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On 21 November 2026, a spacecraft that has been decelerating since 2018 will finally stop. Partway through the day, more than 200 million kilometres from the people flying it, the stacked BepiColombo orbiters will turn their chemical thrusters against their own motion and fire. If the burn behaves, the joint ESA-JAXA mission becomes the first to hold two spacecraft in orbit around Mercury simultaneously. If it does not, eight years of trajectory design has to be rebuilt from scratch around a rock that most spacecraft are barely engineered to survive.

That frame is among the last things the mission photographed with the hardware it no longer needs. M-CAM 1 is bolted to the Mercury Transfer Module, the ESA-built propulsion stage that carried both science orbiters across the inner Solar System and was discarded on 3 September 2026 at a point 63 million kilometres from the Sun (ESA, September 2026). What remains is roughly 1,500 kg of spacecraft still moving fast enough that Mercury cannot simply grab it.

The module carried three of those 1,024 by 1,024 pixel black-and-white cameras, which exist less for science than for triage: they let engineers check hardware health from a distance when the main science instruments are pointed the wrong way or blocked. They also became the mission’s accidental souvenir shop, recording Earth, both Venus encounters and all six Mercury passes. The final swing-by on 8 January 2025 came within about 295 km of the surface and was the last gravitational tug before the long approach.

Mercury’s reputation as a hostile destination is mostly a matter of velocity. It orbits at 0.387 astronomical units, where the Sun’s pull is roughly seven times stronger than at Earth, and a spacecraft launched from Earth arrives there carrying far too much speed. Run the numbers with the vis-viva equation, v^2 = GM(2/r - 1/a), and a direct transfer from Earth’s orbit to Mercury’s comes out near 57 km/s at the arrival point, against Mercury’s own orbital speed of about 48 km/s. That surplus has to go somewhere. Entering a low orbit around a small planet means surrendering most of it to the planet’s gravity, and the only cheap way to surrender velocity is to let a planet take it away for you.

That is what the nine flybys were for. BepiColombo launched from Kourou on an Ariane 5 on 20 October 2018 at 4,100 kg, comprising a 1,230 kg orbital module carrying 85 kg of instruments and a 255 kg Japanese magnetospheric orbiter carrying 45 kg (ESA fact sheet). It swung past Earth once, Venus twice and Mercury six times, shedding heliocentric energy in small instalments, and used solar-electric thrust between encounters to trim the orbit inward. It is named for the Italian engineer Giuseppe Colombo, whose 1970s work on gravity-assist trajectories let Mariner 10 visit Mercury three times. ESA notes that orbit insertion at Mercury demands more energy than sending a probe past Pluto, which is why a nearly $2 billion mission needed a nine-stop itinerary.

The itinerary almost did not survive 2024. On 26 April, while the module was mid-manoeuvre, its power system began drawing unexpected currents between the solar array and the unit that extracts and distributes power, starving the ion engines. Engineers at ESOC in Darmstadt restored thrust to about 90 percent within eleven days but could not recover full power, and the flight dynamics team concluded in September that the reduced thrust could no longer reach the December 2025 insertion date (ESA, September 2024). The hardware was unfixable, so the trajectory moved. The fourth Mercury flyby on 4 September 2024 was flown roughly 35 km lower than planned, a small shave of altitude that conserved propellant and let a redesigned path carry the spacecraft to Mercury a year late while keeping the science programme intact (ISAS).

September 2026 was the handover. When the transfer module let go, the remaining pair had to inherit power generation, propulsion, pointing and thermal control in one shot, at a distance where a radio round trip takes hours. Confirmation came through Doppler shift as the two halves changed velocity, read out from Cebreros in Spain and Malargüe in Argentina (ESA, 3 September 2026). By mid-September the instruments that had spent years staring at the back of a dead engine deck were working. The BepiColombo Laser Altimeter fired more than 700,000 pulses over 21.5 hours, MERTIS returned about a gigabit during a 22-hour look at empty space through its planet and calibration ports, and SIMBIO-SYS returned its first image in space (ESA, 6 October 2026). A thruster rehearsal on 24 September produced 11.4 m/s over 8 minutes 42 seconds, the first trajectory correction of the arrival sequence.

The propulsion that carried it here deserves the credit. ESA loaded 581 kg of xenon into the module’s three tanks at Kourou in June 2018, and that fuel went through four QinetiQ T6 gridded ion thrusters, 22 cm across and rated around 4.5 kW each, producing 75 to 145 mN of thrust at a specific impulse up to 4,300 seconds (Hofer et al., AIAA 2010-7114). Do that through Tsiolkovsky’s rocket equation, Δv = v_e × ln(m_0 / m_f), with an effective exhaust velocity near 39 km/s, and burning a bit over a fifth of the stack’s mass buys on the order of 10 km/s of velocity change. The same job on a chemical engine with a 3.3 km/s exhaust would demand a mass ratio near 20 to one, meaning a spacecraft more propellant than spacecraft. That arithmetic is the whole reason solar-electric propulsion exists.

