Establishing lunar colonies seems like the next logical step, it’s our closest celestial body after all, however it might surprise you to learn that doing that might in fact be a lot harder than establishing a similarly sized colony on Venus or Mars. Without an atmosphere to speak of our Moon’s surface is an incredibly harsh place with the full brunt of our sun’s radiation bearing down on it. That’s only half the problem too as since the day/night cycles last 2 weeks you’ll spend half your time in perpetual darkness at temperatures fast approaching absolute zero. There are ways around it however and recent research has led to some rather interesting prospects.
Whilst the surface of the Moon might be unforgiving going just a little bit below the surface negates many of the more undesirable aspects. Drilling into the surface is one option however that’s incredibly resource intensive, especially when you consider that all the gear required to do said drilling would need to be sent from Earth. The alternative is to use structures that are already present on the Moon such as caverns and other natural structures. We know that these kinds of formations are already present on the Moon thanks to the high resolution imagery and gravity mapping we’ve done (the Moon’s gravity field is surprisingly non-uniform) but just how big these structures could be has remained somewhat of a mystery.
Researchers at Purdue university decided to investigate just how big structures like these could be, specifically looking at how big lava tubes could get if they existed on the Moon. During its formation, which would have happened when a large object collided with the then primordial Earth, the surface of the Moon would have been ablaze with volcanic activity. However due to its much smaller size that activity has long since ceased but it would have still left behind the tell tale structures of its more tumultuous history. The researchers then modelled how big these tubes could have gotten given the conditions present on the Moon and came up with a rather intriguing discovery: they’d be huge.
When you see the outcome of the research it feels like an obvious conclusion, of course they’d be bigger since there’s less gravity, but the fact that they’re an order of magnitude bigger than what we’d see on Earth is pretty astounding. The picture above gives you some sense of scale for these potential structures, able to fit several entire cities within them with an incredible amount of room to spare. Whilst using such structures as a basis for a future lunar colony presents a whole host of challenges it does open up the possibility to the Moon having much more usable space than we first thought.
It seems I can’t go too long without hearing about everyone’s favourite celestial event: the Supermoon. It’s a somewhat rare event, typically occurring once every 14 months or so, but given the amount of attention it seems to get on various news and social media sites you’d be forgiven for thinking it’s more akin to a total solar eclipse. Considering what actually happens during this event, I.E. the coincidental alignment of the moon being full whilst also being at it’s closest point on its orbit around Earth, you wouldn’t expect there to be much interest in it but everyone seems to be wowed at just how huge the moon appears when this happens.
Problem is though that it’s not that much bigger at all.
As you can see the supermoon on the right hand side isn’t really that much bigger than the more regular moon on the left. Indeed if I could somehow show you both of them in the sky at the same time you probably wouldn’t be able to tell the difference between them. Still come tomorrow morning I’m sure there’ll be dozens of pictures showing the moon in all of its super glory, towering over buildings and dwarfing every other source of light in the night sky. So the question is then where do all these pictures come from and why is the moon so gosh darn huge in them.
The answer is somewhat complicated, and we don’t have an exact answer for it yet, but it comes down to something we’ve dubbed the Moon Illusion. Essentially any stellar object in our sky, be it the moon, sun or even stars, will increase in apparent size the closer it is to the horizon. All those amazing pictures you’ll see of supermoons around the globe tomorrow will likely be taken when the moon is rising when this effect is at its most pronounced. This makes the moon appear much, much bigger than it would normally but over the course of it’s full rotation it’ll begin shrinking back down to a more reasonable size. This is why you don’t see any pictures of it up in the middle of the sky, it just doesn’t look as massive as it would otherwise.
Photographers are also somewhat guilty of exacerbating the moon’s super-ness during this time by using telephoto lenses that compress the visual space significantly, often putting other objects near or in front of it to make it appear much bigger than it would with your eyes. Don’t get me wrong it makes for a stunning picture but it also feeds into the idea that the moon appears that huge at all points in the sky. The reality is unfortunately nothing like that.
