Mars is the most studied planet other than our own, currently playing host to no less than 7 different craft currently operating both in orbit and on its surface. It’s of interest to us due to its similarity to Earth, giving us an insight into how certain processes can affect planets differently. Mars is also the easiest of our sister planets to explore, being relatively close and having an atmosphere that won’t outright destroy craft that dare land on it. Still for all that research it still manages to surprise us, most recently by revealing the fact that liquid water still flows on it. We’re still far from done with it however and the MAVEN craft has just revealed some key insights into Mars’ atmosphere and the history behind its current state.
Mars’ atmosphere is extremely thin, over 100 times less dense than the atmosphere here on Earth. To put that in perspective that’s about the same density as the air here is on Earth at an altitude of about 30KM, or about 3 times as high as your typical jet airliner flies. It’s also almost all carbon dioxide with a small smattering of nitrogen and other trace elements. However it wasn’t always this way as numerous studies have revealed that it must have held a much thicker atmosphere in the past. What has remained something of a mystery is just how Mars came to lose its atmosphere and whether those same processes were in effect today. MAVEN, a craft specifically designed to figure this out, has made some key discoveries and it seems that the long held belief that the sun is to blame is true.
For a planet to lose its atmosphere there’s really only two places it can go. In some cases the planet itself can absorb the atmosphere, driving chemical reactions that pull all the gases down into more solid forms. This specific scenario was investigated on Mars however the lack of the kinds of minerals we’d expect to see, mostly carbonates given Mars’ mostly carbon dioxide atmosphere, means that this was unlikely to be the case. The second way is for it to lose the atmosphere to the vacuum of space which can happen in a number of ways, usually through the planet being unable to hold onto its atmosphere. This latter theory has proved to be correct although it’s far more interesting than Mars simply being too small.
In the past Mars would have looked a lot like Earth, a small blue marble wrapped in protective gases. Back then the core of Mars was still active, generating a magnetic field much like that on Earth. However, after a time, the core began to cool and the engine behind the giant magnetic field began to fade. As this field weakened the solar wind began to erode the atmosphere, slowly stripping it away. Today Mars’ magnetic field is around 40 times weaker than Earth’s, no where near enough to stop this process which is still continuing to this day. For Mars it seems that its diminutive core was what sealed its fate, unable to sustain its protective magnetic shield from the relentless torment of our sun.
Whilst this has been the prevailing theory for some time its good to get confirmation from hard data to support it. Our two closest solar relatives, Venus and Mars, provide insights into how planets can develop and what changes produce what outcomes. Knowing things like this helps us to understand our own Earth and what impacts our behaviour might have on it. Mars might not ever see its atmosphere again but at least we now know what it might have looked like once, and where it has gone.
We’ve known for some time that water exists in some forms on Mars. The Viking program, which consisted of both orbiter and lander craft, showed that Mars’ surface had many characteristics that must have been shaped by water. Further probes such as Mars Odyssey and the Phoenix Lander showed that much of the present day water that Mars holds is present at the poles, trapped in the vast frozen tundra. There’s been a lot of speculation about how liquid water could exist on Mars today however no conclusive proof had been found. That was until today when NASA announced it had proof that liquid water flows on Mars, albeit in a very salty form.
The report comes out of the Georgia Institute of Technology with collaborators from NASA’s Ames Research Center, Johns Hopkins University, University of Arizona and the Laboratoire de Planétologie et Géodynamique. Using data gathered from the Mars Reconnaissance Orbiter the researchers had identified that there were seasonal geologic features on Mars’ surface. These dark lines (pictured above) were dubbed recurring slope lineae would change over time, darkening and appearing to flow during the warmer months and then fading during the colder months. It has been thought for some time that these slopes were indicative of liquid water flows however there wasn’t any evidence to support that theory.
This is where the MRO’s Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) comes into play. This instrument was specifically designed to detect water on Mars by looking at varying wavelengths of light emitted from the planet’s surface. Once the target sites were identified CRISM was then pointed at them and their surface composition analysed. What was found at the RSL sites were minerals called hydrated salts which, when mixed with water, would lower the freezing point of the water significantly. Interestingly these hydrated salts were only detected in places were the RSL features were particularly wide as other places, where the RSLs were slimmer, did not show any signs of hydrated salts.