The other constraint was sunlight. At 63 million kilometres the solar flux is roughly 5.6 times what Earth receives, and heat limits how squarely the array can face the Sun, so ESA canted the wings and accepted a deployed span near 30 metres to collect the power four thrusters needed (ESA fact sheet). The September 2024 power fault sat uncomfortably close to that limit, which is why the recovery plan was flown conservatively rather than pushed.

What happens on 21 November is closer to a chemical burn, because capture cannot be done slowly. Arrival commands go up days ahead and execute autonomously, because at Mercury’s distance there is no opportunity to watch a burn and correct it. After capture, the pair separates on 9-10 December, MPO settles into a 480 by 1,500 km polar orbit with a 2.3-hour period, and Mio stretches out to 590 by 11,640 km to study the magnetosphere from outside. Sixteen instruments begin formal operations in April 2027 (ESA fact sheet).

The paired-orbit arrangement matters more than it sounds. MPO works close in, repeatedly crossing the planet’s surface to build topography, map composition and weigh the interior from gravity and radio tracking. Mio works far out, crossing the magnetopause and sampling the solar wind that Mercury sits inside rather than outside. No single spacecraft can do both jobs at once, and building two cost an extra decade and an extra module to carry them.

What MESSENGER left open in 2015 is what these two orbiters are built to close, and the arrival itself is an argument for slowness in a field that rewards speed. BepiColombo spent five years producing thrust no desk lamp could outrun, because that was the cheapest way to buy the velocity change it needed, and the bill for that patience came due in a single burn that nobody will be able to touch.

In a testbed at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, a rotorcraft that has never left Earth crossed a landscape that does not exist. It accelerated over simulated dunes, scanned the ground beneath it, picked out a flat patch, turned, and settled down. On October 23, 2026, NASA described that run as the most thorough rehearsal yet of the moment Dragonfly lifts off for the first time, on Titan in 2034. The test ran in real time on flight-like avionics, with simulated data fed into the navigation cameras, inertial measurement units and lidar the spacecraft will carry (NASA, Oct. 23, 2026). The software did more than fly the vehicle. It searched for a landing site and chose one, and on Titan that choice belongs to the vehicle alone.

Dragonfly is a nuclear-powered octocopter about the size of a small car: roughly 953 kg, 3.85 m across and 1.75 m tall, with four pairs of coaxial 1.35 m blades, a 147 ampere-hour battery and a Multi-Mission Radioisotope Thermoelectric Generator supplied by the Department of Energy through NASA’s radioisotope power program (NASA Dragonfly fact sheet, Sept. 2026). Its five instruments run from a drill that feeds surface material to a mass spectrometer, to a camera suite, a gamma-ray and neutron spectrometer, and a geophysics and meteorology package. Launch is no earlier than 2028, the cruise takes about six years, and the surface mission runs a little over three years.

The world waiting for it is the reason flying makes sense there. Titan’s surface pressure runs about 60 percent above Earth’s, the air is roughly 95 percent nitrogen and 5 percent methane, and the ground sits near -179 degrees Celsius (NASA Titan facts). Sunlight takes about 80 minutes to arrive and lands roughly 100 times fainter than it does at Earth, so solar panels would be close to useless; the radioisotope generator is what keeps the rotors turning. The moon’s pull is weak, with a surface gravity of 1.35 m/s2, about 0.138 times Earth’s (NASA Glenn, 2022). Thick air and weak gravity are the two conditions that turn a spacecraft into an aircraft.

Everything about the recent test follows from that last point. The team fed the flight software simulated sensor data: imagery from the two navigation cameras installed at APL in August 2026, inertial readings, and lidar returns for terrain height and slope (NASA, Oct. 23, 2026). Lidar was the missing piece. The campaign had grown in steps, from spinning a single rotor to a short repositioning flight to a partial scouting flight, and adding lidar finally made a complete first flight reproducible in simulation. A custom camera emulator rendered each synthetic Titan scene on graphics processors with exposure times of roughly 20 to 70 ms, matching what the real cameras will see in flight. Because the run happened on flight-like hardware, the team could watch information move between processes at the millisecond pace it really moves.

Zach Putnam, the mobility subsystem lead engineer at APL, frames the difficulty plainly: “The cool thing about first flight is that it’s our most challenging flight.” It is the case that “uses every piece of flight sensor hardware on the lander” (NASA, Oct. 23, 2026). Leave out a sensor there and you leave out the ability to make a decision.

The part that cannot be rehearsed in software is the moment of release. Dragonfly arrives inside a backshell hanging under a parachute, and has to lower itself clear of that shell before separation, with its rotors already turning. Engineers at Lockheed Martin in Denver, where the cruise stage and entry, descent and landing hardware are being assembled, have been testing that “pose” mechanism: pushing and pulling on it with representative mass to check the loads it must take, lowering it to see how smoothly and quickly it deploys and whether it locks, and tilting the whole rig to reproduce the swing of a backshell beneath a parachute (NASA, Oct. 23, 2026). The pose structure links the backshell to an aluminum interface attached to the lander, and it has to work once, unrepeatably, about 1.6 billion kilometres from home.

