The video above shows an animation of what the Canadian Space Agency hopes will be the first successful self-repair of the Mobile Servicing System aboard the ISS. The mobile servicing system is basically a group of several complicated robots that can either perform complicated tasks on their own, or be combined into a larger unit to extend the dexterity of the system as a whole.
The most recent addition to the servicing system is the Special Purpose Dexterous Manipulator, otherwise known as Dextre. Dextre is somewhat reminiscent of a human torso with two enormous arms. It is just one of the Canadian Space Agency’s contributions to the station. It was installed on the station in 2008 to perform activities that would normally require space walks. Dextre’s very first official assignment was successfully completed in 2011 when the robot was used to unpack two pieces for the Kounotori 2 transfer vehicle while the human crew on board the ISS was sleeping.
Dextre is constructed in such a way that it can be grabbed by the Canadarm2 robot and moved to various work sites around the Space Station. Dextre can then operate from the maintenance site on its own while the Canadarm2 can be used for other functions. Dextre can also be operated while mounted to the end of Canadarm2, essentially combining the two robots into one bigger and more dexterous robot.
One of the more critical camera’s on the Canadarm2 has started transmitting hazy images. To fix it, the Canadarm2 will grab onto Dextre, forming a sort of “super robot”. Dextre will then be positioned in such a way that it can remove the faulty camera. The hazy camera will then be mounted to the mobile base component of the Mobile Servicing System. This will give the ISS crew a new vantage point of a less critical location. The station’s human crew will then place a new camera module in Japan’s Kibo module’s transfer airlock. Dextre will be able to reach this new camera and then mount it on the Canadarm2 to replace the original faulty unit. If successful, this mission will prove that the Mobile Servicing System has the capability to repair itself under certain conditions, opening the door for further self-repair missions in the future.
If the space station were left to its own devices, the living quarters would get incredibly hot. There are computers, hardware, and six crew members, all generating heat that must be gotten rid of. To do this, there are two heat exchangers inside the station that take warm water, dump that heat to ammonia, and send that ammonia out to panels outside the station. On December 11, 2013, Loop A of the thermal control system shut down, putting the station one failure away from evacuation. Plans for a spacewalk were tabled, but the ground crew managed to fix this hardware failure by telling the astronauts to push buttons, a metronome, and a software patch.
The problem with Loop A of the Internal Thermal Control System was a flow control valve that regulated the amount of ammonia flowing through the heat exchange. Too much ammonia, and the station would be far too cold. Too little, and it would be too hot. This valve is electronically controlled and takes exactly 13 seconds to move from open to closed. The first attempt at fixing the problem was having ground crew send the command to open the valve and cut the power halfway through. This involved using a metronome app on a phone to send two commands 6.5 seconds apart. It worked, but not quite well enough.
The failure of the metronome technique led [Todd Quasny] to write a script to turn the ‘on’ and ‘off’ commands from the ground to the ISS with millisecond resolution. This meant the commands to control the valve could be sent with the right delay, but they weren’t received with the right delay. This is a problem that had to be fixed from the station’s computers.
To finally solve the problem, ISS software engineer [Steve Joiner] was called in to write a software patch for the thermal control system. This is spaceflight and writing software is a long a laborious process of testing and code reviews. Nevertheless, the team managed to write and upload a patch in just two days.
This patch gave controllers the ability to control the valve with a resolution of 100 milliseconds, good enough for very fine control of the thermal system, and all without requiring the massive amount of planning that goes into a spacewalk or resupply mission.
The first element of the International Space Station (ISS) launched over fifteen years ago, on November 20, 1998. For more than thirteen years at least two human beings have been continually living off the surface of our planet. Assembly of the Space Station is now complete. It is being utilized by its crews and scientists from around the world to execute its primary mission – scientific investigations that can only be accomplished in the microgravity environment of Low Earth Orbit (LEO). As with any structure, items age, wear out, or break and need to be repaired. What could be rather “simple” repairs on Earth can become much more complex in zero gravity. In some cases, “necessity becomes the mother of invention.”
A few months years ago, [Liam] funded a Kickstarter for a small desk toy that would tell him when the International Space Station was overhead. [Liam] got a little tired of waiting, so he decided to build his own with a Raspberry Pi and an astronomical computation Python library.
The impressive part of this build is computing where an orbiting object is in the sky given the ISS’ orbital elements. For this, [Liam] is using PiEphem, a library that can compute the positions of the sun, moon, planets, asteroids, and Earth-orbiting satellites given a location and a time. Since the ISS orbital elements change every so often, his software is set up to download an update every week or so.
[Liam] developed a few versions of his space station detector, each with a different display. The simplest uses a few LEDs, either through a LedBorg, Blinkstick, or PiGlow to serve as a notification of when the ISS is overhead. Two more complicated versions use an LCD display or LED matrix to signal when the next ISS pass will occur.
[Douglas Adams] will tell you not to forget your towel when it comes to space travel. But NASA may start mandating that astronauts always carry a toothbrush. That’s because when a recent repair on a critical International Space Station component went wrong it was a toothbrush hack that saved the day.
The culprit here is a bolt that wouldn’t re-seat after replacing a power transfer module that routes electricity from solar cells to the station’s electrical systems. About how many times have you had trouble with bolt threads? Now put yourself in a space suit in orbit for eight hours trying to get the thing to work. Yikes!
Just like in the movies there was a team of engineers at the ground center which gathered all the supplies available in the ISS. They figured out that metal shavings in the threaded hole needed to be cleaned out and the area lubed for the bolt. One of the two types of tooth brushes on hand would work for the lube, but needed to be stiffened. There was also a brush for cleaning the threads which was made out of a jumper cable. The images seen above are the step-by-step instructions the team uploaded to the astronauts who reproduced their hacked hardware to complete the repairs.
After reading about an initiative between NASA and Boeing to develop lights for the International Space Station [Rasathus] decided to give it a go at building his own. The project uses RGB pixels to build a circadian rhythm light installation. Without the normal rise and fall of the sun the sleep wake schedule for the astronauts can be pretty rough. This uses color and intensity of light in a well-defined schedule to help alleviate that. [Rasathus] is trying to bring his project in well under the $11.1 million mark which was established for the ISS.
The light modules he’s using are from a strand of LEDs from Adafruit. Each is driven by a WS2801 controller, a common driver used for easy and complicated projects like this huge ball of light which our own [Jesse Congdon] tackled. The board above is the start of an adapter board for interfacing with the Raspberry Pi GPIO header. [Rasathus] wanted to make certain he didn’t fry the control electronics so he built some protection into this adapter. The control software is covered in the second portion of the write up. We’ve embedded the video from that post after the break.
If you want something great to add to your astronaut application, this is your chance. If you can figure out a way to optimize the position of the solar panels for the International Space Station, you’ll win $10,000 from this TopCoder competition.
Positioning the solar arrays on the ISS is an incredibly complex task; if parts of the arrays are in the shadow of other parts, they’ll bend due to the temperature difference and eventually break. NASA would like more power to run science experiments and other cool stuff, so they’re turning to hackers so they can optimize the amount of power generated on the ISS.
Your goal, as a contestant in this completion, is to define the angular position and velocity for each of the joints that connect the solar panels to the station for every point in a 92-minute orbit. Limitations on any solution include making sure the masts for each panel aren’t in a shadow more than they need to be, making sure the cycle can be repeated each orbit, and making sure the most power is generated on board.
The completion is open, so if you haven’t done enough matrix algebra this weekend feel free to sign up. In any event, you’ll get a cool CAD model of the ISS.