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A 51.7-metre rocket lifted off in the dark hours of Friday morning at Sriharikota, on India’s southeast coast, and put a roughly 2,367-kilogram Earth-observation satellite into a Sub-Geosynchronous Transfer Orbit. ISRO’s GSLV-F17 mission was scheduled for 2:55 am IST on 4 September 2026 from the Second Launch Pad at Satish Dhawan Space Centre (ISRO mission page), and the launch itself went according to plan. What made it more than routine was that EOS-05 is the country’s first imaging satellite to operate from a geosynchronous perch, and it flew on a launcher that India’s space agency has spent more than two decades trying to make reliable.

The Geostationary Imaging Satellite programme goes back nearly a decade, to an earlier concept called GISAT-1 that was meant to give India a continuous, fixed-eye view of the subcontinent from 36,000 km up. The original GISAT-1 launch in 2020 was called off because of a technical issue with the cryogenic stage, and a second attempt the following year failed to ignite the cryogenic engine in flight. That delay had already pushed India’s geosynchronous imaging ambition by roughly five years before EOS-05 picked up the work as a direct replacement, with design updates informed by the failure analysis (TechTimes coverage). This time the cryogenic stage behaved. The third stage, designated CUS15, burned for about 814 seconds with the indigenous CE-7.5 engine, which ISRO developed to replace a Russian KVD-1 design after the Missile Technology Control Regime complications of the early 2000s (CE-7.5 Wikipedia entry). The launch matters because India’s earth-observation fleet has until now operated almost entirely from low Earth orbit, where a satellite passes over any given patch of ground for only a few minutes per orbit. From 36,000 km up, EOS-05 will sit over a fixed longitude and stare down at the same region continuously, day and night, gathering visible, near-infrared and shortwave-infrared imagery across roughly the whole visible disc (Wikipedia: EOS-05). That is a qualitatively different tool. A polar-orbiting imager gives you high spatial resolution at the cost of infrequent revisits; a geostationary imager gives you continuous revisits at coarser spatial resolution. EOS-05 is aimed at the second regime, with a 700 mm Ritchey-Chrétien optical telescope tuned for agricultural monitoring, cyclone tracking, and rapid disaster mapping over India, its 7,500-kilometre coastline and the surrounding maritime zones (Times of India mission summary).

This was the 19th flight of the GSLV and only the fifth to use the Mk II configuration with the indigenous cryogenic upper stage, which is the part of the rocket that has historically given ISRO the most trouble. The Mk II stands 51.7 metres tall, weighs 420.5 tonnes at lift-off, and uses a stack of three stages wrapped by a four-metre composite ogive fairing. The first stage is the S139 solid core with four L40H liquid strap-ons clustered around it; the second is the GL40HT liquid-propellant stage; and the third is the cryogenic CUS15 (ISRO mission brochure summary). That third stage is what makes GSLV comparable to other medium-lift geosynchronous launchers in the world: liquid hydrogen and liquid oxygen are notoriously hard to handle because they sit at around -253 °C, which is why cryogenic upper-stage development is often the single largest non-recurring engineering cost for any space agency building a geosynchronous launcher.

The mission was also a deliberate break from a difficult 18 months for the Indian launch programme. PSLV, the workhorse polar-orbit rocket, suffered consecutive failures in May 2025 and again in January 2026, and the investigations into both kept most of ISRO’s launch manifest on the ground (Indian Express on the PSLV investigations). NDTV called GSLV the “Naughty Boy” of the Indian fleet in its post-launch coverage, an affectionate reference to the launcher’s long history of partial failures and stand-downs (NDTV: How ISRO’s ‘Naughty Boy’ Rocket Delivered A Big Win For India). Putting EOS-05 into a precise Sub-GTO is exactly the kind of success that rebuilds confidence launch by launch; ISRO Chairman V. Narayanan confirmed after the mission that the cryogenic upper stage had performed as designed and that the satellite’s Liquid Apogee Motor would now do the work of raising the orbit to its final geosynchronous station.