That hardware has already been through a strange battery of ground tests. In May and June 2026, engineers suspended the fuselage a few inches above the floor on long bungee cords and measured how vibration at the rotor mounts travelled through the frame, then lowered the vehicle onto protective padding to see how it would sit on its skids. They also pressurized the assembled structure to hunt for gaps, because most planetary hardware is built for vacuum and Dragonfly will sit in air 60 percent denser than Earth’s (NASA Dragonfly blog, July 9, 2026). A slotted foam high-gain antenna, 87.4 cm across, folds onto a motorized arm before each flight so it cannot resonate against the vehicle.

The physics of the machine is worth doing roughly, because it explains how a tonne of hardware can hover on another world. Hover needs thrust equal to weight, T = m * g, so 953 kg on Titan asks for about 1.29 kN. Spread across eight rotor discs of 1.35 m diameter, the total swept area is roughly 11.4 m2, giving a disk loading near 112 N/m2. With air density around 5.7 kg/m3, worked out from Titan’s pressure and temperature and about 4.6 times the density of air at sea level, the induced velocity v_i = sqrt(σ / (2ρ)) comes out near 3.1 m/s. The same machine in Earth’s air would need about 6.8 m/s, so ideal hover power P = T * v_i falls from roughly 8.7 kW to about 4.0 kW. Dense air is a gift: the rotors push against more mass of gas for the same thrust. Real numbers run higher once profile drag and rotor efficiency are counted, and the electrical budget comes from a generator and a 147 ampere-hour battery, which leaves no room for waste.

None of that saves a vehicle that cannot decide for itself. Signals from Titan take the better part of an hour and a half to reach Earth, which is why NASA’s engineers talk about autonomy as a requirement rather than a feature; the rule Putnam repeats is that “everything we do on Titan has to happen autonomously” (NASA, Oct. 23, 2026). So the next round of tests is as much about failure as about flight. The team will run the first flight on the actual flight system instead of the testbed, fly other profiles, and deliberately inject faults to see whether the vehicle notices and recovers on its own.

Spread across 2026 and 2027, that work is the quiet way a 2034 landing gets decided. Dragonfly will spend its first years on Titan moving between dune fields and impact craters, drilling and analyzing samples for the chemistry that runs ahead of life rather than life itself (NASA Dragonfly fact sheet, Sept. 2026). If the autonomy holds and the pose mechanism behaves in flight, the thing that looked like an oversized drone in a Maryland clean room becomes the first powered aircraft to work on another world, and the missions designed after it will look different for that reason.

Two years after it left Cape Canaveral on a Falcon 9, the European Space Agency’s Hera spacecraft turned its main science camera toward the place it has been chasing across the inner solar system and saw, for the first time, what it came to see. Didymos appeared as a single bright pixel in a 1020-by-1020 image, surrounded by background stars that the camera was tracking to subtract out. The asteroid was 236,500 kilometers away at the time, far enough that the image looked almost like a software test pattern. The date was 7 October 2026, exactly two years after launch. The first braking maneuver, BRM-1, is scheduled for 15 October 2026, the mission’s 12 km/s relative velocity has been bleeding away in tiny burns, and full arrival at the binary system is planned for next month, almost a month earlier than the original timeline. The image, published by ESA in early October 2026, is the first resolved optical sighting of the asteroid whose small moonlet Dimorphos NASA hit with the DART impactor four years ago, and it is the start of the science campaign the whole mission was built around, covered in a fresh Universe Today feature by David Dickinson and in ESA’s own early-arrival announcement.

The reason Hera is going to Didymos is the question DART left open. In September 2022, NASA crashed a refrigerator-sized kinetic impactor into Dimorphos at roughly 6.6 kilometers per second, in the first deliberate attempt by any space agency to change the trajectory of a celestial body. The impact shortened Dimorphos’s 11 hour 55 minute orbit around its parent by about 32 minutes, a much larger change than the pre-impact models had predicted. The extras came from ejecta, the spray of rock and dust thrown off the surface at the moment of contact, which acted like an unpropelled rocket exhaust pushing the moonlet the other way. The pre-impact momentum budget was therefore incomplete, and the right number to plug into a future deflection plan depends on details that ground-based telescopes could not measure: the mass of Dimorphos before the hit, the size and depth of the crater DART carved, the porosity of the surface, the density of the interior. Hera’s job is to measure all of these, with enough precision that the next time the world considers deflecting a real asteroid, the engineers will know what the impact will do.

