PROVE stands for the Pointable Radiometer for the Observation of Volcanic Emissions. It is an Earth observation payload proposed by the UoBSat team at the University of Bristol. Pathfinder is a thermal infrared (TIR) and visual (VIS) imaging payload used for volcanic ash cloud observation. It is worked on by a team of undergraduate and postgraduate students alongside a team of Staff members. The team has just started the 6-month process of preparing of their environmental testing campaign and we will be documenting our progress over the coming months in this blog.
Building a CubeSat comes with many challenges. Space is a harsh environment for electronics and cameras. At the start of a CubeSat’s life, it is immediately subject to massive vibrations when launched into space on a rocket.
A rocket is essentially an explosive with a tiny section on the top for a payload such as a CubeSat. This means that large G forces are experienced by our CubeSat on launch that can rip it apart. If it survives this, it then has a new challenge to face. In an eclipse, temperatures drop down to as low as -100°C and when in view of the sun, it can be as hot as +100°C. For this reason, we need to test the satellite in an environment similar to space including vibration and thermal vacuum testing. This is called ‘environmental testing’. With the support of the Education Office of the European Space Agency under the educational Fly Your Satellite! Test Opportunities programme, we will be conducting the environmental testing campaign of PROVE-Pathfinder at ESA’s CubeSat Support Facility in ESEC-Galaxia in Belgium.
Over the next 6 months, the team will be preparing for their testing campaign which is due to start in April 2023. They will be using a Thermal Vacuum Chamber (TVAC) to mimic the extreme pressure and temperature changes in space. This means that every part of our 2U payload needs to be able to survive the extreme environment it’ll be put under during environmental testing.
Fun fact: U or Units is a CubeSat sizing convention that means a 10cm x 10cm x 10cm cube! PROVE-Pathfinder is a 2U payload, so we are 20cm x 10cm x 10cm in size!
The next challenge that the Team will face is using a vibration shaker in our testing campaign. This is to simulate the vibrations that PROVE-Pathfinder will experience in a launch. To predict how we will perform in this test we will be completing some Finite Element Method analysis (FEM). This is modelling that we use to determine how strong our structure is and how well it will perform when shaken at different frequencies and amplitudes. On a very tight timescale, it is difficult and time-consuming to conduct this whilst requiring specialist knowledge. Luckily, we have a lot of experienced and skilled researchers and PhD students within the University whose knowledge we can draw on.
Tool access has also been proved to be quite difficult. Currently, standard drilling equipment is used to drill holes in our camera lens. It is bad to have sealed compartments of air in space as they have a tendency to pop! Hence why we drill holes into our lens’ sealed compartments. But this method causes tiny pieces of debris to enter the inside of the lens which is not ideal. To combat this, several cleaning procedures are being considered. This includes inspections with white and UV light to check for debris on a microscopic level and chemical residuals. In addition, after discussing the issue with our friends in the ESA Education Office, we are attempting to use a digital microscope to determine the severity of the debris.
Note that it is vital to have no debris at all present, as we shake the payload on a vibration table it can scratch the lens. Currently, we are looking at cleaning the lens with smear-free wipes, IPA and possibly nitrogen gas.
Being a mix of undergraduate and postgraduate students can get very hectic. The range of knowledge and experience among the students, as well as multitasking with research projects and personal downtime, can become overwhelming at times. However, we are lucky to have an abundance of staff, students, and advisors, internally within the University and externally at the ESA Education Office, willing to help guide us through the programme and provide assistance with testing preparation. The next 6 months is going to be intense but exciting as we put our CubeSat through its paces and get it ready to survive in space.