The CE-7.5 engine that powered that critical third stage is itself the product of a long-running technology development programme. It is a regeneratively cooled, fuel-rich, staged-combustion-cycle engine, which is the same thermodynamic cycle used by the Space Shuttle’s RS-25 main engines (CE-7.5 details). The engine is about 2.14 m long and 1.56 m in diameter, runs at variable thrust, and has a specific impulse of around 454 seconds in vacuum. Staged combustion is the most efficient chemical cycle in practical use, because the propellants are partially burned in a preburner before the main chamber, which extracts more energy from the same mass of fuel. The trade-off is that the engine is harder to build and to test; the preburner runs at extremely high pressures and temperatures, and any leak of the hydrogen-rich preburner gas into the wrong part of the engine can damage it. That is why ISRO’s early GSLV flights used the Russian-supplied KVD-1 instead, which uses a simpler gas-generator cycle at the cost of lower efficiency. By replacing the Russian engine with a domestic one, ISRO removed a long-standing supply-chain risk and aligned the upper stage with India’s existing manufacturing base. It also brought the GSLV’s payload capacity to geosynchronous transfer orbit up to roughly 2,500 kg, which is enough for EOS-05 and for the heavier navigation and communications payloads ISRO has planned for the rest of the decade. The fact that EOS-05 was the first GEO imaging payload to fly on it is not coincidental; ISRO held the satellite back until it had a launcher it trusted enough to put an irreplaceable asset on.

For the broader commercial and strategic picture, EOS-05 also closes a gap that India’s civilian and military users have lived with for years. The Indian National Satellite System’s INSAT fleet has carried transponders for communications and weather imaging for decades, but it has not had a dedicated hyperspectral imager staring down from geostationary orbit. Hyperspectral means the imager splits incoming light into many narrow bands, which lets it distinguish, say, healthy crops from drought-stressed ones in ways that a conventional three-band imager cannot. Continuous coverage from geosynchronous orbit, in turn, lets disaster managers watch a cyclone’s eye wall reorganise in near-real-time or track the spread of a flood across a state hour by hour. The payload does not replace India’s existing low-Earth-orbit earth-observation satellites, which still do most of the heavy lifting on high-resolution mapping. It complements them.

The next test will be whether the satellite reaches its final station and powers up its instruments cleanly. ISRO’s GSLV-F15 in January 2025 placed a navigation satellite into GTO correctly but the satellite’s own Liquid Apogee Motor failed due to an oxidiser valve malfunction, leaving that spacecraft stuck in a transfer orbit (NDTV: What Back-to-Back PSLV Failure Means For ISRO). EOS-05 has the benefit of a fresh cryogenic upper-stage performance record and of a launch-to-orbit precision that should let its own propulsion system do less work. If all goes well, the satellite should be operational at its assigned geostationary slot above the equator within a few months, and India’s weather, agriculture, and disaster-management agencies will have their first continuous watch over the subcontinent.

On Thursday afternoon at 14:00 CEST, a stack of four spacecraft modules that left Earth on an Ariane 5 in October 2018 will, very briefly, become three and then two. ESA’s Mercury Transfer Module is scheduled to detach from BepiColombo’s two science orbiters as the mission’s controllers at the European Space Operations Centre in Darmstadt look on, with the first signal from the freed composite expected back on Earth by 15:53 CEST if everything goes to plan (ESA, 27 August 2026). After eight years and nine gravity assists, the part of the spacecraft that made the trip possible is no longer needed, and the part that has to do the science is, ungainly and for the first time, on its own.

Getting to Mercury is the kind of orbital mechanics problem where the obvious solution is forbidden. Falling toward the Sun does not slow a spacecraft down; it speeds it up, pulled by solar gravity, so the usual chemical-brake trick used at Mars is not enough to be captured into orbit around the smallest planet. BepiColombo has to match Mercury’s velocity almost exactly, and that takes far more energy than reaching even the distant gas giants. The mission’s answer was to spend years bleeding speed against an ion engine instead of staging a single dramatic burn, and the upcoming separation is the moment the engine is, finally, switched off and thrown away. As ESA’s mission manager Santa Martinez put it to Euronews on 1 September, “Mercury is a challenging destination. It’s very difficult to reach, it’s very difficult to operate there.”

Why a separation matters this much, and why the next two months are unusually tense, comes down to what changes about the spacecraft on Thursday. For the cruise the four modules sat one on top of the other inside a tight stack, with their instruments and cameras physically blocked from space by the boxy MTM at the base. Once the MTM floats off, the upper composite begins an entirely new mission with an entirely new thermal and radiation budget. Solar flux near Mercury is roughly ten times what it is near Earth, and the MTM had been there partly to shield the orbiters during the inner solar system transit. The flight director, Ignacio Tanco, has described the moment to Euronews as working “with a very hot pizza oven running right on your back” and “on a knife edge,” because the MPO’s solar panels have to be tilted within fractions of a degree of the Sun. Push them slightly away and the spacecraft starts losing power; angle them slightly closer and they start to bake. There is no second chance to find the right pointing before the thermal balance tips.

