4. I Just Happened To Be In The Neighborhood...
After the space shuttle and the Hubble Space Telescope get shredded, killing everyone except our two principals, hyperventilating Bullock and cool-as-a-cucumber Clooney use the Manned Maneuvering Unit (MMU) to gradually jet their way across the stunningly beautiful spacescape to the nearby International Space Station (ISS). Even if the crew has evacuated, Clooney informs Bullock, there will an extra Soyuz capsule they can pilot back to Earth. Unfortunately, the Soyuz has been damaged and is unable to make reentry. No problem, Clooney assures Bullock. "See that dot on the horizon," he essentially says. "That's the Chinese space station. No one's home, and their version of the Soyuz should be accessible and in working order. Just point this damaged Soyuz at that dot, fire the soft landing jets and allow the inertia to take you there." Meanwhile, as Bullock puts this last ditch plan into action, the wave of debris returns on another orbit and decimates the ISS. Astronaut Tom Jones (not the same as the hep '60s vocalist who helped redefine bare-chestedness) has noted that there's no way Bullock could have used the landing jets to traverse the distance between the two space stations, remarking that they would have just carried her into a higher orbit. And that brings up one major problem with both of these journeys that Gravity's astronauts make, the assumption that the Hubble, the ISS, and the Chinese space station are all on the same orbital plane (the same distance above the earth). In fact, there is about a 200 km (124 mi) difference between Hubble's orbital plane and ISS's orbital plane. The Hubble orbits at 370 km (230 mi) above the earth while the ISS is at 563 km (350 mi). So in addition to traveling what should be a fairly large distance from the Hubble to the ISS, Clooney should also have had to use his MMU's propulsion to take him and Bullock an additional 200 km (124 mi) higher above the earth. Besides the different orbital planes, there are also the different orbital paths of the Hubble and the two space stations. Think about it this way. First, the earth is a very large place. Try to think about just how big it is; contemplate the distance perhaps from the northern Sahara to the southern tip of Madagascar . Second, if you project outward 200 km (124 mi) from the sphere that is the earth, the result is a larger sphere with concomitantly larger distances from point to point. Now, imagine that the orbital path of a satellite such as the Hubble is a highway that stretches around this enlarged sphere. Do you think the ISS would travel on this same highway? Would it be on an adjacent highway? No, it would be on an entirely different highway, far far away. So, even if we forget about the notion of orbital planes, there is still a vast distance to traverse using only bursts of the nitrogen jets from the MMU. It would be like taking a brisk walk from a dusty highway in Zimbabwe to a sheep path in Pakistan, times roughly 3% to account for the larger "sphere" which results from being 200 km (124 mi) above the earth. Considering that Clooney was being conservative with the fuel in the MMU, he wouldn't be going at its top speed of 64 kmh (40 mph) and would likely be putting along at something closer to its normal speed of 5 kmh (3 mph). Even if we triple that speed, our hypothetical trip from an orbital path crossing Zimbabwe to one over Pakistan would take about 480 hours to complete, almost 3 weeks. And, well, the MMU has enough fuel to operate for about 6 hours.