On March 14, the ExoMars mission successfully lifted off on a 7-month journey to the planet Mars but not without a little surprise. The Breeze-M upper booster stage, designed to give the craft its final kick toward Mars, exploded shortly after parting from the probe. Thankfully, it wasn’t close enough to damage the spacecraft.
Michel Denis, ExoMars flight director at the European Space Operations, Center in Darmstadt, Germany, said that the two craft were many kilometers apart at the time of the breakup, so the explosion wouldn’t have posed a risk. Still, the mission team won’t be 100% certain until all the science instruments are completely checked over in the coming weeks.
All went well during the takeoff and final separation of the probe, but then something odd happened. Breeze-M was supposed to separate cleanly into two pieces — the main body and a detachable fuel tank — and maneuver itself to a graveyard or “junk” orbit, where rockets and spacecraft are placed at the end of their useful lives, so they don’t cause trouble with operational satellites.
But instead of two pieces, tracking photos taken at the OASI Observatory in Brazil not long after the stage and probe separated show a cloud of debris, suggesting an explosion occurred that shattered the booster to pieces. There’s more to consider. Space probes intended to either land or be crashed into planets have to pass through strict sterilization procedures that rocket boosters aren’t subject to. Assuming the Breeze-M shrapnel didn’t make it to its graveyard orbit, there exists the possibility some of it might be heading for Mars. If any earthly bugs inhabit the remains, it could potentially lead to unwanted consequences on Mars.
And this isn’t the first time a Russian Breeze-M has blown up.
According to Russian space observer Anatoly Zak in a recent article in Popular Mechanics, a Breeze-M that delivered a Russian spy satellite into orbit last December exploded on January 16. Propellant in one of its fuel tanks may not have been properly vented into space; heated by the sun, the tank’s contents likely combusted and ripped the stage apart. A similar incident occurred in October 2012.
For now, we’ll embrace the good news that the spacecraft, which houses the Trace Gas Orbiter (TGO) and the Schiaparelli lander, are underway to Mars and in good health.
ExoMars is a joint venture between the European Space Agency (ESA) and the Russian Federal Space Agency(Roscosmos). One of the mission’s key goals is to follow up on the methane detection made by ESA’s Mars Express probe in 2004 to understand where the gas comes from. Mars’ atmosphere is 95% carbon dioxide with the remaining 5% divided among nitrogen, argon, oxygen and others including small amounts of methane, a gas that on Earth is produced largely by living creatures.
Scientists want to know how martian methane got into the atmosphere. Was it produced by biology or geology? Methane, unless it is continuously produced by a source, only survives in the Martian atmosphere for a few hundreds of years because it quickly breaks down to form water and carbon dioxide. Something is refilling the atmosphere with methane but what?
TGO will also look at potential sources of other trace gases such as volcanoes and map the planet’s surface. It can also detect buried water-ice deposits, which, along with locations identified as sources of the trace gases, could influence the choice of landing sites of future missions.
The orbiter will also act as a data relay for the second ExoMars mission — a rover and stationary surface science platform scheduled for launch in May 2018 and arriving in early 2019.
On October 16, when the spacecraft is still 559,000 miles (900,000 kilometers) from the Red Planet, the Schiaparelli lander will separate from the orbiter and three days later parachute down to the Martian surface. The orbiter will take measurements of the planet’s atmosphere (including methane) as well as any atmospheric electrical fields.
Mars is a popular place. There are currently five active orbiters there: two European (Mars Express and Mars Odyssey), two American (Mars Reconnaissance Orbiter and MAVEN), one Indian (Mars Orbiter Mission) and two rovers (Opportunity and Curiosity) with another lander and orbiter en route!
I think we were all blown away when the New Horizons spacecraft looked back at Pluto’s dark side and returned the first photos of a surprisingly complex, layered atmosphere. Colorless nitrogen along with a small percentage of methane make up Pluto’s air. Layers of haze are likely created when the two gases react in sunlight to form tiny, soot-like particles called tholins. These can ultimately grow large enough to settle toward the surface and coat and color Pluto’s icy exterior.
Now it seems Pluto’s atmosphere is capable of doing even more — making clouds! In an e-mail exchange with New Scientist, Lowell Observatory astronomer Will Grundy discusses the possibility that streaks and small condensations within the hazes might be individual clouds. Grundy also tracked a feature as it passed over different parts of the Plutonian landscape below, strongly suggesting a cloud. If confirmed, they’d be the first-ever clouds seen on the dwarf planet, and a sign this small 1,473-mile-wide (2,370 km) orb possesses an even more complex atmosphere than imagined.
Given the onion-like layers of haze and potential clouds, perhaps we shouldn’t be surprise that it snows on Pluto. The New Horizons team announced the discovery this week of a chain of exotic snowcapped mountains stretching across the dark expanse of the informally named Cthulhu Regio. Cthulhu, pronounced kuh-THU-lu and named for a character in American horror writer H.P. Lovecraft’s books, stretches nearly halfway around Pluto’s equator, starting from the west of the vast nitrogen ice plain, Sputnik Planum. At 1,850 miles (3,000 km) long and 450 miles (750 km) wide, Cthulhu is a bit larger than the state of Alaska. But ever so much colder!
