The Refined Geek

Even with the proof behind it I still have no idea how the motion in this video works:

There’s 3 distinct angular motions going on but the seemingly discreet switch from one particular state to another (and the transition between them) really baffles me. It’s incredibly cool but thoroughly puzzling.

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:

The USA has always been wary of China’s ambitions in space and I believe it’s mostly for all the wrong reasons. Sure I can understand that the fact that China’s space division is basically a wing of its military might be cause for concern, but the same could be said for the fact that the USA’s Department of Defense’s budget for space exploration exceeds that of NASA’s. Indeed the USA is worried enough about China’s growing power in space and other industries that there’s already been speculation that it could spark another space race. Whilst this would be amazing for a space nut like myself I really wouldn’t wish that kind of tension on the world, especially when the USA is struggling as much as it is right now.

Of course that tension is enough to spark all sorts of other speculation, like for instance the true nature of the mysterious X-37B’s mission. It’s payload bay suggested that it was capable of satellite capture, an attribute shared by it’s bigger cousin the Shuttle, but its previous orbits didn’t put it near anything and it didn’t really have enough delta-v capability to be able to intersect with anything outside a few degrees of its own orbit. However since then there’s been a couple launches and one of them is smack bang in the X-37B’s territory.

The craft in question is none other than China’s Tiangong-1.

Yesterday the BBC ran an article that speculated that the USA was using the X-37B to spy on Tiangong-1. Now initially I dismissed this as pure speculation, there are far easier ways for the USA to spy on a satellite (like using one of their numerous other satellites or ground based dish arrays) than throwing their still experimental craft up in a chase orbit. However checking the orbital information for both Tiangong-1 and the X-37B shows that they do indeed share very similar orbits, varying by only 0.3 of a degree in inclination and having pretty similar apogees and perigees. Figuring this is the future and everything should be a few Google searches away from certainty I set about finding out just how far apart these two satellites actually are to see if   there was some possibility of it being used to spy on China.

To do this I used 2 different tools, the first being n2yo.com a satellite tracking website. This site allows you to input the satellites you want to track and then displays them on a Google map. Once I have that I can then use another tool, this time from findpostcode.com.au which shows me the distance between two points (which thankfully also takes into account the fact the earth isn’t flat). So firstly here’s a picture of the two orbits overlapped:

So as you can see they do indeed share very similar orbits but there does seem to be an awful lot of distance between them. Just how much distance? Well the second picture tells the full story:

Just over 14,000KM which is greater than the diameter of the earth. What this means is that if the X-37B was being used to spy on Tiangong-1 it would have to peer through the earth in order to see it, something which I’m pretty sure it isn’t capable of. Also if you look at the first picture you’ll also notice that Tiangong-1 actually passes over the USA as part of its normal orbital rotation, putting it well within the purview of all the ground observations that they have control of. I’ll note that the distance between Tiangong-1 and the X-37B won’t remain constant, but they will spend a good portion of their lives apart. Enough so that I don’t believe it would be particularly useful for reconnaissance. Additionally unless the USA knew which orbit that Tiangong-1 was going to use (possible, but we’re getting deeper into conspiracy territory here) then technically Tiangong-1 launched onto the X-37B’s orbit and not the other way around (it has not changed its orbit since the second launch, unlike it did the first time).

Honestly the idea that the USA was using the X-37B was definitely an interesting prospect but in reality there’s really no justification apart from conspiracy theory-esque hand waving. The USA has far better tools at their disposal to spy on China’s fledgling space industry than a single run experimental craft that’s only on its second flight. The orbits also put them at a fair distance apart for a good chunk of the time (as far as I can tell, at least) as well making it even less likely that the X-37B is being used for spying. Still it was an interesting idea to investigate, as is most things to do with the ever mysterious X-37B.

Maybe it’s the combination of mission secrecy and close resemblance to the now retired shuttle fleet but the X-37B seems to get more press than any other space craft currently flying in orbit. When I first saw the diminutive shuttle cousin back in April last year I figured it was just a unique experiment that the Department of Defence was carrying out and the rumours about it’s satellite capturing capabilities were greatly exaggerated. Indeed towards the end of the mission I investigated the idea that it was already performing such a task but based on the current trajectories of other satellites it didn’t seem like that was the case. The X-37B blasted off once again at the start of this year again shrouded in mystery as to what its actual mission was and it’s been up there ever since.