The spacecraft itself carries a long memory. BepiColombo launched on Ariane flight VA245 from Kourou on 20 October 2018 and reached escape velocity the same day, then spent almost exactly eight years climbing and falling through the inner solar system using four QinetiQ T6 ion thrusters on the MTM, with a maximum combined thrust of about 290 millinewtons, the most powerful ion engine array ever operated in space. The cruise used one Earth flyby in April 2020, two Venus flybys in October 2020 and August 2021, and six Mercury flybys between October 2021 and January 2025, the last of which imaged the permanently shadowed north polar craters Prokofiev, Kandinsky, Tolkien and Gordimer. The mission’s overall cost is estimated at 1.65 billion euros, and the arrival has already slipped about eleven months from its original December 2025 date because of a power-related anomaly that limited the available thrust before the fourth Mercury flyby in September 2024. On 15 June 2026 at 13:24 UTC the MTM’s solar electric propulsion was switched off for good, and from then on the mission is ballistic: BepiColombo is, in engineering language, “weakly captured” by Mercury’s gravity and following a free-falling trajectory through space.

What happens after 3 September is a sequence of three distinct steps rather than one event. From the separation through late November, the MPO and Mio remain mechanically and electrically joined, with the Magnetospheric Orbiter Sunshield and Interface (MOSIF) still attached, and the two orbiters fly free of the propulsion module for the first time in their lives. Then, between late November and early December 2026, a series of chemical thruster burns raises the orbit’s apocentre and lets Mercury’s gravity do the rest, putting the composite into polar orbit. Once captured, MPO and Mio separate from each other and head to their distinct orbits, MPO in a lower polar orbit for surface and interior science and Mio in a higher polar orbit at 590 by 11,640 kilometres for magnetospheric work. Engineers then spend roughly four months commissioning instruments on both orbiters, and only in April 2027 does the dedicated science campaign begin. The waiting list, when it eventually opens, is unusually long. Mercury’s iron core makes up roughly sixty percent of the planet’s volume, and the mission’s principal question is why a planet that small should pack such a dense metallic interior, and what that interior is doing to the unexpectedly long-lived magnetic field that makes Mercury (along with Earth) the odd rocky planet out. The two orbiters will “taste” the planet’s tenuous exosphere of hydrogen, helium, oxygen, sodium, potassium and calcium at the same time that MPO maps the surface, measuring surface temperatures down to a few hundred metres per pixel and sounding the crust with the RIME ice-penetrating radar that was deployed once in 2023 and has waited seven years to be used on Mercury. Separation on Thursday is the first of a small handful of moments that decide whether any of that science happens, and it is the one the ESA team can already see clearly. After MTM separation, mission controllers listen for the post-separation acquisition of signal and then go through the first health checks. If the composite is in the expected attitude, the high-gain antenna locking on Earth, and the temperatures inside the expected range, MPO and Mio spend the next three months coasting together in what ESA calls a Mercury approach configuration, conservatively waiting for the November capture window. The MTM, the workhorse that brought them there, has no attitude control after separation, so ESA’s flight dynamics manager Frank Budnik has been clear that “you cannot control it, you cannot manoeuvre it,” and the module will begin to tumble away in its own orbit past Mercury rather than around it. After eight years, the most powerful ion engine array ever flown is, for a few million kilometres at least, just a derelict tumbling through interplanetary space with the Sun in its face and no way to turn around.

A sunspot is the last thing to show up. Long before a dark patch breaks through the Sun’s visible surface, the magnetic field that will produce it has already been gathering underneath, and the first reliable hints of its arrival are not in light but in sound. Waves travelling through the Sun’s interior are subtly bent and absorbed as that rising magnetic field pushes through them. Until recently those changes were too small to read reliably. On 14 August 2026, a team led by New Jersey Institute of Technology undergraduate Jonas Tirona reported in the Journal of Geophysical Research: Machine Learning and Computation that a Transformer model they call EarlyDetect can pick out those faint acoustic fingerprints about 9.24 hours before the corresponding sunspots are visible. NASA’s COFFIES team press release confirms the result, and the same paper sits on arXiv as 2601.13144 for those who want to read the full text.

