Deep Space Habitat

Deep Space Habitat

As well as missions straight to Mars and

other planets, NASA has plans for space

stations inside the orbit of the Moon as a

stepping stone for even more-distant goals.

The Deep Space Habitat proposal has

two versions. The basic model supports

four crew for 60 days and would enable a

semi-permanent base floating somewhere

along the L1 or L2 Lagrange point. These are

the points where the Moon and the Earth’s

gravity cancel each other out. A moreambitious,

500-day version could be used to

intercept near-Earth asteroids.

A spacecraft can effectively hover at this

point in space indefinitely and provide a

waypoint for future Lunar or Martian landing

missions. Deep Space Habitat uses modules

and technologies that have been extensively

tested aboard the ISS and could be launched

in sections. A fuel depot at the L1 Lagrange

point would enable lander spacecraft to be

launched from Earth with empty fuel tanks

and collect fuel on the way. This would

reduce their liftoff weight and could have a

massive affect on the feasibility of regular

supply flights to an off-world colony.

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Recycling air and water

Recycling air and water

Before 2009, the ISS could only recycle the small

amount of moisture that was condensed from

astronaut breath and sweat. Urine and waste

water from washing were dumped overboard

and replaced with water that was hauled into

orbit in 41-kilogram (90-pound) bags during

resupply missions. For a space station orbiting 370

kilometres (230 miles) up, that’s expensive, but

for a long-duration mission to another planet, it’s

simply out of the question.

Today’s ISS uses a rack-mounted water treatment

system that filters and distils water on demand. In

microgravity, steam doesn’t rise, so the keg-sized

distillation drum is spun to separate the steam by

centrifugal force. The processed water is cleaner

than tap water on Earth but there’s still a small

amount of water lost from the system each day.

Once efficiency improves from 93 to 95 per cent,

the ISS will be able to obtain all the remaining

water from the moisture present in food supplies.

Oxygen on long-duration missions is actually

less of a problem. The Apollo and Shuttle missions

generated the oxygen they needed as a by-product

of the hydrogen fuel cells that generate electricity.

Oxygen can also be produced by splitting water

and venting the hydrogen into space.

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Radiation shielding

orion spacecraft

Interplanetary space is bathed by radiation from two distinct sources.

The Sun mainly blasts us with waves of high-energy protons accelerated by

solar flares, while cosmic rays consist of a thinner stream of extremely highenergy

atomic nuclei propelled by supernova explosions from beyond

the Solar System. Here on Earth we’re safely protected by the atmosphere and

even astronauts in low orbit also receive some shielding from the Earth’s magnetic field. Once you

travel beyond that, radiation levels quickly build up. Solar protons can

be blocked by the aluminium skin of the spaceship itself, but the strange

thing about galactic cosmic rays is that physical shielding can actually

increase the radiation dose. This is because the heavy particles have

so much energy that they trigger a cascade of secondary radiation from

the atoms of the aluminium shield. Hydrogen atoms don’t generate

secondary radiation, however, so materials that are rich in hydrogen,

like water, work much better. Some of this could be water that’s needed

for life support in any case, stored as cavity insulation in the hull.

To provide a thick enough shield, spacecraft would need to bring along

a lot of extra water, which is more mass that must be accelerated by

the engines. The alternative is to use active shielding to deflect the path of

dangerous particles. Galactic cosmic rays are positively charged, so they

could be deflected by a positively charged electrostatic shield. However,

this would require a huge amount of energy to offset the constant

neutralising effect of deep-space electrons. Magnetic shields are more

promising, but magnetic fields five to ten times stronger than those in an

MRI scanner would be needed. The long-term effects of human exposure

to magnetic fields this strong aren’t known and might actually be worse than the radiation.

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Zero-G compensation

NAUTILUS-X

While floating around in microgravity might seem like the

biggest perk of life aboard a spaceship, it’s also very bad for

your health. Astronauts can lose as much as five per cent

of their muscle mass per week in space and decreased

bone densities can take years to recover after returning

to Earth. Zero-gravity conditions also increase the fluid

pressure on the brain, which leads to eyesight problems at

the same time as reducing the total blood volume, which

causes heart muscles to atrophy. Astronauts currently on

the International Space Station exercise for two hours

every day but it’s still not enough.

