Posts Tagged‘tiangong’

Gravity: An Amazing (Albeit Highly Unscientific) Film.

It should come as no surprise that my favourite movie genre is science fiction. Even though I was born long after the original Star Wars trilogy had finished watching it with my parents is still one of the fondest memories I have and that has long since bloomed into a passion for the genre. Of course this also feeds into my love of sciences as whilst I also enjoy fantasy, in all its forms, nothing quite compares to plausible futures that are based on real science. Whilst I understand that scientific accuracy will often take a back seat when the narrative requires it I can’t help but feel compelled to point out some of the more obvious flaws, especially when it’s such a big movie like Gravity.

Gravity 2013 WallpaperNow before I launch into this let me just be clear: I absolutely enjoyed Gravity. Whilst I was sceptical about George Clooney and Sandra Bullock being able to bring life to the roles they were given it didn’t take me long to warm to their characters. I was also very surprised by how much tension I felt for multiple different scenes, something which I don’t typically feel, at least not to that extent. All this, combined with the beautiful cinematography culminates in a movie that’s thoroughly enjoyable even if you take the hard line with science like I do. With all that being said though there are some points which bear mentioning and should have you not seen the movie I’ll advise you to skip reading on.


The first thing that I, and several others, have taken issue with is the notion that from the orbit of the Hubble Space Telescope you’d be able see both the International Space Station as well as the Chinese Tiangong station (which is way more developed than current plans indicate, but that’s another story). Even if all of them shared identical orbits, which they don’t, the Hubble is in an orbit that’s some 200KM above the ISS and Tiangong making any naked eye visual impossible. Following on from this the idea that you’d be able to then travel between them becomes somewhat difficult as the energy required to do the plane change manoeuvres would be far above the capabilities of Manned Manoeuvring Unit. Indeed the backup plan NASA had for a shuttle that had suffered a catastrophic failure event such as the one in Gravity was to send another shuttle up there to rescue them, dubbed STS-400, which was the reason why we saw 2 fully fuelled shuttles on their respective launch pads the last time we serviced the Hubble.

I’m sort of able to forgive that for the sake of story however one moment that I won’t was when Bullock is holding onto Clooney’s tether and he says he has to let go or they’ll both be doomed. You see at that particular point there’s no more forces acting on them as once they got tangled up and stopped moving all their momentum had been transferred to the ISS, rendering them at equilibrium. If Bullock had simply tugged on the tether slightly Clooney would have then started drifting lazily towards the ISS and Bullock could have pulled herself back along the parachute cords. I would’ve let that slide if it was a minor side point but it’s one of the main turning points of the movie and unfortunately it just has no basis in reality whatsoever.

One thing I was also going to pan Gravity for was the use of fire extinguishers as thrusters since I figured the amount of delta-v available in them wouldn’t have been enough to provide any meaningful thrust. As it turns out, depending on what kind of extinguisher you have, there could be as much as 100m/s in them, a heck of a lot of thrust by any means. Whilst you’d be far more likely to send yourself into an unrecoverable spin if you were using them in the way shown in Gravity it does lend some credence to the idea of using it to correct your trajectory in order to intercept something else.


There were also numerous other minor details but compared to the previous few I mentioned I don’t think they’re worth digging into. Whilst there really were some cringe inducing moments from a science perspective it is a highly enjoyable film, even if you’re not into the whole space scene. It’s also worth it to see it in 3D, something I don’t say often, as the producers have taken care to use 3D as a tool rather than slapping it on in order to increase the ticket price. It might not be super hard sci-fi but then again not many films are and ones of Gravity’s calibre are even rarer.


The Future of Manned Space Stations.

There’s a saying amongst the space enthusiast community that the shuttle only continued on for so long in order to build the International Space Station and the ISS only existed so that the shuttle had some place to go. Indeed for the last 13 years of the shuttle program it pretty much exclusively visited the ISS taking only a few missions elsewhere, usually to service the Hubble Space Telescope. With the shuttle now retired many are looking now looking towards the future of the ISS and the various manned space programs that have contributed to its creation. It’s now looking very likely that the ISS will face the same fate as Mir did before it, but there are a multitude of possibilities of what could be done instead.

Originally the ISS was slated for decommission in 2016 and with it still not being fully constructed (it is expected to be finished by next year) that would give it a full useful life of only 4 years. The deadline was extended back in 2009 to 2020 in order to more closely match the designed functional lifetime of 7 years and hopefully recoup some of the massive investment that has gone into it. It was a good move and many of the ISS components are designed to last well beyond that deadline (especially the Russian ones which can be refurbished on orbit) and there’s still plenty of science that can be done using it as a platform.

The ISS, like Mir before it, has only one option for retirement: a fiery plunge through the atmosphere into a watery grave. Whilst there’s been lots of talk of boosting it up to a higher orbit, sending it to the moon or even using it as an interplanetary craft all these ideas are simply infeasible. The ISS was designed and built to be stuck in low earth orbit its entire life with many assumptions made that preclude it from going any further. It lacks the proper shielding to go any higher than say the Hubble Space Telescope and the structure is too weak to withstand the required amount of thrust that would get it to a transit orbit (at least in any reasonable time frame). The modifications required to make such ideas feasible would be akin to rebuilding the entire station again and thus to avoid cluttering up the already cluttered area of low earth orbit it must be sent back down to earth.

Russia however has expressed interest in keeping at least some of the parts of the ISS in orbit past the 2020 deadline. It appears they want to use them as a base for their next generation space station OPSEK. This space station would differ significantly from all the previous space stations in that it would be focused on deep space exploration activities rather than direct science like its predecessors were. It would seem that those plans have hit some roadblocks as the Russian Federal Space Agency has recently stated that the ISS will need to be de-orbited at the end of its life. Of course there’s still a good 8 years to go before this will happen and the space game could change completely between now and then, thanks in part to China and the private space industry.

China has tried to be part of the ISS project in the past but has usually faced strong opposition from the USA. So strong was the opposition that they have now started their own independent manned space program with an eye to set up their own permanent space station called Tiangong. China has already succeeded in putting several people into space and even successfully conducted an extravehicular activity (EVA), showing that they have much of the needed technology to build and maintain a presence in space. Coincidentally much of their technology was imported from Russia meaning that their craft are technically capable of docking with the Russian segments of the ISS. That’s also good news for Russia as well as their Soyuz craft could provide transport services to Tiangong in the future.

Private space companies are also changing the space ecosystem significantly, both in regards to transport costs and providing services in space. SpaceX has just been approved to roll up two of its demonstration missions to the ISS which means that the next Dragon capsule will actually end up docking with the ISS. Should this prove successful SpaceX would then begin flying routine cargo missions to the ISS and man rating of their capsule would begin in earnest. Couple this with Bigelow Aerospace gearing up to launch their next inflatable space habitat in 2014~2015 the possibility of the ISS being re-purposed by private industry becomes a possible (if slightly far fetched) idea.

The next decade is definitely going to be one of the most fascinating ones for space technologies. The power international power dynamic is shifting considerably with super powers giving way to private industry and new players wowing the world stage with the capabilities. We may not have a definitive future for the ISS but its creation and continued use has provided much of the ground work necessary to flag in the next era of space.