In Simple Terms
NASA sent two small spacecraft toward Mars, but a launch delay meant they had to take a longer route through space. They swung back near Earth, fired their engines to change course, and gathered information about the long magnetic tail stretching behind our planet. They are now heading for Mars, where they will study how the planet interacts with particles from the Sun.
A Journey That Began After the Ideal Launch Window
When Earth and Mars line up in a way that makes travel between them especially efficient, the opportunity comes around only about once every 26 months. That is why missions to Mars are usually planned around a narrow launch window. NASA had intended to launch its ESCAPADE mission in October 2024, when the planets were well positioned for the trip. But delays to Blue Origin’s New Glenn rocket prevented the launch from going ahead.
Rather than leave the mission on the ground until another conventional opportunity opened, planners chose a different route. The twin spacecraft launched in November 2025 on New Glenn’s second flight. They entered an extended trajectory that allowed them to wait in space before returning to Earth’s vicinity. This approach, known as a long-duration orbital loiter, was designed as a loop resembling a kidney bean. It carried the spacecraft through the region around the second Earth-Sun Lagrange point, commonly called L2.
The spacecraft were not circling Earth in a close orbit in the usual sense. Instead, they followed a broad path around the L2 region before heading back toward our planet in early November 2026. Their waiting period therefore became a genuine part of the mission, rather than dead time. The route gave engineers a chance to use Earth’s gravity at just the right moment and took the spacecraft through parts of space that could help them study the magnetic environment around our planet.
Firing Engines During a Close Pass by Earth
As the spacecraft returned to Earth’s neighborhood, they faced a crucial maneuver. A close pass by a large planet can alter a spacecraft’s path through gravity, as happens during the gravity-assist flybys used by many space missions. ESCAPADE, however, was not relying on gravity alone. Each spacecraft also had to fire its engine during the pass, combining the effect of gravity with the push produced by the burn.
The first spacecraft completed the maneuver on November 7, and the second fired its engine on November 9. NASA said both operations went as planned. This marked the first time the agency had used an Earth flyby combined with propulsion from the spacecraft itself on a mission headed to Mars. Asal Nasri, acting deputy flight director in NASA’s heliophysics division, said that successfully carrying out the maneuver twice in two days was a first for the agency.
The significance is that the spacecraft are not simply being deflected by gravity. They adjust their thrust as they pass Earth, changing the effect of the flyby. That requires precise knowledge of the spacecraft’s position, speed, and direction, as well as carefully timed execution. The engine does not act independently of the spacecraft’s orbital motion. Its thrust combines with the spacecraft’s movement through Earth’s gravitational field, sending it away on a new course toward a distant destination.
According to the plan, the spacecraft still need a few small course corrections. They are expected to reach Mars in September 2027. The successful November maneuvers do not mean the mission is over; rather, the interplanetary leg has begun after an important navigation test. Accurately tracking their paths and continuing to monitor both spacecraft will remain essential as they approach the Red Planet.
What Are the Spacecraft Going to Learn About Mars?
ESCAPADE will ultimately study Mars’s magnetic environment, which is not a single, uniform shield surrounding the planet. A broad magnetic influence is created by interactions between charged particles from the Sun and the Martian atmosphere. There are also localized areas in the Martian crust with strong magnetic properties. Understanding how these features fit together helps scientists describe how the environment around Mars interacts with nearby space.
The mission consists of two similar spacecraft, each roughly the size of two refrigerators and equipped with three scientific instruments and several cameras. Having two spacecraft rather than one makes it possible to compare measurements taken at different locations at the same time. When a phenomenon changes quickly or spans a wide area, comparing the two observations can help reveal whether the change was a brief event at one point or part of a larger movement.
The journey to Mars has also given the spacecraft an opportunity to study a subject closer to home: Earth’s magnetic field. Earth’s field is stronger than Mars’s and is generated inside the planet, but it is also affected by the solar wind, the steady stream of charged particles flowing from the Sun. Those particles push against the side of Earth facing the Sun and stretch the magnetic field out behind the planet, forming a long structure called the magnetotail.
