New class of habitable exoplanets are 'a big step forward' in the search for life

New class of habitable exoplanets are 'a big step forward' in the search for life

A new class of exoplanet very different to our own, but which could support life, has been identified by astronomers, which could greatly accelerate the search for life outside our Solar System.

In the search for life elsewhere, astronomers have mostly looked for planets of a similar size, mass, temperature and atmospheric composition to Earth. However, astronomers from the University of Cambridge believe there are more promising possibilities out there.

The researchers have identified a new class of habitable planets, dubbed ‘Hycean’ planets – ocean-covered planets with hydrogen-rich atmospheres – which are more numerous and observable than Earth-like planets.

The researchers say the results, reported in The Astrophysical Journal, could mean that finding biosignatures of life outside our Solar System within the next few years is a real possibility.

“Hycean planets open a whole new avenue in our search for life elsewhere,” said Dr Nikku Madhusudhan from Cambridge’s Institute of Astronomy, who led the research.

Many of the prime Hycean candidates identified by the researchers are bigger and hotter than Earth, but still have the characteristics to host large oceans that could support microbial life similar to that found in some of Earth’s most extreme aquatic environments.

These planets also allow for a far wider habitable zone, or ‘Goldilocks zone’, compared to Earth-like planets. This means that they could still support life even though they lie outside the range where a planet similar to Earth would need to be in order to be habitable.

Thousands of planets outside our Solar System have been discovered since the first exoplanet was identified nearly 30 years ago. The vast majority are planets between the sizes of Earth and Neptune and are often referred to as ‘super-Earths’ or ‘mini-Neptunes’: they can be predominantly rocky or ice giants with hydrogen-rich atmospheres, or something in between.

Most mini-Neptunes are over 1.6 times the size of Earth: smaller than Neptune but too big to have rocky interiors like Earth. Earlier studies of such planets have found that the pressure and temperature beneath their hydrogen-rich atmospheres would be too high to support life.

However, a recent study on the mini-Neptune K2-18b by Madhusudhan’s team found that in certain conditions these planets could support life. The result led to a detailed investigation into the full range of planetary and stellar properties for which these conditions are possible, which known exoplanets may satisfy those conditions, and whether their biosignatures may be observable.

The investigation led the researchers to identify a new class of planets, Hycean planets, with massive planet-wide oceans beneath hydrogen-rich atmospheres. Hycean planets can be up to 2.6 times larger than Earth and have atmospheric temperatures up to nearly 200 degrees Celsius, depending on their host stars, but their oceanic conditions could be similar to those conducive for microbial life in Earth’s oceans. Such planets also include tidally locked ‘dark’ Hycean worlds that may have habitable conditions only on their permanent night sides, and ‘cold’ Hycean worlds that receive little radiation from their stars.

Planets of this size dominate the known exoplanet population, although they have not been studied in nearly as much detail as super-Earths. Hycean worlds are likely quite common, meaning that the most promising places to look for life elsewhere in the Galaxy may have been hiding in plain sight.

However, size alone is not enough to confirm whether a planet is Hycean: other aspects such as mass, temperature and atmospheric properties are required for confirmation.

When trying to determine what the conditions are like on a planet many light years away, astronomers first need to determine whether the planet lies in the habitable zone of its star, and then look for molecular signatures to infer the planet’s atmospheric and internal structure, which govern the surface conditions, presence of oceans and potential for life.

Astronomers also look for certain biosignatures which could indicate the possibility of life. Most often, these are oxygen, ozone, methane and nitrous oxide, which are all present on Earth. There are also a number of other biomarkers, such as methyl chloride and dimethyl sulphide, that are less abundant on Earth but can be promising indicators of life on planets with hydrogen-rich atmospheres where oxygen or ozone may not be as abundant.

“Essentially, when we’ve been looking for these various molecular signatures, we have been focusing on planets similar to Earth, which is a reasonable place to start,” said Madhusudhan. “But we think Hycean planets offer a better chance of finding several trace biosignatures.”

“It’s exciting that habitable conditions could exist on planets so different from Earth,” said co-author Anjali Piette, also from Cambridge.

Madhusudhan and his team found that a number of trace terrestrial biomarkers expected to be present in Hycean atmospheres would be readily detectable with spectroscopic observations in the near future. The larger sizes, higher temperatures and hydrogen-rich atmospheres of Hycean planets make their atmospheric signatures much more detectable than Earth-like planets.

The Cambridge team identified a sizeable sample of potential Hycean worlds which are prime candidates for detailed study with next-generation telescopes, such as the James Webb Space Telescope (JWST), which is due to be launched later this year. These planets all orbit red dwarf stars between 35-150 light years away: close by astronomical standards. Already planned JWST observations of the most promising candidate, K2-18b, could lead to the detection of one or more biosignature molecules.