Thrusters The centrifuge is set spinning by the thrust

from rockets mounted on opposite sides, like a

Catherine wheel. Inflatable The centrifuge uses a soft wall

stretched over a collapsible articulated skeleton that can be

inflated once in space. A double-walled plastic

hull filled with water could block harmful cosmic rays. A

mixture of different shielding might be needed for

missions lasting for long periods

We don’t fully understand the way that the body reacts

to microgravity yet, but it’s possible that no amount

of running on a treadmill in an elasticated harness

will substitute the universal pull of gravity. A spinning

centrifuge compartment, like the one proposed by NASA

for the Nautilus-X long-duration spacecraft, could use

centrifugal force to mimic gravity. However, it would

need to be big – even a 12-metre (39-foot) diameter ring

spinning at 10rpm would only produce 69 per cent of

Earth’s gravity. This could keep astronauts conditioned for

a trip to Mars, as its gravity is only 38 per cent of Earth’s.

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Precise navigation

Precise navigation

In space the only way to measure distance is by measuring time.

Without accurate clocks, spacecraft can’t measure their speed relative to

anything else and ground control can’t compensate for the time it takes to

send radio messages across the huge distances between planets.

Atomic clocks have long provided the accuracy that space missions require,

but until now the best ones have all been on the ground. This means the

timing signals need to be beamed up to each spacecraft, which introduces

errors and reduces the number of spacecraft that can be controlled at

once. The Deep Space Atomic Clock (DSAC) is a miniaturised version of the

most accurate clock available on Earth. It’s packaged in a housing that’s rugged

enough to withstand the trip to space, while still only weighing 17.5 kilograms

(39 pounds). When it launches in 2015, it will be in orbit for a year to calibrate

and verify its own performance against the most accurate clocks currently

in space – those on GPS satellites. However, DSAC is over ten times more

accurate than GPS and will eventually enable spacecraft to determine their

position and speed, completely independently of ground control.

This is important, because the further we venture from Earth, the

greater the communication delay. Depending on the relative position of

the planets, it can take anything from 3 to 22 minutes for radio signals to

travel from Earth to Mars. That’s far too long for real-time control of orbital

manoeuvres. Even worse, spacecraft are cut off from Earth every time they

orbit around the far side of another planet. Whether a mission is manned

or robotic, it simply isn’t realistic for spacecraft to depend on timely

instructions from Earth. The DSAC is a key technology that will enable precise

and autonomous navigation.

“ Without accurate clocks, spacecraft can’t 

measure their  speed”

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Planetary descent

Planetary descent

Mars has an atmospheric at least 60 times less

dense than Earth’s, but this isn’t enough to slow a

spacecraft down using parachutes alone. The Mars

Curiosity rover used a combination of parachutes and

rockets, but even then the landing site was restricted

to the lowlands of the Gale crater, to increase the

amount of atmospheric braking available. NASA has

used the same design for every Mars mission since

the Viking landers. Now new inflatable aerobrakes

and 30.5-metre (100-foot) parachute canopies are

being developed to enable heavier payloads and

more-accurate landings, but they’ll also enable

missions to target higher-altitude terrain.

Testing entry, descent and landing (EDL) tech

is tricky because it’s hard to simulate the Martian

atmosphere. NASA has used a rocket sled to drag

parachutes at supersonic speeds, but the rocket

motors used for the final phase of the landing can

only be fully modelled in computer simulations.

NASA supercomputers use 900 processors running

in parallel to simulate the complex fluid dynamics.

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Solar Electric Propulsion

Solar Electric Propulsion

The chemical rockets used on most spacecraft today

produce thrust by burning fuel and oxidiser in a

chemical reaction and expelling the exhaust gasses

backwards. This produces very high thrust but uses

a lot of fuel and some of the thrust is burned simply

to accelerate the mass of the fuel. Solar Electric

Propulsion, also known as an ion drive, achieves

much more-efficient thrust by doing away with the

chemical reaction. Instead, the Xenon gas propellant

is positively charged by bombarding it with electrons

in a magnetic chamber and then accelerated with

a negatively charged grid. As the atoms leave

the exhaust nozzle, they’re travelling at 144,840

kilometres (90,000 miles) per hour. Although the

thrust from SEP can only lift a sheet of paper, it’s ten

times more-efficient than chemical rockets.

Solar sails offer even better efficiency by doing

away with propellant altogether, with the reflective

material harnessing the momentum of light itself.

As the Sun’s rays bounce off the sail, the deflected

photons impart a tiny but constant force. Over

several months or years the gentle thrust from these

ultra-efficient propulsion methods can accelerate a

spacecraft to interplanetary – or interstellar – speeds.