Cthulhu’s red color probably comes from a covering of dark tholins formed when methane interacts with sunlight. But new close-up images reveal that the region’s highest mountains appear coated with a much brighter material. Scientists think it’s methane, condensed as ice onto the peaks from Pluto’s atmosphere.
“That this material coats only the upper slopes of the peaks suggests methane ice may act like water in Earth’s atmosphere, condensing as frost at high altitude,” said John Stansberry, a New Horizons science team member.
Compositional data from the New Horizon’s Ralph/Multispectral Visible Imaging Camera (MVIC), shown in the right panel in the image above, shows that the location of the bright ice on the mountain peaks correlates almost exactly with the distribution of methane ice, shown in false color as purple.
New Horizons still has plenty of images stored on its hard drive, so we’re likely to see more clouds, frosty peaks and gosh-knows-what-else as the probe speeds ever deeper into space while returning daily postcards from its historic encounter.
Could there be life on Saturn’s large moon Titan? Asking the question forces astrobiologists and chemists to think carefully and creatively about the chemistry of life, and how it might be different on other worlds than it is on Earth. In February, a team of researchers from Cornell University, including chemical engineering graduate student James Stevenson, planetary scientist Jonathan Lunine, and chemical engineer Paulette Clancy, published a pioneering study arguing that cell membranes could form under the exotic chemical conditions present on this remarkable moon.
In many ways, Titan is Earth’s twin. It’s the second largest moon in the solar system and bigger than the planet Mercury. Like Earth, it has a substantial atmosphere, with a surface atmospheric pressure a bit higher than Earth’s. Besides Earth, Titan is the only object in our solar system known to have accumulations of liquid on its surface. NASA’s Cassini space probe discovered abundant lakes and even rivers in Titan’s polar regions. The largest lake, or sea, called Kraken Mare, is larger than Earth’s Caspian Sea. Researchers know from both spacecraft observations and laboratory experiments that Titan’s atmosphere is rich in complex organic molecules, which are the building blocks of life.
All these features might make it seem as though Titan is tantalizingly suitable for life. The name ‘Kraken’, which refers to a legendary sea monster, fancifully reflects the eager hopes of astrobiologists. But, Titan is Earth’s alien twin. Being almost ten times further from the sun than Earth is, its surface temperature is a frigid -180 degrees Celsius. Liquid water is vital to life as we know it, but on Titan’s surface all water is frozen solid. Water ice takes on the role that silicon-containing rock does on Earth, making up the outer layers of the crust.
The liquid that fills Titan’s lakes and rivers is not water, but liquid methane, probably mixed with other substances like liquid ethane, all of which are gases here on Earth. If there is life in Titan’s seas, it is not life as we know it. It must be an alien form of life, with organic molecules dissolved in liquid methane instead of liquid water. Is such a thing even possible?
The Cornell team took up one key part of this challenging question by investigating whether cell membranes can exist in liquid methane. Every living cell is, essentially, a self-sustaining network of chemical reactions, contained within bounding membranes. Scientists think that cell membranes emerged very early in the history of life on Earth, and their formation might even have been the first step in the origin of life.
Here on Earth, cell membranes are as familiar as high school biology class. They are made of large molecules called phospholipids. Each phospholipid molecule has a ‘head’ and a ‘tail’. The head contains a phosphate group, with a phosphorus atom linked to several oxygen atoms. The tail consists of one or more strings of carbon atoms, typically 15 to 20 atoms long, with hydrogen atoms linked on each side. The head, due to the negative charge of its phosphate group, has an unequal distribution of electrical charge, and we say that it is polar. The tail, on the other hand, is electrically neutral.
These electrical properties determine how phospholipid molecules will behave when they are dissolved in water. Electrically speaking, water is a polar molecule. The electrons in the water molecule are more strongly attracted to its oxygen atom than to its two hydrogen atoms. So, the side of the molecule where the two hydrogen atoms are has a slight positive charge, and the oxygen side has a small negative charge. These polar properties of water cause it to attract the polar head of the phospholipid molecule, which is said to be hydrophilic, and repel its nonpolar tail, which is said to be hydrophobic.
When phospholipid molecules are dissolved in water, the electrical properties of the two substances work together to cause the phospholipid molecules to organize themselves into a membrane. The membrane closes onto itself into a little sphere called a liposome. The phospholipid molecules form a bilayer two molecules thick. The polar hydrophilic heads face outward towards the water on both the inner and outer surface of the membrane. The hydrophobic tails are sandwiched between, facing each other. While the phospholipid molecules remain fixed in their layer, with their heads facing out and their tails facing in, they can still move around with respect to each other, giving the membrane the fluid flexibility needed for life.