Forecasting storms on Earth usually means watching for the ingredients of a storm and giving people time to react. The same logic is starting to govern space weather, the stream of high-energy radiation and charged particles the Sun sends our way when active regions erupt. Solar flares and coronal mass ejections can disable satellites, disrupt radio communications, and put astronauts at risk, which is why NASA’s Moon to Mars program and NOAA’s Space Weather Prediction Center track every visible sunspot the moment it darkens on the disk. Predicting where and when the next sunspot group will emerge, rather than just classifying one that is already there, has been a long-standing gap in operational forecasting. The current approach relies on human analysts at NOAA and the US Air Force characterizing regions that are already on the disk and estimating their odds of producing a flare. It is reactive by construction. EarlyDetect, if it can be made operationally reliable, would be the first step toward a forecast that announces an active region before it has even arrived.

The team built the model around a sliding-window Transformer architecture, the broad family of neural networks that underpins large language models, and trained it on observations from NASA’s Solar Dynamics Observatory, which has been staring at the Sun continuously since 2010. The Helioseismic and Magnetic Imager aboard SDO records full-disk images at 617.3 nm (the Fe I absorption line) every 45 seconds; from those, the researchers assembled hourly maps of acoustic power over the disk and overlaid them with magnetic field measurements. They then searched for the characteristic dip in acoustic power that happens when a magnetic field rising through the convective zone begins to disturb the normal pattern of solar oscillations. The Transformer, sliding a fixed-size window across a long stream of these hourly maps, picked up the dips and learned to associate them with the appearance of a visible sunspot a few hours later. Once trained, the model was tested against a held-out set of active regions it had never seen. Average lead time was 9.24 hours; the model outperformed both a baseline Transformer and a long short-term memory network that the same group had been developing earlier.

What surprised the team was how much standard preprocessing worked against them. Researchers often smooth acoustic time series to filter out noise and make the underlying trends easier to see, but the cleaned-up signal made the model worse. Tirona and his colleagues Irina N. Kitiashvili at NASA Ames and Alexander G. Kosovichev at NJIT argued in the paper that the temporal smoothing layers averaged away the faintest high-frequency dips the model was supposed to find. The faint signals turned out to be carrying the early warning. Kosovichev compared the effect to hearing a slight change in rhythm within a very noisy orchestra; the louder instruments had to be removed for the quieter beat to count, and Tirona put it more bluntly: noise-cancelling filters, which usually help, were detrimental in almost every case in this specific application. The detection itself relies on an older idea: that the Sun rings like a bell, and you can listen to its hum to learn what is happening inside. Helioseismology, the same field that mapped the rotation of the solar core and the structure of sunspot magnetic fields decades ago, supplies the raw material the Transformer chews on. A helioseismic cutaway of a sunspot’s subsurface structure is visible in the NASA SVS visualization by Kosovichev and colleagues; acoustic waves bounce between the surface and deeper layers of the convection zone, and when a magnetic flux tube pushes up from below, it bends the wave paths and changes how much energy reaches the surface in any given frequency band. Visually, the sunspot at the surface gets all the attention, but the subsurface acoustic distortion has been there for hours, waiting to be read.

The team did not stop at the paper. They released the Solar Active Region Emergence Dataset (SolARED), a curated set of SDO observations of labelled active region emergence events, plus the Solar Active Region Portal at NJIT, an interactive platform for downloading and exploring them. Mengjia Xu, the principal investigator, called SolARED the first public dataset of its kind and positioned it as a shared resource for both the machine learning and heliophysics communities to develop and test new approaches. That kind of release is what turns a single result into a research program. The caveats still matter. Detecting that an active region is about to emerge is not the same as predicting that it will erupt; many active regions, even large ones, never produce a major flare or coronal mass ejection, and the lead time of 9.24 hours is statistical, not deterministic. The paper tested against held-out active regions rather than in real time, so operational performance on live data is still an open question, and the SciTechDaily writeup notes Tirona’s own caution that the model is not yet operational and can still produce false alarms or predictions that arrive too late.

The next milestone is a real-time test. EarlyDetect trained on historical data; running it on the SDO feed as observations arrive, and proving that the 9.24-hour average translates into useful forecasts on individual events, is the open problem. The data and code being public should mean other teams can run that test without waiting for the NJIT group to do it themselves. NASA’s COFFIES program, which funded the work alongside NJIT’s Grace Hopper AI Research Institute, has been working since 2020 to bridge heliophysics theory and the kind of high-cadence data work that machine learning was built for. The 14 August paper is the first concrete demonstration that the bridge can carry weight in both directions.

Image source: Isar Aerospace’s mission page. The image is a launch photograph supplied by Isar Aerospace; the official mission page identifies the flight and company source.

