nail an engine burn inside Earth's gravity well. Spacecraft routinely use gravity-assist flybys to adjust their paths, but these probes fired their engines to amplify the effect rather than coasting on gravity alone. That's a meaningful difference. A slightly off burn would have sent them somewhere other than Mars.
"This is the first time NASA has used a powered Earth flyby to propel a spacecraft toward Mars, and we've now executed this maneuver twice, flawlessly, in just two days," said Asal Naseri, acting associate flight director for NASA's Heliophysics Division, in a statement.
After a few minor course corrections, ESCAPADE is headed for a Mars arrival in September 2027.
A detour that's paying off in science
The detour isn't just a logistics workaround. Each spacecraft is about the size of two refrigerators and carries three scientific instruments plus a couple of cameras. The payload is built to study Mars's unusual magnetic field, which has two sources: a global field produced when charged particles from the sun interact with the atmosphere, and local fields from patches of highly magnetic crust.
Earth's magnetic field is far stronger and originates in the planet's core, but the solar wind still reshapes it. That constant stream of charged particles from the sun stretches Earth's field on the side facing away from the sun, forming a long tail, something like a windsock.
Missions have studied this magnetotail out to nearly 800,000 miles (1.27 million kilometers) from Earth. Beyond that, it's been largely a blank. ESCAPADE filled part of that gap. Early last year, the two probes spent about 10 days passing through the tail at roughly 1.19 million miles (1.91 million km) from Earth.
"We were able to capture the magnetic field structure of that distant tail, how it flaps, how it moves, how the plasma flows within it," Lillis said, describing data he called "unprecedented." "And not only that but for the first time, we were able to do that with two spacecraft simultaneously."
A second pass came over the summer. The spacecraft were much closer to Earth, and the moon happened to be moving through the same magnetic structure. The ESCAPADE probes teamed up with the twin ARTEMIS-THEMIS spacecraft near the moon, which let researchers watch the tail from four vantage points at once.
That kind of coverage matters because the tail's field lines and plasma are constantly shifting. "These are generally not things you can measure remotely," Lillis said. "You kind of have to be there."