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.
Whilst Mars might not be the most lively planet around, with any tectonic activity ceased since its core cooled and its atmosphere stripped by our sun, it’s by no means a dead planet. We’ve bore witness to many things that we didn’t initially expect to see like dust devils flitting across Mars’ vast plains to massive avalanches that sent plumes of dust billowing up into the martian atmosphere. Still these events aren’t particularly common and the rovers we’ve sent to explore our red sister don’t usually see drastic changes in their surrounding landscape. That was until very recently when a strange looking rock seemingly appeared out of no where, causing rampant speculation and excitement about its origins.
The rock itself is fairly interesting, being around 4cm wide and having what many have called a “jelly doughnut” like appearance thanks to its white crust containing a red centre. Further analysis just deepened the mystery as Pinnacle Island (as it was then dubbed) contained levels of sulphur and manganese far above that of any other rock formation previously analysed from Mars. Such composition suggests that this rock formed in the presence of water, adding fuel to the theory that Mars was once not unlike Earth, but its uniqueness didn’t help in identifying where it had come from and thus the theories began rolling in.
Many initially postulated that it was an ejecta from a nearby asteroid strike, something that would be very likely to dig up unusual specimens like this and land them at our feet. Unfortunately since this was the only potential piece of ejecta found anywhere nearby this was unlikely as something like that would have created much more debris than just a single rock. Most of the other explanations devolved into conspiracy theories and crazy talk although I will admit that it was entertaining to think that aliens would mess with us by placing single rocks in front of our rovers. Now, after many months of speculation, NASA has announced the source of the mysterious rock and it’s as intriguing as it is mundane.
In short Opportunity created it.
The before and after pictures that made the rounds on the Internet are actually from 2 different cameras. The first is from the high resolution, typically forward facing, camera responsible for most of the beautiful images we see beamed back. The after picture is from a reward facing camera which was taken a couple days after Opportunity had passed by that particular location. Between those two pictures Opportunity actually ran over a small rock, crushing it into pieces and sending this one fragment rolling down the hill it was climbing up. This gave rise to Pinnacle Island and it’s former compatriot Stuart Island both of which can bee seen a mere 3 feet from each other.
This was always going to be the most plausible explanation (anything else would’ve been a little too fantastical) but it was great to see the wider world captivated by this scientific mystery, even if the speculation got a little bit crazy at times. Whilst it won’t lead to any major scientific revelations or brilliant insights into Mars it did serve as a good exercise in figuring out the origin of strange happenings, even if the origin turns out to be us.
As many know my experience with 3D printing has come with mixed results, as the kit I bought with 3 friends required more calibration than I was willing to do and my friend’s Solidoodle proved to be a reliable way to create the objects I needed. I’m still highly interested in the area (I was going to post a review of Microsoft’s 3D Builder but just never found the time to hook it all up) and I strongly believe that the commoditization of manufacturing at the small scale will prove to be revolutionary. One area of particular interest was the idea of a food printer, something that could potentially make a meal out of some base nutritional components.
As it turns out this might be closer than I first imagined (skip to 1 minute in for the good stuff):
NASA stated investigating the idea of 3D printing food a little while ago, investing a small amount of money into research to create a device capable of creating edible foodstuffs on the International Space Station. Primarily this was to fuel a longer term goal to provide food for an interplanetary trip to Mars as its believed that 3D printed food could dramatically reduce waste and improve efficiency with transported materials. Whilst this current demonstration appears to be limited to producing pizza (something which seems a perfect fit for a first run) NASA’s vision is for something far more general and it looks like they’re well on their way to achieving that.
It’s a big step considering that we’ve had printers capable of producing chocolate models for some time, but the leap to other food has proved somewhat elusive. It will likely be quite some time before it gets much more general than your run of the mill pizza however although some of the designs making the rounds are really quite impressive. Time will tell if they’ll ever become mass market devices but I can definitely see themselves finding a home in space stations and high end restaurants looking to create truly unique dishes.
Whenever the idea of establishing a colony off-world comes to mind the first place many think of is Mars. Primarily this is due to Mars being the most similar of all the other planets to ours, having an atmosphere and land features that look very similar to some of our own. However that’s where the likeness ends as its lack of magnetic field has meant that its atmosphere has been stripped bar to a thin layer of carbon dioxide, taking all of the surface water along with it. Thus whilst it would seem like the best candidate for humans to establish themselves elsewhere in this solar system there are other potential sites that have distinct advantages over what Mars can provide.
One surprisingly good candidate for a potential human colony is Mercury. Now initially this would seem like a pretty bad idea as its surface temperatures regularly exceed several hundred degrees celsius and the only atmosphere to speak of is a tenuous layer is mostly made up of solar wind and vaporized surface material. However it’s close proximity to the sun gives it access to abundant solar power, orders of magnitude more than what is available on the surface of Mars. Considering that power is probably one of the biggest limiting factors for a colony and the size it can grow this advantage could prove invaluable, so long as the initial challenges could be overcome.