That last fact is interesting as the X-37B’s stated capabilities put it at being on-orbit for a maximum of 270 days. The deadline for its return to earth would have then been around November 30th, a date that has well past now. The United States Air Force has stated that its mission has been extended and it should be on orbit for a while to come. This is interesting because it tells us that the X-37B is a lot more capable than they’ve state it is. Whilst this could just be good old fashioned American over-engineering it does lead some credence to the theories that there’s a whole bunch of capabilities hidden within the X-37B that aren’t officially there.

What’s been really interesting however are the discussions surrounding a potential manned variant of the X-37B. As it stands the X-37B is quite a small craft, measuring a mere 10 meters long and a payload bay that’s only got a few cubic meters of storage space. Overall its very similar in size to the Soyuz craft so there’s definitely some potential for it to be converted. Rumour has it that the X-37B would be elongated significantly though, bringing its total length up to 14 metres with enough space to sit 7 astronauts. Granted it wouldn’t be as roomy as the shuttle was (nor could it deliver non-crew payloads at the same time) but it would be a quick path to restoring the USA’s manned flight capability. That would hinge on the man rating Atlas V launch system which is currently under investigation. 

It’s not just space nuts that are getting all aflutter about the X-37B either. China has expressed concerns that the X-37B could be used as a orbital weapons delivery system. The secrecy surrounding the actual mission profiles that the X-37B has been flying is probably what has prompted these concerns and it being under the sole purview of the Air Force doesn’t help matters. In all honesty I doubt the X-37B would be used as a weapons platform since it’s more of a generalist/reconnaissance craft than a weapons platform. If there’s someone you want to worry about launching weapons into orbit it would be the Russians as they are the only (confirmed) nation to have launched armed craft. A dedicated weapons platform would also look nothing like the X-37B, especially if it was going to be designed for on-orbit combat (who needs wings in space?).

The next couple months will give us some more insight as to the true purpose of the X-37B. It’s quite likely that these first couple flights have just been complete shake downs of all the systems that make up the X-37B with the first flight being orbital manoeuvring verification and the current flight being an endurance test. Should it stay up there for a significant amount of time it’s more likely that it’s some form of advanced reconnaissance craft rather than something crazy like a satellite capturer or orbital weapons platform. The prospect of a manned variant is quite exciting and I’ll be waiting anxiously to see if the USA pursues that as an option.

Pushing the envelope of capabilities in space is a slow and arduous task where small step after small step eventually makes its way to the ultimate goal. Even with today’s technology it still takes us the better part of a decade to go from concept to reality, especially if you’re trying to build launch capability from scratch. Hell even my current crush, SpaceX, has taken 10 years to get to the stage they’re at and that’s considered blindingly fast even when you compare them to the superpowers of the world. China on the other hand has proven themselves to be extremely capable, innovating at an extremely rapid pace.

So rapid in fact that I was sure I had already covered their most recent accomplishment, docking Shenzhou 8 with Tiangong 1:

China’s technological capabilities took a major surge forward with the successful docking in space today for the first time ever of two Chinese built and launched spaceships - orbiting some 343 kilometers in the heavens above at 1:37 a.m. Beijing time Nov. 3(1:37 p.m. EDT, Nov. 2). China’s goal is to build a fully operational space station in Earth orbit by 2020 – about the time when the ISS may be retired.

Today’s space spectacular joining together the Shenzhou-8 unmanned spacecraft and the Tiangong-1 prototype space station was an historic feat for China, which now becomes only the 3rd country to accomplish a rendezvous and docking of spacecraft in Earth orbit.

In fact the last thing I wrote was just over a month ago when China had successfully launched their Tiangong 1 prototype. In that time they managed to prep, launch and have Shenzhou 8 rendezvous with Tiangong 1 putting China on par with the small number of nations who have developed such capability. Over the next couple weeks Shenzhou 8 will un-dock and re-dock with Tiangong 1 in order to prove that the technology is solid. Once the mission has been completed Shenzhou 8 will return to earth for further analysis.