Hera almost did not happen. The original plan, in the early 2010s, was a joint ESA-NASA mission called AIDA, in which NASA would supply DART and ESA would supply an orbiter called AIM that would arrive at Didymos first and watch the impact happen in real time. ESA cancelled AIM in 2016 because the agency’s member states would not underwrite the cost, and for several years the only follow-up to DART was a network of ground-based observatories that the LICIACube flyby camera and Hubble time had to substitute for. ESA’s member states eventually funded a stripped-down replacement called Hera in 2019, and the agency awarded the prime contract to OHB in Bremen, with a launch contract to SpaceX. The spacecraft left Earth on 7 October 2024 from Cape Canaveral’s SLC-40, riding a Falcon 9 first stage, booster B1061-23, that had already flown 22 missions and was expended to give Hera enough energy for a direct transfer, as documented in the mission’s Wikipedia timeline.

The cruise was longer than a Mars transfer and shorter than a trip to a comet. Hera flew by Mars on 12 March 2025, using the planet’s gravity to bend its trajectory and align it for the Didymos encounter, and took the opportunity to image the smaller Martian moon Deimos from a few hundred to a thousand kilometers away, the closest observations of that body since Viking 2 in 1977. Those images later fed a Nature Astronomy study in 2026 arguing that Deimos is a rubble-pile body reshaped by an oblique impact of a 320-meter asteroid, useful as a sanity check on the radar instruments aboard the Juventas CubeSat. Through 2025 and the first half of 2026, the spacecraft’s flight dynamics team used Hera’s Asteroid Framing Camera, a pair of baffle-protected 1020-by-1020 monochrome sensors built by Jena-Optronik in Germany, to practice the eventual arrival on two main-belt asteroids, Otero and Kellyday, that happened to be near the spacecraft’s line of travel. Tracking Otero for three hours and the much fainter Kellyday in July 2025 taught the team how to keep a tiny, slowly-moving point of light centered in a camera designed to image objects thousands of times closer, in the camera test ESA reported in August 2025. In October 2025, with the cruise going smoothly, ESA announced that the arrival had been pulled forward by a month. In March 2026, Hera performed its largest single deep-space maneuver, burning 123 kilograms of hydrazine for a 367 m/s change in velocity. In June and July 2026 the flight software was upgraded, the asteroid phase began.

The arrival sequence itself starts with the first pixel and ends with a network of small spacecraft hovering above a pair of dark, fast-spinning rocks. On 2 October 2026, controllers executed a short test burn to verify the braking configuration. BRM-1, the first real braking maneuver, is set for 15 October 2026, two days after the publication of this post, and a series of further burns will put Hera into orbit around Didymos. From orbit, the spacecraft will map both bodies in detail. The Asteroid Framing Camera, working alongside the Thermal Infra-Red Imager TIRI and the Planetary Altimeter PALT, will return global shape models of Didymos at a few-meter resolution and a 10-centimeter view of the DART impact site, the first close-up of the crater NASA made. The HyperScout-H visible and near-infrared mapper will look for compositional fingerprints across the surface. A Radio Science Experiment will track Hera’s orbit closely enough to pin down the gravity field of the binary, which is the cleanest way to get the mass of Dimorphos and therefore the cleanest measurement of the momentum DART actually transferred.

The CubeSats will do the part of the science Hera cannot do from a safe orbit. Juventas, built by GomSpace in Luxembourg, carries a low-frequency radar called JuRa, a laser altimeter, and a gravimeter, the first radar sounder ever aimed at an asteroid’s interior, and the data it returns will tell the team whether Dimorphos is a uniform rubble pile, a fractured monolith, or a coherent body with a deep layer of regolith over a denser core. If conditions allow, Juventas will also touch down on the surface and use its accelerometers to measure the mechanical response of the regolith, the first in-situ measurement of asteroid surface stiffness. Milani, built by Tyvak International in Italy, is a hyperspectral imager that will survey the surface mineralogy of both bodies and characterize the dust around the binary. Both CubeSats will be released after Hera is in a stable orbit and will operate on their own for a few months before their trajectories carry them away. Once the science is done, the plan is to repurpose the mission as a software laboratory for autonomous deep-space operations, running new code on the spare core of the spacecraft’s LEON3 processor and using the binary system as a long-duration test bench.

The reason the planetary defense community is watching this closely is that the DART impact was a real-world test of a method that only existed in textbooks before 2022, and the textbooks are being rewritten. If Hera measures a momentum transfer close to the simple mass-times-velocity prediction, the kinetic-impactor method works about as well as the engineers hoped, and a future asteroid on an Earth-crossing orbit could be pushed off course with a single heavy spacecraft launched a few years in advance. If the momentum transfer is much larger, the ejecta boost is doing more of the work than the impactor itself, and the design of a real deflection mission should emphasize surface coupling rather than impactor mass. The point of Hera is to give the answer in numbers that can be written into a flight plan. Didymos, a 780-meter rock discovered by the Spacewatch survey in 1996 with a 151-meter moonlet found seven years later, is the laboratory. The first photograph of it from the spacecraft built to study it is, on its own, just a single bright pixel. The work begins now.