I know I’m probably being a killjoy for some people mentioning this but honestly things like this fall into the same realms as those claiming we’d have 2 moons when Mars was at its closest approach to Earth. Sure it’ll be bigger than it would be otherwise but the effect is usually beyond our ability to perceive and the photos just give a false impression of what a supermoon actually is. To be fair though the term supermoon isn’t a scientific term at all (it comes from astrology) so I guess I shouldn’t be too surprised about the smoke and mirrors that surrounds it.
The moon is a barren and desolate place. The face which every human on Earth has stared at for centuries was shaped long ago by the innumerable impacts that peppered its surface. This is in stark contrast to say the surface of planets (or even some other moons) whose surfaces have been shaped through volcanic or tectonic means. This lack of surface activity is what led us to believe that the Moon was dead, a solid ball of rock that solidified many billions of years ago. However recent studies have shown that the Moon might not be as dead as we first thought with its center being not unlike that of our own Earth.
Data from the Selenological and Engineering Explorer (SELENE or Kaguya as it’s known to JAXA), as well as information gleaned from other missions, was used to model the Moon’s interior at different levels. We’ve known the rough structure of the Moon’s interior for some time now, ever since the astronauts on the Apollo missions deployed seismometers, however we never had much insight into the viscosity of those layers or whether or not the core was molten. This research shows that the mantle actually has 2 sections, the upper layer with a high viscosity and a lower layer that’s low viscosity. This would then suggest that there’s a source of heat in the Moon’s core that’s causing the lower mantle to become more liquid, indicating that the Moon’s core is likely molten.
Since the Moon is much smaller than Earth the processes that keep our core molten aren’t likely to have as much of an effect which is why it was long thought to be dead. However it appears that tidal forces, the same things that responsible for warping and shaping the moons around other planets, is what is responsible for causing the heating in the Moon’s core. In all honesty I didn’t think Earth would have the mass required to exert a strong enough tidal force to do that, we’re not exactly sitting on a gas giant, however it appears that Earth has sufficient mass to accomplish this.
Whilst this won’t be fueling the next revolution in space exploration it does open up some interesting possibilities for future expeditions to our celestial sister. Having some kind of temperature gradient opens up the possibilities of using that heat for useful work on the Moon’s surface from things like power generation to good old fashioned heating. Of course the challenge of drilling a couple kilometers into the lunar surface in order to do this is an exercise I’ll have to leave up to the reader but it’s at least an option instead of a science fiction fantasy now.
For a country that was barred from ever working with the leader in space technology the progress China has made in the last decade has been incredibly impressive. They’ve quickly gone from humble beginnings in 2003 where their first taikonaut made it into orbit to a fully fledged space station in 2013, showing that they have the technical expertise required to consistently attempt envelope pushing activities. Of course whilst the most interesting aspect of any space program is the manned activities (who doesn’t love seeing people in space!) there’s always the quiet sibling in the robotics departments, attempting missions that few humans will be able to attempt. I must admit that until today I was also ignorant of China’s robotic efforts in space but suffice to say they’re just as impressive as their human based accomplishments.
China’s Chang’e program (the name of the Chinese Goddess of the Moon) is a series of lunar spacecraft tasked with creating highly detailed maps and models of the Moon’s surface with the intent that that data will be used for future manned missions. Chang’e 1 was launched back in 2007 and remained in lunar orbit for 2 years. It created the most accurate and detailed sufrace map of the moon to date and, once it was done, plummeted into the surface it just mapped to send up a spray of regolith that could be studied from here on Earth. It’s successor, Chang’e 2, was launched in 2010 and had similar capability (albeit with higher resolution instruments and a lower orbit) but instead of being plunged into the moon at the end of its mission it was instead sent out to do a flyby of asteroid 4179 Toutatis. Its current trajectory will eventually see it hit interstellar space however its likely it’ll run out of fuel long before that happens and the purpose of the extend mission is to validate China’s Deep Space Tracking network.