Launching two separate vehicles rapidly one after another is par for the course of any space program but what really surprised me was China’s plans for the next 2 craft to visit Tiagong 1. China has no less than 2 more missions planned before the end of 2012 and one of those will be a manned. When you take into consideration that China has only managed to complete their first EVA 3 years ago (a critical capability for keeping a station in orbit) having a manned station so soon afterwards is an incredible achievement. Going on their timeline we could see China have their own Salyut level space station before the decade is out, and that’s just incredible.

I’m hoping that with these accomplishments that both Russia and the USA recognize how valuable China could be for the future of their space programs and seek to include them in future endeavours. So far China is the only country explicitly excluded from participating with the International Space Station, most because the USA thought they’d be nothing more than a burden to them. Such rapid progress shows that they’re not only capable of replicating current technology but also innovating their own solutions, something which would be highly valuable to all current space fairing nations. It’ll take a long time for those political barriers to start coming down, but I hold out every hope that one day they eventually will.

Debris in orbit are becoming one of the greatest challenges that we face as we become a space fairing species. You see by the simple fact that something is in orbit means that it has an incredible amount of potential energy, zipping around the earth at Mach 25 ready to wreck anything that might cross its path. Thankfully there’s quite a lot of empty space up there and we’re really good at tracking the larger bits so it’s usually not much of an issue. However as time goes by and more things are launched into orbit this problem isn’t going to get any better, so we need to start thinking of a solution.

Problem is that recovery of space junk is an inherently costly exercise with little to no benefits to be had. A mission to recover a non-responsive satellite or other spacecraft is almost as complex as the mission that launched said object in the first place, even more so if you include humans in the equation. Additionally you can’t send up a single mission to recover multiple other missions as typically satellites are on very different orbits, done so that they won’t collide with each other (although that has happened before). Changing orbits, known as a plane change, is extremely expensive energy wise and as such most craft aren’t capable of changing more than a couple degrees before their entire fuel supply is exhausted. The simple solution is to deorbit any spacecraft after its useful life but unfortunately that’s not the current norm and there’s no laws governing that practice yet.

It’s even worse for geostationary satellites as in that particular orbit things don’t tend to naturally deorbit over time. Instead anything in a geostationary orbit is pretty much going to be there forever unless some outside force acts on them. Geostationary orbits are also particularly valuable due to their advantageous properties for things like communication and location so the problem of space debris up there is of a much bigger concern. Thankfully most geostationary satellites have the decency to move themselves into a graveyard orbit (one just outside geostationary which will eventually see them flung from earth orbit) but this method isn’t guaranteed. Mass that’s already in orbit is incredibly valuable however and DARPA has been working on a potential solution to debris in geostationary orbit.

The DARPA Phoenix program is an interesting idea, in essence a in orbit salvager that cannibalizes other satellites’ parts in order to create new “satlets”. These new satlets won’t be anywhere near as capable as their now defunct donors were but they do have the potential to breathe a whole lot of life back into the hardware that’s just sitting there idle otherwise. Compared to a regular geosynchronous mission something like Phoenix would be quite cheap since a good chunk of the mass is already up in orbit. Such a mission can really only be done in geostationary orbit since all the satellites are in the same plane and the energy required to move between them is minimal. That is our most valuable orbit however so such a mission could prove to be quite fruitful.

Dealing with the ever growing amount of space debris that we have orbiting us is a challenge that we’ve still yet to answer. Programs like DARPA’s Phoenix though are the kinds of projects we’ll need to both reduce the amount of orbital junk we have as well as making the most out of the stuff we’ve already put up there. I’m really keen to see how the Phoenix project goes as it’d would be quite a step forward for on orbit maintenance and construction as well as being just plain awesome.

I can remember sitting in one of my university lectures a long time ago being taught about development philosophies. It was all pretty standard stuff, we were walked through the “traditional” methods of development (basically the once through, waterfall technique) and then brought up to speed on the more modern iterative approaches. However one little soundbite always stuck out in my head and that was when the lecturer asked us who pays for rework when a product doesn’t fit a customer’s expectations? The simple answer was you, the one who developed it and it’s something that always plays over in my head when I’m working on a project, especially those ones I do at home.