Two days after the UK Space Agency signed a contract worth around eighty million US dollars with the in-orbit services company ClearSpace, the post is still drawing puzzled responses from engineers who have watched ClearSpace miss one launch deadline after another. The October 15 award puts ClearSpace’s UK subsidiary in charge of the country’s first nationally commissioned active debris removal mission, called UK ADR, with the goal of capturing two defunct British satellites in low Earth orbit and pulling them down to burn up on a single flight. The contract is the largest piece of business yet for a company whose European Space Agency mission to grab a single space debris target has slipped from 2025 to 2029, and it lands on a small spacecraft stack whose design is still being finalised.

What the UK Space Agency has bought is a service, not a satellite. The agency will hand ClearSpace a list of two retired UK-licensed payloads, then wait while the company flies a robotic servicer to meet them, grapples each in turn, and drops them into the atmosphere in sequence. The contract covers everything from the design and build of the servicer, through ground test and qualification, to the launch, the rendezvous in orbit, and the final disposal burns. Space Minister Liz Lloyd described the mission as the first time any spacecraft will dispose of more than one satellite in this way, and UK Space Agency officials were careful to frame the work as a building block for a broader in-orbit servicing economy rather than a one-off clean-up job (GOV.UK, October 15 2026).

The deal matters because the amount of junk in low Earth orbit has been climbing faster than any country has been willing to clean up. Hundreds of thousands of tracked objects now whiz around the planet at closing speeds that can exceed seventeen thousand miles per hour, and every newly launched mega-constellation adds more mass to a regime that already bristles with abandoned rocket bodies, dead payloads, and fragments from past collisions. The standard response so far has been passivation, the practice of venting leftover fuel and disconnecting power on a dying spacecraft so it does not explode later, combined with rules that ask operators to remove their own hardware within five years of mission end. Passivation reduces future debris, but it does nothing about the cloud of derelicts already up there. Active debris removal, in which a separate spacecraft goes out and grabs the offending object, has been on every space agency’s wish list since the 1980s and on none of their budgets until very recently. A 2025 update to the UK National Space Strategy named in-orbit servicing, assembly, and manufacturing, abbreviated ISAM, as one of four priority areas, and the ADR mission is the first concrete contract to come out of that policy.

ClearSpace did not win the work uncontested. The UK Space Agency ran a competitive procurement in which three bidders responded: ClearSpace UK, Japan’s Astroscale, and the US-based Starfish Space. Astroscale has already completed a commercial active debris removal demonstration, the ADRAS-J mission that flew up to a Japanese rocket stage in 2024 and is still working through rendezvous operations. Starfish Space has flown the Otter pup-sized servicing vehicle on a 2024 orbital transfer test and is now building a larger vehicle called Bluebonnet. ClearSpace itself has not yet reached orbit on its own propulsion stage, having lost its original 2025 launch slot when the ESA payload it was sent to remove was struck by a fragment in 2023 and had to be swapped out for a different target (Behind the Black, October 16 2026, SatNews, October 15 2026). ClearSpace was nonetheless judged the strongest offer, in part because the capture architecture it has been building for the European Space Agency’s Proba-1 retrieval mission is the closest existing match to what UK ADR needs. The two retired UK satellites that UK ADR will go after have not been identified publicly, but both are non-cooperative, meaning they were never built with a grapple fixture or docking adapter, so the servicer has to deal with whatever geometry it finds.

The price tag, around sixty-one million British pounds, lands at the high end of what an active debris removal demonstration has ever cost. The contract is structured so that the money stretches from the present through a launch window that closes in August 2029, with the bulk of the spending sitting on integration, qualification, and operations rather than on the bus itself. ClearSpace UK’s Managing Director, Rob Atchison, framed the next phase in unusually direct terms, telling reporters that the program would hire engineers across several spacecraft disciplines, and that the team would design, build, and qualify a spacecraft capable of safely approaching an object never meant to be captured and bringing it under control. ClearSpace UK will manage industrial delivery and mission operations, targeting a 2029 launch from Saxavord Spaceport on Unst, a Shetland launch site that received thirty million pounds of UK government money in 2024 to keep Britain’s sovereign launch capability alive (GOV.UK, October 15 2026). If the schedule works, the servicer will share its ride to orbit with other payloads heading to low Earth orbit.

The way the servicer is meant to work is the part that has drawn the most attention from debris-removal engineers. After separating from its launch vehicle, the spacecraft will use autonomous rendezvous and proximity operations, the choreography of thruster firings, sensor reads, and trajectory corrections that brings one spacecraft safely next to another, to match orbits with the first derelict target. Once in close formation, a multi-arm robotic manipulator will reach out and clamp onto whatever structural feature the dead satellite offers, since neither target has a standard grapple point. With the first satellite locked in its arms, the servicer will fire its thrusters in the direction that lowers the combined stack’s perigee, the low point of its orbit, into the upper reaches of the atmosphere. The first derelict is then released onto a decaying trajectory that brings it down within months. The servicer, now lighter and carrying a full tank of propellant by design, raises its orbit back up, repeats the rendezvous with the second target, captures it, and brings it down the same way. The sequence is what makes this mission a world first rather than a duplicate of ClearSpace-1, which is only designed to retrieve one object.

