The Week in Space and Physics: The Crash of Luna-25
On Luna-25, a horde of lost planets, LK-99 and the seasons of Mars

What went wrong? On Friday afternoon, as Russia’s Luna-25 fired its thrusters to prepare for a landing, the lunar probe abruptly fell silent. Moments later, if early reports are to be believed, the spacecraft smashed into the Moon, putting a sudden end to the mission.
Until then, things seemed to be going to plan. Luna-25 lifted off on August 11, beginning a five day journey towards the Moon. It arrived on schedule, completed several planned manoeuvres and entered into the expected orbit. In doing so, it became the first Russian probe in almost five decades to reach lunar orbit.
The Russians celebrated the moment, taking the opportunity to capture a few Moon pictures. Some of those, showing craters on the dark side of the Moon, echoed the achievements of Luna-3, the first probe to show us that mysterious half of the Moon. By Thursday, as the spacecraft executed a manoeuvre to correct its orbit, all looked set for a landing.
Russia had said a landing attempt would take place on August 21, putting it on the surface two days before India’s Chandrayaan-3 touched down. Though both nations denied they were in a race to reach the surface, Russia's timing certainly made it look like they were trying to get there first.
Before landing, however, Russia needed to lower Luna-25’s altitude, bringing it closer to the surface. Here something seems to have gone badly wrong. According to a statement from Roskosmos, the Russian space agency, an "emergency situation" occurred. Contact with Luna-25 had been lost, they said.
Rumours suggested that thrusters had fired for too long, thus sending the craft plunging towards the surface. Repeated attempts to contact the probe over the next day failed. Russia then announced that it had probably crashed, with the impact likely happening a few minutes after the manoeuvre.
Anatoly Zak, who covers the Russian space program, reported that issues with Luna-25 had been discovered well before the manoeuvre took place. But rather than fix them, managers may have pressured engineers to go ahead with the landing, possibly with the aim of beating India to the surface.
Whatever the reasons, this crash is the latest in a string of failures for Russia’s space program. An earlier mission to Mars, Phobos-Grunt, failed to even leave Earth orbit, eventually burning up in the atmosphere. Other issues have appeared with Russian rockets, and even on Russian parts of the International Space Station.
The breakdown of relations with Europe following Russia’s invasion of Ukraine has not helped either. ESA was supposed to form part of Luna-25, notably providing technology to assist with the landing. But after the invasion, ESA withdrew from the project. Russia has instead been looking towards China for a future Moon program. The failure of Luna 25, however, seems unlikely to inspire their confidence in Russia’s capabilities.
Rogue Planets Litter the Galaxy
The Solar System, some astronomers reckon, once contained another planet. It may have spent several hundred million years with us, quietly circling the Sun in some distant orbit. Yet, at one point, the evidence suggests, Jupiter and Saturn upset the balance of the system. The two gas giants seem to have swung wildly inwards and then outwards. The result was a bout of sudden chaos that reshaped the Solar System, and may have sent one unfortunate world spiralling into the void.
If so, Earth has a long lost companion floating somewhere in the galaxy. The chances of finding it, if it exists, are next to nil. Other such lost worlds, termed “rogue planets”, have, however, been spotted lurking between the stars. Telescopes have already picked out a few examples - but since these planets are usually dark and cold, they are usually hard to find.
A recent study, involving both NASA and Osaka University, used nine years of data to figure out how many rogue planets might be in our galaxy. By looking for evidence of microlensing - a slight shift in starlight caused by heavy objects - they found signs that trillions of lost planets could be out there.
Many of these, they say, would be small planets, roughly the size of Earth. Indeed, they even think Earth-size rogue planets could be more common than larger ones. Smaller planets, they say, are theoretically easier to knock out of a solar system.
These worlds would not, however, look anything like Earth. Deprived of sunlight, they would be frozen solid, doomed to float in an eternal darkness. No warm oceans could support life there; nor could plant life flourish on their surfaces.
Still, new telescopes may soon help us spot more of them. The Osaka study suggests the Nancy Grace Roman telescope, to be launched in 2027, could pick out hundreds of rogue planets. Simultaneous measurements of the same planet from Earth and space could, they say, help us work out the mass and size of any rogue planets it does find.
LK-99 is Not a Superconductor
When a pair of papers last month claimed to have discovered the first room temperature superconductor, they attracted world-wide attention. Such a material has long been sought by material scientists, who hope that it could transform the way we use and manipulate electricity.
After the papers were published, labs around the world thus tried to reproduce the results. The material, known as LK-99, at first glance appeared easy to make. Yet those who tried quickly uncovered errors and omissions in the published recipe, which hindered efforts to recreate it. The first attempts, indeed, failed to create a material that looked anything like a superconductor.
In the original papers on LK-99, the authors described several ways in which the material looked like a superconductor. Crucially, they saw signs of currents flowing through it without any electrical resistance and observed it levitating over magnets, two traits that are common to superconductors.
Some outside researchers were unconvinced by the levitation, noting that LK-99 was not acting as other superconductors do around magnets. A study in China then found signs LK-99 is itself magnetic. In a strong enough magnetic field, they say, LK-99 will therefore appear to float even without being a superconductor.
Other explanations have also appeared for its apparent electrical properties. Impurities in the tested samples contain a compound of copper. At a certain temperature this compound is known to experience a shift in behaviour that results in a fall in electrical resistance. When this is accounted for, researchers say, LK-99 no longer looks like a superconductor.
The Seasons of Mars
NASA’s Curiosity rover has found evidence that Mars once had a regular cycle of wet and dry seasons. For the past few years the rover has been exploring the Gale Crater. In that time, it has found clear signs that a shallow lake long ago filled much of that crater. Fossilised ripples, spotted earlier this year, show that waves once washed over the surface of that lake.
Now, however, Curiosity has found cracks in ancient Martian mud. These cracks form a hexagonal pattern which, planetary scientists say, shows they were made by cycles of wet and dry periods. These cracks could, in other words, be evidence of long gone seasonal shifts in Martian weather.
What this means for the possibility of ancient Martian life is harder to say. The presence of water, along with other chemicals detected by Curiosity, is a strong sign that the right ingredients for life were present. Seasonal shifts could, some think, have created the right conditions for it to have begun. Still, in the absence of harder proof, all that is still just speculation.