These salts, called perchlorates, have been seen before by several other Mars missions although they’ve never been witnessed in hydrated form before. These perchlorates can potentially keep water from freezing at temperatures down to -70°C. Additionally some of these perchlorates can be used in the manufacturing of rocket fuel, something which could prove to be quite valuable for future missions to Mars. Of course they’re likely not in their readily usable form, requiring some processing on site before they can be utilized.
Data like this presents many new opportunities for further research on Mars. It’s currently postulated that these RSLs are likely the result of a shallow subsurface flow which is wicking up to the surface when the conditions are warmer. If this is the case then these sites would be the perfect place for a rover to investigate as there’s every chance it could directly sample martian water at these sites. Considering that wherever we find liquid water on Earth we find life then there’s great potential for the same thing to happen on Mars. If there isn’t then that will also tell us a lot which means its very much worth investigating.
The way we get most of the scientific data back from the rovers we currently have on Mars is through an indirect method. Currently there are four probes orbiting Mars (Mars Odyssey, Mars Express, Mars Reconnaissance Orbiter and MAVEN) all of which contain communications relays, able to receive data from the rovers and then retransmit it back to Earth. This has significant advantages, mostly being that the orbiters have longer periods with which to communicate with Earth. Whilst all the rovers have their own direct connections back to Earth they’re quite limited, usually several orders of magnitude slower. Whilst current rovers won’t have their communication links improved for future missions having a better direct to Earth link could prove valuable, something which researchers at the University of California, Los Angeles (UCLA) have started to develop.
The design is an interesting one essentially being a flat panel of phased antenna array elements using a novel construction. The reasoning behind the design was that future Mars rover missions, specifically looking towards the Mars 2020 mission, would have constraints around how big of an antenna it could carry. Taking this into account, along with the other constraint that NASA typically uses X-band for deep space communications like this, the researchers came up with the design to maximise the gain of the antenna. The result is this flat, phased array design which, when tested in a prototype 4 x 4 array, closely matched their simulated performance metrics.
With so many orbiters around Mars it might seem like a better direct to Earth communications relay wouldn’t be useful however there’s no guarantees that those relays will always be available. Currently mission support for most of those orbiters is slated to end in the near future with the furthest one out slated for decommissioning in 2024 (MAVEN). Since there’s a potential new rover slated to land sometime in 2020, and since we know how long these things can last once they’ve landed, having better on board communications might become crucial to the ongoing success of the mission. Indeed should any of the other rovers still be functioning at that time the new rover may have to take on board the relay responsibilities and that would demand a much better antenna design.
There’s still more research to be done with this particular prototype, namely scaling it up from its current 4 x 4 design to the ultimate 16 x 16 panel. Should the design prove to scale as expected then there’s every chance that you might see an antenna based on this design flying with an orbiter in the near future. I’m definitely keen to see how this progresses as, whilst it might have the singular goal of improving direct to Earth communications currently, the insights gleaned from this design could lead to better designs for all future deep space craft.
MESSENGER was a great example of how NASA’s reputation for solid engineering can extend the life of their spacecraft far beyond anyone’s expectations. Originally slated for a one year mission once it reached it’s destination (a 7 year long journey in itself) MESSENGER continued to operate around Mercury for another 3 years past its original mission date, providing all sorts of great data on the diminutive planet that hugs our sun. However after being in orbit for so long its fuel reserves ran empty leaving it unable to maintain its orbit. Then last week MESSENGER crash landed on Mercury’s surface putting an end to the 10 year long mission. However before that happened MESSENGER sent back some interesting data around Mercury’s past.
As MESSENGER’s orbit deteriorated it creeped ever closer to the surface of Mercury allowing it to take measurements that it couldn’t do previously due to concerns about the spacecraft not being able to recover from such a close approach. During this time, when MESSENGER was orbiting at a mere 15KMs (just a hair above the max flight ceiling of a modern jetliner) it was able to use its magnetometer to detect the magnetic field emanating from the rocks on Mercury’s surface. These fields showed that the magnetic field that surrounds Mercury is incredibly ancient, dating back almost 4 billion years (right around the creation of our solar system). This is interesting for a variety of reasons but most of all because of how similar Mercury’s magnetic field is to ours.