I’ve been paying extensively for rework with my latest forays into the world of game development. My regular readers and Twitter followers would’ve noticed that I cheerfully announced my success in cracking the stable orbit problem. Indeed in a round about way I had, basically my Unity scripts would push the planet around until it hit a stable orbit and afterwards would calculate the required velocity before turning off completely, letting the heavenly body orbit in a near perfect circle around its star. This worked for the 2 planets I had in there but unfortunately the equations I had developed didn’t generalize very well and adding in planets at random locations with random weights led to all sorts of wobbly orbits with planets meeting both fiery deaths and cold extinctions at the cruel hand of my orbit stabilizer. I was back to square one and I spent most of the weekend trying to figure out a fix.

Eventually I came back around to the idea that my smart-ass subconscious came up with a while ago. I had tried to implement it before but I gave up in frustration when the results I got were no different than from my far more complicated “find the angle between the sun and body, increment it a bit, find the new position, create a vector to it then apply force in that direction” when in reality the fault lied in the orbit stabilization code. All that pushing and pulling that made the orbit look stable was in fact imparting all sorts of wild forces on the poor little planet, when in fact the best way is just to simply let gravity do the work for you. With this in mind I re-implemented my perpendicular force calculations and then devised a rudimentary equation that combined the mass, radius and a fudge factor that let me hand stabilize the orbit. In the past attempting to do this stuff manually took me an hour or so per planet, with this revised code I was able to do one in minutes and have developed a new equation that is able to accurately send a planet into a stable orbit no matter where I place it in the game.

This solution was far more simple and elegant than what I had been trying to do previously but the cost in terms of rework was tremendously high. I’m lucky in this respect in that the client for this is just myself and my friend at the moment but had this been for someone else with whom I had a contractual relationship with that kind of rework would’ve been extremely costly. Of course I could try to make the client pay for it but ask anyone who’s gone back to a client asking for more money after saying they could do it for a certain price and you’ll usually be laughed out of the office, if not walked out of there by security.

Working around this isn’t easy as clients will usually want to have a strict set of deliverables and time frames which seems to rule out any iterative or agile development methodology. It also pushes a team dangerously towards suffering from analysis paralysis as you agonize over every requirement to make sure it’s covered off in the final product. A healthy amount of analysis is good for any project, especially if it makes the product easy to maintain or modify, but it’s also incredibly easy to fall into a never ending spiral of pointlessness. Thankfully however I’ve noticed that clients are far more receptive to the idea of milestones these days which lines up well with any iterative process, skirting around these problems easily.

Going after the most simple and elegant solution might seem like the best idea at the time but in my experience it’s those kinds of solutions that take the longest to achieve. It’s almost always worth it, especially if all you’re spending is your own time, but when you’re working for someone else they might not be so keen for you to spend inordinate amounts of time chasing your white whale solution. This probably explains why a lot of software contains incomprehensible code riddled with bugs, but that’s a whole ‘nother ball game and a blog post for another day.

I’ve often found that trying that sticking with a problem from start to finish is usually the least efficient way of getting it completed. Quite often if I take a 1 hour break whilst I’m in the thick of trying to solve something I’ll usually figure the answer out before I return, being able to move onto the next bit of work in far less time than if I had tried to struggle my way through. I think this is the main reason why the lawn gets mowed routinely during he summer months, that 30 mins~1 hour of basically mindless work let’s my subconscious tackle the problem in ways that I can’t do normally.

The most recent example I can think of was the problem of producing realistic gravity in the game I’m developing with a good friend of mine. I’ve had the basic gravity mechanics working for ages and even managed to get a planet into a near-circular orbit around a star. Unfortunately from there finding other stable orbits for varying distances and masses proved to be quite troublesome as there didn’t seem to be any kind of simple relationship that I could derive that would produce the same circular orbits as I had achieved after tinkering around with initial forces for a couple hours.

It’s been a real pearler of a problem too as whilst I’ve been able to make steady progress despite this (my one little test planet is enough to get most things working) I still couldn’t figure out how to give a planet a stable orbit based on its mass and initial distance from the sun. I tried many different things, from trying to map an equation based on a couple stable orbits to pushing the planet around so it would stay on course (which hilariously flung planets out of sight). Then late one night just before I was about to fall asleep it hit me: I could use the force that was being applied to the planet by the sun as the magnitude for the initial force. I then just have to work out the components along the desired orbital trajectory (breaking out some good old fashion trigonometry) and I should be on my way. I haven’t tested this yet, but it’s the only idea I’ve had that hasn’t involved fussing around with variables for hours on end.

