Orbital Debris

As explained before, when preparing the games, we need to coordinate our lasing activities with the Laser Clearinghouse, so we know that we don’t accidentally illuminate a satellite. By the time our laser beam reaches orbital altitudes (let’s say 200 km) it is very dispersed – about 200 meters across – but it can still pose a risk to sensitive downwards looking optical equipment (wink wink nudge nudge).  The Laser Clearinghouse is a Department of Defense service whose purpose is to coordinate lasing activities above the horizon, so that commercial lasing activity is not impeded. In military parlance, this is called “Deconfliction”.  Sounds more like a psychiatric term to me.

When the real Space Elevator is built, laser-satellite deconfliction will have to be undertaken on a constant basis, but we’re also going to be faced with a more difficult problem: tether-satellite deconfliction. The tether, unlike the laser beam, cannot be turned off when an impending collision is predicted.  Instead, it has to be physically moved out of the way, which is done by moving the ship-borne anchor point, since the rest of the tether will follow the anchor.  The risk we’re mitigating is actually greater than in the case of optical satellites – the risk here is of actually breaking the tether, causing the portion that is below the cut point to fall back down to earth.

The same deconfliction technology – projecting satellite orbits far enough in advance and looking for collisions threats – also comes into play today when looking at multiple satellite and other metal fragments (known as orbital debris, or “space junk”). Remember that all low-orbit objects are moving at a speed of about 5 miles per second, but they all move in different directions!  Not too recently, a commercial communication satellite was destroyed by such a collision with an inactive satellite. It is interesting to note that each collision creates a large number of additional fragments, and so if there are enough satellites in orbit, the increase in fragment density will cause additional collisions, and so we will end up with a cascade effect, a chain reaction, and lot of dead satellites.  We’re not there yet, but the problem of orbital debris is an important one to keep track of, especially in the context of a Space Elevator.

The good news is that the orbits of small orbital debris objects decay faster, especially at the low orbital altitudes where they are prevalent. If we stop producing space junk, a large fraction of it will disappear after 5-10 years. This is a lot cheaper than going after the pieces afterwards. The problem is that it is human nature to save money at the present, even if it means incurring large expenses in the future, since the future is someone else’s problem.

Which brings us back to Spaceward’s motto – “The future is closer than it appears” – if we keep polluting low earth orbit at the current rate, it will become our problem very soon. Yet even today, satellites are not equipped with de-orbiting devices that will prevent them from becoming orbital debris sources.

Livecast Console

Since technology challenges are equal parts technology development and science outreach, it is very important that we expose a wide audience to what we do.

Towards this goal, NASA TV and Dryden are helping us capture the games and bring them out to your screen like we’ve never been able to before.

The games’ media center will be in this livecast console, which you can reach by click the honkin’ Yellow “LIVE COVERAGE” button at the top of the page. (Top and center, can’t miss it.  Really.)  The console features four sections:

• The Twittertype – a teletype-like skin for the SEgames twitter account. (Follow it!)
• The Status display – this is where we display messages that we don’t want scrolling off the page.
• The Slide show – the slide show will automatically update with the latest photos we capture.
• The Video screen – switch between the live broadcast, the scoreboard, and four instant replays which will hold the most recent video clips shown on the life broadcast. All videos will be available at our youTube channel.

Of course the blog will be live during the games, and will continuously be updated with the latest and greatest. If you want to catch up to what you missed earlier in the day, just scroll down. (Just like the live-cast console, the blog will update automatically, no need to hit “refresh”)

For the live video coverage, we will have multiple vantage points – a remote telephoto looking at the games from some 1.5 km, a mobile camera at the anchor, a camera at the team staging area where the other teams can watch first place slip from their fingers…  We will have the capability to add live voice-over commentary, but are still looking for a narrator.

In addition, we’ll have a few extra cameras in more exotic locations, such as right under the launch point (looking up), right above the end-of-climb marker (looking down), maybe a camera on some of the climbers (the camera counts as payload) etc. While we won’t be able to get these video streams out to you live, we will be able to compile them into a “climb digest” video, and push that out within perhaps an hour after a team’s window is done.

We’re also preparing  “offline” or “B-roll” material, which will serve as background content to the live-cast. Over at the media center (back inside Dryden) Ted Semon will be in charge of blogging, tweeting, and video posting.

If all goes well, therefore, we’ll be treating you to a full Space Elevator media experience - hope you’ll like it! 

Phaser Stuff

If the TRUMPF Laser was ever featured in a Star Trek episode, most people would complain that the art director is trying to make the props TOO futuristic.

At 8 kWatt of pristine photonic power, the TRUMPF laser is an industry heavy-weight, capable of cutting, welding, ablating – and even (as we demonstrate) boiling water for coffee.

In an typical industrial setting one of these laser is located in a “Laser server room”, with fiber optic cables running from it to a large number of laser client machines, such as robotic welding arms, laser drills, and coffee makers.

When a client machine (say a welding robot) is in position, it calls up the laser source and basically requests some packets of photons. The laser responds almost instantaneously by unleashing a photonic salvo through the fiber optic (which looks very much like a yellow Ethernet cable) and Shazzam! the weld is done.  The entire process takes only a fraction of a second.

In the games, this same capability is employed to support multiple power beaming teams. The laser clients, in this case, are beam directors, which take the light out of the fiber optic, expand it to a much larger area and lower intensity, collimate it (make it parallel) and project it onto the moving climber unde the guidance of a tracking system.

The laser itself is located on a truck nearby, with a fiber optic connecting it to the beam director. When one team is done and the next is up, we simply switch the fiber to the next team.  (In a factory, there are actually fiber routing switches that control this functionality, but at the games we like the extra safety feature of having only one team at a time “photonically powered”.