On the evening of 5 September, a narrow white line rose from the coast of northern Norway and bent across the darkening sky. It was the exhaust trail of Spectrum, a 28-metre rocket built by German startup Isar Aerospace. The vehicle left Andøya Spaceport at 22:12 CEST on the mission called Onward and Upward, then completed the sequence that a small launcher must get right: clear the pad, survive maximum aerodynamic pressure, separate its stages, restart the upper stage, and build enough horizontal speed to stay above Earth.

This time, it worked. Isar said the mission deployed its payloads into orbit on Spectrum’s second flight, making the company the first commercial space company from Europe to successfully deliver satellites to orbit. The distinction needs a little care. European rockets have launched from sites outside continental Europe for decades, especially from Europe’s Spaceport in French Guiana. This flight was about a privately developed European launcher operating from European soil. Isar Aerospace’s mission release describes the result and the company is still checking the status of the satellites with its customers.

That makes the photograph at the bottom of this post useful in a plain way. It shows the launch as a bright trail reflected in the sea, with the shoreline and mountains reduced to silhouettes. The image does not show the satellites or the rocket in orbit. It shows the first few minutes of a supply chain that ends there, far above the frame.

Launch capacity is the part of the space business that is easiest to underestimate. Designing a satellite is one problem; finding a rocket, a launch slot, the right orbit, and a place in the payload queue is another. A working small launcher gives customers a different schedule and a different set of possible inclinations. It also gives a government another option when access to space is treated as infrastructure rather than a one-off science project.

For Europe, the argument is also about control. The continent has major spacecraft manufacturers and a large scientific programme, but launch services have been concentrated in a small number of systems and locations. A rocket that is designed, assembled, tested, and launched by a European company does not remove every dependence on international supply chains. It does provide another route to orbit, and it lets European institutions buy a service from a newer supplier while the vehicle is still being qualified.

ESA supported the flight through its Boost! programme, while the payload selection came through the German Space Agency at DLR’s Microlauncher Competition. That connection matters because the first customers were not all large commercial operators. They included educational institutions and startups that needed a relatively inexpensive chance to put hardware in orbit. The launch therefore tested two things at once: the rocket’s flight system and the market around it.

The flight followed a difficult first attempt. Spectrum’s first test flight in March 2025 lasted 30 seconds, according to ESA’s pre-launch briefing. The vehicle cleared the launch pad, but it did not proceed to orbit. For a new launcher, that short flight is still useful data, but it leaves the next mission with a very specific burden: the company must demonstrate that it understood what happened and changed enough of the vehicle or its operation to make the next attempt meaningful.

The second flight was designated a qualification mission, not simply a repeat demonstration. ESA described it as an attempt to prove the Spectrum launch system in the context of the European Launcher Challenge, which requires selected launch-service providers to achieve an orbital launch no later than 2027. Isar’s own account says the vehicle passed maximum aerodynamic pressure, completed main-engine cutoff and stage separation, ignited its second stage, crossed the Kármán line at 100 kilometres, jettisoned the fairing, reached orbital velocity, completed its circularization burn, and separated the spacecraft.

Those milestones are a chain, not a checklist of independent tricks. The first stage must produce thrust while steering through a thickening aerodynamic environment. At maximum dynamic pressure, the vehicle feels the combined effect of air density and speed, so the guidance system cannot treat the rocket as if it were moving through a vacuum. Once the first stage has done its work, separation has to happen cleanly, and the second stage must ignite without upsetting the trajectory. A launcher can survive an engine problem and still fail to deploy a payload if the upper stage cannot finish the job.

Spectrum uses liquid oxygen and propane, with a multi-ignition second-stage engine, according to Isar’s vehicle description. The company lists a payload capacity of up to 1,000 kilograms to low Earth orbit. That number is a capability claim for the launch vehicle, not the mass carried on this mission. This flight carried five CubeSats and one non-separable experiment, the six passengers described by ESA before launch.

The physics behind orbital launch is less about reaching a particular altitude than reaching sideways fast enough. A satellite in low Earth orbit is continually falling toward Earth, but its horizontal velocity makes the ground curve away beneath it. The rocket spends much of its flight building that velocity while gravity pulls down and the atmosphere pushes back. The upper stage then uses a precisely timed burn to raise and circularize the trajectory. Crossing 100 kilometres is a useful boundary for describing spaceflight, but it is not the same as achieving an orbit that can carry a satellite for long.

Propellant choice shapes the engineering trade. Liquid oxygen is the oxidizer; propane is the fuel. The combination can be stored as a liquid at temperatures and pressures that fit a practical launch system, while the engine still needs turbomachinery, ignition hardware, cooling passages, valves, and controls capable of handling rapid changes in flow. Isar says the propellants offer a high density-specific impulse among carbon-based fuel options. That is a design advantage, not a promise that the rocket will have lower total environmental impact in every comparison.