Chang’e 3, launched just yesterday, will be the first craft China has ever launched that will land on the Moon’s surface. For a first attempt it’s a fairly ambitious little project consisting of both a lander and a rover, whereas similar missions usually go for a lander first prior to attempting a rover. The lander is an interesting piece of equipment as it contains a RTG as a power source as well as an ultra-violet telescope, making it the first luna based observatory. Whilst it won’t be anything like the Hubble or similar space telescopes it will still be able to do some solid science thanks to its location and it makes the lander’s useful life much longer than it typically would be.
The rover is just as interesting, being roughly equivalent to the Mars Exploration Rovers (Spirit and Opportunity) in terms of size and weight. It can provide real time video back to Earth and has sample analysis tools on board. The most important instrument it carriers however is a radar on its base allowing it to probe the lunar surface in a level of detail that hasn’t been done before, giving us insights into the make up of the regolith and the crust beneath it. It will be interesting to see what its longevity will be like as its power source is its solar panels (unlike its parent lander) and the lack of atmosphere should mean they’ll remain clean for the forseeable future.
As of right now there’s another 2 more missions in the Chang’e line both of which have similar capabilities with the exception of Chang’e 5 which will be a lunar sample return mission. After that it’s expected that China will start to eye off manned lunar missions, starting with the traditional flag planting operations and then quickly escalating to a fully fledged moon base not long after. It’s quite possible that they’ll accomplish that within the next 2 decades as well as their past accomplishments show how quickly they can churn out envelope pushing missions, something that other space fairing nations have been lacking as of late.
Whilst it might not be of the same heights we saw during the cold war there’s definitely another space race starting to heat up, although this time it’s between the private space industry and China. Whilst it’s likely that China will win the race to the Moon and possibly Mars I can’t help but feel that the private industry isn’t too far behind. Heck, combine Bigelow Aerospace and SpaceX and you’ve already got the majority of the Chinese manned program right there! Still this does not detract from the accomplishments the Chinese have made and I only hope that eventually the USA changes its stance on co-operating with them.
The moon is our closest celestial neighbour and as a consequence is by far one of the most studied celestial bodies. By all accounts it’s a barren wasteland, covered in numerous pot marks from the asteroids that have bombarded it over its lifetime. However the more we investigate it the more we find out that, whilst there’s almost no chance of life being present there, many of the resources that life depends on can be found there. Whilst we’ve known for a while that it would be possible to extract water from the regolith on the surface new observations from NASA’s Moon Mineralogy Mapper instrument aboard India’s Chandrayaan-1 have revealed that there might be actual water on the Moon, just waiting there for us to use.
The initial implications of this are obvious. Water is one of the fundamental resources required for any human based space mission and the amount required usually has to be brought along for the ride. This means the payload capacity used for bringing water along can’t be used for other things, like additional supplies or more equipment, and presents a big challenge for long duration flights. Having a source on the Moon means that any potential bases or colonies established there would have much less reliance on resupply missions from Earth, something which is the primary limiting factor for any off-world colonies that we attempt to establish.
However that pales in comparison when compared to what water on the Moon means for space in general: it’s a primary component for rocket fuel.
Water’s basic composition is hydrogen and oxygen which are the components which power many of the liquid fuelled rocket engines that operate today. Of course in their bonded state they’re not a ready to use propellent exactly so a process is required to break those bonds and get those atoms separated. Thankfully such a process exists, called electrolysis, which splits water down into its component gasses which can then be stored and later used to send rockets on their way. Of course such a process relies on a stable power source which would likely be some like of large solar array backed up by a large battery bank to last through the 2 week long darkness that regularly blankets half the surface.
The biggest challenge that many of the long duration or large payload missions face is the fact that they require more fuel. Carrying more fuel unfortunately also means carry more fuel and there’s points of diminishing returns where you’re spending far too much fuel just to get yourself out of our gravity well. Having a refuelling station or the Moon (or, even better, constructing and launch payloads from there) would mean that we would put larger payloads into space and then push them to the outer reaches of the solar system without having to waste as much fuel to get ourselves out of Earth’s gravitational influence.
