We have only one example of biology forming in the universe—life on Earth. But what if life can form in other ways? How do you look for alien life when you don’t know what alien life might look like?

These questions are preoccupying astrobiologists—scientists who look for life beyond Earth. Astrobiologists have attempted to come up with universal rules that govern the emergence of complex physical and biological systems both on Earth and beyond.

I’m an astronomer who has written extensively about astrobiology. Through my research, I’ve learned that the most abundant form of extraterrestrial life is likely to be microbial, since single cells can form more readily than large organisms. But just in case there’s advanced alien life out there, I’m on the international advisory council for the group designing messages to send to those civilizations.

Detecting Life Beyond Earth

Since the first discovery of an exoplanet in 1995, over 5,000 exoplanets, or planets orbiting other stars, have been found.

Many of these exoplanets are small and rocky, like Earth, and in the habitable zones of their stars. The habitable zone is the range of distances between the surface of a planet and the star it orbits that would allow the planet to have liquid water and thus support life as we on Earth know it.

The sample of exoplanets detected so far projects 300 million potential biological experiments in our galaxy—or 300 million places, including exoplanets and other bodies such as moons, with suitable conditions for biology to arise.

The uncertainty for researchers starts with the definition of life. It feels like defining life should be easy, since we know life when we see it, whether it’s a flying bird or a microbe moving in a drop of water. But scientists don’t agree on a definition, and some think a comprehensive definition might not be possible.

NASA defines life as a “self-sustaining chemical reaction capable of Darwinian evolution.” That means organisms with a complex chemical system that evolve by adapting to their environment. Darwinian evolution says that the survival of an organism depends on its fitness in its environment.

The evolution of life on Earth has progressed over billions of years from single-celled organisms to large animals and other species, including humans.

Exoplanets are remote and hundreds of millions of times fainter than their parent stars, so studying them is challenging. Astronomers can inspect the atmospheres and surfaces of Earth-like exoplanets using a method called spectroscopy to look for chemical signatures of life.

Spectroscopy might detect signatures of oxygen in a planet’s atmosphere, which microbes called blue-green algae created by photosynthesis on Earth several billion years ago, or chlorophyll signatures, which indicate plant life.

NASA’s definition of life leads to some important but unanswered questions. Is Darwinian evolution universal? What chemical reactions can lead to biology off Earth?

Evolution and Complexity

All life on Earth, from a fungal spore to a blue whale, evolved from a microbial last common ancestor about four billion years ago.

The same chemical processes are seen in all living organisms on Earth, and those processes might be universal. They also may be radically different elsewhere.

In October 2024, a diverse group of scientists gathered to think outside the box on evolution. They wanted to step back and explore what sorts of processes created order in the universe—biological or not—to figure out how to study the emergence of life totally unlike life on Earth.

Two researchers present argued that complex systems of chemicals or minerals, when in environments that allow some configurations to persist better than others, evolve to store larger amounts of information. As time goes by, the system will grow more diverse and complex, gaining the functions needed for survival, through a kind of natural selection.

They speculated that there might be a law to describe the evolution of a wide variety of physical systems. Biological evolution through natural selection would be just one example of this broader law.

In biology, information refers to the instructions stored in the sequence of nucleotides on a DNA molecule, which collectively make up an organism’s genome and dictate what the organism looks like and how it functions.

If you define complexity in terms of information theory, natural selection will cause a genome to grow more complex as it stores more information about its environment.

Complexity might be useful in measuring the boundary between life and non-life.

However, it’s wrong to conclude that animals are more complex than microbes. Biological information increases with genome size, but evolutionary information density drops. Evolutionary information density is the fraction of functional genes within the genome, or the fraction of the total genetic material that expresses fitness for the environment.

Organisms that people think of as primitive, such as bacteria, have genomes with high information density and so appear better designed than the genomes of plants or animals.

A universal theory of life is still elusive. Such a theory would include the concepts of complexity and information storage, but it would not be tied to DNA or the particular kinds of cells we find in terrestrial biology.

Implications for the Search for Extraterrestial Life

Researchers have explored alternatives to terrestrial biochemistry. All known living organisms, from bacteria to humans, contain water, and it is a solvent that is essential for life on Earth. A solvent is a liquid medium that facilitates chemical reactions from which life could emerge. But life could potentially emerge from other solvents, too.

Astrobiologists Willam Bains and Sara Seager have explored thousands of molecules that might be associated with life. Plausible solvents include sulfuric acid, ammonia, liquid carbon dioxide, and even liquid sulfur.

Alien life might not be based on carbon, which forms the backbone of all life’s essential molecules—at least here on Earth. It might not even need a planet to survive.

Advanced forms of life on alien planets could be so strange that they’re unrecognizable. As astrobiologists try to detect life off Earth, they’ll need to be creative.

One strategy is to measure mineral signatures on the rocky surfaces of exoplanets, since mineral diversity tracks terrestrial biological evolution. As life evolved on Earth, it used and created minerals for exoskeletons and habitats. The hundred minerals present when life first formed have grown to about 5,000 today.

For example, zircons are simple silicate crystals that date back to the time before life started. A zircon found in Australia is the oldest known piece of Earth’s crust. But other minerals, such as apatite, a complex calcium phosphate mineral, are created by biology. Apatite is a primary ingredient in bones, teeth, and fish scales.

Another strategy for finding life unlike that on Earth is to detect evidence of a civilization, such as artificial lights, or the industrial pollutant nitrogen dioxide in the atmosphere. These are examples of tracers of intelligent life called technosignatures.

It’s unclear how and when a first detection of life beyond Earth will happen. It might be within the solar system, or by sniffing exoplanet atmospheres, or by detecting artificial radio signals from a distant civilization.

The search is a twisting road, not a straightforward path. And that’s for life as we know it—for life as we don’t know it, all bets are off.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Image Credit: NASA’s Goddard Space Flight Center/Francis Reddy

Slowly repeating bursts of intense radio waves from space have puzzled astronomers since they were discovered in 2022.

In new research, my colleagues and I have for the first time tracked one of these pulsating signals back to its source: a common kind of lightweight star called a red dwarf, likely in a binary orbit with a white dwarf, the core of another star that exploded long ago.

A Slowly Pulsing Mystery

In 2022, our team made an amazing discovery. Periodic radio pulsations that repeated every 18 minutes, emanating from space. The pulses outshone everything nearby, flashed brilliantly for three months, then disappeared.

We know some repeating radio signals come from a kind of neutron star called a radio pulsar, which spins rapidly (typically once a second or faster), beaming out radio waves like a lighthouse. The trouble is, our current theories say a pulsar spinning only once every 18 minutes should not produce radio waves.