The technologies the mission leans on have been in development for nearly a decade. The capture architecture descends from the design ClearSpace built under an ESA contract first awarded in 2019, which uses four robotic arms that wrap around the target like fingers closing around a pen. The rendezvous and proximity operations software draws on Phase 2 of the UK’s Clearing the LEO Environment with Active Removal study, abbreviated CLEAR, in which ClearSpace partnered with Orbit Fab to study in-space refueling and ran a long autonomous approach sequence in simulation. The refueling capability is what makes the spacecraft useful beyond one mission. UK ADR will fly with a refuellable propellant system the company intends to top up between flights, which is the only way a single bus can plausibly clean up more than a handful of derelicts over its lifetime. The wider ISAM sector the mission anchors includes satellite inspection, life extension through on-orbit refueling, and eventually on-orbit assembly of larger structures, with analysts at the UK Space Agency estimating that the segment could grow into a billion-dollar annual market by the mid-2030s (GOV.UK, October 15 2026, Via Satellite, October 15 2026).

Two years is not a long time to design, build, qualify, and launch a brand-new spacecraft, and the skeptics in the debris-removal community are easy to find. ClearSpace’s earlier deadline slippage, the 2024 management shake-up that pushed OHB into a majority role, and the parallel pressure of an ESA contract for a 2027 proximity-operations demonstration all have to resolve before the UK ADR launch window closes. If the company meets its 2029 target, the mission will hand the UK Space Agency the first operational data set on multi-target active debris removal in orbit and give ClearSpace the flight heritage its future servicing business depends on. If it slips, the contract is structured in phases that protect the UK taxpayer from paying for a bus that never flies, and the second target does not get removed.

On August 4, 2026, with a single coordinated command sequence, engineers at NASA’s Jet Propulsion Laboratory switched three power-hungry heaters on Voyager 2 for three lower-power substitutes and turned off a redundant device whose residual heat was already doing the job. The maneuver was nicknamed the “Big Bang” by the mission team because it had to be executed in one uninterrupted block: the probe cannot tolerate a half-finished sequence when the new configuration leaves critical fuel lines running on borrowed thermal margins. Forty-eight years after launch, with plutonium steadily depleting inside its three radioisotope thermoelectric generators, Voyager 2 was running on roughly four watts less available power than it had the year before, and the mission was weeks from a forced instrument shutdown. The swap changed that math. The savings should keep all three of Voyager 2’s remaining science instruments returning data from interstellar space for at least another year before the team has to choose which one to power down next.

Voyager 2 crossed the heliopause in November 2018 and is currently the only spacecraft in the solar system making direct in-situ measurements of the plasma, magnetic field, and energetic particle environment beyond the Sun’s magnetic bubble. Voyager 1 crossed the boundary six years earlier, but Voyager 2 is still returning plasma data that Voyager 1 cannot, because Voyager 1’s plasma science instrument failed in 1980 and was never replaced. The two spacecraft together form humanity’s only working sensor network in the local interstellar medium, and every instrument shutdown is permanent. Once powered off, Voyager’s 1970s electronics cannot be brought back. With Voyager 1 already down to two operating instruments after an unexpected February 2025 power drop forced the LECP shutdown in April of that year, losing a third instrument on Voyager 2 would have left the interstellar mission with a thinner, more asymmetric scientific footprint. The Big Bang also matters as an engineering template. Voyager’s power budget is now so thin that similar swaps will be needed every year or two until the RTGs decay below the threshold needed to run any science instruments at all, which NASA estimates will happen sometime in the 2030s. The procedure the JPL team developed for this swap is the same procedure they will repeat on Voyager 1, and likely on both spacecraft multiple more times before the mission ends.

The Voyager 2 swap was first reported by NASA’s Voyager mission blog on August 4, 2026. The Register’s follow-up the next day added the most concrete engineering detail: a NASA spokesperson told the paper that the swap involved “two heaters and a device that was being kept on since its residual heat was in the right location and it used less power than the actual nearby heater.” The trio was replaced with another three components that together still generated enough heat to keep the fuel lines warm, but at lower wattage. Past swaps on the Voyager spacecraft were usually one-for-one. The Big Bang’s innovation was doing three replacements at once and accepting the temporary thermal risk to the fuel lines in exchange for the combined power savings. Voyager 2 carries a single 70-centimeter titanium tank holding about 100 kilograms of hydrazine at launch, used for attitude control and trajectory correction maneuvers; keeping that fuel from freezing in interstellar space is one of the load-bearing thermal jobs on the spacecraft, and it is the constraint that bounds how aggressively JPL can trade heat-generating components for power savings. Voyager 2’s LECP instrument had already been turned off in March 2025; the plasma science instrument was shut down in September 2024; a third instrument on each Voyager has been off since long before that, leaving three on Voyager 2 and two on Voyager 1. Without the Big Bang, NASA confirmed, another Voyager 2 instrument would have had to be switched off before the end of 2026. With the savings from the swap, that decision has been pushed into 2027 at the earliest. JPL plans to run the same swap on Voyager 1 in the coming months. Voyager 1 is currently farther from Earth than Voyager 2, and both probes are still inside the solar system in the strict astronomical sense, even though both are now in the interstellar medium.

