Odyssey Communications

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The TET is far enough away from Earth that the crew goes into suspended animation for the initial travel to it. This initial travel is either automated or controlled from Earth. After waking up, the crew speak conversationally with their mission controller Sally.

This conversation between Jack, Vika, and [actual human] Sally happens over a small 2d video communication system. The panel in the middle of the Odyssey’s control panel shows Sally and a small section of Mission Control, presumably back on Earth. Sally confirms with Jack that the readings Earth is getting from the Odyssey remotely are what is actually happening on site.

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Soon after, mission control is able to respond immediately to Jack’s initial OMS burn and let him know that he is over-stressing the ship trying to escape the TET. Jack is then able to make adjustments (cut thrust) before the stress damages the Odyssey.

FTL Communication

Communication between Odyssey and the Earth happens in real-time. When you look at the science of it all, this is more than a little surprising.

Vika tells Sally that the Odyssey was traveling for at least 39 days in suspended animation. We see in the same scene that the Odyssey’s engines are thrusting that whole time. Even the low thrust of an ion engine would send the Odyssey a long way out into the Solar System in 39 days.

Current communication technology in space relies on radio communication for voice and video. NASA is testing out laser-based signaling, which would provide higher bandwidth but doesn’t travel faster than the speed of light. Time lag is a constant in both technologies.

In space, real-time communication and measurable distance do not go together at all. There should be a lag, especially at the distances implied by the story.

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How Far?

The engines on the Odyssey look a lot like NASA’s prototype ion engines. This would fit nicely with the compact nuclear reactor on board, which would be the perfect size for generating living power and engine power for low-thrust ion engines.

Ion engines don’t have the same thrust capacity as our current rockets, but have the advantage of constant thrust over long distances that chemical rockets can’t match. NASA’s Dawn probe has an acceleration of about 0.22m/s/s (very, very rough math). A quick run through a calculator at (http://www.cthreepo.com/lab/math1/) says that over 39 days (Odyssey’s travel time), they would go about 8 astronomical units (AUs). That is 8x the distance from the Earth to the Sun just with Dawn’s level of thrust. That is a low end calculation, and doesn’t factor in any thrust from a more traditional rocket on the Earth end, or any slingshot maneuvers to add speed.

8 AUs would be more than an hour of light speed lag. That means that the Odyssey should take almost two hours to complete a single back-and-forth of a conversation.

Communication-Time

If the compact nuclear reactor was actually able to produce thrust (unlikely, but possible), then in 39 days the Odyssey could have traveled even further.

At any distance beyond the Moon’s orbit, light-speed communication would become increasingly delayed. If the TET was even in a Mars orbit, it could take between 4 and 24 minutes for radio and video signals to go back and forth between Earth and the Odyssey. Further distances increase the lag time significantly.

This means that Humanity has…gasp…developed Faster-than-Light communications technologies by the time Oblivion occurs (and, yes, even before the TET could have provided the advanced alien tech to make it happen).

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Despite this FTL comm system, as the Odyssey approaches, the TET is able to disrupt the comm signal and cut off Earth from Odyssey. Jack looks concerned by this (as well as Sally’s order to cut his thrust), and stops trying to fight being drawn into the TET.

An unanswerable question here is: what kind of technology from the TET would be able to disrupt an FTL signal? Wouldn’t that require them to be time travelers? Wouldn’t this be a different movie, then?

Don’t Trust New Technology

Neither Jack nor Vika interact with the communication system during the flight that we see besides talking to it. When the signal cuts out, neither of them rushes to check settings or flip switches to try and get the signal back. Instead, they go to a backup plan and focus on what they are able to do without help from Earth. The screen that held Sally’s image cuts over to a secondary information display as soon as it detects that the signal is gone.

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This implies two things:

  1. The crew were trained to not rely on the communication system
  2. The communications system is a ‘black box’ to Jack and Vika: it either works or it doesn’t.

Given the previous realization that the comm system is built around an FTL link, both of these make sense. It is unlikely that a single person (or even two people) would be able to understand the equipment behind a new FTL system well enough to maintain it or fix it in an emergency. Similarly, the early Astronauts of NASA weren’t expected to maintain the advanced computers (for the time) on their ships.

If the FTL system was recently invented, and rushed through testing for this mission, it also makes sense that Jack and Vika don’t rely on it. NASA now is very careful about testing equipment to make sure that they will always work, or at least work well enough that they can be constantly relied on. (see the Kepler mission http://en.wikipedia.org/wiki/Kepler_(spacecraft) for what happens when a well-tested and critical component fails).

Jack and Vika reveal their training during the emergency situation: They have no time to think, so they fall back on memorized actions. The lack of interaction with the communications system implies that there was no training around trying to make it work.

Have a Backup Plan

Designers planning to introduce new and advanced technology into important situations should always be sure they have a backup plan for when that advanced technology fails. Likewise, if a highly efficient workflow has advanced technology introduced to improve that efficiency, make sure that failures in the new technology won’t make the workflow slower than before.

Technology should assist and improve, never impede users. And if it’s valuable enough to warrant the risk, give users a backup plan.

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