So we thought our 2022 discovery could point to new and exciting physics—or help explain exactly how pulsars emit radiation, which despite 50 years of research is still not understood very well.

More slowly blinking radio sources have been discovered since then. There are now about 10 known “long-period radio transients.”

However, just finding more hasn’t been enough to solve the mystery.

Searching the Outskirts of the Galaxy

Until now, every one of these sources has been found deep in the heart of the Milky Way.

This makes it very hard to figure out what kind of star or object produces the radio waves, because there are thousands of stars in a small area. Any one of them could be responsible for the signal, or none of them.

So, we started a campaign to scan the skies with the Murchison Widefield Array radio telescope in Western Australia, which can observe 1,000 square degrees of the sky every minute. An undergraduate student at Curtin University, Csanád Horváth, processed data covering half of the sky, looking for these elusive signals in more sparsely populated regions of the Milky Way.

And sure enough, we found a new source! Dubbed GLEAM-X J0704-37, it produces minute-long pulses of radio waves, just like other long-period radio transients. However, these pulses repeat only once every 2.9 hours, making it the slowest long-period radio transient found so far.

Where Are the Radio Waves Coming From?

We performed follow-up observations with the MeerKAT telescope in South Africa, the most sensitive radio telescope in the southern hemisphere. These pinpointed the location of the radio waves precisely: They were coming from a red dwarf star. These stars are incredibly common, making up 70 percent of the stars in the Milky Way, but they are so faint that not a single one is visible to the naked eye.

Combining historical observations from the Murchison Widefield Array and new MeerKAT monitoring data, we found that the pulses arrive a little earlier and a little later in a repeating pattern. This probably indicates that the radio emitter isn’t the red dwarf itself, but rather an unseen object in a binary orbit with it.

Based on previous studies of the evolution of stars, we think this invisible radio emitter is most likely to be a white dwarf, which is the final endpoint of small to medium-sized stars like our own sun. If it were a neutron star or a black hole, the explosion that created it would have been so large it should have disrupted the orbit.

It Takes Two to Tango

So, how do a red dwarf and a white dwarf generate a radio signal?

The red dwarf probably produces a stellar wind of charged particles, just like our sun does. When the wind hits the white dwarf’s magnetic field, it would be accelerated, producing radio waves.

This could be similar to how the Sun’s stellar wind interacts with Earth’s magnetic field to produce beautiful aurora and also low-frequency radio waves.

We already know of a few systems like this, such as AR Scorpii, where variations in the brightness of the red dwarf imply that the companion white dwarf is hitting it with a powerful beam of radio waves every two minutes. None of these systems are as bright or as slow as the long-period radio transients, but maybe as we find more examples, we will work out a unifying physical model that explains all of them.

On the other hand, there may be many different kinds of system that can produce long-period radio pulsations.

Either way, we’ve learned the power of expecting the unexpected—and we’ll keep scanning the skies to solve this cosmic mystery.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Image Credit: An artist’s impression of the exotic binary star system AR Scorpii / Mark Garlick/University of Warwick/ESO, CC BY

Water is ubiquitous on Earth—about 70 percent of Earth’s surface is covered by the stuff. Water is in the air, on the surface, and inside rocks. Geologic evidence suggests water has been stable on Earth since about 4.3 billion years ago.

The history of water on early Mars is less certain. Determining when water first appeared, where, and for how long, are all burning questions that drive Mars exploration. If Mars was once habitable, some amount of water was required.

My colleagues and I studied the mineral zircon in a meteorite from Mars and found evidence that water was present when the zircon crystal formed 4.45 billion years ago. Our results, published in the journal Science Advances, may represent the oldest evidence for water on Mars.

A Wet Red Planet

Water has long been recognized to have played an important role in early Martian history. To place our results in a broader context, let’s first consider what “early Mars” means in terms of the Martian geological timescale and then consider the different ways to look for water on Mars.

Like Earth, Mars formed about 4.5 billion years ago. The history of Mars has four geological periods. These are the Amazonian (from today back to 3 billion years), the Hesperian (3 billion to 3.7 billion years ago), the Noachian (3.7 billion to 4.1 billion years ago) and the Pre-Noachian (4.1 billion to about 4.5 billion years ago).

Evidence for water on Mars was first reported in the 1970s when NASA’s Mariner 9 spacecraft captured images of river valleys on the Martian surface. Later orbital missions, including Mars Global Surveyor and Mars Express, detected the widespread presence of hydrated clay minerals on the surface. These would have needed water.

The Martian river valleys and clay minerals are mainly found in Noachian terrains, which cover about 45 percent of Mars. In addition, orbiters also found large flood channels—called outflow channels—in Hesperian terrains. These suggest the short-lived presence of water on the surface, perhaps from groundwater release.

Most reports of water on Mars are in materials or terrains older than 3 billion years. More recent than that, there isn’t much evidence for stable liquid water on Mars.

But what about during the Pre-Noachian? When did water first show up on Mars?

A Window to Pre-Noachian Mars

There are three ways to hunt for water on Mars. The first is using observations of the surface made by orbiting spacecraft. The second is using ground-based observations such as those taken by Mars rovers.

The third way is to study Martian meteorites that have landed on Earth, which is what we did.

In fact, the only Pre-Noachian material we have available to study directly is found in meteorites from Mars. A small number of all meteorites that have landed on Earth have come from our neighboring planet.

An even smaller subset of those meteorites, believed to have been ejected from Mars during a single asteroid impact, contain Pre-Noachian material.

The “poster child” of this group is an extraordinary rock called NWA7034, or Black Beauty.

Black Beauty is a famous Martian meteorite made of broken-up surface material, or regolith. In addition to rock fragments, it contains zircons that formed from 4.48 billion to 4.43 billion years ago. These are the oldest pieces of Mars known.

While studying trace elements in one of these ancient zircons we found evidence of hydrothermal processes—meaning they were exposed to hot water when they formed in the distant past.

Trace Elements, Water, and a Connection to Ore Deposits

The zircon we studied is 4.45 billion years old. Within it, iron, aluminum, and sodium are preserved in abundance patterns like concentric layers, similar to an onion.

This pattern, called oscillatory zoning, indicates that incorporation of these elements into the zircon occurred during its igneous history, in magma.

The problem is that iron, aluminum, and sodium aren’t normally found in crystalline igneous zircon—so how did these elements end up in the Martian zircon?

The answer is hot water.

