Testing Campaigns for Space Hardware

Before being launched into space, each system has to prove that it is compliant with the loads of the launch vehicle. This is a mandatory and very important procedure

It typically involves several types of mechanical tests, thermal vacuum testing and sometimes acoustic and EMC testing. For the majority of CubeSat projects, acoustic testing and EMC can be omitted. Our team has developed a proprietary approach in cooperation with our partners from EXOLAUNCH and several launch vehicle manufacturers from all over the world. Our multilauncher qualification campaign guarantees, that the customers hardware will be accepted for launch by any authority covered by the campaign. Our customers can easily select which launchers need to be covered – our database automatically delivers hull curves for all loads as well as eventual specific reporting requirements. We prepare the test documentation in a way that leaves no room for questions. By choosing our services, our customers significantly de-risk their projects.

Mechanical Testing

For a majority of CubeSat missions, a successful mechanical testing campaign is enough to get a launch clearance

It typically involves static or quasistatic testing, sine and random vibration as well as shock testing. To simulate the static loads due to the acceleration of the launch vehicle, which can be 12g or more, static testing is performed. In some cases, large centrifuges can be used to simulate the static load. In most cases nevertheless, a quasistatic approach is selected. It makes use uses sine vibration with peak accelerations higher or equal to the desired static load to simulate the load environment. The frequency of the sine vibration is selected to be lower then 1/3 of the first resonance frequency of the device under test – to prevent damage or fatigue effects. For many launchers a sine-burst approach with 8-12 cycles is acceptable. The biggest advantage of the quasistatic approach is that it can be performed on a vibration table.

A vibration table is also used for the subsequent sine vibration and random vibration testing. For some launchers, in case of very stiff test objects and if case quasistatic testing has been successfully performed, sine vibration testing can be omitted – as it only simulates the low frequency loads of the first stage of the launcher. Random vibration is carried out to simulate the loads of the upper stages and is the most severe test for regular CubeSats. In some cases (e.g. protoflight philosophy), notching can be applied on the resonance frequencies of the object to protect it from damage.

Depending on satellite, separation system type and its location on the launch vehicle, shock testing can be omitted. Nevertheless, this is always subject to negotiation. For low shocks, testing can be performed on the same vibration table as the previous tests. Higher shock levels can only be simulated with special equipment.

German Orbital Systems has performed dozens of different mechanical test campaigns for our own and for customer satellites. We know how complicated campaigns can be – especially if multiple launchers should be considered. Entrusting us with your mechanical test campaign allows you to focus on the really important things in your project while being absolutely sure that your test approach is correct.

Thermal Vacuum Testing

For typical CubeSats two types of thermal vacuum tests are relevant

The so called Thermal Bakeout is not a test in its common sense, it’s a mandatory procedure which can be requested by the launch authorities or by the launch service provider. For the thermal bakeout, the test object is “parked” inside a thermal vacuum chamber (TVAC) on a temperature between 50°-75° for approximately 24 hours. This provokes outgassing of eventual volatile materials which are then soaked away by the vacuum pump. The Bakeout is mandatory, if a CubeSat shares its deployer slot with another CubeSat (e.g. for 1U and 2U formats), it also can’t be omitted if the primary payload customer insists on it.

Thermal Cycling tests simulate the temperature conditions in orbit. In absence of an atmosphere, the main principle of heat exchange is thermal radiation. Systems which work correctly in the laboratory might tend to overheat under orbit conditions. In case of small satellites, low temperatures are even more dangerous. Due to the small thermal capacity of the structure, small satellites tend to cool down significantly during eclipse. This can have an impact on the lifetime of the batteries and ultimately on the overall mission lifetime. Thermal Cycling tests can help to improve the understanding of the system, to verify existing thermal models and to build confidence in the overall system design. While this type of tests is not mandatory – we highly advise our customers to consider thermal cycling in their testing campaign planning.

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