Of course seeing this kind of technology implemented is some ways off as it seems like NASA’s next target will be a flag planting mission on Mars. Such technology would be quite applicable to Mars as well seeing as the soil there has a lot of trapped water (and there’s plentiful water ice pretty much everywhere but the equatorial region) but it’d be far more valuable if it was implemented on the moon. In either case I believe this is foundational technology that will be pivotal in humanity pushing itself to the far reaches of our own solar system and, maybe one day, beyond.
I’m sure I’m not alone in being someone who loves playing around in the sand at a beach even though I’m pushing 30. My friends and I always seem to end up building some kind of sand castle whenever we all make our way down there even though we usually have no intention of doing so. There’s probably some nostalgia at work there, I mean almost everyone has great memories of playing the sand as a child, but I’ve also been told it’s actually quite therapeutic something a cursory stroll through Wikipedia appears to verify. However bringing the beach with you is usually frowned upon (What do you mean I can’t make sand castles on the carpet??) but it seems like there’s a pretty awesome substitute in the form of Moon Sand.
It’s a pretty awesome substance, one that’s been around for some time from what I can gather, as it emulates the properties of wet sand pretty well without requiring water. I haven’t been able to track down the exact polymer that they use (confusingly the hydrophobic sand I blogged about also carries the name moon sand) but it seems a workable substitute can be made with good old fashioned corn starch. That does require water however which leads me to believe that the polymer they use has some non-Newtonian properties to it as that’s exactly what you get when you mix corn starch and water. If I could find the exact polymer they’re using (searching for non-toxic non-Newtonian polymers didn’t give me any viable leads) so if you happen to know what it is I’d be keen to hear from you.
One of the interesting points that came up in my research to this is people wondering whether or not this would be anything like real moon sand. Strangely enough the surface of the moon is coated in a layer of what you could classify as sand but it’s formed quite differently and it’s called regolith. Sand on earth is made by rock being slowly eroded away, typically by some form of moving water. Regolith on the other hand has rather violent origins with its primary mode of creation being through impacts on the surface by meteors. That’s why you don’t have regolith on earth as the amount of impacts required to generate it simply don’t happen (thankfully) due to our atmosphere. The moon on the other hand isn’t so lucky and gets bombarded constantly with generates the layer of dust upon it.
However that regolith isn’t composed of worn particles like sand is, instead the base structures are typically jagged and this actually became an issue with the early sample return missions to the moon. Those jagged particles stick to everything they and actually punctured the vacuum membrane on the sample return jars, contaminating them. More interesting still is that regolith appears to be highly reactive as Armstrong and Aldrin (and many other astronauts) reported smelling gunpowder after completing their moon walks something that wasn’t reported by scientists studying the samples back home. Moon Sand by comparison is quite inert and not at all abrasive.
Now I just need an excuse to buy some of this. I mean it’d be completely normal for a near 30 year old to do this, right?
To celebrate the Luna Reconnaissance Orbiter being in orbit around the moon for 1000 days NASA has celebrated by releasing not 1 but 2 very cool videos about the moon. The first is probably my favourite of the two, depicting the violent birth of our closest heavenly body:
The second is equally as cool though showing (in incredible detail) what the moon looks like today:
Carl Sagan is quote as saying that “life looks for life”. Indeed if our own history is anything to go by we’re in a constant state of searching out other forms of life and just recently we’ve extended that search beyond the confines of the world that gave rise to us. So far our search beyond our home world has proved fruitless as we’ve been unable to find any direct indications of life on any other heavenly body that’s within our reach. Thus we find Earth in what appears to be some great isolation which is a somewhat disconcerting notion given the age of the universe and the number of potential habitable planets in our galactic backyard. We should not be discouraged however as our quest to find life elsewhere is only just beginning.
Of all the other heavenly bodies that inhabit our solar system there’s one that stands out as the best candidate for housing life. Now if I was to ask the question of which body it was most people would respond with Mars as it’s the only planet that resembles Earth in some fashion, with the next closest candidate being the raging hell of Venus. It’s not a bad guess either as we’ve proven several times over that there was once vast amounts of water there and there’s still a very good chance there’s liquid water present today. However Mars is a very inhospitable place so much so that the best hope for life there is nothing above microbial and even that seems like a far reaching prospect.