In Earth rocks, finding zircon with growth zoning patterns for elements like iron, aluminum, and sodium is rare. One of the only places where it has been described is from Olympic Dam in South Australia, a giant copper, uranium, and gold deposit.

The metals in places like Olympic Dam were concentrated by hydrothermal (hot water) systems moving through rocks during magmatism.

Hydrothermal systems form anywhere that hot water, heated by volcanic plumbing systems, moves through rocks. Spectacular geysers at places like Yellowstone National Park in the United States form when hydrothermal water erupts at Earth’s surface.

Finding a hydrothermal Martian zircon raises the intriguing possibility of ore deposits forming on early Mars.

Previous studies have proposed a wet Pre-Noachian Mars. Unusual oxygen isotope ratios in a 4.43-billion-year-old Martian zircon were previously interpreted as evidence for an early hydrosphere. It has even been suggested that Mars may have had an early global ocean 4.45 billion years ago.

The big picture from our study is that magmatic hydrothermal systems were active during the early formation of Mars’ crust 4.45 billion years ago.

It’s not clear whether this means surface water was stable at this time, but we think it’s possible. What is clear is that the crust of Mars, like Earth, had water shortly after it formed—a necessary ingredient for habitability.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Image Credit: JPL-Caltech/NASA

The European Space Agency has given the go-ahead for initial work on a mission to visit an asteroid called Apophis. If approved at a key meeting next year, the robotic spacecraft, known as the Rapid Apophis Mission for Space Safety (Ramses), will rendezvous with the asteroid in February 2029.

Apophis is 340 meters wide, about the same as the height of the Empire State Building. If it were to hit Earth, it would cause wholesale destruction hundreds of miles from its impact site. The energy released would equal that from tens or hundreds of nuclear weapons, depending on the yield of the device.

Luckily, Apophis won’t hit Earth in 2029. Instead, it will pass by Earth safely at a distance of 19,794 miles (31,860 kilometers), about one-twelfth the distance from the Earth to the Moon. Nevertheless, this is a very close pass by such a big object, and Apophis will be visible with the naked eye.

NASA and the European Space Agency have seized this rare opportunity to send separate robotic spacecraft to rendezvous with Apophis and learn more about it. Their missions could help inform efforts to deflect an asteroid that threatens Earth, should we need to in the future.

The Threat From Asteroids

Some 66 million years ago, an asteroid the size of a small city hit Earth. The impact of this asteroid brought about a global extinction event that wiped out the dinosaurs.

Earth is in constant danger of being hit by asteroids, leftover debris from the formation of the solar system 4.5 billion years ago. Located in the asteroid belt between Mars and Jupiter, asteroids come in many shapes and sizes. Most are small, only 10 meters across, but the largest are hundreds of kilometers across, larger than the asteroid that killed the dinosaurs.

The asteroid belt contains one to two million asteroids larger than a kilometer across and millions of smaller bodies. These space rocks feel each other’s gravitational pull, as well as the gravitational tug of Jupiter on one side and the inner planets on the other.

Because of this gravitational tug-of-war, every once in a while an asteroid is thrown out of its orbit and hurtles towards the inner solar system. There are 35,000 such “near-Earth objects” (NEOs). Of these, 2,300 “potentially hazardous objects” (PHOs) have orbits that intersect Earth’s and are large enough that they pose a real threat to our survival.

Do Not Go Gentle Into That Good Night

During the 20th century, astronomers set up several surveys, such as Atlas, in order to detect and study hazardous asteroids. But detection is not enough; we have to find a way to defend Earth against an incoming asteroid.

Blowing up an asteroid, as depicted in the movie Armageddon, is no use. The asteroid would be broken into smaller fragments, which would keep moving in much the same direction. Instead of being hit by one large asteroid, Earth would be hit by a swarm of smaller objects.

The preferred solution is to deflect the incoming asteroid away from Earth so that it passes by harmlessly. To do so, we would need to apply an external force to the asteroid to nudge it away. A popular idea is to fire a projectile at the asteroid. NASA did this in 2022, when a spacecraft called DART collided with an asteroid. Before we do this out of necessity, we have to understand how different types of asteroids would react to such an impact.

Apophis, Ramses, and Osiris-Apex

Apophis was discovered in 2004. The asteroid passed by Earth on December 21, 2004 at a distance of 14 million kilometers. It returned in 2021 and will swing by Earth again in 2029, 2036, and 2068.

Until recently, there was a small chance that Apophis could collide with Earth in 2068. However, during Apophis’ approach in 2021, astronomers used radar observations to refine their knowledge of the asteroid’s orbit. These showed that Apophis would not hit our planet for the next 100 years.

The Ramses mission will rendezvous with Apophis in February 2029, two months before its closest approach to Earth on Friday, April 13. It will then accompany the asteroid as it approaches Earth. The goal is to learn how Apophis’s orbit, rotation, and shape will change as it passes so close to Earth’s gravitational field.

In 2016, NASA launched the “Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer” (Osiris-Rex) mission to study the near-Earth asteroid Bennu. It intercepted Bennu in 2020 to collect samples of rock and soil from its surface and dispatched the rocks in a capsule, which arrived on Earth in 2023.

The spacecraft is still out there, so NASA renamed it the “Origins, Spectral Interpretation, Resource Identification and Security–Apophis Explorer” (Osiris-Apex) and assigned it to study Apophis. Osiris-Apex will reach the asteroid just after its 2029 close encounter. It will then fly low over Apophis’s surface and fire its engines, disturbing the rocks and dust that cover the asteroid to reveal the layer underneath.

A close flyby of an asteroid as large as Apophis happens only once every 5,000 to 10,000 years. Apophis’s arrival in 2029 presents a rare opportunity to study such an asteroid up close, and seeing how it is affected by Earth’s gravitational pull. The information gleaned will shape the way we choose to protect Earth in the future from a real killer asteroid.

Ancient Egyptian Mythology

When Ramses and Osiris-Apex meet up with Apophis in 2029 they will inadvertently reenact a core component of ancient Egyptian cosmology. To the ancient Egyptians, the sun was personified by several powerful gods, chief among them Re. The sun’s setting in the evening was interpreted as Re dying and entering the netherworld.

During his nighttime journey through the netherworld, Re was menaced by the great snake Apophis, who embodied the powers of darkness and dissolution. Only after Apophis had been defeated could Re be revitalized by Osiris, the king of the netherworld. Re could then once again be reborn in the east, rising in the sky once more.

Tomb murals, coffins, and funerary papyri depict Apophis as a large, coiled snake threatening Re as he sails in his solar barque (sailing ship). But Apophis is always defeated, his body pierced by a spear or riven by knives.