It’s that same process that jolts you awake in the middle of the night with that name that you couldn’t remember or that fact you were trying to come up with at a crucial time. I find it really intriguing as I obviously have the ability to solve these kinds of problems somewhere in my head however I just can’t have it on tap, I’ve just got to let my brain do its thing whilst I wait around for the solution.

Space travel is on the rough end of the stick when it comes to physics. To get ourselves out of the massive gravity well that keeps us from travelling to the stars we have to expend vast amounts of energy, usually in the form of a chemical rocket. It’s a tried and true system however with chemical rockets powering every single mission that has left the confines of earth. There has been talk of many other forms of propulsion that could potentially perform a lot better than our trusty chemical companions but thanks to their fuel being of the nuclear variety they’ve never made it past the theoretical stage. Still for all their successes chemical rockets still have their draw backs, not least of which is the ungodly amount of fuel they use.

Take a look at any rocket and you’ll notice that the vast majority of it is taken up by a single component, the fuel tank. Whilst the actual cost of the fuel is a rounding error when compared to the cost of developing the rocket itself the fuel still makes up the vast majority of the wet mass of the craft, usually 85% or more. To put in in perspective the biggest rocket ever built, the Saturn V, weighed in at a massive 3 million kg when it was on the launch pad but only delivered 120,000 kg to low earth orbit (with 45,000kg eventually reaching the moon). A mere 4% of the total launch weight made it out of earth’s gravity, a truly staggering figure. This is more commonly referred to as the mass ratio.

It should come as no surprise then that the limiting factor for many space missions is weight related. As payloads get bigger so does the rockets and the amount of fuel required to lift them into orbit. This puts an upper limit on how big rockets can get before the amount of fuel required becomes unmanageable and instead many missions will favor multiple, smaller launches in order to get the required payload launched. The International Space Station is a good example of this as its current mass, some 420,000 kg, would have required a rocket of unimaginable size to launch all once. Instead it has been assembled in numerous smaller flights each adding around 20,000 kg each time. Most missions do not have this kind of luxury however and their designs represent a trade off between capabilities and the maximum launch weight they can have.

Most notably this affects missions that want to reach further than earth orbits, such as missions to other planets. Since they have to carry all the fuel required to get into orbit and to get them started towards their destination the payloads they can deliver are far smaller than they could be. Whilst we’ve still been able to do an amazing amount of science and exploration with such vehicles it’s still one of the most limiting factors that keeps more ambitious missions (read: ones with us humans in them) from being realized. There is however one ingenious solution to this problem, and that’s refueling in orbit.

Whilst the notion of flying just fuel up into orbit might seem like a strange idea it’s one that will enable subsequent missions to be far more capable. Indeed the cost of carrying several tons of fuel for pushing out past earth’s orbit adds many times that in launch mass. Thus craft that can refuel once in orbit can be significantly heavier at launch (since they’re not carrying the fuel) and can then fuel up for their trip beyond earth. The idea originally started to get traction back when Obama announced his plan for space exploration back in early 2010 and it seems that it’s finally going to become a reality:

Space explorers who need to top off the fuel tanks on the way to the moon or Mars may soon get their orbital refueling stations. NASA has put out the call for a $200 million mission to show how to store and transfer rocket propellants in space.

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NASA wants to look specifically at liquid oxygen and liquid hydrogen, which have powered the main engines of the space shuttle and several commercial rockets. Its proposal calls for “zero boil-off storage” of liquid oxygen, and at least “minimal boil-off storage” of liquid hydrogen.

The proposal comes with the promise of $200 million for the company who wins the opportunity to build the station with an additional $100 million should they be able to demonstrate significant benefits for the additional investment. Whilst there are already companies working on these sorts of ideas NASA’s proposal goes far beyond what they’re currently capable of and is being built with the vision for larger missions beyond earth rather than refueling satellite’s station keeping fuel reserves. The proposal could also have flow on benefits to companies like the United Launch Alliance and SpaceX who could design future crafts around the idea of being able to refuel on orbit.