The Voyager power budget is governed by three multihundred-watt radioisotope thermoelectric generators, each containing 24 pressed plutonium-238 oxide spheres. At launch in August 1977, the three RTGs together produced about 470 watts of electrical power. The plutonium-238 half-life is 87.7 years, so the electrical output has dropped by roughly a factor of two over the mission’s lifetime. The probes lose about 4 watts of available power per year, and the drop is accelerating slowly as the thermocouple junctions age and the thermal gradient they exploit shrinks. NASA first began drawing on a backup power reservoir in April 2023; without that step, the mission would have lost at least one more instrument sooner. The thermal architecture is what makes the Big Bang clever. Many components on Voyager 2 give off waste heat as a side effect of operating, and several of those components are physically adjacent to fuel lines, propulsion latches, or science instruments that need to stay above their minimum operating temperatures. Replacing a high-power heater with a lower-power one usually means the heat budget has to be rearranged, but if the old heater was already heating something the new heater does not need to heat, the swap can be near-power-neutral. The Big Bang worked because the three devices that were turned off had already been “ghost heating” their neighbors, with the residual heat in the right place. The three replacements are less powerful individually, but together they keep the fuel lines and adjacent subsystems at the required temperature with a net lower draw from the RTGs. The constraint is sequencing. If the swap had been interrupted partway through, the spacecraft would have been left with an underheated fuel line and an instrument bay that was relying on a component that was about to be turned off. JPL engineers therefore treated the Big Bang as a single atomic operation, sent the entire command sequence as one batch, and then waited more than 23 hours for the signal to reach Voyager 2 and another 23 hours for the engineering telemetry to return confirming the new configuration was stable. The same near-24-hour round trip will apply when the team runs the swap on Voyager 1.

Voyager 2 is now expected to keep all three of its remaining science instruments (the magnetometer, the plasma wave subsystem, and the cosmic ray subsystem) returning interstellar data through at least late 2027, with the team planning to run the same Big Bang swap on Voyager 1 within the next several months. The next decision point is whether the LECP instrument that was shut off on Voyager 1 in April 2025 can be brought back online after that swap, which would give Voyager 1 a third working instrument for the first time in roughly a year. Beyond that, the Voyager power budget will continue to tighten by about four watts per year, and JPL will likely need to run a similar coordinated swap every twelve to twenty-four months until the RTGs decay below the threshold needed for any science operation sometime in the 2030s. The Big Bang is not a permanent fix. It is a way of buying one more year of an interstellar science mission that is now forty-eight years past its design life, using only the hardware that is already aboard the spacecraft.

Source: Wikimedia Commons file page.

Half a gram of asteroid dust, split among three transition metals, has rewritten where Bennu came from. A team led by Maria Schönbächler at ETH Zurich reports on 23 September 2026 in Science Advances that Bennu, the near-Earth asteroid visited by NASA’s OSIRIS-REx spacecraft between 2018 and 2021, did not assemble in the cold outer reaches of the young solar system the way most researchers assumed. It assembled instead near the water-ice line, in the narrow band where temperatures were cold enough to freeze water vapour into solid ice and warm enough inside to keep it as a gas. The work leans on isotopes of iron, titanium and chromium measured in five Bennu sample portions at ETH’s isotope geochemistry lab, and it points to a culprit for the unusual chemistry: Jupiter, which grew large enough, fast enough, to filter coarse material out of the dust disk before Bennu’s parent body could form.

Source: NASA/Goddard/University of Arizona Bennu mosaic on Wikimedia Commons (public domain).

Bennu’s chemistry has been a quiet puzzle for most of the past decade. Earlier sample studies, including the joint OSIRIS-REx and Hayabusa2 preliminary results, had placed it in a family of carbon-rich objects whose closest meteoritic relatives on Earth are the rare CI chondrites: carbon-rich, water-bearing, and chemically the closest match in the meteorite collection to the Sun’s own composition, with very little thermal alteration since the solar system’s birth. What no one had pinned down was where in the protoplanetary disk that fingerprint had been laid down.

The old model put Bennu-class objects far out in the disk, beyond where most comets form, where accretion was slow and hydrated minerals could survive undisturbed. The new isotope measurements turn that on its head. Iron and titanium are distributed so well throughout the Bennu material that the parent object cannot have been a single coarse clump; it must have been built from fine dust mixed across the disk, with ice acting as a glue that bound fine particles into larger aggregates on the cold side of the water-ice line.