Phospholipid bilayer membranes are the basis of all terrestrial cell membranes. Even on its own, a liposome can grow, reproduce and aid certain chemical reactions important to life, which is why some biochemists think that the formation of liposomes might have been the first step towards life. At any rate, the formation of cell membranes must surely been an early step in life’s emergence on Earth.
If some form of life exists on Titan, whether sea monster or (more likely) microbe, it would almost certainly need to have a cell membrane, just like every living thing on Earth does. Could phospholipid bilayer membranes form in liquid methane on Titan? The answer is no. Unlike water, the methane molecule has an even distribution of electrical charges. It lacks water’s polar qualities, and so couldn’t attract the polar heads of phospholipid molecule. This attraction is needed for the phospholipids to form an Earth-style cell membrane.
Experiments have been conducted where phospholipids are dissolved in non-polar liquids at Earthly room temperature. Under these conditions, the phospholipids form an ‘inside-out’ two layer membrane. The polar heads of the phospholipid molecules are at the center, attracted to one another by their electrical charges. The non-polar tails face outward on each side of the inside-out membrane, facing the non-polar solvent.
Could Titanian life have an inside out phospholipid membrane? The Cornell team concluded that this wouldn’t work, for two reasons. The first is that at the cryogenic temperatures of liquid methane, the tails of phospholipids become rigid, depriving any inside-out membrane that might form of the fluid flexibility needed for life. The second is that two key ingredients of phospholipids; phosphorus and oxygen, are probably unavailable in the methane lakes of Titan. In their search for Titanian cell membranes, the Cornell team needed to probe beyond the familiar realm of high school biology.
Although not composed of phospholipids, the scientists reasoned that any Titanian cell membrane would nevertheless be like the inside-out phospholipid membranes created in the lab. It would consist of polar molecules clinging together electrically in a solution of non-polar liquid methane. What molecules might those be? For answers the researchers looked to data from the Cassini spacecraft and from laboratory experiments that reproduced the chemistry of Titan’s atmosphere.
Titan’s atmosphere is known to have a very complex chemistry. It is made mostly of nitrogen and methane gas. When the Cassini spacecraft analyzed its composition using spectroscopy it found traces of a variety of compounds of carbon, nitrogen, and hydrogen, called nitriles and amines. Researchers have simulated the chemistry of Titan’s atmosphere in the lab by exposing mixtures of nitrogen and methane to sources of energy simulating sunlight on Titan. A stew of organic molecules called ‘tholins’ is formed. It consists of compounds of hydrogen and carbon, called hydrocarbons, as well as nitriles and amines.
The Cornell investigators saw nitriles and amines as potential candidates for their Titanian cell membranes. Both are polar molecules that might stick together to form a membrane in non-polar liquid methane due to the polarity of nitrogen containing groups found in both of them. They reasoned that candidate molecules must be much smaller than phospholipids, so that they could form fluid membranes at liquid methane temperatures. They considered nitriles and amines containing strings of between three and six carbon atoms. Nitrogen containing groups are called ‘azoto’ –groups, so the team named their hypothetical Titanian counterpart to the liposome the ‘azotosome’.
Synthesizing azotosomes for experimental study would have been difficult and expensive, because the experiments would need to be conducted at the cryogenic temperatures of liquid methane. But since the candidate molecules have been studied extensively for other reasons, the Cornell researchers felt justified in turning to the tools of computational chemistry to determine whether their candidate molecules could cohere as a flexible membrane in liquid methane. Computational models have been used successfully to study conventional phospholipid cell membranes.
The group’s computational simulations showed that some candidate substances could be ruled out because they would not cohere as a membrane, would be too rigid, or would form a solid. Nevertheless, the simulations also showed that a number of substances would form membranes with suitable properties. One suitable substance is acrylonitrile, which Cassini showed is present in Titan’s atmosphere at 10 parts per million concentration. Despite the huge difference in temperature between cryogenic azotozomes and room temperature liposomes, the simulations showed them to exhibit strikingly similar properties of stability and response to mechanical stress. Cell membranes, then, are possible for life in liquid methane.
The scientists from Cornell view their findings as nothing more than a first step towards showing that life in liquid methane is possible, and towards developing the methods that future spacecraft will need to search for it on Titan. If life is possible in liquid methane, the implications ultimately extend far beyond Titan.
When seeking conditions suitable for life in the galaxy, astronomers typically search for exoplanets within a star’s habitable zone, defined as the narrow range of distances over which a planet with an Earth-like atmosphere would have a surface temperature suitable for liquid water. If methane life is possible, then stars would also have a methane habitable zone, a region where methane could exist as a liquid on a planet or moon, making methane life possible. The number of habitable worlds in the galaxy would be greatly increased. Perhaps, on some worlds, methane life evolves into complex forms that we can scarcely imagine. Maybe some of them are even a bit like sea monsters.
If we really want to find life on other worlds, why do we keep looking for life based on carbon and water? Why don’t we look for the stuff that’s really different?
In the immortal words of Arthur C. Clarke, “Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.”
I’m seeking venture capital for a Universal buffet chain, and I wondering if I need to include whatever the tentacle equivalent of forks is on my operating budget. If there isn’t any life, I’m going to need to stop watching so much science fiction and get on with helping humanity colonize space.