The other design choice is industrial. Isar says Spectrum vehicles 3 through 7 are already in production and that a new 40,000-square-metre facility near Munich is intended to support production of up to 40 launch vehicles per year. These are plans and production targets, not a flight cadence already demonstrated. The difference is important. A rocket company can prove a vehicle once and still fail to create a dependable service if manufacturing, testing, range operations, and customer integration cannot keep pace.

Isar is also building a launch complex in Nova Scotia, Canada, for mid- to high-inclination orbits used by Earth-observation and communications missions. That site would complement Andøya rather than replace it. Different launch locations open different orbital geometries, but they also multiply the work: regulations, range safety, ground equipment, weather planning, logistics, and local operations all have to be made routine.

The next test is repetition. One successful orbital flight changes the conversation, but it does not yet establish a launch service with predictable timing and recovery from ordinary problems. Spectrum’s second flight showed that a European startup could move from a 30-second first test to payload deployment on the next attempt. The company now has to show that this was the beginning of a production programme rather than the high point of a long development cycle.

For the customers waiting on small satellites, the practical result is simple: there is now another European launcher with an orbital success on its record. The hard part starts after the photograph. Isar must turn a successful qualification flight into vehicles that can be built, tested, licensed, and launched often enough for customers to plan around them.

A two-faced Mars has been hiding under its skin for as long as the planet has had a southern half and a northern half. The surface has always advertised the asymmetry: cratered, elevated highlands to the south and smooth, low-lying plains to the north, with a roughly 5 kilometer elevation drop at a boundary that traces most of a great circle around the planet. A study published in Nature on August 27, 2026 now reports that the split goes deeper than anyone had measured, all the way into the mantle. Alexander Berne, formerly at Caltech and now a postdoctoral associate at the University of Arizona, and twelve collaborators used nearly two decades of radio tracking data from three NASA Mars orbiters to infer that the mantle beneath the southern highlands is between 200 and 400 degrees Celsius warmer than the mantle beneath the northern lowlands, and that the contrast is preserved to the present day.

The crustal dichotomy has been one of the most stubborn puzzles in Mars science since the first global topographic maps arrived from the Mars Orbiter Laser Altimeter in the late 1990s. The northern lowlands sit about 5 kilometers lower than the southern highlands on average, and the southern crust is roughly 25 kilometers thicker. Magnetic stripes recorded in the southern crust by Mars Global Surveyor’s magnetometer imply that a once-active dynamo imprinted its field there, while the northern lowlands carry almost no such signature. Seismic waves from marsquakes detected by NASA’s InSight lander between 2018 and 2022 lose energy much more quickly when they travel through the mantle under the southern Terra Cimmeria region than when they pass through Cerberus Fossae in the north. Each of those observations had an individual explanation; what was missing was a single piece of physics that could pull them together.

Tidal tomography is a way to read a planet’s interior by watching how its shape responds to changing gravitational stresses from a partner body. Mars’s orbit is eccentric and its rotation axis is tilted, so the Sun’s tidal pull on the planet varies over the 687-day seasonal cycle. The deformation of the planet under that varying pull depends on the rigidity of the mantle at depth, and a stiffer or softer region flexes by a different amount, leaving a small but measurable fingerprint on the spacecraft flying overhead. Berne and his team analyzed X-band Doppler tracking collected by NASA’s Deep Space Network from Mars Global Surveyor, Mars Odyssey, and Mars Reconnaissance Orbiter over sixteen years and extracted the time-varying component of the Martian gravity field, as described in the Caltech press release. The degree-3 spherical harmonic coefficients of that field, which should be vanishingly small for a spherically symmetric planet, deviated from zero by up to 300 percent, with high statistical significance. A Bayesian Markov-chain Monte Carlo inversion using the semi-analytical code LOV3D translated those gravity deviations into a map of effective shear modulus in the mantle, which in turn implies the temperature contrast.