Europa on the other hand is quite the curiosity. As far as moons go it really is something out of left field being a striking combination of bright whites and browns. It’s surface is also one of the smoothest in the solar system thanks to it being made almost entirely of water ice. That doesn’t mean it’s featureless however as the entire surface is criss-crossed with fracture lines from the giant ice sheet breaking apart and reforming. Many have speculated that this is because the surface actually lies on top of a giant subsurface ocean and when cracks form the ocean rushes up to fill it, forming the characteristic lines. It’s this undersea ocean that makes Europa one of the best candidates for life forming outside of Earth and recent studies show it just got a little better.
The potential ocean on Europa would be some 3KM below the surface, quite a ways away from any direct sunlight or other potential energy sources. It’s theorized then that the ocean is kept liquid by the tidal flexing that Europa undergoes every time it orbits Jupiter which could also drive the same kinds of volcanism processes that gives rise to life in the depths of our oceans. However recent research shows that there’s potential for some subsurface lakes that are much closer to the surface than the great ocean below. These lakes would have a higher rate of churn between water and ice providing a much a habitat that’d be more nutrient rich and hopefully more hospitable to life. Of both these recently modelled oceans and the great subsurface ocean haven’t yet been conclusively proven, but that just makes Europa a really tantalizing target for exploration.
Quite a few missions have swung past Europa already with the most detailed analysis being done by the Galileo craft from 1995 to 2003. However we haven’t been back there recently save for a short flyby by the New Horizons craft that imaged it on its way to Pluto. If we were to go back there my favourite mission candidate would be the Crybot style mission. In essence it’s a probe that’s fitted with a giant heater on the front of it, capable of plunging through several kilometres of ice. Once it broke through it would then deploy a small autonomous underwater vehicle that could investigate the subsurface ocean. This mission hasn’t got past the back of the napkin style planning stages yet, but I’m hopeful that we’ll one day attempt such a mission.
Europa is a curiosity unlike any other in our solar system and there’s so much we could learn from it if we were to send a mission there. Whilst the environment there isn’t really human friendly (the radiation at the surface is quite large, about 450 chest x-rays a day worth) it’s definitely within our current capabilities of robotic exploration. I know that one day we’ll see a dedicate mission there but until then I’m quite content to continue fantasizing about the undersea world that it contains and the tantalizing possibility that as of yet unknown life forms exist there.
Our Moon has been a constant source of amazement and wonder for the human species. For as long as we’ve been able to observe it from our earthly bounds it has only ever shown us one side and wobbling ever so slightly as if to tease us as to what we couldn’t see. For the longest time we speculated about what could be on the other side of our closest celestial partner with theories ranging from the mundane to the outright fantastical. Of course since 1959 when Luna 3 first photographed the far side of the moon most of that mystery and wonder has since evaporated, but even today it still manages to throw a couple curve balls our way.
One of the most puzzling aspects is the distinct difference in terrain between the near and far sides of the moon. Comparatively the near side of the moon is quite smooth with many “maria” or land seas covering its surface. The far side on the other hand is deeply cratered with a considerably more rough appearance than the side we’re all familiar with. There are many explanations for this with the most accepted being that the near side contained a higher concentration of radioactive elements when it was first formed, and this has been confirmed from data from orbiting craft. There is however a new theory that’s come out and it depicts a story of an Earth that once had two moons:
The moon is thought to have formed when a Mars-sized body slammed into the infant Earth. This threw a cloud of vaporised and molten rock into orbit, which coalesced into the moon.
Simulations have previously shown that additional moons could have formed from the debris cloud, sharing an orbit with the one large moon that survives today. Eventually, gravitational tugs from the sun would destabilise the moonlets, making them crash into the bigger one.
