Passive CubeSats for Remote Inspection of Space Vehicles

In 2003, the Space Shuttle Columbia fractured into pieces amongst attempting an emergency reentry into Earth’s atmosphere, and the crew and vehicle were lost. A hole had developed in the wing of the shuttle due to a piece of foam insulation that broke off from the external tank and hit the wing, and in an attempt to save the vessel and it’s passengers, NASA instructed the crew to return to Earth. However, the heat from reentry penetrated the interior systems through the hole in the wing, and ruined many critical systems, including the control system. This led to the destruction of the Space Shuttle Columbia, a vessel who flew 27 times successfully beforehand.

The ultimate conclusion of the accident report was that if Columbia had simply remained in space, another space shuttle could have met up with Columbia and, at the very least, the crew could have been saved. There were several methods of inspection that Columbia could’ve done, but due to either unpreparedness or expense, they were not. To prevent any future tragedies similar to Columbia, a way to remotely inspect vehicles in space was needed, and CubeSat are ideal for filling that need.

Currently, there are many ways to remotely inspect a space vehicle, which are listed below along with their pros and cons.

• Telescopes: telescopes can be used on Earth to observe vehicles in space. They are reliable and affordable, but they have very limited coverage and resolution, which can make spotting issues hard. They also have a slow response time, because if one spots an issue with a telescope, it must go through the chain of command and then be transmitted to the crew, and the vehicle’s issue must align with the telescope to be spotted.
• Spacecraft Rendezvous: By using another spacecraft, repairing materials may be offered or, if needed, crew members may be evacuated. Spacecraft rendezvous provides good coverage and resolution of the issue. However, it is not a reliable way to find issues, it is expensive, it is slow, and it is not even an option for many vessels in distress.
• EVA Inspection: Similar to spacecraft rendezvous in pros and cons, EVA inspection provides good coverage and resolution, but is not reliable, cheap, or quick. Furthermore, it can be dangerous, especially if the issue with the craft is severe, and it requires there to be an onboard crew to inspect any damage.
• Dedicated Robotic Arm: This method of inspection has many pros, but one big con. It is reliable, has good coverage and resolution, and it quick to respond. It is very expensive, however, and therefore can only be used sparingly.
• General Purpose Arm: A general purpose arm is cheaper than a dedicated robotic arm, but in order to do so, it had to give up good resolution and coverage. On-board Inspection: On-board inspection is relatively inexpensive, reliable, and provides good resolution and response time. The coverage, however, is not good and it requires the presence of a crew.
• Free-flying Inspectors: These have the potential to be very useful, as they have high coverage and resolution, but their response time varies depending on the original location/orbit of the free-flying inspector and they can also be potentially expensive and/or risky.

BYU’s Passive Inspection CubeSat (PICs) offers a powerful alternative to the above inspections in many cases. Because PICs is passive, the inspection risk is low. With its 360 degree by 180 degree spherical camera system, the coverage is very good, and the resolution can be good depending on the separation tumble. Depending on how it’s used, the CubeSat can respond quickly, and it is low cost.

The PICs CubeSat chassis is made up of 6 interlocking walls. On the outside of the chassis, there are solar panels on the four long sides. On top there are 2 stowed antennas. Within the chassis, there are batteries, the radio, the EPS board, the Separation Switch, and the cameras, which stick out of the chassis to record the footage. An image of the CubeSat can be seen in Fig. 3.

Furthermore, as CubeSat is used in space, it will get better in both price and performance, and further uses can be explored. For example, one potential future use is by changing it so that the cubesat relays not to the ground but to the parent satellite, it could greatly reduce the amount of time that it needs to be on. Therefore, the size and price could be greatly decreased. As the CubeSat is used, it will only get better.

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Reference: Patrick Walton, Josh Cannon, Brian Damitz, Tyler Downs, Dallon Glick, Jacob Holtom, Nicholas Kohls, Alex Laraway, Iggy Matheson, Jason Redding, Cory Robinson, Jared Ryan, Niall Stoddard, Jacob Willis, Karl Warnick, Michael Wirthlin, Doran Wilde, Brian D. Iverson, David Long, “Passive CubeSats for remote inspection of space vehicles,” J. Appl. Remote Sens. 13(3), 032505 (2019), doi: 10.1117/1.JRS.13.032505.