Of all the planets in our solar system only Earth and Mars have a sustained magnetic field that comes from an internal dynamo of undulating molten metals. Whilst the gas giants also generate magnetic fields they come from a far more exotic form of matter (metallic hydrogen) and our other rocky planets, Venus and Mars, have cores that have long since solidified, killing any significant field that might have once been present. Mercury’s field is much weaker than Earth’s, on the order of only 1% or so, but it’s still enough to produce a magnetosphere that deflects the solar wind. Knowing how Mercury’s field evolved and changed over time will give us insights not only into our own magnetic field but of those planets in our solar system who have long since lost theirs.
There’s likely a bunch more revelations to come from the data that MESSENGER gathered over all those years it spent orbiting our tiny celestial sister but discoveries like this, ones that could only be made in the mission’s death throes, feel like they have a special kind of significance. Whilst it might not be the stuff that makes headlines around the world it’s the kind of incremental discovery that gives us insight into the inner workings of planets and their creation, something we will most definitely need to understand as we venture further into space.
We’ve known for a long time now that Mars once contained vast reservoirs of water and that even in its apparently dry state there was indications of water still hiding in various places. The search for water on Mars is a twofold with the two main objectives being finding environments suitable to life and secondly for potential use by future manned missions. Whilst we’ve succeed in confirming that yes, water once covered Mars and it still exists there today, we’re still finding out just how extensive the reservoirs are. As it turns out Mars may be flush with more water than we first expected and it’s been right under our noses this entire time.
The surface of Mars is a barren wasteland, covered in the same monotonous coloring that gives it that signature red tinge. The poles are the exception to this, harboring large water ice caps that get blanketed with a layer of dry ice (frozen carbon dioxide) in the winter. The reason for this is that due to the low pressure of Mars’ atmosphere exposed water anywhere else on the planet simply subliminates, turning straight from ice to water vapor before being swept away by Mars’ turbulent winds. However new research from the University of Copenhagen has revealed that water ice has managed to survive in other places around Mars and has done so in great quantities.
As it turns out many of the geological features we’ve observed on Mars that we’ve assumed to simply be mountains or hills are in fact dust covered glaciers which pepper the martian surface near the poles. This thick layer of dust has protected them from Mars’ atmosphere, preventing the ice from sublimation away. This dust also makes them appear like any other geological feature that you’d find on Mars’ surface instead of the towering walls of ice that we’re used to seeing here on Earth. The researchers were able to determine that these were water ice glaciers by using radar measurements from the numerous spacecraft we have orbiting the red planet and how they’re flowing under their protective dust blankets.
The amount of ice that these glaciers contain is quite staggering, enough that if it was spread out over the surface of Mars it would blanket it in a layer 1.1m thick. Such giant reservoirs provide huge opportunities for both exploration and scientific purposes and potentially paves a way for a sustainable human settlement. Whilst liquid water is always the most viable place to look for life we’ve found dozens of examples of microbial life living in some pretty harsh conditions and these glaciers might be a great place to start looking. That and water is one of the main components in several types of rocket fuel, something we’ll need if we want to do multiple return missions to Mars.
It’s incredible to note that our view of Mars has changed so drastically over the past couple decades, going from a barren wasteland that could never have housed life to a viable candidate, flush with water reserves everywhere. This latest discovery just goes to show that we can’t simply rely on visual data alone as even a well studied planet like Mars can still hide things from us and can do it in plain sight. The next step is to dig beneath Mars’ thick dust blanket to peer into these glaciers and, potentially, find something wriggling down there.
The last decade has seen NASA change tack quite a few times, mostly under the direction of different presidents who had very different ideas about how the venerable agency should function. Much of it came in the form of a lot of hand wringing about whether or not we should return to the Moon or simply go straight to Mars, with the current strategy to put NASA astronauts on our red sister sometime in the 2030s (although they might be too late if SpaceX has their way). This new direction included sending astronauts to a near-Earth asteroid by 2025 in order to vet some of the technology required to eventually send those astronauts to Mars and NASA has just detailed what that mission will be.