The map lines up almost perfectly with the surface topography. The team recovered a peak-to-peak variation in mantle shear modulus of 81 percent with a 60 percent uncertainty, with stiffer mantle beneath the northern lowlands, centered near Vastitas Borealis at 45 degrees north, 138 degrees west, and softer mantle beneath the southern highlands, centered near the Hellas basin at 45 degrees south, 42 degrees east. A colder mantle is stiffer, so the inversion translates the stiffness pattern into a present-day temperature anomaly of 200 to 400 degrees Celsius, biased hot to the south. The team also constrained compositional differences: up to 5 percent iron enrichment in the southern mantle relative to the north, a modest but non-negligible contribution that helps the gravity field match without breaking the observed center-of-figure to center-of-mass offset, per Space.com’s coverage. The paper notes that even this 5 percent compositional contribution requires the temperature anomaly; pure composition cannot reproduce the rigidity contrast without violating independent constraints on Mars’s interior structure.

The InSight lander had already left a strong clue, as ScienceDaily summarized. Quality factors, a measure of how much energy a seismic wave loses as it travels through a given region, came in around 500 for events in Terra Cimmeria in the south and between 800 and 2000 for events in Cerberus Fossae in the north. A few hundred kelvin of extra heat in the southern mantle can drive that contrast, and the new tidal tomography result sits right at the temperature the seismic attenuation had implied. Magnetic anomalies in the southern highlands crust also make more sense if the mantle beneath them was unusually hot for part of Mars’s early history: a deep heat source under the south could have driven stronger convection in the underlying outer core, sustaining a localized dynamo that imprinted the crust as it cooled through the Curie temperature before the global field died out around 4 billion years ago. The InSight quality factors are still well above what fully molten rock would produce, so the southern mantle is warm rather than liquid, and three competing explanations remain in play. A giant impact, the so-called Borealis basin formation often invoked to explain the lowlands, would have left the southern mantle iron-enriched relative to the north, consistent with what the team infers, but a single impact is not expected to keep a hemisphere several hundred kelvin hotter than the other for four billion years without help. Spontaneous degree-1 convection would naturally produce a thermal asymmetry but predicts the opposite compositional signature. Thermal insulation by the thick southern crust can sustain the observed temperatures in geodynamic simulations and matches the seismic data, but does not by itself explain why the southern crust is thick in the first place. Berne and his co-authors favor a hybrid story: a giant impact removed or depleted the northern mantle early, leaving the south iron-enriched, and the resulting thicker southern crust then insulated the mantle beneath it long enough for the present-day thermal contrast to survive.

The next probes of this structure will not be landers but gravity missions. Today’s Mars orbiters can resolve degree-3 variations in the time-varying field only because the team pooled two decades of data. A dedicated gravity mission, the Mars-equivalent of GRACE on Earth or GRAIL at the Moon, could resolve similar or finer heterogeneities in a small fraction of the time, and the same technique generalizes to other asymmetric worlds. The authors specifically call out Ganymede, Mercury, Io, and Enceladus as targets where tidal tomography could reveal deep interior structure that no lander has yet touched. The deeper message is that the Martian dichotomy is not just a story about an ancient surface; it is a story about an interior that has remembered its first billion years and is still telling the tale, one radio photon at a time, to anyone with sixteen years of patience to listen.

On 2 September 2026, the German small-launch startup HyImpulse announced that it had closed a Series A extension of more than €50 million, lifting its lifetime equity and grant total to roughly €125 million and growing its commercial order book to over €350 million. The round was jointly led by JOIN Capital, a Berlin-based early-stage venture firm, and Ace Capital Partners, an Israeli aerospace and defence investor, neither of which had participated in the company’s initial €15 million Series A in October 2025. CEO Christian Schmierer framed the raise as Europe’s bid to build an “independent” small launcher: “While providers such as SpaceX offer a scheduled bus service to space, our solutions allow us to develop a flexible taxi service so that our customers can choose individual launch solutions and flexibly plan their schedules” (SpaceNews, European Spaceflight).

The funding matters because HyImpulse is the only European launch startup flying on a hybrid-propulsion architecture, and the first in the world with a published roadmap to put a paraffin-fuelled vehicle into orbit. Its suborbital SR75 has flown once, from the Koonibba Test Range in South Australia on 3 May 2024, and is preparing for a commercial re-flight from SaxaVord Spaceport in Shetland before the end of the year. Its larger orbital rocket, the SL1, has not yet flown but is now scheduled to attempt a maiden launch in 2027, a target the company has consistently described as a stretch goal contingent on further capital. The €50 million buys time on both fronts.

