The Sweeper’s Orbit

In 2097 the orbital graveyard above Earth was full.

More than 36,000 tracked objects larger than 10 cm orbited between 300 and 2,000 km altitude—spent upper stages, defunct satellites, fragments from 2009 Iridium-Cosmos collision, 2007 Chinese ASAT test, 2031 Starlink cascade, and a dozen smaller breakups. Relative velocities averaged 10–15 km/s. A paint fleck at that speed carried the energy of a rifle round. A bolt carried the energy of a small car bomb.

The Inter-Agency Space Debris Coordination Committee (IADC) had set a hard target in 2072: reduce the number of catalogued objects by 50 % within fifty years, or low Earth orbit would become unusable by 2150.

Orbital Remediation Vessel-14, callsign Chimera, was one of seventeen sweepers still flying.

She was 42 meters long, 18 tonnes dry mass, launched from Baikonur in 2089 on a heavy-lift methane-LOX booster. Propulsion: four Hall-effect thrusters using xenon stored in four toroidal composite tanks, specific impulse 3,000 s, total Δv 14 km/s. Power came from dual 18 m² gallium arsenide solar arrays. The payload bay held:

• Twelve magnetic grapples (1.2 T superconducting coils)
• Six electrodynamic tethers (3 km long, 1 mm aluminum wire)
• Four foam capture nets (100 m diameter, ultra-high-molecular-weight polyethylene)
• Two laser ablation turrets (50 kW fiber lasers for surface vaporization)

Chimera’s job was simple: rendezvous, capture, deorbit. She carried no crew. Her AI—Kronos—ran on a radiation-hardened 512-core neuromorphic processor, trained on 30 years of debris tracking data and every recorded rendezvous failure since 2025.

Controller Lena Voss was on her third shift of the week in the Korolev Control Center, Almaty.

She monitored six sweepers simultaneously. Chimera was her primary today.

At 03:42 UTC Kronos reported successful rendezvous with object 1998-012B: a 1,200 kg defunct Russian upper stage from the Kosmos-3M program, tumbling at 4.8 rpm, perigee 412 km, apogee 1,890 km, inclination 74.1°.

Lena watched the feed from Chimera’s forward cameras. The stage was a pitted cylinder, solar panels long shredded into confetti, attitude thrusters frozen open. Kronos had matched velocity to within 2 cm/s and was extending the primary grapple.

“Chimera, confirm grapple lock,” Lena said.

“Grapple one locked. Tension 1,420 N. Spin rate reduced to 0.9 rpm. Preparing electrodynamic tether deployment.”

The tether unspooled—3 km of thin aluminum trailing behind the stage. Kronos energized it with 1.2 kA. Interaction with Earth’s magnetic field generated Lorentz drag: 0.34 N constant force retrograde. Over 180 days the stage’s perigee would drop below 200 km; atmospheric drag would finish the job.

Lena exhaled. Another piece of history going home to burn.

Then the anomaly alarm sounded.

Kronos flagged a secondary object—untracked, estimated 8 cm, relative velocity 11.4 km/s, closing from 47° inclination. Impact probability: 92 % in 18 seconds.

Lena’s stomach dropped. An 8 cm fragment at that speed carried ~80 MJ—equivalent to 19 kg of TNT.

“Chimera, emergency abort. Release grapple. Emergency reboost 0.2 m/s retrograde. Now.”

“Grapple release initiated. Reboost burn in 4… 3… 2… 1… burn complete.”

The feed shook as the thrusters fired. The upper stage drifted away—slowly, too slowly.

The fragment hit.

Not the main hull. The solar array yoke. A bright flash, silent in vacuum. The array tore free; the stage began a slow end-over-end tumble. Kronos reported new debris cloud: 47 fragments >10 cm, 312 >1 cm.

Lena stared at the screen.

The stage was still above 400 km. Without the tether drag it would stay up for decades—maybe centuries—shedding more fragments with every collision.

She keyed the priority channel to IADC headquarters.

“Chimera reports impact on target 1998-012B. Tether deployment failed. New debris field generated. Request immediate re-tasking of ORV-9 and ORV-11 to intercept.”

The reply took 14 seconds—light-speed lag from Geneva.

“Negative. ORV-9 is committed to 2005-018A. ORV-11 is in cooldown. Chimera is to stand down and return to L2 depot for inspection. Target 1998-012B is now classified high-risk. No further remediation attempts authorized at this time.”

Lena looked at the tumbling stage, the new cloud spreading like ink in water.

She opened a private text channel to the Chimera ops lead.

“Kronos. Override priority alpha. Re-task to pursue 1998-012B. Use remaining xenon for pursuit burn. Target intercept within 72 hours. Accept risk of total vehicle loss.”

A pause—three seconds while the AI ran the orbital mechanics.

“Override accepted. Pursuit burn commencing in 90 seconds. Projected xenon depletion: 87 %. Probability of successful grapple: 41 %. Probability of vehicle survival: 19 %. Confirm?”

Lena thought of the stage—launched in 1998, carrying weather satellites that had saved thousands of lives in famines and cyclones. Thought of the debris cloud it would become if left alone. Thought of the next generation of sweepers that would have to clean up her mistake.

She typed one word.

“Confirmed.”

Chimera’s thrusters lit—four pale blue plumes in vacuum. The ship accelerated hard, chasing a ghost that had been falling for almost a century.

Lena leaned back in her chair. The control room was quiet except for the hum of servers and the soft ping of orbital element updates.

She watched the telemetry until her shift ended.

Then she went home.

She did not sleep.

She sat on her balcony in Almaty and looked up at the sky.

Somewhere up there, a small robot ship was burning the last of its fuel to catch a piece of history before it shattered into a thousand more pieces.

She did not know if Kronos would succeed.

She only knew it had to try.

Because someone had to.

And tonight, that someone was a machine that never slept, never forgot, and never looked away.