Currently, astrobiologists are hard at work searching for life, trying to answer this question. The SETI Institute is scanning radio signals from space, hoping to catch a message. Since humans use radio waves, maybe aliens will too. NASA is using the Curiosity Rover to search for evidence that liquid water existed on the surface of Mars long enough for life to get going. The general rule is if we find liquid water on Earth, we find life. Astronomers are preparing to study the atmospheres of extrasolar planets, looking for gasses that match what we have here on Earth.
Isn’t this just intellectually lazy? Do our scientists lack imagination? Aren’t they all supposed to watch Star Trek How do we know that life is going to look anything like the life we have on Earth? Oh, the hubris!
Who’s to say aliens will bother to communicate with radio waves, and will transcend this quaint transmission system and use beams of neutrinos instead. Or physics we haven’t even discovered yet? Perhaps they talk using microwaves and you can tell what the aliens are saying by how your face gets warmed up. And how do we know that life needs to depend on water and carbon? Why not silicon-based lifeforms, or beings which are pure energy? What about aliens that breathe pure molten boron and excrete seahorse dreams? Why don’t these scientists expand their search to include life as we don’t know it? Why are they so closed-minded?
The reality is they’re just being careful. A question this important requires good evidence. Consider the search for life on Mars. Back in the 1970s, the Viking Lander carried an experiment that would expose Martian soil to water and nutrients, and then try to detect out-gassing from microbes. The result of the experiment was inconclusive, and scientists still argue over the results today. If you’re going to answer a question like this, you want to be conclusive. Also, getting to Mars is pretty challenging to begin with. You probably don’t want to “half-axe” your science.
The current search for life is incremental and exhaustive. NASA’s Spirit and Opportunity searched for evidence that liquid water once existed on the surface of Mars. They found evidence of ancient water many times, in different locations. The fact that water once existed on the surface of Mars is established. Curiosity has extended this line of research, looking for evidence that water existed on the surface of Mars for long periods of time. Long enough that life could have thrived. Once again, the rover has turned up the evidence that scientists were hoping to see. Mars was once hospitable for life, for long periods of time. The next batch of missions will actually search for life, both on the surface of Mars and bringing back samples to Earth so we can study them here.
The search for life is slow and laborious because that’s how science works. You start with the assumption that since water is necessary for life on Earth, it makes sense to just check other water in the Solar System. It’s the low hanging fruit, then once you’ve exhausted all the easy options, you get really creative.
Scientists have gotten really creative about how and where they could search for life. Astrobiologists have considered other liquids that could be conducive for life. Instead of water, it’s possible that alternative forms of life could use liquid methane or ammonia as a solvent for its biological processes. In fact, this environment exists on the surface of Titan. But even if we did send a rover to Titan, how would we even know what to look for?
We understand how life works here, so we know what kinds of evidence to pursue. But kind of what evidence would be required to convince you there’s life as you don’t understand it? Really compelling evidence.
Go ahead and propose some alternative forms of life and how you think we’d go searching for it in the comments.
Thanks for watching! Never miss an episode by clicking subscribe. Our Patreon community is the reason these shows happen. We’d like to thank Kuri the Vegan Traveller and Craig Hayes, and the rest of the members who support us in making great space and astronomy content. Members get advance access to episodes, extras, contests, and other shenanigans with Jay, myself and the rest of the team. Want to get in on the action? Click here.
On Tuesday, December 16, 2014, NASA scientists attending the American Geophysical Union Fall Meeting in San Francisco announced the detection of organic compounds on Mars. The announcement represents the discovery of the missing “ingredient” that is necessary for the existence – past or present – of life on Mars.
Indeed, the extraordinary claim required extraordinary evidence – the famous assertion of Dr. Carl Sagan. The scientists, members of the Mars Science Lab – Curiosity Rover – mission, worked over a period of 20 months to sample and analyze Martian atmospheric and surface samples to arrive at their conclusions. The announcement stems from two separate detections of organics: 1) ten-fold spikes in atmospheric Methane levels, and 2) drill samples from a rock called Cumberland which included complex organic compounds.
Methane, of the simplest organic compounds, was detected using the Sample Analysis at Mars instrument (SAM). This is one of two compact laboratory instruments embedded inside the compact car-sized rover, Curiosity. Very soon after landing on Mars, the scientists began to use SAM to periodically measure the chemical content of the Martian atmosphere. Over many samples, the level of Methane was very low, ~0.9 parts per billion. However, that suddenly changed and, as scientists stated in the press conference, it was a “wow” moment that took them aback. Brief daily spikes in Methane levels averaging 7 parts per billion were detected.
The detection of methane at Mars has been claimed for decades, but more recently, in 2003 and 2004, independent research teams using sensitive spectrometers on Earth detected methane in the atmosphere of Mars. One group led by Vladimir Krasnopolsky of Catholic University, and another led by Dr. Michael Mumma from NASA Goddard Space Flight Center, detected broad regional and temporal levels of Methane as high as 30 parts per billion. Those announcements met with considerable skepticism from the scientific community. And the first atmospheric measurements by Curiosity were negative. However, neither group backed down from their claims.