“A biosignature detection would transform our understanding of life in the universe,” said Madhusudhan. “We need to be open about where we expect to find life and what form that life could take, as nature continues to surprise us in often unimaginable ways.”

Research Report: “Habitability and Biosignatures of Hycean Worlds”

News Related

OTHER NEWS

Space Babes

Houston, we have a problem! Love and sex need to happen in space if we hope to travel long distances and become an interplanetary species, but space organizations are not ... Read more »

Two astronauts return to ISS after 7-Hour Spacewalk

Two international astronauts, Japan’s Akihiko Hoshide and France’s Thomas Pesquet have returned safely to the International Space Station (ISS) after completing a spacewalk that spanned nearly seven hours, NASA said. ... Read more »

Better weather forecasting through satellite isotope data assimilation

As the global climate continues to change and extreme weather events increasingly threaten regions all over the world, accurate weather forecasting is becoming more important than ever. In a new ... Read more »

Quasars as Cosmic Standard Candles

In 1929, Edwin Hubble published observations that galaxies’ distances and velocities are correlated, with the distances determined using their Cepheid stars. Harvard astronomer Henrietta Swan Leavitt had discovered that a ... Read more »

Adaptable optical communications to facilitate future low-earth orbit networks

As government and commercial small-satellite constellations continue to proliferate in low-earth orbit (LEO), DARPA has unveiled a new effort to create a novel optical communications terminal to interconnect diverse constellations ... Read more »

New ocean temperature data help scientists make their hot predictions

We’ve heard that rising temperatures will lead to rising sea levels, but what many may not realise is that most of the increase in energy in the climate system is ... Read more »

A gem of a lab will bring the world of quantum physics into the light

The novel design for a next-generation diamond sensor with capabilities that range from producing magnetic resonance imaging (MRI) of single molecules to detecting slight anomalies in the Earth’s magnetic field ... Read more »

Modern snakes evolved from a few survivors of dino-killing asteroid

A new study suggests that all living snakes evolved from a handful of species that survived the giant asteroid impact that wiped out the dinosaurs and most other living things ... Read more »

Scientists explore method to produce composites with 'shape memory'

Skoltech researchers have investigated a promising type of composite materials in terms of their shape memory behavior: how they resume their original shape following deformation if exposed to the right ... Read more »

Jet stream changes could amplify weather extremes by 2060s

New research provides insights into how the position and intensity of the North Atlantic jet stream has changed during the past 1,250 years. The findings suggest that the position of ... Read more »

TROPICS pathfinder satellite produces global first light images and captures Hurricane Ida

On August 8, NASA’s TROPICS Pathfinder satellite captured global first light images as well as a look inside the structure of Hurricane Ida before and after it made landfall. The ... Read more »

New research takes us closer to figuring out supermassive black holes

Galaxies host supermassive black holes, which weigh millions to billions times more than our Sun. When galaxies collide, pairs of supermassive black holes at their centres also lie on the ... Read more »

Rerun of supernova blast expected to appear in 2037

It’s challenging to make predictions, especially in astronomy. There are however, a few forecasts astronomers can depend on, such as the timing of upcoming lunar and solar eclipses and the ... Read more »

SpaceX launches Starlink satellites into orbit from West Coast

Elon Musk’s SpaceX successfully launched a stack of Starlink satellites into space Monday night, the first such launch since May. The Falcon 9 rocket lifted off through a cloud of ... Read more »

Ballistic air guns and mock moon rocks aid in search for durable space fabrics

The surface of the Moon is a harsh environment with no air, low gravity, dust, and micrometeorites-tiny rocks or metal particles-flying faster than 22,000 mph. These conditions can pose a ... Read more »

CuPID CubeSat will get new perspective on Sun-Earth boundary

When you help build a satellite the size of a shoebox, you learn pretty much everything about it, says Emil Atz, a PhD candidate in Mechanical Engineering at Boston University. ... Read more »

TPY-4 Radar earns official US Government Designation

As the world’s most capable and flexible ground based multi-function long-range radar, Lockheed Martin’s TPY-4 has received its official U.S. Government nomenclature – AN/TPY-4(V)1 – officially marking the radar’s maturity ... Read more »

China launches Zhongxing-9B satellite

China successfully launched a new direct broadcast satellite (DBS) from the Xichang Satellite Launch Center in southwest China’s Sichuan Province Thursday. The satellite, Zhongxing-9B, was launched at 7:50 p.m. (Beijing ... Read more »

DLR agrees cooperation with Spanish start-up Pangea Aerospace

The German Federal Government is turning to efficient start-ups in its quest to ensure independent and competitive access to space for Europe. With their ideas and vision, they can accelerate ... Read more »

Winds delay South Australian launch attempt

UPDATE: Friday’s launch attempt was delayed due to strong upper winds. The Australian Government has given regulatory approval for a commercial rocket launch to take place from a newly licensed ... Read more »