Though the asteroid Apophis poses no danger in the near future, Ramses (named after the pharaohs of the same name, which meant “born of Re”) and Osiris-Apex will study it so that one day we will know how to defeat it—or any of its distant brethren.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

NASA plans to send crewed missions to Mars over the next decade—but the 140 million-mile (225 million-kilometer) journey to the red planet could take several months to years round trip.

This relatively long transit time is a result of the use of traditional chemical rocket fuel. An alternative technology to the chemically propelled rockets the agency develops now is called nuclear thermal propulsion, which uses nuclear fission and could one day power a rocket that makes the trip in just half the time.

Nuclear fission involves harvesting the incredible amount of energy released when an atom is split by a neutron. This reaction is known as a fission reaction. Fission technology is well established in power generation and nuclear-powered submarines, and its application to drive or power a rocket could one day give NASA a faster, more powerful alternative to chemically driven rockets.

NASA and the Defense Advanced Research Projects Agency are jointly developing NTP technology. They plan to deploy and demonstrate the capabilities of a prototype system in space in 2027—potentially making it one of the first of its kind to be built and operated by the US.

Nuclear thermal propulsion could also one day power maneuverable space platforms that would protect American satellites in and beyond Earth’s orbit. But the technology is still in development.

I am an associate professor of nuclear engineering at the Georgia Institute of Technology whose research group builds models and simulations to improve and optimize designs for nuclear thermal propulsion systems. My hope and passion is to help design the nuclear thermal propulsion engine that will take a crewed mission to Mars.

Nuclear Versus Chemical Propulsion

Conventional chemical propulsion systems use a chemical reaction involving a light propellant, such as hydrogen, and an oxidizer. When mixed together, these two ignite, which results in propellant exiting the nozzle very quickly to propel the rocket.

These systems do not require any sort of ignition system, so they’re reliable. But these rockets must carry oxygen with them into space, which can weigh them down. Unlike chemical propulsion systems, nuclear thermal propulsion systems rely on nuclear fission reactions to heat the propellant that is then expelled from the nozzle to create the driving force or thrust.

In many fission reactions, researchers send a neutron toward a lighter isotope of uranium, uranium-235. The uranium absorbs the neutron, creating uranium-236. The uranium-236 then splits into two fragments—the fission products—and the reaction emits some assorted particles.

More than 400 nuclear power reactors in operation around the world currently use nuclear fission technology. The majority of the nuclear power reactors in operation are light-water reactors. These fission reactors use water to slow down the neutrons and absorb and transfer heat. The water can create steam directly in the core or in a steam generator, which drives a turbine to produce electricity.

Nuclear thermal propulsion systems operate in a similar way, but they use a different nuclear fuel that has more uranium-235. They also operate at a much higher temperature, which makes them extremely powerful and compact. Nuclear thermal propulsion systems have about 10 times more power density than a traditional light-water reactor.

Nuclear propulsion could have a leg up on chemical propulsion for a few reasons.

Nuclear propulsion would expel propellant from the engine’s nozzle very quickly, generating high thrust. This high thrust allows the rocket to accelerate faster.

These systems also have a high specific impulse. Specific impulse measures how efficiently the propellant is used to generate thrust. Nuclear thermal propulsion systems have roughly twice the specific impulse of chemical rockets, which means they could cut the travel time by a factor of two.

Nuclear Thermal Propulsion History

For decades, the US government has funded the development of nuclear thermal propulsion technology. Between 1955 and 1973, programs at NASA, General Electric, and Argonne National Laboratories produced and ground-tested 20 nuclear thermal propulsion engines.

But these pre-1973 designs relied on highly enriched uranium fuel. This fuel is no longer used because of its proliferation dangers, or dangers that have to do with the spread of nuclear material and technology.

The Global Threat Reduction Initiative, launched by the Department of Energy and National Nuclear Security Administration, aims to convert many of the research reactors employing highly enriched uranium fuel to high-assay, low-enriched uranium, or HALEU, fuel.

High-assay, low- enriched uranium fuel has less material capable of undergoing a fission reaction compared with highly enriched uranium fuel. So, the rockets need to have more HALEU fuel loaded on, which makes the engine heavier. To solve this issue, researchers are looking into special materials that would use fuel more efficiently in these reactors.

NASA and the DARPA’s Demonstration Rocket for Agile Cislunar Operations, or DRACO, program intends to use this high-assay, low-enriched uranium fuel in its nuclear thermal propulsion engine. The program plans to launch its rocket in 2027.

As part of the DRACO program, the aerospace company Lockheed Martin has partnered with BWX Technologies to develop the reactor and fuel designs.

The nuclear thermal propulsion engines in development by these groups will need to comply with specific performance and safety standards. They’ll need to have a core that can operate for the duration of the mission and perform the necessary maneuvers for a fast trip to Mars.

Ideally, the engine should be able to produce high specific impulse while also satisfying the high thrust and low engine mass requirements.

Ongoing Research

Before engineers can design an engine that satisfies all these standards, they need to start with models and simulations. These models help researchers, such as those in my group, understand how the engine would handle starting up and shutting down. These are operations that require quick, massive temperature and pressure changes.

The nuclear thermal propulsion engine will differ from all existing fission power systems, so engineers will need to build software tools that work with this new engine.

My group designs and analyzes nuclear thermal propulsion reactors using models. We model these complex reactor systems to see how things such as temperature changes may affect the reactor and the rocket’s safety. But simulating these effects can take a lot of expensive computing power.

We’ve been working to develop new computational tools that model how these reactors act while they’re starting up and operated without using as much computing power.

My colleagues and I hope this research can one day help develop models that could autonomously control the rocket.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Image Credit: NASA

When scientists discovered permafrost ice caps on Mars’ north pole in 1976, the news immediately sparked speculation about potential life on the red planet. The later discovery of exposed ice on the south pole further teased the idea.

In 2003, the Mars Odyssey orbiter spacecraft, equipped with cameras that could see both visible and infrared reflections from the Martian surface, found a surprisingly hefty amount of ice across the planet. These and other missions are looking to answer one of science’s biggest questions: Was Mars ever a habitable world—and more importantly, is it still?

But water is just one part of the equation. Solar radiation is another. Radiation destroys DNA, contributing to mutations and cancer. For astronauts, a flare up in solar radiation could damage the body’s ability to repair itself—even with protective shielding.

“On Mars, the lack of an effective ozone shield allows roughly 30 percent more damaging ultraviolet radiation to reach the surface in comparison with Earth,” wrote Aditya Khuller at NASA’s Jet Propulsion Laboratory and colleagues in a new study of Martian habitability.