The phrase Schönbächler uses for the result is direct: Bennu is a hybrid. It does not clearly match either the inner or the outer solar system. It bears characteristics of both regions, because it was assembled in the specific transition zone where material from both sides met, according to the ETH Zurich announcement.

To anchor that conclusion, the team compared Bennu against the other carbon-rich sample-return target in the modern catalogue: Ryugu, the asteroid Hayabusa2 visited in 2019. The two objects share an isotopic fingerprint with each other and with the CI chondrites, all distinct from the rest of the meteorite collection and from other sampled asteroids. The authors frame the open question as a population question: if Bennu and Ryugu both formed in the same zone, what is that zone producing that sends objects to near-Earth orbits, and are these two a coincidence or a sample of a broader pattern?

That question hands the baton to the next sample-return missions. China’s Tianwen-2 arrived at the quasi-satellite Kamoʻoalewa this summer and is expected to return a sample in 2027. Japan’s MMX mission, scheduled to launch from Tanegashima in October 2026 on an H3, is set to bring back material from Phobos in 2031; Phobos is itself a possible captured asteroid, and a Phobos sample with a Bennu-like signature would extend the snow-line zone picture to the Mars system. The next-mission parallel was also flagged in Space.com’s coverage.

The water-ice line is not a feature of the finished solar system; it is a feature of the protoplanetary disk, the rotating torus of gas and dust around the young Sun. Inside the line, water vapour stays in gas form. Outside it, water freezes onto dust grain surfaces as ice. In standard models the boundary sits somewhere near the present-day orbit of Jupiter, roughly five astronomical units out, and that distance matters because the disk’s solid inventory changes composition sharply there: inside the line, rocky dust; outside, ice-coated dust; and right at the boundary, a transition layer where ice can sublimate, migrate inward as vapour, and recondense.

The new analysis proposes that this transition layer was the assembly site for Bennu, Ryugu, and the CI chondrites, with Jupiter acting as an active filter rather than background. The gas giant formed within roughly one million years of the Sun’s birth, and its gravitational influence quickly became a barrier in the disk. Coarse, clumpy material could not easily cross Jupiter’s orbital neighbourhood; fine dust could, routing around Jupiter from multiple radial directions and arriving well mixed. The result is an unusually homogeneous feedstock for planetesimals forming in the transition zone near the snow line, and that homogeneity is what the Bennu isotope data see.

The team’s mechanism also explains two aspects of the sample. The first is water. Bennu’s parent body incorporated enough ice that, when it was later broken up and the fragments were warmed by the Sun, hydrated minerals appeared in the regolith in the proportions the OSIRIS-REx analysis measured. Ice from just outside the snow line can sublimate as the disk evolves, drift inward as vapour, and recondense inside the line, so a transition-zone planetesimal ends up with both rocky and icy inputs. The second is the chemical match to the Sun. Fine dust, mixed by the disk’s turbulence and routed around Jupiter, ends up with a bulk composition close to the pre-solar nebula because it has not been sorted into coarse and fine reservoirs. Bennu samples that average composition better than any other available asteroid material.

For the broader picture, the implication is that the asteroid belt is not the only reservoir of primitive material in the inner solar system. Near-Earth asteroids like Bennu and Ryugu may be sampling a specific radial slice of the early disk that the main belt, with its heavy thermal and collisional processing, has blurred out. If planetary migration can scatter snow-line objects into near-Earth orbits, then the Bennu sample is not a quirk of one asteroid but a window onto a specific formation environment that the meteorite collection only hints at.

What is striking about the result is how much depends on a small measurement. The five Bennu sample portions, totalling a fraction of a gram, were analysed for isotopic ratios of three elements at a single laboratory over months. None of that is large-scale geophysics or a flagship space telescope survey. It is the kind of bench-scale work that historically has rewritten meteorite science, and it has now done so for an asteroid whose sample exists on Earth only because a NASA spacecraft flew for two and a half years to a rock the size of a small mountain, picked up its surface with a robotic arm, and parachuted the result home.

The Bennu story is not finished. Sample analysis at laboratories around the world is ongoing, with new allocations going out in waves as the OSIRIS-REx curatorial team works through the 120 grams that came back. Schönbächler and her collaborators flag the open question directly: are other asteroids in the same isotopic family, and how widespread is the snow-line zone fingerprint across the inner solar system? That question will not be answered by Bennu alone. It will be answered by what comes back from Kamoʻoalewa, then Phobos, then whatever the next generation of sample-return missions chooses to visit.

For now, the picture is this: Bennu is chemically the closest match in our sample collection to the mixture of elements the Sun itself inherited. Its formation was not a quiet outer-disk story; it was a product of a specific radial neighbourhood in the young solar system, with Jupiter acting as the gatekeeper that kept coarse material out and let fine dust through. The fact that we have a piece of it in a laboratory in Zurich, three years after it fell out of the Utah sky, is a measure of how much of the early solar system can be reconstructed from a sample small enough to lose between your fingers.