“Space clutter,” that collection of debris and defunct satellites that is accumulating in orbit around Earth, is a serious concern for future space exploration. Being able to move or eliminate this debris is essential to improving the safety of space launches, the ISS and any future orbital endeavors.
Attempting to find a solution to the problem of space debris is what makes a new Purdue University CubeSat project so interesting. Recently, the Aerodynamic Deorbit Experiment CubeSat proposal by aeronautics professor David Spencer was chosen to be included as a secondary payload for a future Atlas V rocket launch by United Launch Alliance.
What’s even more exciting is that students who are interested in this type of space exploration project will have the opportunity to be involved from start to finish, as Spencer intends to base a course around the project next spring. Tentatively called Space Flight Project Implementation, the course will bring in undergraduate students from the School of Aeronautics and Astronautics to design, implement and test Spencer’s CubeSat project.
The ADE CubeSat
Satellites without deorbit capabilities can end up staying in orbit more than 100 years past their period of active use. Purdue’s ADE CubeSat will be a small-scale prototype of a device that could be used to deorbit 150kg-class satellites from orbit altitudes of up to 750 miles in a less than 25-year timeline.
The ADE features a drag sail that the prototype aims to test and demonstrate as a viable method of deorbiting satellites. The CubeSat is a 10-cm cube in its initial launch configuration, and the sail will be deployed using either an autonomous pre-programmed timer, or by a command sent from ground controllers.
The experimental sail deploys on four booms that extend from the ADE, with a thin and lightweight membrane material stretched between them. Once fully deployed, the sail will present a drag area of about 0.7 square meters.
The booms measure about one meter long and are comparable to a tape measure for flexibility. Spencer said he is still considering three different material options for the sail membrane, which needs to be approximately five micrometers thick.
Although flat drag sails have been tested before, Spencer stated that the four-sided pyramid geometry of his sail’s design improves on the concept, promising to enable the sail to self-right its orientation in the upper atmosphere. This will ensure the sail can provide the maximum amount of drag.
Along with the drag sail prototype, the CubeSat will contain an inertial measurement unit, flight computer and telecommunications equipment.
During the launch test phase, currently intended for a 2018 Atlas V rocket launch, the CubeSat will have a one-week on-orbit checkout after deployment to verify that all the systems are functioning and to allow initial determination of the ADE’s orbit. Once the drag sail is deployed, the ADE is expected to deorbit in about eleven days.
As an example of exactly the problem this project aims to solve, if the CubeSat did not have a drag sail, it could be expected to remain in orbit for as long as seven years. Instead, the drag sail will deorbit the CubeSat, with both sail and satellite expected to burn up about 40 miles above the Earth’s surface during atmosphere re-entry.
“Private companies are actively pursuing the deployment of thousands of small satellites into this regime for global internet service,” Spencer said. “A successful ADE mission will demonstrate the viability of the drag device, with commercial applications relevant to the deorbit of large constellations of satellites.”
For more information on the ADE or to learn more about the Space Flight Project Implementation course, check out the Purdue University College of Engineering website.