Somewhere out in the depths of the cosmos, life could be thriving on a strange kind of planet. Around 2.6 times the size of Earth, this alien world would be hot and covered in ocean, with an atmosphere that’s rich with hydrogen. Humans couldn’t survive there, but maybe we could detect the creatures that do. It’s even possible we could make that detection – and confirm that we’re not alone in the Universe – in the next two or three years.

This radical idea comes from researchers at the University of Cambridge, who published a paper in August speculating on the existence of such a world. Researchers have dubbed the category a world like this would belong to as Hycean planets.

If the existence of Hycean planets is confirmed, it could turbocharge the search for extraterrestrial life because detecting biosignatures from such worlds is potentially a lot easier than doing the same for Earth-like planets. Plus, a lot of already known exoplanets could fall into this class.

“The fundamental advancement here is that this idea will expand and accelerate the search for life elsewhere,” said study author Dr Nikku Madhusudhan. “In a very practical sense, it literally increases our chances.”

Traditionally, astronomers have scanned the skies for hints of oxygen, methane and other biomarkers produced in large quantities by microorganisms here on Earth.

“On Hycean worlds, we’ll be looking for molecules such as methyl chloride and dimethyl sulphide,” said Madhusudhan. These are also produced by life, but in much smaller quantities – something that’s not a problem when it occurs on Hycean worlds.

“The observability of these [planets’] atmospheres would be so good that even if these molecules are present at one part per million, they’ll still be observable,” he said.

Madhusudhan hopes to take advantage of the James Webb Space Telescope, the largest space telescope ever built. He believes that all it would take is a few hours trained on a Hycean planet for the telescope to pick up biosignatures using transit spectroscopy (a technique in which researchers measure the changes in starlight as it filters through the atmosphere of a planet that’s passing in front of it).

As significant as such a discovery would be, it would also beg further questions. “One fundamental question would be: is life possible in such environments? And how would life originate on this planet? You need to do a lot more follow-up observations to robustly establish whether [what you’re seeing] is indeed a signature of life,” said Madhusudhan.

“I may be risking making a big statement here, but this could be our entry point to extraterrestrial biology. But if you’re quoting me on that, please make it clear I’m saying it with some caution!”

Could Neanderthals talk like us?

Big talk from palaeontologists this year, who claimed that Neanderthals had the capacity to hear – and possibly speak – just like us high-minded Homo sapiens.

Once dismissed as uncultured knuckle-dragging cave-dwellers, perspective on our evolutionary cousins has been shifting in recent years. They may have worn ornamental dress, for example. We certainly share DNA with them, and now researchers believe there’s a good chance they were capable of sophisticated verbal communication.

The conclusion comes from researchers in Madrid, who created 3D models of the ear structures of Neanderthals, allowing them to model the frequencies at which they could hear. Neanderthal hearing was attuned to frequencies around 4-5kHz, which happens to match the majority of human speech sounds. Researchers believe if they could hear it, there’s a good chance they could speak it.

What have we found at Mars this year?

2021 has been a busy year for the Red Planet. Three missions arrived in February, having set out seven months before to take advantage of the alignment of Earth and Mars’s orbit, an event that only happens once every 26 months.

The first mission to arrive on 9 February was the United Arab Emirates’ Hope orbiter, the nation’s first planetary mission. The spacecraft’s goal is to study the past and present climate of Mars from orbit. Unlike previous missions from other space agencies, which would only look at specific locations at the same time, Hope will look at changes throughout the day. Over time it will monitor Mars’s daily, monthly and yearly changes to build up a comprehensive image of what the weather is like on the Red Planet.

The next arrival – Tianwen-1, belonging to the Chinese National Space Agency (CNSA) – reached Mars a day later, on 10 February. The spacecraft spent its first few months at Mars surveying the surface from orbit, reconnoitring for the next stage of the mission: setting down the Zhurong rover. The CNSA eventually selected a site in the large Utopia Planitia and successfully touched down on 22 May.

The main goal of the mission was a test of China’s ability to operate on the surface of Mars, paving the way for future missions, however, both orbiter and rover are equipped with cameras, radar and spectrometers that will continue to survey the planet’s surface and atmosphere.

But, back on 18 February – before the Tianwen-1 mission had located a landing site for the Zhurong rover – the last, and largest, of the three missions arrived at Mars, in the form of NASA’s Perseverance lander. It touched down in the Jezero Crater, near what appears to be the site of a past river delta, making it a great place to study the history of water on the Red Planet and its potential past habitability.

Perseverance is closely based on the design of its predecessor, Curiosity, but has one major addition – a suite of instruments dedicated to drilling and storing rock samples from the Martian surface. But although Perseverance is a highly equipped robo-geologist, there’s only so much you can pack onto a rover and send to Mars.

To truly understand the planet (particularly if we want to find evidence of any past life) scientists need to be able to study a Martian sample in the best labs here on Earth. Perseverance represents the first step in that process. It will spend the next few years travelling across Jezero Crater, collecting up to 43 rock samples that it will then leave in caches for a future Sample Return mission (currently being planned by NASA, in collaboration with the European and Japanese space agencies) to collect and return to Earth.

Perseverance attempted to collect its first sample on 5 August, only to discover the next day that the sample vessel was empty, as the rock appears to have crumbled as Perseverance pulled it out of the ground. The rover moved to a more solid-looking rock, nicknamed Rochette, and successfully stored its first sample on 7 September.

At the time of writing the rover had travelled over 2.6km – quite a fast pace for a Martian rover. Its progress has been aided in large part by a spacecraft that hitched a ride to Mars with Perseverance: the Ingenuity Helicopter. The small drone-like rotocraft is a technology demonstration mission, intended to see if it’s possible to fly through the thin Martian atmosphere, the answer to which is a comprehensive ‘yes’. Since its first 39-second test flight on 19 April, Ingenuity has flown over a dozen times, travelling more than 2km.

More elaborate missions using the same technology are being planned, but as Ingenuity is only equipped with a camera, it’s being used to scout ahead of Perseverance, highlighting any potential hazards or objects of interest.

So what have we learned at Mars this year? The UAE learned how to orbit, China learned how to land, and NASA learned how to fly.

• This article first appeared in issue 371 of BBC Science Focus Magazine – find out how to subscribe here

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