Earth’s Magnetotail: A Laboratory Far Out in Space
The magnetotail does not stay fixed like a shape in a drawing. It moves and changes, and plasma—a material made up of charged particles—flows through it. Different missions have observed parts of the tail at distances of nearly 800,000 miles, or about 1.27 million kilometers, from Earth. What happens farther away has been less clear, because reaching those regions and observing them directly across such vast distances pose major challenges.
The two ESCAPADE spacecraft passed through a distant part of the tail, about 1.19 million miles, or 1.91 million kilometers, from Earth. They spent roughly ten days in the region. Instead of collecting measurements from a single spacecraft, scientists were able to gather data from both twins at the same time and compare what each one observed from its different position. Rob Lillis, a planetary and space physicist at the University of California, Berkeley, and the mission’s principal investigator, described the data as an unprecedented opportunity to observe the distant tail’s structure, motion, and plasma flow.
Simultaneous measurements matter because a single observation does not always show how a phenomenon changes across space. If a spacecraft records a change in the magnetic field, that could mean the structure itself has moved, or it could mean the spacecraft has moved to a different location within the structure. With two spacecraft observing at once, researchers gain two perspectives. That helps them distinguish the spacecraft’s own motion from actual changes in the field and the charged material flowing through it.
The mission had another chance to examine the magnetotail during the summer. The Moon was passing through the structure too, and the ESCAPADE spacecraft coordinated their observations with the two ARTEMIS-THEMIS spacecraft near the Moon. This made it possible to collect observations from four locations at the same time, rather than relying on just one or two. The more locations scientists can measure at the same time, the more accurately they can build a picture of the shape and movement of magnetic field lines, as well as the behavior of plasma in different regions.
Why Isn’t Looking From Far Away Enough?
Some astronomical phenomena can be measured remotely, but studying a magnetic field and the plasma around it often requires instruments to be inside the region itself. A spacecraft traveling through the environment can directly record the properties of the particles and the magnetic field where it is located, rather than inferring them from light arriving across a great distance. The magnetotail also changes over time, which makes simultaneous observations especially useful: they show multiple parts of a phenomenon at the same moment, rather than separate snapshots that may be divided by important changes.
That means the long loop before the journey to Mars was more than a workaround for a delayed launch. It also created an additional scientific opportunity, allowing the spacecraft to study distant regions of Earth’s magnetotail. The participation of the ARTEMIS-THEMIS spacecraft further expanded the view, making it possible to examine the structure from four locations. The original goal—investigating the magnetic environment of Mars—still lies ahead, with the twin spacecraft expected to arrive in September 2027.
It is important to separate what the spacecraft have accomplished so far from what they may discover later. The successful engine burns show that the maneuver was carried out correctly, but they are not themselves a result about Mars; the spacecraft are still on their way there. Likewise, the measurements of Earth’s magnetotail came from an earlier stage of the journey. The study of Mars’s environment will begin when the spacecraft reach their destination and start observations there.
The Bottom Line
ESCAPADE combines a new navigation experiment with a science mission unfolding in several stages. After the spacecraft were unable to launch in October 2024, when the planets were in a favorable alignment that comes around every 26 months, they lifted off in November 2025. They followed a long route through the L2 region before returning near Earth. On November 7 and 9, 2026, they successfully fired their engines during a flyby of our planet. NASA says this was the first maneuver of its kind for a mission bound for Mars.
Along the way, the twin spacecraft made simultaneous measurements of Earth’s magnetotail from 1.19 million miles, or 1.91 million kilometers, away. They also joined the two ARTEMIS-THEMIS spacecraft near the Moon in a four-location observing campaign. After a few planned course corrections, the spacecraft are now headed for an expected arrival in September 2027. That is when the mission’s central work begins: studying Mars’s magnetic environment and how the planet interacts with particles streaming from the Sun.