If life exists on Mars, a creature would have to withstand radiation and have access to water. One potential niche fulfilling these requirements? Dusty ice. Normally, ice allows dangerous levels of ultraviolet radiation to shine through. The new study simulated radiation and water flow and found that just a small amount of Martian dust inside ice resulted in dangerous ultraviolet levels 25 times lower than in pure ice. The results suggest any organisms inside this “dirty” ice shield could sip water and still be protected against radiation.

Unlike previous studies focusing on Mars’ icy polar regions, the team zeroed in on the planet’s temperate zone. In Earth terms, it would be a band that covers most of North America, Europe, Asia, North Africa, and Australia in latitude—most of the places where people currently live.

Ice, Ice, Baby

Mars isn’t exactly a vacation destination.

Its thin atmosphere of mostly carbon dioxide, nitrogen, and argon is far from habitable for us humans. In contrast to Earth’s blue vistas, the planet’s dusty sky is a hazy red. Temperatures are wildly unpredictable, with highs varying between a comfortable 70 degrees Fahrenheit and an unlivable -225 degrees Fahrenheit. Extreme winds stir up planet-wide dust storms.

Like Earth, Mars also has icy glaciers at its polar regions that never melt. But when summer rolls around, the planet’s temperate zone warms up enough to melt ice into tiny drops of water—creating a potential nursery for life.

This got scientists wondering: It is possible there is life on Mars now?

The question isn’t all academic. We’ve been eyeing Mars as a second home for us Earthlings. Though astronomers are searching for habitable planets around the galaxy, in the near term, Mars may be our best bet. SpaceX, famously, is aiming to launch a trip to the red planet.

If, or when, humans first step on Mars, we need to know whether life already exists there. As many movies have made clear: Alien microbes are bad news. And we may want to take steps to conserve life too. One way to find out is by looking for photosynthesis, the chemical reaction that spurred much of Earth’s life today. On early Earth, living organisms—bacteria, plants, algae—captured certain wavelengths of light and transformed them into energy.

Light Up the Life

For life as we know it to exist, it would need access to water and the wavelengths of light that power photosynthesis as well as protection from harmful radiation.

Here’s where dusty ice could play a role. Martian ice likely began as dusty snow, which eventually compacted into ice over a few million years. Some of this turned into smaller ice fields and some into glaciers. In its mid-latitudes—the “comfortable” zone—some dusty ice fields were covered up by rocks then later excavated by meteorite impacts to re-expose the ice.

“Polar locations on Mars are too cold for snow and ice to melt,” wrote the authors. “But exposed dusty ice in the mid-latitudes might be melting at present.”

In other words, Mars may already have a habitable zone for microbes.

To test the idea, the team developed a computer program to predict how snow morphs into ice blobs or glaciers on Earth and Mars based on historical data. The simulation tapped the physics of water, ice, and snow and how they change when mixed with impurities such as Martian dust. The authors also developed a way to gauge how Martian dust absorbs light and other radiation. They compared the Martian results to relatively similar ice sheets with impurities in Greenland.

The results were clear: Compared to pure water ice, ice spiked with Martian dust absorbed at least seven orders of magnitude more radiation overall and slashed levels of dangerous ultraviolet radiation. In ice made up of just 0.1 percent dust, ultraviolet radiation levels tanked without blocking the crucial wavelengths of light that support photosynthesis.

Mars is far colder than our home planet, but the Martian simulations showed results similar to those observed in near-freezing conditions on Earth. Here, microbial habitats blossom in shallow ice sheets, glaciers, and ice-covered lakes, where dark dust and sediment layers absorb solar radiation and heat up, forming holes in the ice. Liquid water and dust mix at the bottom of these holes, while a translucent ice lid freezes over the top, sealing in nutrients that living creatures below use for photosynthesis.

Although Martian polar ice is too cold to melt, mid-latitude snowpacks with a little dust just a few inches below the ice could similarly generate enough water to support life and combat solar radiation. In other words, the simulated scenario is eerily similar to what we see on Earth, with conditions that could allow microbial life to thrive.

To be clear, the results are all hypothetical. Martian water runoffs, for example, rely on the size of ice chunks. How dust is distributed among Martian ice could also change its melting patterns. However, the study suggests that photosynthesis just might be possible for organisms buried in snow and ice on Mars.

“If small amounts of liquid water are available at these depths, mid-latitude ice exposures could represent the most easily accessible locations to search for extant life on Mars,” wrote the team.

Image Credit: Areas of dusty ice (white) in a Martian gully / NASA/JPL-Caltech/University of Arizona

For the past few years, a series of controversies have rocked the well-established field of cosmology. In a nutshell, the predictions of the standard model of the universe appear to be at odds with some recent observations.

There are heated debates about whether these observations are biased, or whether the cosmological model, which predicts the structure and evolution of the entire universe, may need a rethink. Some even claim that cosmology is in crisis. Right now, we do not know which side will win. But excitingly, we are on the brink of finding that out.

To be fair, controversies are just the normal course of the scientific method. And over many years, the standard cosmological model has had its share of them. This model suggests the universe is made up of 68.3 percent “dark energy” (an unknown substance that causes the universe’s expansion to accelerate), 26.8 percent dark matter (an unknown form of matter) and 4.9 percent ordinary atoms, very precisely measured from the cosmic microwave background—the afterglow of radiation from the Big Bang.

It explains very successfully multitudes of data across both large and small scales of the universe. For example, it can explain things like the distribution of galaxies around us and the amount of helium and deuterium made in the universe’s first few minutes. Perhaps most importantly, it can also perfectly explain the cosmic microwave background.

This has led to it gaining the reputation as the “concordance model.” But a perfect storm of inconsistent measurements—or “tensions” as they’re known as in cosmology—are now questioning the validity of this longstanding model.

Uncomfortable Tensions

The standard model makes particular assumptions about the nature of dark energy and dark matter. But despite decades of intense observation, we still seem no closer to working out what dark matter and dark energy are made of.

The litmus test is the so-called Hubble tension. This relates to the Hubble constant, which is the rate of expansion of the universe at the present time. When measured in our nearby, local universe, from the distance to pulsating stars in nearby galaxies, called Cepheids, its value is 73 km/s/megaparsec (Mpc is a unit of measure for distances in intergalactic space). However, when predicted theoretically, the value is 67.4 km/s/Mpc. The difference may not be large (only 8 percent), but it is statistically significant.