The sudden detection of ten-fold spikes in methane levels in Gale crater is not inconsistent with the earlier remote measurements from Earth. The high seasonal concentrations were in regions that do not include Gale Crater, and it remains possible that the Curiosity measurements are of a similar nature but due to some less active process than exists at the regions identified by Dr. Mumma’s team.
The NASA scientists at AGU led by MSL project scientist Dr. John Grotzinger emphasized that they do not yet know how the methane is being generated. The process could be biological or not. There are abiotic chemical processes that could produce methane. However, the MSL SAM detections were daily spikes and represent an active real on-going process on the red planet. This alone is a very exciting aspect of the detection.
The team presented slides to describe how methane could be generated. With the known low background levels of methane at ~ 1 part per billion, an external cosmic source, for example micro-meteoroids entering the atmosphere and releasing organics which is then reduced by sunlight to methane, could be ruled out. The methane source must be of local origin.
The scientists illustrated two means of production. In both instances, there is some daily – or at least periodic – activity that is releasing methane from the subsurface of Mars. The source could be biological which is accumulated in subsurface rocks then suddenly released. Or an abiotic chemistry, such as a reaction between the mineral olivine and water, could be the generator.
The subsurface storage mechanism of methane proposed and illustrated is called clathrate storage. Clathrate storage involves lattice compounds that can trap molecules such as methane which can subsequently be released by physical changes in the clathrate, such as solar heating or mechanical stresses. Through press Q&A, the NASA scientists stated that such clathrates could be preserved for millions and billions of years underground.
The second discovery of organics involved more complex compounds in surface materials. Also since arriving at Mars, Curiosity has utilized a drilling tool to probe the interiors of rocks. Grotzinger emphasized how material immediately at the surface of Mars has experienced the effects of radiation and the ubiquitous soil compound perchlorate reducing and destroying organics both now and over millions of years. The detection of no organics in loose and exposed surface material had not diminished NASA scientists’ hopes of detecting organics in the rocks of Mars.
Drilling was performed on several selected rocks and it was finally a mud rock called Cumberland that revealed the presence of organic compounds more complex than simple methane. The scientists did emphasize that what exactly these organic compounds are remains a mystery because of the confounding presence of the active chemical perchlorate which can quickly breakdown organics to simpler forms.
The detection of organics in the mud rock Cumberland required the drilling tool and also the scoop on the multifaceted robotic arm to deliver the sample into the SAM laboratory for analysis. To detect methane, SAM has an intake valve to receive atmospheric samples.
Dr. Grotzinger described how Cumberland was chosen as a sample source. The rock is called a mud stone which has undergone a process called digenesis – the metamorphosis of sediment to rock. Grotzinger emphasized that fluids will move through such rock during digenesis and perchlorate can destroy organics in the process. Such might be the case for many metamorphic rocks on the Martian surface. The panel of scientists showed a comparison between rock samples measured by SAM. Two in particular – from the rock “John Klein” and the Cumberland rock — were compared. The former showed no organics as well as other rocks that were sampled; but Cumberland’s drill sample from its interior did reveal organics.
The analysis of the work was painstaking – harking back to the Sagan statement. The importance of discovering organics on Mars could not be understated by the panel of scientists and Grotzinger called these two discoveries as the lasting legacy of the Mars Curiosity Rover. Furthermore, he stated that the discovery and analysis methods will go far to guide the choice of instruments and their use during the Mars 2020 rover mission.
The discovery of organics completes the necessary set of “ingredients” for past or present life on Mars: 1) an energy source, 2) water, and 3) organics. These are the basic requirements for the existence of life as we know it. The search for life on Mars is still just beginning and the new discoveries of organics is still not a clear sign that life existed or is present today. Nevertheless, Dr. Jim Green, introducing the panel of scientists, and Dr. Grotzinger both emphasized the magnitude of these discoveries and how they are tied into the objectives of the NASA Mars program — particularly now with the emphasis on sending humans to Mars. For the Mars Curiosity rover, the journey up the slopes of Mount Sharp continues and now with greater earnestness and a continued search for rocks similar to Cumberland.
Everywhere we look on Earth, we find life. Even in the strangest corners of planet. What other places in the Universe might be habitable?
There’s life here on Earth, but what other places could there be life? This could be life that we might recognize, and maybe even life as we don’t understand it.
People always accuse me of being closed minded towards the search for life. Why do I always want there to be an energy source and liquid water? Why am I so hydrocentric? Scientists understand how life works here on Earth. Wherever we find liquid water, we find life: under glaciers, in your armpits, hydrothermal vents, in acidic water, up your nose, etc.
Water acts as a solvent, a place where atoms can be moved around and built into new structures by life forms. It makes sense to search for liquid water as it always seems to have life here. So where could we go searching for liquid water in the rest of the Universe?