If we want to get serious about extending our presence beyond our home world (and we’re too afraid to use nuclear rockets) then orbital refueling stations are the key to realizing that vision. We’ve started to make the first steps to commoditizing space travel and the next logical step is to start unlocking access to other parts of our solar system, both for science and the simple prospect of exploring the unknown. Whilst this idea might not be realized tomorrow its a helluva lot more real today than it was yesterday and humanity is one step closer to taking our rightful place amongst the stars.

50 years is an almost incomprehensible amount of time for a young person like myself. That’s nearly double my entire time on this planet and even in my short 26 years I’ve seen wild changes to this world, so I can only imagine the changes anyone someone who has lived 50 years or more has seen. One of the most incredible changes that the last 5 decades has brought us has been the invention of space flight which has dramatically influenced humanity as we know it today, even if its presence is mostly invisible. Two days ago saw the anniversary of our very first tenuous steps into the final frontier with the Russian cosmonaut Yuri Gagarin becoming the first ever human to enter space and orbit our beautiful blue marble.

Winding the clock back 50 years puts us right in the middle of the cold war, a political battle fought over decades on a global scale. The first artificial satellite was created just 4 years prior and the space race between the then USSR and the USA had reached a fever pitch. Both sides were working fervently to stake their claim on being the first to accomplish anything in space and at this point the Russians were winning after their success with Sputnik. They weren’t resting on the laurels however and they were aggressively pursuing the goal of getting the first man into space. The mission was to be called Vostok 1.

The craft Gagarin was to ride into space wasn’t a large one by any stretch of the imagination, being a mere 2.3 meters in diameter and looking a lot more like a submersible craft than one destined for the vacuum of space. In true Russian fashion it was also incredibly robust and when compared to its American counterparts it was incredibly simple. The craft also lacked any control surfaces and didn’t have any backup thrusters, which is why the craft was mostly spherical, since unlike the American craft it couldn’t orientate a heat shield to protect it on re-entry. This also meant that in the event that retrorockets didn’t fire Gagarin would have been stuck in orbit for up to 10 days, and as such the craft was equipped with enough supplies to ensure that he’d survive.

The mission began at 5:30AM, 12th of April 1961. Both Gagarin and his backup pilot, Gherman Titov, were awoken at this time with the launch scheduled to start 2 hours later. Things went pretty smoothly although doctors reported that Gagarin wasn’t himself at this time, being somewhat pale and unusually reserved. Still in comparison to Titov, who had to take medication to calm himself down, Gagarin was as calm as ever with a resting heart rate of that of a long distance runner. About an hour after being awoken he was secured in the Vostok capsule (which had to be resealed once due to it failing the first time) and was left in there for another 40 minutes before blasting off into space.

In total Gagarin spent just over an hour orbiting the earth, completing one full orbit and touching down in a field outside of Engels in the Saratov region. His descent from the heavens startled a farmer and his daughter who witnessed this alien like creature in an orange suit with a white helmet descending from the heavens. He later recalled the situation:

When they saw me in my space suit and the parachute dragging alongside as I walked, they started to back away in fear. I told them, don’t be afraid, I am a Soviet like you, who has descended from space and I must find a telephone to call Moscow!

Gagarin and his capsule were both successfully recovered. He returned back to Moscow a hero and a figure that will be remembered as one of the great pioneers of the final frontier. Although he never orbited the earth again he was heavily involved in the USSR’s space program afterwards, helping design new craft and was a backup pilot for the very first Soyuz mission a craft that is still in use today. Tragically his life was cut short in 1968 in a routine test flight over a Russian air base, but the legacy he laid down will last on for as long as humanity exists.

I’ve often said that I don’t give the Russians enough attention on this blog and they should be recognized for their amazing accomplishments in space. 50 years on the influence of early pioneers like Gagarin and his team are clearly visible in all facets of the Russian space program. It’s a testament to their strong ideals of simplicity and robustness that a craft designed decades ago can still be in service today and still meet the needs of both NASA and the ROSCOSMOS. Whilst I may be a bit late to the party in remembering the great feats of the Russian space program I hope you’ll join me today in recognizing their accomplishments, and wishing them all the best for the next 50 years.