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10 ways to conquer space

 conquer space

It’s the hardest thing humanity has ever attempted, but
the technology to pull it off is finally within our grasp

We went to the Moon not because it is easy, butvbecause it is hard. 45 years later, it seems harder

than ever. Many Saturn V components are no longer manufactured and the largest rockets currently in service can only lift payloads a fifth of the size. Although manned exploration has been stuck in low Earth orbit since Apollo, scientists haven’t been idle. Technologies tested on the International Space Station have vastly improved the computing, communication and life-support capabilities of modern spacecraft, while unmanned probes have mapped our solar system in great detail. As global interest gathers momentum, we are now ready to take the next leap: to the planets.
A spacecraft comprises dozens of different subsystems to propel it to its destination, land intact and protect the crew during the journey. Over the following pages we’ll show you ten of the most promising technologies currently being developed by NASA and the European Space Agency for missions beyond Earth orbit. Some of these are already being tested aboard the ISS, while others will be launched as demonstration missions next year. Even the most speculative design concepts here use components and engineering that have already been successfully flown to space. A manned mission to Mars will be extremely challenging, but it isn’t science fiction any longer.

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New Worlds mission

New Worlds

By putting a huge umbrella into
space, we could come closer to
finding extraterrestrial life

The question of whether life exists on other planets is one that scientists frequently ponder, but have

so far failed to answer. Hoping to change this is the New Worlds mission that, while still in the early

phases of development following years of research, is likely to bear fruit in the near future. One of the problems with observing extrasolar planets is the amount of light emitted by the parent star they orbit. When scientists use a telescope to look deep into space, they find the brightness of these stars drowns out the light from the orbiting planets. They still see the more-intense glow of larger planets, but the smaller ones are virtually impossible to spot. Since those tinier planets are, like Earth, more likely to contain signs of life, it means experts risk missing potential life-supporting worlds. Dr Webster Cash, of the University of Colorado at Boulder, has devised a method to combat this problem. He proposes using a starshade, effectively a large blocker spacecraft that would be placed

between the telescope and the target star. It would prevent light from the star reaching the telescope that would, in effect, be cast within a shadow. Just as a ball heading your way from up high on a bright day is better seen if you hold your hand to block the By putting a huge umbrella into space, we could come closer to finding extraterrestrial life New Worlds mission The telescope A telescope will sit behind the starshade in the dark. The starshade acts as a barrier between the telescope and the star. Distances Obtaining the right distance between the stars, starshade and telescope is vital.
There's little room for error, as the device sits 200,000km (124,000mi) away from the starshade. sunlight, so the planets orbiting their parent star are brought into view when the brighter light is blocked. In 2013 NASA created a mockup of the starshade. The initial plan had been to produce a round disc, but this caused a problem with diffraction. When light from the parent star hits a round circle, it will diffract around the edge. Not only does this give a halo-like glow but it also drowns out the dimmer light of the smaller extrasolar terrestrial planets being sought, because it remains so bright. The idea is to make the starshade look like a series of slit petals, each one sitting around the inner disk. Since the perimeter shape of the object the light is hitting governs diffraction, this design controls the way the light waves of the star behave, drastically cutting diffraction. Because the starshade will be tilted when put into space, the light from our own Sun will not disrupt the telescope’s view of the extrasolar planetary system either. Although the proposal is to fly the starshade and the telescope into space in formation, it’s more likely that the telescope will be sent up first and the starshade will follow at a later date. Though a launch date is far from being confirmed, the mission concept is being put together and should be complete by 2015. The team behind it is conscious of cost – with a budget of around £1.8 billion ($3 billion) – so it’ll either work with an existing collector, such as the James Webb Space Telescope, or a four-metre (13-foot) telescope likely to be built in the future. This won’t be an easy mission, as the starshade will be sent to space in a folded state before unfurling. It also needs to be aligned with a telescope around 200,000 kilometres (124,000 miles) away. With little room for error and the need to maintain alignment, so much could go wrong. If the mission enables scientists to see planets they’d otherwise miss, enabling them be to analysed for water vapour, carbon dioxide and oxygen, the big question of the universe could be answered soon.

“ It needs to be aligned with a telescope
around 200,000 kilometres away”

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Escape to Titan

Escape to Titan

It’s destination Titan, as what we
once knew as our home becomes
unfit for human habitation

The Earth is dying. The planet that we once knew to

be covered in oceans and greenery is nothing more

than a hot, parched world with life forms struggling

to survive in the heat. This is the state of the Earth

that we shouldn’t be sticking around to witness if

we intend for humanity to outlive such a disastrous

change to our planet. Experts think that Titan could be our hope of

survival, because we don’t require interstellar travel

to get to it and it possesses favourable conditions.