The company’s place in Europe’s launcher debate is awkward. Continent-wide, Ariane 6 and Vega C already provide operational access to space for medium and small payloads, with Ariane 6 capable of carrying over 21 tonnes to low Earth orbit and Vega C rated for up to 2,300 kilograms (European Spaceflight). At the bottom of the mass range, the SL1 is sized for payloads of up to 600 kilograms, small by European standards but large for the kind of responsive, single-customer rides that the global small-launch market has been chasing for a decade. The gap Schmierer is pointing at is real: European providers accounted for less than one per cent of all global launches in 2024, and ArianeGroup’s flagship is optimised for institutional rides, not the weekly cadence a single small-sat operator might want. Whether a hybrid rocket fills that gap, or duplicates it, is the question HyImpulse’s next eighteen months will answer.

HyImpulse was founded in March 2018 as a privately financed spin-off from the German Aerospace Center’s Institute of Space Propulsion at Lampoldshausen, the same facility where the V-2 and early post-war European rocket engines were tested (Wikipedia, DLR). The headquarters sit in Neuenstadt am Kocher in Baden-Württemberg, between Frankfurt and Stuttgart, and the team has grown out of the Lampoldshausen hybrid-motor programme that produced the research the company was built to commercialise. The German government separately committed €95 million in additional funding in late 2024 to support HyImpulse alongside two rival small-launch startups, Isar Aerospace and Rocket Factory Augsburg (European Spaceflight). The new equity raise sits alongside that public funding and brings HyImpulse’s total disclosed war chest close to €125 million in equity and grants combined.

The SR75 is a single-stage suborbital rocket. On its 3 May 2024 flight, named “Light this Candle”, the SR75 launched from the Koonibba Test Range in South Australia, reached an apogee of 50 kilometres, deployed parachutes, and was recovered intact (Southern Launch, ESA Multimedia). The Australian Space Agency called the launch one of the largest commercially launched rockets in Australian history at the time. The mission was supported through ESA’s Boost! programme, which is designed to fund commercial space transportation services in Europe. A second flight from SaxaVord Spaceport in Shetland, planned before the end of 2026, will mark the first launch from European soil under the company’s new agreement with the Scottish spaceport (BBC).

The SL1 is where the technology bet gets serious. The three-stage vehicle stands 33 metres tall, carries a payload fairing 2.2 metres in diameter, and has a lift-off mass of about 54 tonnes (HyImpulse SL1). Each stage burns the same propellant combination as the SR75 (aerospace-grade paraffin wax and liquid oxygen) through clusters of HyPLOX 75 turbopump-fed engines. The first stage carries eight of the engines, the second four, and the third one. According to the company, the SL1’s payload performance was boosted in 2024 to 600 kilograms to low Earth orbit, up from earlier estimates of 500 kilograms to a 400-kilometre sun-synchronous orbit (European Spaceflight – SL1 design update). The vehicle is designed for high flight cadence: the company states it is targeting up to 12 launches per year initially, with a goal of 50 per year by 2030, and turnaround times as short as three weeks between flights.

Hybrid propulsion is the architectural choice that distinguishes the SL1 from every other orbital launcher in development. A hybrid motor stores its fuel as a solid (paraffin in this case, a low-melting-point wax) and pumps its oxidiser as a liquid (cryogenic LOX) into the combustion chamber. The two never mix on the pad, which makes the rocket far safer to handle than a solid or bipropellant liquid stage: a hybrid cannot detonate, can be shut down by closing the oxidiser valve, and stores fuel at ambient temperature. The trade-off has historically been low regression rate and combustion instability, both of which constrain the achievable thrust-to-weight ratio. Paraffin wax partially solves the regression problem because it sublimes and vaporises under heat, exposing fresh surface area more quickly than a rubbery solid fuel like HTPB. The DLR research programme at Lampoldshausen spent more than a decade working on paraffin-LOX combustion, which is the line of work HyImpulse’s founders continued after spinning out (DLR electronic library). The published performance estimates, very high specific impulse comparable to LOX-kerosene bipropellant engines, depend on those gains holding up at full scale. The SR75 proved the motor at suborbital scale; the SL1 will test it at orbital scale.

Whether the SL1 reaches orbit on its first attempt in 2027 is the single question that matters for HyImpulse. The company has booked a €350 million order book, but orders are commitments, not revenue, and small-launch startups have a long history of paper demand evaporating after a failed first flight. The SaxaVord SR75 flight, if it succeeds in the December quarter, will mark the first time a European commercial operator has flown a hybrid rocket from European soil. The SL1 maiden flight, whenever it lands, will be the first attempt to put a paraffin-fuelled orbital launcher on a real flight profile. Both milestones are tractable engineering problems rather than physics ones; whether HyImpulse reaches them on schedule will depend on how fast the new €50 million lets it close the gap between a motor that has flown suborbitally and a launch system that can deliver a payload to orbit. The runway just got longer.