The initial mission was going to attempt to capture an entire asteroid, one around 8m in diameter, using an inflatable cylinder that would envelope the asteroid and then return it to a cis-lunar (between the Earth and the Moon) orbit. Now this wouldn’t have been a massive asteroid, probably on the order of 8m or so, but it still would have been a pretty massive endeavour to bring it back to a closer orbit. However there was another potential option for this mission: instead of retrieving the whole asteroid a probe would instead pluck a small boulder from the surface of a much larger asteroid and then return that back to the cis-lunar orbit. NASA announced today that the second option would be the one they’d pursue going forward with the mission timeframe still slated for sometime in the next decade.
Interestingly the second option is significantly more expensive, to the tune of $100 million, however the technology that will be developed to support it was seen as being of much more benefit than the other mission. Once a candidate asteroid has been selected the craft will be launched into orbit around it where it will identify and select a boulder for retrieval. It will then land on the boulder, capture it, and then lift it back off into orbit around the asteroid again. The craft will remain there for some time afterwards to see if the idea of a gravity tractor craft could work to divert a potentially dangerous asteroid from colliding with Earth. Then, depending on how successful that was, the craft will either remain there a little longer or begin the journey back towards earth, it’s newly captured asteroid boulder in tow. Then astronauts from Earth will embark on a month long mission to travel to the asteroid, study it and then potentially bring it (or at least samples) back to Earth.
It’s an ambitious mission but one that will be the proving ground for the vast majority of technologies required to get humans to Mars. Whilst we’ve learnt a lot about long duration spaceflights thanks to the International Space Station there’s a lot more we need to develop in order to support the same duration flights away from the protection of our Earth. Specifically this relates to the radiation shielding requirement (something which still doesn’t have a great solution) but there’s also numerous other questions that will need to be answered before we launch a craft towards Mars. A month to a nearby asteroid fragment might not sound like much but it will be another giant leap forward technology wise.
NASA is stil a far cry from its heydays during the cold war but its starting to rekindle that explorer spirit that drove them to achieve such great things all those years ago. Opting for the more ambitious mission profile means that our understanding will be more greatly increased as a result, hopefully fueling further exploration with a view to us one day becoming a multi-planet species. We’re still a while away from seeing this happen but it’s so good to finally see a light at the end of the tunnel.
Moving things between planets is a costly exercise no matter which way you cut it. Whilst we’ve come up with some rather ingenious ideas for doing things efficiently, like gravity assists and ion thrusters, these things can only take us so far and the trade offs usually come in the form of extended duration. For our robotic probes this is a no brainer as machines are more than happy to while away the time in space whilst the fleshy counterparts do their bits back here on Earth. For sending humans (and larger payloads) however these trade offs are less than ideal, especially if you want to do round trips in a reasonable time frame. Thus we have always been on the quest to find better ways to sling ourselves around the universe and NASA has committed to investigating an idea which has been dormant for decades.
NASA has been charged with the task of getting humans to Mars by sometime in the 2030s, something which shouldn’t sound like an ambitious feat (but it is, thanks to the budget they’ve got to work with). There are several technical hurdles that need to be overcome before this can occur not least of which is developing a launch system which will be able to get them there in a relatively short timespan. Primarily this is a function of the resources required to keep astronauts alive and functioning in space for that length of time without the continual support of launches from home. Current chemical propulsion will get us there in about 6 months which, whilst feasible, still means that any mission to there would take over a year. One kind of propulsion that could cut that time down significantly is Nuclear Thermal which NASA has investigated in the past.
There are numerous types of Nuclear Thermal Propulsion (NTP) however the one that’s showing the most promise, in terms of feasibility and power output, is the Gas Core Reactor. Mostly this comes from the designs high specific impulse which allows it to generate an incredible amount of thrust from a small amount of propellant which would prove invaluable for decreasing mission duration. Such designs were previously explored as part of the NERVA program back in the 1970s however it was cancelled when the supporting mission to Mars was cancelled. However with another Mars mission back on the books NASA has begun investigating the technology again as part of the Nuclear Thermal Rocket Element Environmental Simulator (NTREES) at their Huntsville facility.
NTP systems likely wouldn’t be used for the initial launch instead they’d form part of the later stage to be used once the craft had made it to space. This negates many of the potential negative aspects like radioactive material being dispersed into the atmosphere and would allow for some concessions in the designs to increase efficiency. Several potential craft have been drafted (including the one pictured above) which use this idea to significantly reduce travel times between planets or, in the case of supply missions, dramatically increase their effective payload. Whether any of these will see the light of day is up to the researchers and mission planners at NASA but there are few competing designs that provide as many benefits as the nuclear options do.