Under the surface of Europa, there are deep oceans. They’re warmed by the gravitational interactions of Jupiter tidally flexing the surface of the moon. There could be life huddled around volcanic vents within its ocean. There’s a similar situation in Saturn’s Moon Enceladus, which is spewing out water ice into space; there might be vast reserves of liquid water underneath its surface. You could imagine a habitable moon orbiting a gas giant in another star system, or maybe you can just let George Lucas imagine it for you and fill it with Ewoks.
Let’s look further afield. What about dying white dwarf stars? Even though their main sequence days are over, they’re still giving off a lot of energy, and will slowly cool down over the coming billions of years. Brown dwarfs could get in on this action as well. Even though they never had enough mass to ignite solar fusion, they’re still generating heat. This could provide a safe warm place for planets to harbor life.
It gets a little trickier in either of these systems. White and brown dwarfs would have very narrow habitable zones, maybe 1/100th the size of the one in our Solar System. And it might shift too quickly for life to get started or survive for very long. This is our view, what we know life to be with water as a solvent. But astrobiologists have found other liquids that might work well as solvents too.
What about life forms that live in oceans of liquid methane on Titan, or creatures that use silicon or boron instead of carbon. It might just not be science fiction after all. It’s a vast Universe out there, stranger than we can imagine. Astronomers are looking for life wherever makes sense – wherever there’s liquid water. And if they don’t find any there, they’ll start looking places that don’t make sense.
What do you think? When we first find life, what will be its core building block? Silicon? Boron? or something even more exotic?
And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!
Comets are renowned for their big beautiful tails that stretch across the sky. But what’s in those things, anyway? And how can comets get multiple tails?
In the past, humans generally used one of two greetings for comets:
1. Dear God, what is that thing? Terrible omens! Surely we will all die in fire.
2. Dear God, what is that thing? Great omens! Surely we will all have a big party… where we all die in fire?
For example, the appearance of what came to be known as Halley’s comet in 1066 was seen as a bad omen for King Harold II. Conversely, it was a good omen for William the Conqueror.
Because of their tails and transitory nature, comets were long thought to be products of the Earth’s atmosphere. It wasn’t until the 1500s, when Tycho Brahe used parallax to determine a comet’s distance. He realized that they were Solar System objects, like planets.
So, good news, we no longer regard them as omens and everyone stopped panicking. Right? Wrong. When Comet Halley approached Earth in 1910, astronomers detected cyanide gas in its tail. French astronomer Camille Flammarion was quoted as saying the gas could “impregnate the atmosphere and possibly snuff out all life on the planet.” This caused a great deal of hysteria. Many bought gas masks and “comet pills” to protect themselves.
With the rise of photographic astronomy, it was found that comets often have two types of tails. A bright tail composed of ionized gas, and a dimmer one composed of dust particles. The ion tail always points away from the Sun. It’s actually being pushed away from the comet by the solar wind.
We now know that a comet’s ion tail contains “volatiles” such as water, methane, ammonia and carbon dioxide. These volatiles are frozen near the comet’s surface, and as they approach the Sun, they warm and become gaseous. This also causes dust on the comet’s surface to stream away. The heating of a comet by the Sun is not uniform.
Because of a comet’s irregular shape and rotation, some parts of the surface can be heated by sunlight, while other parts remain cold. In some cases this can mean that comets can have multiple tails, which creates amazing effects where different regions of a comet stream off volatiles.
These ion tails can be quite large, and some have been observed to be nearly 4 times the distance of the Earth from the Sun. And even though they fill a great volume, they are also pretty diffuse. If you condensed a comet’s tail down to the density of water, it wouldn’t even fill a swimming pool.
We also now know that there isn’t a clear dividing line between comets and asteroids. It’s not the case the comets are dirty snowballs and asteroids are dry rocks. There is a range of variation, and asteroids can gain dusty or gaseous tails and take on a comet-like appearance. In addition, we’ve also found comets orbiting other stars, known as exocomets.
And finally one last fact, the term comet comes from the Latin cometa, which indicated a hairy star.
So, what’s your favorite comet? Tell us in the comets below. And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!
Jupiter is like a jawbreaker. Dig down beneath the swirling clouds and you’ll pass through layer after layer of exotic forms of hydrogen. What’s down there, deep within Jupiter?
What’s inside Jupiter? Is it chameleons? Candy? Cake? Cheddar? Chemtrails? No one knows. No one can ever know.
Well, that’s not entirely true… or even remotely true. Jupiter is the largest planet in the Solar System and two and a half times the mass of the other planets combined. It’s a gas giant, like Saturn, Uranus, and Neptune. It’s almost 90% hydrogen and 10% helium, and then other trace materials, like methane, ammonia, water and some other stuff. What would be a gas on Earth behaves in very strange ways under Jupiter’s massive pressure and temperatures.