The Hubble tension became known about a decade ago. Back then, it was thought that the observations may have been biased. For example, the cepheids, although very bright and easy to see, were crowded together with other stars, which could have made them appear even brighter. This could have made the Hubble constant higher by a few percent compared to the model prediction, thus artificially creating a tension.

With the advent of the James Webb Space Telescope (JWST), which can separate the stars individually, it was hoped that we would have an answer to this tension.

Frustratingly, this hasn’t yet happened. Astronomers now use two other types of stars besides the cepheids (known as the tip of the red giant branch stars (TRGB) and the J-region asymptotic giant branch (JAGB) stars). But while one group has reported values from the JAGB and TRGB stars that are tantalizingly close to the value expected from the cosmological model, another group has claimed that they are still seeing inconsistencies in their observations. Meanwhile, the cepheids measurements continue to show a Hubble tension.

It’s important to note that although these measurements are very precise, they may still be biased by some effects uniquely associated with each type of measurement. This will affect the accuracy of the observations, in a different way for each type of stars. A precise but inaccurate measurement is like trying to have a conversation with a person who is always missing the point. To solve disagreements between conflicting data, we need measurements that are both precise and accurate.

The good news is that the Hubble tension is now a rapidly developing story. Perhaps we will have the answer to it within the next year or so. Improving the accuracy of data, for example by including stars from more far away galaxies, will help sort this out. Similarly, measurements of ripples in spacetime known as gravitational waves will also be able to help us pin down the constant.

This may all vindicate the standard model. Or it may hint that there’s something missing from it. Perhaps the nature of dark matter or the way that gravity behaves on specific scales is different to what we believe now. But before discounting the model, one has to marvel at its unmatched precision. It only misses the mark by at most a few percent, while extrapolating over 13 billion years of evolution.

To put it into perspective, even the clockwork motions of planets in the solar system can only be computed reliably for less than a billion years, after which they become unpredictable. The standard cosmological model is an extraordinary machine.

The Hubble tension is not the only trouble for cosmology. Another one, known as the “S8 tension,” is also causing trouble, albeit not on the same scale. Here the model has a smoothness problem, by predicting that matter in the universe should be more clustered together than we actually observe—by about 10 percent. There are various ways to measure the “clumpiness” of matter, for example by analyzing the distortions in the light from galaxies produced by the assumed dark matter intervening along the line of sight.

Currently, there seems to be a consensus in the community that the uncertainties in the observations have to be teased out before ruling out the cosmological model. One possible way to alleviate this tension is to better understand the role of gaseous winds in galaxies, which can push out some of the matter, making it smoother.

Understanding how clumpiness measurements on small scales relate to those on larger scales would help. Observations might also suggest there is a need to change how we model dark matter. For example, if instead of being made entirely of cold, slow moving particles, as the standard model assumes, dark matter could be mixed up with some hot, fast-moving particles. This could slow down the growth of clumpiness at late cosmic times, which would ease the S8 tension.

JWST has highlighted other challenges to the standard model. One of them is that early galaxies appear to be much more massive that expected. Some galaxies may weigh as much as the Milky Way today, even though they formed less than a billion years after the Big Bang, suggesting they should be less massive.

However, the implications against the cosmological model are less clear in this case, as there may be other possible explanations for these surprising results. Improving the measurement of stellar masses in galaxies is key to solving this problem. Rather than measuring them directly, which is not possible, we infer these masses from the light emitted by galaxies.

This step involves some simplifying assumptions, which could translate into overestimating the mass. Recently, it has also been argued that some of the light attributed to stars in these galaxies is generated by powerful black holes. This would imply that these galaxies may not be as massive after all.

Alternative Theories

So, where do we stand now? While some tensions may soon be explained by more and better observations, it is not yet clear whether there will be a resolution to all of the challenges battering the cosmological model.

There has been no shortage of theoretical ideas of how to fix the model though—perhaps too many, in the range of a few hundred and counting. That’s a perplexing task for any theorist who may wish to explore them all.

The possibilities are many. Perhaps we need to change our assumptions of the nature of dark energy. Perhaps it is a parameter that varies with time, which some recent measurements have suggested. Or maybe we need to add more dark energy to the model to boost the expansion of the universe at early times, or, on the contrary, at late times. Modifying how gravity behaves on large scales of the universe (differently than done in the models called Modified Newtonian Dynamics, or MOND) may also be an option.

So far, however, none of these alternatives can explain the vast array of observations the standard model can. Even more worrisome, some of them may help with one tension but worsen others.

The door is now open to all sorts of ideas that challenge even the most basic tenets of cosmology. For example, we may need to abandon the assumption that the universe is “homogeneous and isotropic” on very large scales, meaning it looks the same in all directions to all observers and suggesting there are no special points in the universe. Others propose changes to the theory of general relativity.

Some even imagine a trickster universe, which participates with us in the act of observation, or which changes its appearance depending on whether we look at it or not—something we know happens in the quantum world of atoms and particles.

In time, many of these ideas will likely be relegated to the cabinet of curiosities of theorists. But in the meantime, they provide a fertile ground for testing the “new physics.”

This is a good thing. The answer to these tensions will no doubt come from more data. In the next few years, a powerful combination of observations from experiments such as JWST, the Dark Energy Spectroscopic Instrument (DESI), the Vera Rubin Observatory and Euclid, among many others, will help us find the long-sought answers.

Tipping Point

On one side, more accurate data and a better understanding of the systematic uncertainties in the measurements could return us to the reassuring comfort of the standard model. Out of its past troubles, the model may emerge not only vindicated, but also strengthened, and cosmology will be a science that is both precise and accurate.

But if the balance tips the other way, we will be ushered into uncharted territory, where new physics will have to be discovered. This could lead to a major paradigm shift in cosmology, akin to the discovery of the accelerated expansion of the universe in the late 1990s. But on this path we may have to reckon, once and for all, with the nature of dark energy and dark matter, two of the big unsolved mysteries of the universe.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Image Credit: NASA, ESA, CSA, STScI, Webb ERO Production Team

The rings of Saturn are some of the most famous and spectacular objects in the solar system. Earth may once have had something similar.

In a paper published last week in Earth and Planetary Science Letters, my colleagues and I present evidence that Earth may have had a ring.

The existence of such a ring, forming around 466 million years ago and persisting for a few tens of millions of years, could explain several puzzles in our planet’s past.

The Case for a Ringed Earth

Around 466 million years ago, a lot of meteorites started hitting Earth. We know this because many impact craters formed in a geologically brief period.

In the same period, we also find deposits of limestone across Europe, Russia, and China containing very high levels of debris from a certain type of meteorite. The meteorite debris in these sedimentary rocks shows signs that they were exposed to space radiation for much less time than we see in meteorites that fall today.