It’s good to see NASA pursuing alternative ideas like this as they could one day become the key technology for humanity to spread its presence further into our universe. The decades of chemical based rocketry that we have behind us have been very fruitful but we’re fast approaching the limitations of that technology and we need to be looking further ahead if we want to further our ambitions. With NASA (and others) investigating this technology I’m confident we’ll see it soon.
There’s many ways to look for life on other planets. Most of our efforts currently focus on first finding environments that could sustain life as we know it which is why the search (and subsequent discovery) of water on other celestial bodies is always a cause for celebration. Once we’ve got a target though the search needs to become more nuanced as we have to seek out the clues that life leaves behind or the blocks that build it. For life as we know it one of the first things we can look for is the presence of organic molecules, the essential parts that make up all of life as we know it. One of these such molecules is methane, reknown for being a component in flatulence, something which Curiosity recently detected on Mars.
Methane, and other organic compounds, don’t necessarily require life in order to form however their presence does indicate that there was an environment favourable to life at one point in time. For Mars this was some time ago, on the order of billions of years, and so it’s highly unlikely that any remaining methane is due to microbial activity. However there has to be some local source of methane near Curiosity as it detected a ten fold spike in the amount of methane in Mars’ atmosphere, something which it has never seen before. Additionally Curiosity detected other organic molecules in a rock it drilled into recently, indicating that there was a time when organics must have been prevalent across the entire surface of Mars.
The discovery was made sometime ago however the researchers needed to rule out the possibility that the reading was caused by organics that were trapped in Curiosity’s sensors from Earth. Things like this happen more often than you think as whilst we take every precaution to ensure that there isn’t any contaminations on craft like this it’s inevitable that the sensors, all of which are highly complex machines, end up having stray molecules trapped within them. Because of that however we’ve gotten pretty good at identifying when things came along for the ride and this particular methane spike didn’t originate from Earth.
The organics in the rock are most intriguing however as they tell a story of Mars’ atmosphere that stretches back to the point where it still held liquid water on its surface. The ratio of isotopes in the water (which I talked about yesterday in regards to the discoveries Rosetta has made) indicates that the mineral formed some time after Mars lost much of its water, if we assume that the water on Mars and Earth came from the same place. However the ratio is also radically different to the water in Mars’ atmosphere today indicating that it formed before Mars lost the rest of its surface water. It will be interesting to see how this sample compares to other places around Mars as it will paint a detailed picture of the planet’s surface over time.
It seems like it will be only a matter of time before we find a large source of water on Mars, buried deep beneath the surface somewhere. From there we’ll have an exciting period of analysis to determine if microbial life still thrives on what appears to be a dead planet. Unfortunately that’s not likely to happen any time soon, at least not until we get people there anyway, but with NASA recommitting themselves to such an endeavour it might come sooner than many first thought. Honestly I can’t wait for that to occur as it will shed so much light on how life evolves and, possibly, what it can become.
When you think of space faring nations India probably isn’t one of the first to come to mind but they’re fast becoming one of the big players in terms of capability. Their space agency, the Indian Space Research Organisation (ISRO), began back in 1975 and has primarily focused on developing both launch and satellite capabilities. They made headlines back in 2008 with Chandrayaan-1 which was their first satellite to visit another celestial body. Every year since then has seen India launch multiple satellites every year, with the vast majority of them blasting to orbit aboard their very own Satellite Launch Vehicle brand of rockets. Last week saw them tick off another incredible milestone: their first interplanetary mission arriving successfully at its destination.
The Mars Orbiter Mission (or Mangalyaan) is a comparatively small craft, weighing in at just on 500 kgs with only 15kg of that being dedicated to the various payloads it’s carrying. It’s primarily a technology demonstration mission, designed to provide a shakedown for the various systems required to maintain an interplanetary mission. Thus the payload of the mission is relatively simple, consisting of some atmospheric and particle sensors along with your standard imaging affair, although it does have the rather interesting capability of being able to radically change its orbit over time. Just the fact that India has joined the rather exclusive club of nations that have sent craft to Mars (3 total, now) would be noteworthy in of itself but there’s one more thing that makes MOM noteworthy.
