Cubesat De-Orbit Device Team

CubeSat De-Orbit Device Team

Status Report 1

MAE 435: Project Management and Design II

February 7, 2012

Structure

During the last few weeks the structure team has been researching potential launch options through a few different sounding rocket programs. RockSAT-C and RockSAT-X are two sounding rocket programs that have been researched as viable flights for the air brake system. The sounding rocket team has sent emails to NASA and made contact with one of the members in charge of the RockSAT-X program. The purpose for this was to determine any further design constraints to a deployable experiment that might be flown through the RockSAT-X program. Some initial design sketches were made after brainstorming options for releasing a payload into space. Contact with the air brake team was maintained to stay up to date with the experiment dimensions and requirements for deployment. These design parameters will be integrated into the bus structure in order to refine the design.

Through continued research, a document surfaced containing an experiment performed by two other universities in the past. This experiment’s flight option matches so perfectly with what the sounding
rocket team hopes to achieve. The structure team will make contact with the students and faculty who worked on the past experiment and use them as a primary source for design advice on the de-orbit device experiment.

CubeFlow Team

The CubeFlow Hardware Team has been tasked with using the CubeFlow hardware and software systems in order to establish an active communication and data feed connection between the CubeSat and the main computer. CubeFlow is a system which uses extensible transducer electronic data sheets, or xTEDS, in order to establish connections between the main computer and a variety of sensors. The team met on Wednesday, February 1st , 2012 in an attempt to set up a connection between the CubeSat and the main computer. The team proved successful in establishing an active connection between the two devices, by using code that was provided by Utah State University. This computer code was found in conjunction with Utah State University’s “CubeFlow Plug and Play Manual” and is meant to provide a framework upon which more complex commands can be executed. While this code did establish a successful connection between the CubeSat and the main computer, the team ran into difficulties in collecting data from a temperature sensor connected to the CubeSat. This error in data collection is likely due to an error in the computer code used, or a faulty temperature sensor/sensor connection.

The team is now working on certifying each member for access to the CubeFlow Space Dynamics Laboratory as it is restricted to US citizens. This online resource allows users to create their own computer code to be uploaded onto the CubeSat, as opposed to using the USU provided framework codes. Once the members are certified, a “blank-slate” run will be initiated on these systems. Using this method, it will become more apparent where the errors may be in to data collection systems. The team is aiming to have these systems up and running in time to be able to include them in the vacuum chamber test.

Air Brake

The Air Brake team is tasked with developing a passive air brake and deployment system in order to de-orbit satellites within 25 years after completion of their mission. The team is considering two design options for a passive air brake system. One system involves the use of a sublimating compound, benzoic acid, to inflate an air brake. The other involves the use of a Shape Memory Alloy, Nitinol, to expand a collapsed frame.

Another design consideration for the team is the folding pattern used for the collapsed membranes that are to be inflated and/or expanded. The team is reviewing and investigating efficient folding techniques that will result in a structurally sound compact system.

Finally, the last design consideration is the material selection for the membrane and adhesives. Due to the high range of temperatures and UV bombardment that the de-orbit system will experience, space-grade materials must be used. After extensive research, the polyimide that is most likely to be used is Kapton. Along with meeting all of the requirements for space, Kapton is easily the most feasible material for us to acquire. The creator of Kapton, DuPont, is well known for making donations to schools.

At the beginning of the semester, the vacuum chamber that the team was supposed to use was inoperable. Since then, the team has invested time and resources into restoring the functionality of the chamber through a lengthy retrofit. As of a week ago, the team successfully completed the retrofitting process.

-Nitinol

NDC and Memry Corp were both contacted about providing materials and prototyping services for us. NDC was not able to help and Memry refused to do any prototyping but did offer some 0.04" diameter Nitinol wire. It looks like they are supplying the wire for free as long as the $10 for shipping is paid for. We do not know exactly how much we are getting. We were originally told by the sales rep that we would get 20-30ft but after asking him about annealing times he said he would try to get us 50ft so we would have plenty of extra to experiment with. We supplied the sales rep with a FedEx account number for billing andan address for shipping. A week and a half later (earlier last week) we received a 50ft spool of Nitinol in the mail.

Since we are not going to be able to have it fabricated, we will have to make the frame ourselves. This will require the use of a high temperature oven (or something else that can heat the material to 500C). As for how long it will take to anneal, I found information on NDC's website that says that it must be long enough to heat the entire cross section of the material to 500C. From this we should be able to get a good idea of how long it will take but some experimentation will still probably be necessary to hone in the right time. The biggest concern with heating will be the amount of space we have in the oven and how to hold the material in the desired shape as it heats. The other major concern for construction is welding. We are hoping to have all the welding necessary to construct the frame done by the ODU Machine shop.

-Sublimating compound

The sublimating compound which we will be using to inflate our de-orbit device is Benzoic Acid. This compound has a vapor pressure of around 500 Pa which is right around the pressure at which our CubeSat will be pressurized. Once released, the air brake will inflate.

We have been in contact with Dr. Brown from the chemistry department and it seems as if we will be able to create any chemicals that we need in the Physical Chemistry Lab. We will require approval from the Department Chair in order to use the lab and participate in a lab safety course. We are scheduled to meet with Dr. Brown later this week.

-Adhesive compound and Polyimides

Originally, Upilex-S was chosen as the polyimide of choice for the air brake membrane. After the exchange of emails with a few vendors of the materials, it seems as if we will be unable to have the material donated to us. This shifted our focus from Upilex-S to Kapton. The previous team was able to receive a substantial donation of Kapton from DuPont, we have been unable to find the unused quantity in the Space Systems Lab. We plan to contact DuPont later this week with a request for a quote in hopes that they offer us a donation.

For the adhesive that will be used to adhere polyimide panels, we have a rough idea of what compound we want to use. The adhesive which is looking the most promising is DC93-500.