Probably the biggest thing that Mercury has going against it is the time it would take to get a mission there. Whilst we’ve got craft today capable of covering the distance in under 40 days or so its tight orbit around our sun makes it incredibly difficult to get into orbit with it. It’s not so much that it’s hard to do, more that the time typically required to transit to there with an approach that will get you into orbit takes on the order of years, not days. This would mean the development of systems to support humans for a sustained period in space which would open up other alternative locations for a human colony.
Interestingly such systems could be used to establish a colony on Venus, although not the type you’d think of. Whilst Venus’ surface is a hellish place where it rains metal it would be quite possible to create cloud cities that float around an area that’s much more hospitable to humans. Indeed the pressure at 50KM above the surface is the same as Earths and thanks to the dense, mostly carbon dioxide atmosphere a lifting gas that’s simply breathing air has a lifting power of 50 times that of helium on earth. The protections required then are far less strenuous than those required to get to Mercury initially and the dangers posed by the atmosphere are far less severe than that of a harsh vacuum.
Past these planets though are options start to get limited as whilst many moons of the gas giants of the outer solar system have an abundance of things like water or other useful materials they’re typically quite harsh environments, either being flooded with ionizing radiation or lacking any kind of atmosphere without the benefit of having high amounts of light to take advantage of. They’re essentially equivalent to space itself in that regard and whilst I love the idea of large human colonies in space there’s really no substitute for colonizing another planet.
For what its worth we’re likely going to see a Mars colony within our lifetimes, one that will likely be limited to a few one way pioneers or entrepreneurs looking to take advantage of the first new frontier in a century. The other options, whilst being only slightly more fantastical than that of a Mars colony, aren’t likely to happen any time soon as there needs to be much more ground broken in engineering terms before they become viable. Regardless of where it happens a human colony off our planet is fast becoming a necessity if we want to ensure the human race doesn’t have a single point of failure in our own planet.
Mars is by far the most studied planet that isn’t our own, having had 46 separate missions launched to it since the 1960s and is currently host to no less than 5 active missions both in orbit and on its surface. Those missions have taught us a lot about our red celestial sister, the most intriguing of which is that it was once not unlike Earth, covered in vast swaths of ocean which could potentially have been host to all sorts of life. Even more interesting is that while it’s little more than a barren desert that’s only notionally above vacuum it still contains water ice in non-trivial quantities, leading many to speculate that somewhere its liquid form must also exist. The process by which Mars transformed from a lush landscape like ours to the wasteland it is today is still shrouded in mystery and is something that MAVEN, NASA’s latest mission to Mars, is seeking to solve.
MAVEN successfully launched yesterday atop of an ATLAS V rocket and will spend the better part of a year transiting the distance between Earth and Mars. Its primary objective is to investigate the evolution of Mars’ atmosphere to try and ascertain the factors that influenced its demise. Since the current prevailing theory is that a cooling planetary core led to a loss of a protective magnetic field which then allowed the solar wind to slow strip away the atmosphere many of the instruments aboard the craft are geared towards measuring solar particles around Mars’ orbit. The rest of the instrumentation is focused on directly measuring Mars’ atmosphere which will then allow scientists to reconstruct a full picture of it and the influences working on it.
I believe this is also (and someone feel free to correct me on this) the reason for its slightly abnormal orbit for when it arrives at Mars. Instead of taking the usual approach of having a near circular orbit (like the Mars Reconnaissance Orbiter) it instead has a highly elliptical orbit with the closet approach being a mere 150KM above the surface whilst its furthest point is 6200KM out. This would allow the craft to get good measurements of the levels of solar particles as it gets closer to the surface and how that compares to it further out. Considering the orbital period will also only be 4.5 hours it would make for some rather exciting flybys if you were aboard that craft but then again that’s not an orbit you’d use if you had people on board.
The orbit also has the rather unfortunate effect of limiting one of MAVEN’s more long term capabilities: it’s link back to Earth. MAVEN has a 10Mbit/s link thanks to an updated Electra array which is almost twice as powerful as MRO’s. However due to the rather eccentric orbit it won’t be available as often which will limit the amount of data that can be passed back. This doesn’t just impact the satellite itself though as whilst the rovers on Mars can communicate directly to Earth it’s not a very fast connection, so most offload onto a local satellite for their more data hungry applications. Since it’s currently only an augment to the other fleet of satellites around Mars this isn’t too much of an issue although it could present some contention issues later on the track when the other satellites are retired.
The science that MAVEN will conduct on its planned 1 year mission will prove invaluable in determining just what happened to Mars’ atmosphere and, by extension, what the chances are of any life existing on its surface today. It will also provide infrastructure for future missions, allowing them to be more ambitious in the goals that they attempt to reach. For now though it’s 1 day into its long trip to our celestial sister, quietly awaiting the day when it can finally start fulfilling its purpose.