A typical Mars mission usually costs on the order of hundreds of millions of dollars, usually tickling the billion dollar mark when all things are considered. The Phoenix Lander, for instance, cost about $386 million and was considered to be quite cheap as it reused a lot of technology from other projects. MOM however was done for a total budget of $74 million including launch costs making it the cheapest interplanetary mission by any nation to date. A lot of this comes down to the simplicity of the mission however a big part of it is the fact that their launch vehicle costs around $19 million per launch, a cost that rivals even that of SpaceX’s Falcon launch system. If ISRO is able to keep their costs at this level there’s every chance that other nations will look to them to provide launch capabilities like this in the future.
Even though MOM is a simple craft it has the capability to provide extremely useful data like its predecessor Chandrayaan-1 did. The instruments might be few in number but the data they provide will function as a validation point for all the missions that have come before it, ensuring that the models we’ve developed for Mars are still valid. Having another set of eyes on Mars means that we’ll be able to catch many more of the geological phenomenon in action that we’ve seen in the past which will provide us even more insight into how its environment is changing, even today.
It always amazes me to see how rapidly space capability is being developed not only by private industry but also nation states. Exploring space is an incredibly expensive affair, one that seemingly doesn’t contribute to the nation’s economy directly, but the benefits always outstrip any cost that follows them. For India the ROI is going to be amazing as they’ve built a capability that took other nations decades and several billion dollars to achieve. I’m very excited to see what they accomplish next and whether or not they can continue the tradition of doing it far cheaper than anyone else.
It’s hard to believe that Curiosity, the successor to the incredibly successful Spirit and Opportunity Mars Exploration Rovers, has been on the martian surface for a total of 2 years now. Not only did it prove many of the complicated engineering processes behind getting such a large craft onto Mars’ surface it’s also greatly improved our understanding of our celestial neighbour. Like its predecessors Curiosity has already outlived its original mission parameters, although not by the same margin, and barring any catastrophic failures it’s highly likely that it will continue to be productive long into the future. However it did recently come dangerously close to falling victim to one of Mars’ most insidious features: the sand traps.
Curiosity’s current mission is to get to Mount Sharp, a 5KM tall peak which NASA scientists hope will have varying layers of rock they’ll be able to study as they climb up it. This would give a better insight into the evolution of Mars’ environment over the years, showing us how it transitioned from a once wet planet into the barren desert that it is today. However between Curiosity and the base of Mount Sharp there’s a trench of wavy sand that’s been dubbed the “Hidden Valley” and up until recently NASA scientists were just going to drive across it. However upon attempting to do this Curiosity has found that the sand is far more slippery than it first anticipated and thus it has been turned back whilst NASA figures out what approach they’ll take.
This is a very similar situation to the one that was eventually the downfall of Spirit. A lot of the surface of Mars looks visually similar however often the makeup of the underlying surface varies drastically. In both Curiosity’s and Spirit’s cases the soil lacked cohesion making it extremely difficult for the rovers to get traction. For Spirit this meant that it was no longer able to get its solar panels into the required angle for the martian winter, meaning it couldn’t generate enough electricity to keep its circuits functioning. If the same fate had befallen Curiosity however it wouldn’t matter as much (well apart from the obvious) as it’s internal power supply doesn’t rely on solar energy.
In terms of the mission profile it’s likely that this will probably just be a delay more than anything else as whilst there aren’t many ways out of the valley that Curiosity is currently in there are other potential paths it can take to get to Mount Sharp. In actual fact the delay might not be all bad news for Curiosity either as the return journey from the slippery slopes of Hidden Valley actually revealed a potential rock for further investigation, dubbed the Bonanza King. We’ll have to wait and see if anything interesting can be derived from that, however.
I guess things like this just go to show that no matter how well you prepare, nor how good the equipment is that you bring with you, it’s still entirely possible for old problems to come back and bite you. Thankfully this time around we were prepared for such things and we haven’t ended up with another stationary science platform. Hopefully this won’t delay Curiosity’s mission for too long as it’s proven to be incredibly valuable thus far and the Mount Sharp mission could really give us clarity over how Mars became the desolate place that it is today.