So what’s deep down inside Jupiter? What are the various layers and levels, and can I keep thinking of it like a jawbreaker? At the very center of Jupiter is its dense core. Astronomers aren’t sure if there’s a rocky region deep down inside. It’s actually possible that there’s twelve to forty five Earth masses of rocky material within the planet’s core. Now this could be rock, or hydrogen and helium under such enormous forces that it just acts that way. But you couldn’t stand on it. The temperatures are 35,000 degrees C. The pressures are incomprehensible.
Surrounding the core is a vast region made up of hydrogen. But it’s not a gas. The pressure and temperature transforms the hydrogen into an exotic form of liquid metallic hydrogen, similar to the liquid mercury you’d see in a thermometer. This metallic hydrogen region turns inside the planet, and acts like an electric dynamo. Similar to our planet’s own iron core, this gives the planet a powerful magnetic field.
The next level up is still liquid hydrogen, but the pressure’s lower, so it’s not metallic any more. And then above this is the planet’s atmosphere. The upper layers of Jupiter’s atmosphere is the only part we can see. Those bands on the planet are clouds of ammonia that rotate around the planet in alternating directions. The lighter color zones are colder ammonia ice upwelling from below. Here’s the exciting part. Astronomers aren’t sure what the darker regions are.
Still think you want to descend into Jupiter, to try and walk on its rocky interior? NASA tried that. In order to protect Jupiter’s moons from contamination, NASA decided to crash the Galileo spacecraft into the planet at the end of its mission. It only got point two percent of the way down through Jupiter’s radius before it was completely destroyed.
Jupiter is a remarkably different world from our own. With all that gravity, normally lightweight hydrogen behaves in completely exotic ways. Hopefully in the future we’ll learn more about this amazing planet we share our Solar System with.
What do you think? Is there a rocky core deep down inside Jupiter?
And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!
The search for life is largely limited to the search for water. We look for exoplanets at the correct distances from their stars for water to flow freely on their surfaces, and even scan radiofrequencies in the “water hole” between the 1,420 MHz emission line of neutral hydrogen and the 1,666 MHz hydroxyl line.
When it comes to extraterrestrial life, our mantra has always been to “follow the water.” But now, it seems, astronomers are turning their eyes away from water and toward methane — the simplest organic molecule, also widely accepted to be a sign of potential life.
Astronomers at the University College London (UCL) and the University of New South Wales have created a powerful new methane-based tool to detect extraterrestrial life, more accurately than ever before.
In recent years, more consideration has been given to the possibility that life could develop in other mediums besides water. One of the most interesting possibilities is liquid methane, inspired by the icy moon Titan, where water is as solid as rock and liquid methane runs through the river valleys and into the polar lakes. Titan even has a methane cycle.
Astronomers can detect methane on distant exoplanets by looking at their so-called transmission spectrum. When a planet transits, the star’s light passes through a thin layer of the planet’s atmosphere, which absorbs certain wavelengths of the light. Once the starlight reaches Earth it will be imprinted with the chemical fingerprints of the atmosphere’s composition.
But there’s always been one problem. Astronomers have to match transmission spectra to spectra collected in the laboratory or determined on a supercomputer. And “current models of methane are incomplete, leading to a severe underestimation of methane levels on planets,” said co-author Jonathan Tennyson from UCL in a press release.
So Sergei Yurchenko, Tennyson and colleagues set out to develop a new spectrum for methane. They used supercomputers to calculate about 10 billion lines — 2,000 times bigger than any previous study. And they probed much higher temperatures. The new model may be used to detect the molecule at temperatures above that of Earth, up to 1,500 K.
“We are thrilled to have used this technology to significantly advance beyond previous models available for researchers studying potential life on astronomical objects, and we are eager to see what our new spectrum helps them discover,” said Yurchenko.
The tool has already successfully reproduced the way in which methane absorbs light in brown dwarfs, and helped correct our previous measurements of exoplanets. For example, Yurchenko and colleagues found that the hot Jupiter, HD 189733b, a well-studied exoplanet 63 light-years from Earth, might have 20 times more methane than previously thought.
The paper has been published in the Proceedings of the National Academy of Sciences and may be viewed here.
Indian space engineers initiated the 440 Newton liquid fueled engine firing precisely as planned at 00:49 hrs (IST) on Sunday, Dec. 1, 2013 during a critical nail-biting burn lasting some 22 minutes.
The Trans Mars Insertion (TMI) firing propelled India’s Mars Orbiter Mission (MOM) away from Earth forever and placed the spacecraft on course for a rendezvous with the Red Planet on September 24, 2014 – where it will study the atmosphere and sniff for signals of methane.
Sunday’s Mars insertion burn imparted the vehicle with an incremental velocity of 647.96 meters per second (m/sec) consuming 198 kg of fuel.
The maneuver dubbed ‘The mother of all slingshots’, enabled MOM to finally achieve escape velocity and catapulted the 1,350 kilogram (2,980 pound) spacecraft on an historic flight streaking towards Mars.
And in a rare but rather delightful coincidence, MOM is not alone on her remarkable Martian sojourn. Following the triumphant engine burn, she now joins NASA’s MAVEN orbiter in a gallant marathon race to the Red Planet.