Building off the most accepted theory of the Moon’s formation (the Giant Impact) this new theory about the far side of the moon’s appearance postulates that the impact also created another, smaller Earth bound satellite. Now usually smaller bodies are quickly engulfed by their bigger neighbours but this smaller moon stabilized into an orbit long enough for it to fully form. However millions of years later it impacted with the current moon at a relatively slow pace of about 8,000KM/H (for reference, the International Space Station orbits at around 25,000KM/H). So instead of smashing each other to bits they instead squished together forming a turbulent far side of the moon. Such a hypothesis also explains some discrepancies between mineral concentrations on either side of the moon as such an impact would have pushed the moon’s magma to the other side.
Now whilst this theory would explain some of the phenomena we’re seeing with our celestial sister there’s not a whole bunch of direct evidence to support it. The heavily crated far side of the moon could easily be explained by the tidal locking with Earth, which means any incoming asteroids are far more likely to hit the side facing outwards. This is made all the more difficult by the fact that there has been no landed exploration of the far side of the moon and definitely no sample return missions. Getting some rock samples from the far side of the moon would provide the answers we need to rule out or pursue this theory further.
I always find it amazing how we can think we’ve explored something so thoroughly yet it can still surprise us. The moon is something we’re all so familiar with yet it’s still so foreign when you get up close and it’s origins are as mysterious and intriguing as our own. I love that these ideas could lead to us sending a sample return mission to the far side of the moon and what’s even more exciting is that such a mission would probably lead to many more questions than answers. That’s the beauty of science, it’s a never ending journey of discovery into the origins and mechanics of the universe that surrounds us.
Mercury is a strange little beast of a planet. It’s the closest planet to our sun and manages to whip around it just under 88 days. Its “days” are 59 earth days long and whilst it’s not tidally locked to our parent star (like the moon is to us, always showing the same face to the earth) it is in a 3:2 spin-orbit resonance. This has led to some interesting phenomena when we’ve sent probes to image it as the only probe to ever visit it, Mariner 10, only managed to image 45% of the planet’s surface on it’s 2 encounter trip with the tortured little planet. That all changed a few years ago when MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) made its first approach to Mercury in January 2008 and sent back images of the as of yet unseen side of the planet. Ever since then MESSENGER has been on a long trajectory that will eventually bring it into orbit with Mercury and it will begin it’s year long mission of observations.
It just so happens that that day is today.
MESSENGER has been in space for an extremely long time, almost 7 years. You might be wondering why it has taken this craft so long to reach Mercury and the answer requires that you understand a little about orbital mechanics. You see as a heavenly body, in this case a satellite, moves closer to another body it will tend to speed up. This is known as the conservation of angular momentum and it’s the same principle that governs the increase in speed when you bring your arms in closer whilst you’re spinning. Thus for a satellite that’s launched from Earth to be able to orbit Mercury it has to shed all that extra speed so it can match up to it, otherwise it would just whiz right past it. Since doing this with a rocket is rather expensive (the fuel required would be phenomenal) NASA instead opts to shed velocity by a complicated set of maneuvers between planets, each of which removes a portion of the satellite’s velocity. This is cheap fuel wise but means the space craft will have to endure many years in space before it reaches its destination.
As I write this MESSENGER is making its final preparations to insert itself into an orbit around Mercury. MESSENGER hopes to demystify the diminutive planet by providing hi-resolution imaging of the planet (there’s still 5% we haven’t seen yet), doing chemical analysis to determine the planet’s makeup and attempting to figure out why Mercury has a magnetic field. Probably the most interesting part of MESSENGER will be the last part as our current theories on planet formation point to Mercury being much like our moon with a solid core and no magnetic field to speak of. The presence of one there suggests that part of Mercury’s core is still molten and raises a number of questions over how planets and natural satellites like our moon form. It will also be the first ever artificial satellite of Mercury, something that still eludes many of the other planets in our solar system.
This is the kind of science that NASA really excels at, the stuff that just hasn’t been done before. It’s really amazing to see NASA flex their engineering muscle, designing systems that survive in the most unforgiving environment we know for decades and still function as expected. The next year will be filled with all kinds of awesome discoveries about our tortured little cousin Mercury and I for one can’t wait to see how the analysis of its magnetic field changes the way we model planet formations in the future.