This is somewhere that, given the helping hand

of technology, could be a viable place to

continue humanity's existence.

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Earth’s future is certainly bright, just not in the way we’d hoped

the Chicxulub

An impact from an asteroidsimilar to the size that caused the Chicxulub crater would befatal for human life on Earth

While researchers think that the Earth will meet a frazzled and devastated end, along with the

innermost worlds Mercury and Venus that will be gobbled up by the star’s expanding limbs, they have reasoned that for our planet to survive, the entire orbital setup needs to keep a hold of its momentum. Such a feat would also see the outermost planets shuffle in response. “Accordingly, the orbits of all of the planets are going to expand by 50 per cent,” says Schröder. “However, that’s true only if the momentum is conserved. In that case, the orbit of Earth would exceed the maximum solar giant radius by some 25 per cent.” It’s here that some scientists are romancing the idea of an Earth that survives the odds, attempting to find hope that would see humanity beat the rules of the universe. “We could try to steer every asteroid that passes Earth ahead of its orbital movement, then we should gain angular movement to enlarge our orbit well in time,” Schröder suggests. Whether our planet manages to survive or not, it doesn’t really matter – at least when it comes to the future of mankind, thinks Schröder. He believes that the Sun has something else in store for us and our star is looking to present us with it much sooner than the latter stages of its evolution. “In about one billion years, long before [the red giant phase] and more gradually, will come the end of the habitability of Earth,” he tantalisingly tells us. This is the stage between now and when it uses up all of its hydrogen, before swelling into a red giant. In this respect Earth’s future is certainly bright, just not in the way we'd hoped it would be. You’re unlikely to notice it, but the Sun is slowly and ever so slightly picking up in both brightness and size. At the moment, and at a comfortable distance from our star, temperatures are perfect for the existence of liquid water, the region we know as the Goldilocks or Habitable Zone. However, as billions of years pass, what we regard to be a privileged spot in our Solar System will become somewhere that isn’t really the place for life as we know it. This is because, for every billion years that pass, our Sun will be kicking up its power output by around ten per cent, in a race to use up the hydrogen that it finds knocking about its core.
With our star turning up the heat, solar warmth mixes with the gases in the Earth’s atmosphere, shifting the Habitable Zone backwards through the Solar System and towards the outer giants of the system. “That will be enough to drive the climate into a runaway greenhouse state. That is, when all water boils off and temperatures will exceed 100 degrees Celsius [212 degrees Fahrenheit],” says Schröder. Clearly Earth’s future is shaping up to be a global disaster. With no life able to adapt to the abrupt end of cycles of nutrients and life-supporting gases, there’s nothing left to breathe life into its dead surface as even the smallest pockets of water evaporate. Worse still, the brutal treatment dished out by our Sun won’t be over even at this point. It all begins when our planet’s interior breathes a death rattle, turning from a molten liquid to a solid that kills off the magnetic field holding the ozone layer in place. It’s this cloak that makes our planet resilient to the harmful ultraviolet rays that our Sun throws at us. Without it, our planet’s surface would be treated to a bath of high-energy radiation that has already left Mars with its barren landscape that we are learning more and more about. Temperatures will continue to rise for our planet and the gas mark will be well and truly turned up, equating to a rise of more than 140 degrees Celsius (284 Fahrenheit) over the average of around 2.8 billion years from now. Earth will then become host to a climate that bears some similarity to the hellish surface of Venus, long before the red giant phase of the Sun takes hold. With many experts, including American geoscientist Professor James Kasting, thinking that Earth is heading for higher temperatures and devastation all round, there’s a certain urgency to act to escape what would ultimately spell the end of humanity. We know that as the Habitable Zone shifts back, even Mars will get its time in the Sun as our star gets bigger and hotter. The relatively chilly Red Planet will eventually reach a temperature similar to the levels likely to have existed during the Earth’s ice age. Further into the future, when Mars is no longer a valid outpost for future colonisation, we will need to look to the gas giants: Jupiter’s moon Europa and Saturn beckon. The ringed planet in particular could hold the key to our escape in the form of Titan. “In certain ways, Titan is the most hospitable extraterrestrial world within our Solar System for human colonisation,” explains Robert Zubrin, an aerospace engineer advocating the manned exploration of Mars. He has also established the Mars Society, an organisation dedicated to promoting the human exploration and settlement of the Red Planet. When it comes to Titan’s potential, Zubrin refers to its atmospheric mix of nitrogen, methane and ethane with the liquid oceans, lakes and rivers implied by the observations of spacecraft such as Cassini. NASA’s famous orbiter also deployed its Huygens lander on Titan to reveal the first and currently only image of an extraterrestrial moon’s surface. Combined with a Sun that’s continually heating up, this somewhat cooler analogue to Earth could be the answer that the survival of humanity is looking for. However, will we get there before our Sun inevitably expands into us?