MOM was designed and developed by the Indian Space Research Organization’s (ISRO) at a cost of $69 Million and marks India’s inaugural foray into interplanetary flight.
“The Earth orbiting phase of the spacecraft ended,” with this maneuver said ISRO.
MOM is healthy and all systems are functioning normally.
While MOM was cycling Earth, ISRO scientists and engineers activated and tested the probes systems and science payloads.
MOM is nicknamed ‘Mangalyaan’ – which in Hindi means ‘Mars craft.’
MOM’s journey bagen with a picture perfect Nov. 5 liftoff atop India’s highly reliable four stage Polar Satellite Launch Vehicle (PSLV) C25 from ISRO’s Satish Dhawan Space Centre SHAR, Sriharikota.
The PSLV booster precisely injected MOM into an initial elliptical Earth parking orbit of 247 x 23556 kilometers with an inclination of 19.2 degrees.
PSLV does not have sufficient thrust to send MOM streaking directly to the Red Planet.
Therefore since the flawless launch, the engine has been fired 6 times on November 7, 8, 9, 11, and 16 plus one supplementary maneuver to gradually raise the spacecrafts apogee from 23556 km to 192,874 km.
The most recent orbit raising maneuver occurred on Nov 16, 2013 with a burn time of 243.5 seconds and increased the apogee from 118,642 km to 192,874 km.
Today’s burn was the final one around Earth and absolutely crucial for setting her on course for Mars.
MOM was the first of two missions dispatched to Mars by Earthlings this November.
Half a world away, NASA’s MAVEN orbiter blasted off on Nov. 18 from Cape Canaveral Air Force Station, Florida atop an Atlas V booster on a direct path to the Red Planet.
The MOM spacecraft is now on traveling on a heliocentric elliptical trajectory to begin a 300 day long interplanetary voyage of more than 700 Million kilometers (400 Million miles) to the Red Planet.
Along the path to Mars, ISRO plans to conduct a series of Trajectory Correction Maneuvers (TCMs) using MOM’s Attitude and Orbit Control System (AOCS) thrusters to precisely navigate the probe to the point required to achieve orbit around the Red Planet
Following the ten month cruise through space the orbital insertion engine will fire for a do or die burn on September 24, 2014 placing MOM into an 377 km x 80,000 km elliptical orbit around Mars.
MOM will reach Mars vicinity just two days after MAVEN’s arrival on Sept. 22, 2014.
If all continues to goes well, India will join an elite club of only four who have launched probes that successfully investigated the Red Planet from orbit or the surface – following the Soviet Union, the United States and the European Space Agency (ESA).
Both MAVEN and MOM’s goal is to study the Martian atmosphere, unlock the mysteries of its current atmosphere and determine how, why and when the atmosphere and liquid water was lost – and how this transformed Mars climate into its cold, desiccated state of today.
Although MOM’s main objective is a demonstration of technological capabilities, the probe is equipped with five indigenous instruments to conduct meaningful science – including a multi color imager and a methane gas sniffer to study the Red Planet’s atmosphere, morphology, mineralogy and surface features. Methane on Earth originates from both geological and biological sources – and could be a potential marker for the existence of Martian microbes.
MOM’s 15 kg (33 lb) science suite comprises:
MCM: the tri color Mars Color Camera images the planet and its two tiny moons, Phobos and Deimos
LAP: the Lyman Alpha Photometer measures the abundance of hydrogen and deuterium to understand the planets water loss process
TIS: the Thermal Imaging Spectrometer will map surface composition and mineralogy
MENCA: the Mars Exospheric Neutral Composition Analyser is a quadrapole mass spectrometer to analyze atmospheric composition
MSM: the Methane Sensor for Mars measures traces of potential atmospheric methane down to the ppm level.
Scientists will be paying close attention to whether MOM detects any atmospheric methane to compare with measurements from NASA’s Curiosity rover – which found ground level methane to be essentially nonexistent – and Europe’s upcoming 2016 ExoMars Trace Gas Orbiter.
India’s MOM – ‘Mangalyaan’ mission is expected to continue gathering measurements at the Red Planet for at least six months and hopefully much longer.
MAVEN could operate for a decade or longer and is also crucial for relaying images and data collected by NASA’s current and upcoming surface rovers and landers.
Although they were developed independently and have different suites of scientific instruments, the MAVEN and MOM science teams will “work together” to unlock the secrets of Mars atmosphere and climate history, MAVEN’s top scientist told Universe Today.
“We have had some discussions with their science team, and there are some overlapping objectives,” Bruce Jakosky told me. Jakosky is MAVEN’s principal Investigator from the University of Colorado at Boulder.
“At the point where we [MAVEN and MOM] are both in orbit collecting data we do plan to collaborate and work together with the data jointly,” Jakosky said.
Stay tuned here for continuing MOM and MAVEN news and Ken’s MAVEN and SpaceX Falcon 9 launch reports from on site at the Kennedy Space Center press center and Cape Canaveral Air Force Station, Florida.