Many tsunamis also occurred at this time, as can be seen from other unusual jumbled up sedimentary rocks.

We think all these features are likely related to one another. But what links them together?

A Pattern of Craters

We know of 21 meteorite impact craters that formed during this high-impact period. We wanted to see if there was a pattern in their locations.

Using models of how Earth’s tectonic plates moved in the past, we mapped out where all these craters were when they first formed. We found all of the craters are on continents that were close to the equator in this period, and none are in places that were closer to the poles.

So, all the impacts occurred close to the equator. But is this actually a fair sample of the impacts that occurred?

Well, we measured how much of Earth’s land surface suitable for preserving a crater was near the equator at that time. Only about 30 percent of the suitable land was close to the equator, with 70 percent at higher latitudes.

Under normal circumstances, asteroids hitting Earth can hit at any latitude, at random, as we see in craters on the moon, Mars, and Mercury.

So it’s extremely unlikely that all 21 craters from this period would form close to the equator if they were unrelated to one another. We would expect to see many other craters at higher latitudes as well.

We think the best explanation for all this evidence is that a large asteroid broke up during a close encounter with Earth. Over several tens of millions of years, the asteroid’s debris rained down onto Earth, creating the pattern of craters, sediments, and tsunamis we describe above.

How Rings Form

You may know that Saturn isn’t the only planet with rings. Jupiter, Neptune, and Uranus have less obvious rings, too. Some scientists have even suggested that Phobos and Deimos, the small moons of Mars, may be remnants of an ancient ring.

So, we know a lot about how rings form. Here’s how it works.

When a small body (like an asteroid) passes close to a large body (like a planet), it gets stretched by gravity. If it gets close enough (inside a distance called the Roche limit), the small body will break apart into lots of tiny pieces and a small number of bigger pieces.

All those fragments will be jostled around and gradually evolve into a debris ring orbiting the equator of the larger body. Over time, the material in the ring will fall down to the larger body, where the larger pieces will form impact craters. These craters will be located close to the equator.

So, if Earth destroyed and captured a passing asteroid around 466 million years ago, it would explain the anomalous locations of the impact craters, the meteorite debris in sedimentary rocks, craters and tsunamis, and the meteorites’ relatively brief exposure to space radiation.

A Giant Sunshade?

Back then, the continents were in different positions due to continental drift. Much of North America, Europe, and Australia were close to the equator, whereas Africa and South America were at higher southern latitudes.

The ring would have been around the equator. And since Earth’s axis is tilted relative to its orbit around the sun, the ring would have shaded parts of Earth’s surface.

This shading in turn might have caused global cooling, as less sunlight reached the planet’s surface.

This brings us to another interesting puzzle. Around 465 million years ago, our planet began cooling dramatically. By 445 million years ago it was in the Hirnantian Ice Age, the coldest period in the past half a billion years.

Was a ring shading Earth responsible for this extreme cooling? The next step in our scientific sleuthing is to make mathematical models of how asteroids break up and disperse and how the resulting ring evolves over time. This will set the scene for climate modeling that explores how much cooling could be imposed by such a ring.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Image Credit: Artist’s impression of Earth with rings like Saturn / Oliver Hull

Do aliens sleep? You may take sleep for granted, but research suggests many planets that could evolve life don’t have a day and night cycle. It’s hard to imagine, but there are organisms living in Earth’s lightless habitats, deep underground or at the bottom of the sea, that give us an idea of what alien life without a circadian rhythm may be like.

There are billions of potentially habitable planets in our galaxy. How do we arrive at this number? The Milky Way has between 100 billion and 400 billion stars.

Seventy percent of these are tiny, cool red dwarfs, also known as M-dwarfs. A detailed exoplanet survey published in 2013 estimated that 41 percent of M-dwarf stars
have a planet orbiting in their “Goldilocks” zone, the distance at which the planet has the right temperature to support liquid water.

These planets only have the potential to host liquid water, though. We don’t yet know if any of them actually do have water, much less life. Still, that comes to 28.7 billion planets in the Goldilocks zones of M-dwarfs alone. This is not even considering other types of stars like our own yellow sun.

Rocky planets orbiting in an M-dwarf’s habitable zone are called M-Earths. M-Earths differ from our Earth in fundamental ways. For one thing, because M-dwarf stars are much cooler than the sun, they are close-in, which makes the gravitational pull of the star on the planet immensely strong.

The star’s gravity pulls harder on the near side of the planet than the far side, creating friction that resists and slows the planet’s spin over eons until spin and orbit are synchronized. This means most M-Earths are probably tidally locked, which is when one hemisphere always faces the sun while the other always faces away.

A tidally locked planet’s year is the same length as its day. The moon is tidally locked to the Earth, which is why we always see only one face of the moon and never its far side.

A tidally locked planet may seem exotic, but most potentially habitable planets are probably like this. Our closest planetary neighbor, Proxima Centauri b (located in the Alpha Centauri system four light-years away), is probably a tidally locked M-Earth.

Unlike our Earth, then, M-Earths have no days, no nights, and no seasons. But life on Earth, from bacteria to humans, has circadian rhythms tuned to the day-night cycle.

Sleep is only the most obvious of these. The circadian cycle affects biochemistry, body temperature, cell regeneration, behavior, and much more. For example, people who receive vaccinations in the morning develop more antibodies than those who receive them in the afternoon because the immune system’s responsiveness varies throughout the day.

We don’t know for sure how important periods of inactivity and regeneration are to life. Maybe beings that evolved without cyclical time can just keep on chugging, never needing to rest.

To inform our speculation, we can look at organisms on Earth that thrive far from daylight, such as cave-dwellers, deep-sea life, and microorganisms in dark environments like the Earth’s crust and the human body.

Many of these life forms do have biorhythms, synchronized to stimuli other than light. Naked mole rats spend their entire lives underground, never seeing the sun, but they have circadian clocks attuned to daily and seasonal cycles of temperature and rainfall. Deep-sea mussels and hot vent shrimp synchronize with the ocean tides.

Bacteria living in the human gut synchronize with melatonin fluctuations in their host. Melatonin is a hormone your body produces in response to darkness.

Temperature variations caused by thermal vents, humidity fluctuations, and changes in environmental chemistry or currents can all trigger bio-oscillations in organisms. This hints that biorhythms have intrinsic benefits.

Recent research shows M-Earths could have cycles that replace days and seasons. To study questions like these, scientists have adapted climate models to simulate what the environment on an M-Earth would look like, including our neighbor Proxima Centauri b.