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The Earth on fire

The Earth on fire

This hellish Earth of the future will

be devoid of water, meaning it will likely

support no life forms. While its surface

will burn with an unbearable heat,

its once fiery core will be frozen solid.

Cold outer core

Our planet’s outer core will freeze in 2.3 billion

years, so without this liquid surrounding, our

planet’s magnetic field will shut down. This

field could then let go of the ozone

that protects us from the Sun’s harmful rays.

Frozen core

Currently the Earth’s inner core is growing

at a rate of around one millimetre (0.04 inches)

per year, but this might not be the case some 2.3

billion years from now.

Burning surface

In 2.8 billion years Earth’s surface will

reach unbearably hot temperatures with

everywhere averaging 147 degrees Celsius (297

degrees Fahrenheit).

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What is the future of Earth?

the future of Earth?

Blistering temperatures,asteroid impacts and a red giant for a Sun-and that's just a small taste of what's in store for our home planet

As the most tranquil planet our Solar System has ever known spins on its axis, seeming to lead us

through an infinite amount of days, it’s hard to imagine our Earth is going to feel the strain of a

variety of events that are set to truly put it through its paces. Yet, as it goes through the motions of

its future evolution, the planet we rely on for our survival has a trying time ahead of it. Will our

haven grow for the better, or will it become a shadow of its former self as it struggles to counteract

the chaos of the universe? You might take it for granted, but Earth is being

tested even at this very moment. Somewhere in the universe there could be a comet or asteroid

headed our way. We orbit in a corner of the cosmos containing numerous chunks of rock and ice

hurtling through the Solar System, so you’d think that, given the amount of times we’ve been buzzed

by an approaching asteroid that misses us by an astronomical hair’s breadth, our days would be

numbered. It only takes one behemoth piece of space debris to be at the same place and time as

us for disaster to strike, driving a mass extinction across the planet. After all, we know this has

happened in the past – just thinking about the fate of the dinosaurs is proof enough.

An asteroid similar to the massive chunk of rock that
wiped out the dinosaurs could one day wipe out humanity
if we don’t find ways to deflect them

Ed Lu, a former astronaut and co-founder of the B612
Foundation, is aiming for the construction of the Sentinel
Space Telescope that will alert Earth to potentially
dangerous asteroids

“ The only thing so far preventing a
catastrophe from a city-killer-sized
asteroid has been blind luck”
-Ed Lu, B612 Foundation

Around 65 million years ago an asteroid belted our world with such a force

 that a good portion of life was thrown into disarray as the land shook and great tsunamis took a hold of the world. The 180 kilometre- (112 mile-) wide Chicxulub crater in the Gulf of

Mexico, along with bones and fossils of the final resting places of ancient life, marked the beginning

of the Earth’s Cenozoic Era, a period that continues to this day. Though we’ve been lucky since, we’re always in the potential firing line. “While most large asteroids with the potential

to destroy an entire country or continent have been detected, less than 10,000 of over a million

dangerous asteroids with the potential to destroy a major metropolitan area have been found by all

existing space or terrestrially operated observatories,” says Ed Lu, a former US Shuttle and Soyuz astronaut. Lu, as part of his organisation the B612 Foundation, aims to build the Sentinel Space Telescope, an Earthorbiting sentry that would keep a watchful telescopic