SpaceX to raise bar for space tourism with Inspiration4 launch

SpaceX plans to reach new heights, literally, for space tourism Wednesday by launching the Inspiration4 mission from Florida — the first all-private spaceflight to orbit the Earth. Two men and ... Read more »

Next generation of Orion spacecraft in production for future Artemis missions

Over the next decade, NASA’s Orion spacecraft will carry astronauts during Artemis missions to the Moon to help prepare for human missions to Mars. Work on the spacecraft for Artemis ... Read more »

Orbit MPT30-Ku 12" Airborne SATCOM Terminal receives Intelsat FlexAir for government qualification

Orbit Communication Systems Ltd. reports that the Orbit MPT-30-Ku multi-purpose terminal (MPT) has received full qualification for use with the Intelsat FlexAir for Government service offering. FlexAir is a global ... Read more »

The beach is back: French Riviera marsh ditches seawalls for sand

To save one of the last wetlands on the French Riviera from rising sea levels, conservationists have taken the unusual step of removing its protective seawalls. Instead, they have let ... Read more »

Hughes and OneWeb announce agreements for low earth Orbit satellite service in US and India

Hughes Network Systems, LLC (HUGHES), an innovator in satellite and multi-transport technologies and networks for 50 years, and OneWeb, the low Earth orbit satellite communications company, has announced that they ... Read more »

Groundbreaking technique yields important new details on possible 'fifth force'

A group of researchers have used a groundbreaking new technique to reveal previously unrecognized properties of technologically crucial silicon crystals and uncovered new information about an important subatomic particle and ... Read more »

Dates set for Space Station change of command as Franco-German relations awarded Media prize

The dates have been set for ESA astronaut Thomas Pesquet’s upcoming command of the International Space Station, as ESA astronaut Matthias Maurer prepares to join him on board. Thomas, who ... Read more »

Allen Coral Atlas completes map of the world's coral reefs using satellite imagery

The Allen Coral Atlas partners has announced that after three years, 450+ research teams and counting, and two million satellite images, the habitat mapping of the world’s shallow coral reefs ... Read more »

Some coral reefs are keeping pace with ocean warming

Some coral communities are becoming more heat tolerant as ocean temperatures rise, offering hope for corals in a changing climate. After a series of marine heatwaves hit the Phoenix Islands ... Read more »

Researchers reveal a novel metal where electrons flow with fluid-like dynamics

A team of researchers from Boston College has created a new metallic specimen where the motion of electrons flows in the same way water flows in a pipe – fundamentally ... Read more »

Space junk traffic dangers to be tackled by first-of-its-kind research centre in UK

New ways of tackling the threat that space junk in our skies poses are being explored by University of Warwick scientists, as they pioneer new research that could help the ... Read more »

Milky Way is not homogeneous

In order to better understand the history and evolution of the Milky Way, astronomers are studying the composition of the gases and metals that make up an important part of ... Read more »

Safeguarding clean water for spaceflight missions

By all appearances, the universe beyond Earth is a vast, lonely, and sterile space. Yet, wherever humans may travel, an abundance of microbial life will follow. In a first study ... Read more »

China develops sustainable development satellite

The Chinese Academy of Sciences (CAS) has developed a satellite for pursuing sustainable development. The satellite, SDGSAT-1, has already passed the round-the-clock and multi-load coordinated observation. It is expected to ... Read more »

Space industry grapples with COVID-19-related oxygen fuel shortage

A pandemic-related shortage of a key rocket propellant, liquid oxygen, could force rocket launches to be postponed in coming months, possibly delaying important scientific and national defense missions, industry observers ... Read more »

Gaofen 5-02 satellite launched from Taiyuan

China launched the Gaofen 5-02 Earth-observation satellite on Tuesday morning at the Taiyuan Satellite Launch Center in Shanxi province, according to the China National Space Administration. The administration said the ... Read more »

Largest virtual universe free for anyone to explore

Forget about online games that promise you a “whole world” to explore. An international team of researchers has generated an entire virtual UNIVERSE, and made it freely available on the ... Read more »

Laser solid-phase synthesis of single atom catalysts

Laser fabrication of nanoparticles offers a powerful and flexible alternative to the purely chemical approaches. In recent years, laser synthesized precious metal nanoparticles are becoming increasingly important in catalysis due ... Read more »

Kleos secures A$12.6 million to grow constellation

Kleos Space S.A, a space-powered Radio Frequency Reconnaissance data-as-a- service (DaaS) company, has secured A$12.6 million (equivalent to 9.3 million USD) from new and existing institutional and sophisticated investors in ... Read more »

Eutelsat completes OneWeb equity investment

Eutelsat Communications confirms the closing of its $550m equity investment in OneWeb announced on April 27, 2021. Subject to completion of the subsequently announced investments in OneWeb by Bharti and ... Read more »