Swift is falling.
cmetracker.ai/swiftNASA's Swift observatory lost 0.7 km of height in all of 2019. In 2026 it lost 185 km.
NASA's Neil Gehrels Swift Observatory has watched the sky for gamma-ray bursts since 2004. It has no engine to hold its orbit, and the Sun has spent the last three years puffing up the air it flies through. Now it is coming down. This page follows it, with the same daily orbit data that drives our Atmosphere view.
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1The Sun did this
Swift flies through the thermosphere, the thin top layer of our air. When the Sun is busy, its ultraviolet light heats that layer and it swells upward. Air that sat below Swift rises to meet it. More air means more drag, and drag steals a little height on every orbit.
Swift's whole loss of height for the year. The Sun was nearly blank.
Its loss so far this year. In the last week it lost 0.7 km about every 3 hours.
The fall feeds itself. Lower down the air is denser, so Swift falls faster, which takes it into denser air still. That is why the line on the chart bends ever more sharply. It took Swift about 16 months to fall from 500 km to 400 km. The next 100 km took about 7 months. The 50 km after that took about two weeks.
The lower panel of the chart pulls the two causes apart. Both lines are the air density from the model behind our Atmosphere view, which works out how hot the upper air is from the Sun's ultraviolet output and from geomagnetic storms. The amber line holds still at 560 km, where Swift flew through the quiet years, so it shows the Sun's heating alone. At the busiest point it made that air about 50 times thicker than in 2019. The Sun has calmed since, and that line has eased back to about 4 times. The pink line follows Swift down. It now sits in air about 1,400 times thicker than in 2019. The Sun started the fall, and the sinking finished it.
Storms add short bursts on top. A geomagnetic storm dumps energy into the upper air within hours. The red marks are the days Kp reached 6 or more. Switch the chart to Since July to see the storm of October 10. The next day Swift fell about 4 km, roughly twice its pace on the days around it. In the model, storms are small next to the slow swing of the solar cycle. One caution: below about 330 km our model ran up to two times low against how fast Swift really fell, so the real air down there was likely thicker still.
2The rescue that didn't happen
NASA tried to save it. In September 2025 the agency hired Katalyst Space to build a small robotic spacecraft that would fly up, grab Swift and push it higher. Swift was never built to be grabbed, so this was a first. The rescue craft launched on July 3, 2026. It then lost control of its own orientation and went into a spin. On August 19, NASA and Katalyst called off the boost. Below about 300 km a boost was not expected to be possible anyway, and Swift crossed that line in mid October.
3When and where it comes down
The date above is the latest forecast from the U.S. Space Force, published on Space-Track. We refresh it every hour. The window is wide for a good reason. Swift circles Earth about every 90 minutes, so a window of 14 hours either way spans close to 20 orbits. Nobody can say where it will fall until the last few hours. Most of Swift will burn up. Its orbit stays within about 21 degrees of the equator, so whatever is left will come down in the tropics, and most of that band is ocean.
Two measurements feed the numbers on this page. The height comes from daily orbit data from CelesTrak and Space-Track, archived here back to 2015. The fall rate is that height's change over the last seven days. Our own drag model, which runs on the Atmosphere view, predicts how fast Swift should fall in today's air. Below about 330 km it has run up to two times slower than Swift really fell, so for the date we trust Space-Track, not ourselves.
4What Swift did
Gamma-ray bursts are the brightest explosions in the universe, from collapsing stars and colliding neutron stars. They flash for seconds. Swift was built to catch one, swing its telescopes onto the spot within about a minute, and tell observatories on the ground where to look. It was named for that speed. In 2018 NASA added the name of Neil Gehrels, the mission's lead scientist, who died in 2017. Over two decades it found well over a thousand bursts, and it caught the ultraviolet glow of the 2017 neutron star merger that was also seen in gravitational waves.
Sources: altitude from CelesTrak and Space-Track orbit data; reentry forecast from Space-Track; solar flux from NOAA SWPC; the rescue from NASA and SpaceNews. Related: how the Atmosphere view works, where we are in the solar cycle.