eye for any potential dangers. Sentinel would raise an early alarm for any dangerous asteroids heading our way. The idea is that finding these threats in advance of them arriving will gift us enough time to deflect anything looking to snuff us out with a single blow. “Because we don’t know where or when the next major impact will occur, the only thing so far preventing a catastrophe from a city-killer-sized asteroid has been blind luck,” adds Lu. It's estimated that some 1.4 million years from now we’re going to need to thwart comets raining on the inner Solar System from the Oort Cloud, a halo of icy bodies in orbit at the very edge of our celestial neighbourhood. The possible culprit responsible for the future battering Earth could receive is Gliese 710 – a main sequence orange dwarf that will approach the Sun as close as one light year before swinging away again, disrupting the Oort Cloud's structure along the way. Lu has highlighted an important point with his venture – whether it’s asteroids or the uncomfortable proximity of comets, we need to ensure that the likes of the current NEOWISE telescope, as well as the future Sentinel, assist us in keeping our world out of harm’s way. However, that’s only one hurdle that we have to overcome as thousands of years turn into millions. Provided we can deflect these murderous travellers, we will get a bit of a reprieve from Earth’s ultimate fate. From the surface of the Earth, thousands of years in the future, we will be able to see some significant changes in the night sky. The small red dwarf star astronomers have dubbed Ross 248, which rests in the constellation Andromeda some ten light years away, will move in closer to our Solar System to make it our nearest star ahead of Proxima Centauri, a current 4.24 light years away. It’s thought that the pint-sized Ross 248 is likely to reach a minimum distance of roughly three light years from us, in around 33,000 years from now. However, it won’t be this way forever. Once again the system Alpha Centauri and then Gliese 445 will be made the nearest stars around 8,000 years after Ross 248 has decided to loop away from our planetary system. In fact, the night sky will change over time with several stars taking it in turns to move closer to our Solar System. If this weren’t enough, we can also expect some major activity beneath our very feet. The continents that we live on will be unpicked and sandwich onto others, jostling in such a way that a new supercontinent will be formed 250 million years from now. Some experts call this future landmass Pangaea Proxima, while others have put forward other supercontinent contenders such as Amasia, which would see Asia and North America joining together. Another possibility, Novopangaea, has been predicted by the University of Cambridge’s Roy Livermore and would see the closure of the Pacific as Australia docks with eastern Asia and Antarctica moves further north. The general consensus is that Pangea                             Proxima, also referred to as Pangaea Ultima, could be the leading setup for                           the Earth’s future landmass. “It’s all pretty much fantasy to start with, but it’s a fun 

exercise to think about what might happen,” says

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Fossil galaxy could be first that ever formed

galaxy Zwicky 18

Segue 1 differs from other dwarfgalaxies, such as I Zwicky 18, as it’s nolonger in a state of evolution

Galactic partnercould shed new
light on how theearly universe was composed

Segue 1, a dwarf galaxy that’s a satellite to the Milky Way and has been under

scrutiny by an international team of astronomers, has now been revealed to

be an ancient relic left over from the early universe.

The fossil galaxy, whose chemical composition was analysed to unravel

its history, is made up of a uniquely ancient composition. Not only that,

but the galaxy’s star formation wasn’t as cyclic as the galaxies we

see today, which form and die in a great supernova explosion, before

seeding nearby gas with the necessary elements to begin the process again.

According to researchers, Segue 1 gave up on its star birth at what would be

an early stage of development. “Our work suggests that Segue 1 is

the least chemically evolved galaxy known,” says the Carnegie Institution

for Science’s Josh Simon. “After the initial few supernova explosions, it

appears that only a single generation of new stars were formed and then for

the last 13 billion years the galaxy has not been creating [any].”

Since the galaxy has been preserved in a state of low iron-abundance,

among other heavy elements, and only seven stars in the galaxy are

actually in the red giant phase, Segue 1 offers unique information about the

conditions in the universe shortly after the Big Bang.

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Ganymede: a frozen sandwich of oceans and ice?

Ganymede

Jupiter’s largest moon could once have been home to
life in its many inner layers

Companion to Jupiter and the largest moon in our Solar system, Ganymede
is likely to have stacked its sheets of ice and oceans into several layers.
The moon was thought to possess a deep ocean stuck between layers
of ice. However, theoretical evidence suggests that such an organised
structure leaves room for the possibility that primitive life could
have been found the icy moon. The first layer on top of the rocky core is
likely to be awash with saltwater. “This is good news for Ganymede,”
says Steve Vance of NASA’s Jet Propulsion Laboratory (JPL) in
Pasadena. “Its ocean is huge, with enormous pressures, so it was thought
that dense ice had to form at the bottom of the ocean…”
While the team feels the moon’s ice and water stack is likely, they aren’t
sure how long the structure will last. “This represents a stable state, but
various factors could mean the moon doesn’t reach this stable state,” says
Christophe Sotin, also at JPL.

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