In these simulations, the contrast between dayside and nightside seems to generate rapid jets of wind and atmospheric waves like those that cause Earth’s jet stream to bend and meander. If the planet has water, the dayside probably forms thick clouds full of lightning.

Interactions between winds, atmospheric waves, and clouds may shift the climate between different states, causing regular cycles in temperature, humidity, and rainfall. The lengths of these cycles will vary by planet from tens to hundreds of Earth days, but they won’t be related to its rotation period. While the star remains fixed in the sky of these planets, the environment will be changing.

Perhaps life on M-Earths would evolve biorhythms synchronized to these cycles. If a circadian clock organizes internal biochemical oscillations, it may have to.

Or perhaps evolution would find a weirder solution. We could imagine species that live on the planet’s dayside and migrate to the nightside to rest and regenerate. A circadian clock in space instead of in time.

This thought should remind us that, if life exists out there, it will upend assumptions we didn’t know we had. The only certainty is that it will surprise us.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Image Credit: Earth at twilight from space / Image Science & Analysis Laboratory, NASA Johnson Space Center

SpaceX’s Falcon 9 rocket is set to propel the Dragon crew capsule and four private astronauts into space. The Polaris Dawn mission will fly to the highest altitude yet recorded in commercial spaceflight. It’ll also be the first to traverse belts of dangerous radiation surrounding Earth and attempt a spacewalk by private citizens, rather than highly trained astronauts.

Meanwhile, the crew will monitor their health before, during, and after the flight—from eye and bone health to cognition. This will help further our understanding of how just a few days of spaceflight transforms our biology—for example, which genes are turned on or off, how immunity changes, and why well-known challenges such as eye problems and loss of bone density emerge even with a short stay in space.

This information will go into an open-source biobank and help scientists collaborate on treatments for short-term flights and even longer jaunts to the moon, Mars, and beyond.

The launch is the first of three planned Polaris missions, which aim to advance technologies and healthcare that could one day propel us deeper into space. Here’s what you need to know.

Pushing Boundaries

Heading the mission is Jared Isaacman, who is no stranger to space travel.

In 2021, he funded Inspiration 4, the first all-civilian mission to orbit the Earth. The mission showed that the average person is capable of spaceflight with a short bout of training and brought a wealth of insights into how a brief stint in space changes the body.

Accompanying Isaacman are mission pilot Scott “Kidd” Poteet, a former US Air Force Lieutenant Colonel, and two SpaceX employees. Thirty-year-old operations engineer Sarah Gillis is the youngest of the team and will join Isaacman on the spacewalk. Anna Menon, a mission specialist and medical officer, previously worked at NASA for seven years coordinating medical care from mission control.

The team will spend five days inside the Dragon capsule as it travels as high as 870 miles—the furthest from Earth humans have been since NASA’s Apollo program.

Their trajectory will take them through one of two deadly “circles” of high radiation called the Van Allen radiation belts, where highly charged particles from the sun and other sources are captured by Earth’s magnetic field. These regions are especially risky, as the particles can potentially tear through a space capsule and penetrate the body. To expand into the cosmos, we need to learn how to protect astronauts from such radiation.

Medicine in Space

Polaris Dawn partnered with 31 institutions to probe the health effects of spaceflight. Professional astronauts have been conditioned for spaceflight for years—the civilian crew offers a rare chance to examine the impact of microgravity on the health of an average space traveler.

Many of the studies are collaborations between NASA’s Human Research Program and the Translational Research Institute for Space Health (TRISH). Led by Baylor College of Medicine, the California Institute of Technology, and MIT, TRISH is a scientific consortium investigating how we can keep astronauts safe and healthy during deep space missions.

Spaceflight changes the body. Spacewalks could bring on additional changes. One project, building on Inspiration 4, will collect biological samples from the crew—like an annual health checkup—before, during, and after the flight. These samples will then be processed and added to the Space Omics and Medical Atlas, which includes the crew’s genetic makeup and gene expression changes—which genes are turned on or off—after a sprint into the radiation belts.

Other studies will delve into the effects of radiation and microgravity.

One team from TRISH will analyze how radiation impacts different bodily tissues during the mission and check to see whether any changes linger or return to normal back on Earth. Previous studies have mostly researched astronauts living for months on the International Space Station, which is closer to our home planet. Polaris Dawn’s crew will experience much more radiation at higher altitudes. This data could provide help us reduce radiation risk in the future.

Another team will test a hand-held ultrasound tool called Butterfly IQ+. It’s not fully automated, like the AI medical pods in the science fiction movie Prometheus, but the idea is similar: Being able to diagnose and treat unexpected medical troubles on the fly is crucial for space travel. The crew will test the device in space for myriad potential uses, like, for example, collecting medical-grade images of bladder function or blood and bodily fluid status.

The tool will be especially useful for spacewalks. Unlike the International Space Station, Dragon does not have an airlock. When Isaacman and Gillis go on their spacewalk, the entire capsule will open to the vacuum of space. The sudden change in pressure can cause potentially life-threatening conditions, known as decompression sickness or “the bends.” Scuba divers experience this condition when they ascend too rapidly and nitrogen forms gas bubbles in the bloodstream. A diagnostic tool could capture these dangerous conditions.

Another set of studies will focus on bone density and fluids. Working with TRISH, the University of Calgary is using a high-resolution device to scan the bone structure of the crew’s wrists and ankles—which are indicators of potential bone loss. If they detect a change, it will be the earliest ever to capture spaceflight’s effect on bone health. Meanwhile, a Dartmouth study is monitoring whether a first morning urine sample can predict bone and muscle health.

Microgravity also makes the effects of medicine—say, an Advil—unpredictable. Our bodily fluids, gut function, and metabolism all go topsy-turvy in space, which impacts how common medications work. The Polaris Dawn crew will test several common medications and chart how they behave in space.

Meanwhile, the team will also challenge their minds with a battery of cognitive tests. Developed by NASA and others, the tests include ten different tasks—kind of like Wordle or other games—to be completed on a tablet. But these specifically measure brain functions relevant to spaceflight. Other tests ask how much each crew member is willing to tolerate risk when making decisions, if they’re able to focus, and whether they can healthily process emotions.

There’s no doubt the mission is risky. On their spacewalk, Isaacman and Gillis will be testing SpaceX’s newly designed extravehicular activity suit, which doesn’t include life support. Instead, the two will receive all oxygen and other support from umbilical hoses attached to Dragon.

Still, the mission will hopefully strengthen our ability to adapt, live, and work in space.

Image Credit: Polaris Program