Environmental Test Campaign Research Articles

LPT6510 development up to flight model

The LPT6510 is a compact integral pulse-tube cryocooler for 50–120 K applications, with a design derived from the Thales Cryogenics MPTC compressor developed under ESA TRP and the Absolut System SSC80 pulse-tube.An update will be given on tests and development performed on the LPT6510 cooler, including test results up to TRL6, additional work done towards the build of flight coolers in the frame of the TRISHNA project, and planned future work.Detailed cryogenic performance results will be shown over the entire operational envelope, the environmental test campaign will be highlighted, and specific aspects such as off-state parasitic losses and induced vibrations will be discussed.

Thermal Vacuum Test Campaign of the EIRSAT-1 Engineering Qualification Model

CubeSats facilitate rapid development and deployment of missions for educational, technology demonstration, and scientific purposes. However, they are subject to a high failure rate, with a leading cause being the lack of system-level verification. The Educational Irish Research Satellite (EIRSAT-1) is a CubeSat mission under development in the European Space Agency’s (ESA) Fly Your Satellite! Programme. EIRSAT-1 is a 2U CubeSat with three novel payloads and a bespoke antenna deployment module, which all contribute to the complexity of the project. To increase the likelihood of mission success, a prototype model philosophy is being employed, where both an engineering qualification model (EQM) and a flight model of EIRSAT-1 are being built. Following the assembly of the EQM, the spacecraft underwent a successful full functional test and month-long mission test. An environmental test campaign in ESA Education Office’s CubeSat Support Facility was then conducted with the EQM where both vibration and thermal verification test campaigns were performed. The focus of this paper is the thermal testing and verification of the EIRSAT-1 EQM. Over three weeks, the EQM was subjected to one non-operational cycle, three and a half operational cycles, and a thermal balance test in a thermal vacuum chamber. After dwelling at each temperature extreme, functional tests were performed to investigate the performance of the spacecraft in this space representative environment. The approach to planning and executing the thermal testing is described in detail including the documentation required, set up of the test equipment, and determination of the test levels. Overall, the campaign demonstrated that the mission can successfully operate in a space environment similar to that expected in orbit, despite encountering a number of issues. These issues included a payload displaying anomalous behaviour at cold temperatures and needing to redefine test levels due to an insufficient understanding of the internal dissipation in the spacecraft. A total of two major and three minor non-conformances were raised. Crucially, these issues could not have been found without thermal testing, despite the comprehensive ambient tests performed. The main results and lessons learned during this thermal test campaign are presented with the aim of guiding future missions on optimal approaches in organising and executing the thermal testing of their CubeSats.

ATmospheric LIDar (ATLID): Pre-Launch Testing and Calibration of the European Space Agency Instrument That Will Measure Aerosols and Thin Clouds in the Atmosphere

ATLID (ATmospheric LIDar) is the atmospheric backscatter Light Detection and Ranging (LIDAR) instrument on board of the Earth Cloud, Aerosol and Radiation Explorer (EarthCARE) mission, the sixth Earth Explorer Mission of the European Space Agency (ESA) Living Planet Programme. ATLID’s purpose is to provide vertical profiles of optically thin cloud and aerosol layers, as well as the altitude of cloud boundaries, with a resolution of 100 m for altitudes of 0 to 20 km, and a resolution of 500 m for 20 km to 40 km. In order to achieve this objective ATLID emits short duration laser pulses in the ultraviolet, at a repetition rate of 51 Hz, while pointing in a near nadir direction along track of the satellite trajectory. The atmospheric backscatter signal is then collected by its 620 mm aperture telescope, filtered through the optics of the instrument focal plane assembly, in order to separate and measure the atmospheric Mie and Rayleigh scattering signals. With the completion of the full instrument assembly in 2019, ATLID has been subjected to an ambient performance test campaign, followed by a successful environmental qualification test campaign, including performance calibration and characterization in thermal vacuum conditions. In this paper the design and operational principle of ATLID is recalled and the major performance test results are presented, addressing the main key receiver and emitter characteristics. Finally, the estimated instrument, in-orbit, flight predictions are presented; these indicate compliance of the ALTID instrument performance against its specification and that it will meet its mission science objectives for the EarthCARE mission, to be launched in 2023.

Total ionizing dose effects on digital micromirror devices

There is interest in deploying digital micromirror devices (DMDs) in space for use in multi-object spectrometers, but the devices must first be qualified for space deployment. An environmental test campaign has been carried out on eXtended Graphics Array (XGA) DMDs to qualify the devices for space deployment. The campaign has included mechanical shock and vibration, low temperature, proton radiation, and heavy ion radiation testing. XGA DMDs have passed each test at a level suitable for space deployment. Our paper reports on gamma radiation testing of XGA DMDs, the final portion of the environmental test campaign. Gamma radiation causes total ionizing dose (TID). A total of 19 DMDs were irradiated to TIDs between 16 and 45 krad(Si) while biased and 24 and 76 krad(Si) while unbiased. The effects of TID on DMDs are similar to other electrostatically operated micro-electrical mechanical systems, and all irradiated DMDs were fully recovered by annealing. In addition to testing, radiation modeling of the space environment was performed to determine the expected TID for various space mission scenarios. DMDs have minimal susceptibility to TID effects, and the effects do not significantly compromise the use of the devices for space missions in orbit at L2 or low Earth orbit.

Design of a synthetic jet actuator for flow separation control

This paper describes the development of a piezo-electric synthetic jet actuator (SJA) of the AFLoNext project. Active flow—loads and noise control on next generation wing (AFLoNext) is a project within European Union’s 7th Framework Program. One of the main project goals is the application of active flow control (AFC) techniques, such as SJAs and pulsed jet actuators (PJAs) in two different application scenarios to evaluate the potential benefit for retrofit of current aircraft and also for future aircraft designs. This paper is focusing on the SJAs. For large-scale wind tunnel testing, an actuator panel with 84 SJAs including the drive electronics system was designed and pre-tested in a laboratory environment. The performance exceeds 100 m/s with outlet nozzles of 2.5 mm diameter and a span wise clearance of 10 mm. A second actuator design was prepared for the application on the outer wing region and was investigated in a harsh environmental test campaign. Two span wise rows of five actuators were integrated in a panel with 10 × 0.5 mm2 slotted outlet nozzles. With this design also velocities exceeding 100 m/s were measured. The actuators withstand different harsh environmental conditions including extreme temperature, rain, mechanical vibration and shock. With the results of the project, a technology readiness level (TRL) evaluation will conclude the maturity of the technology. Depending on the final test and evaluation results, achievement of TRL4 is expected.

Space Environmental Testing of Novel Candidate Materials for Multilayer Insulation

Multilayer insulation forms the outer barrier of a satellite towards space. Polymer foils used in multilayer insulation have to withstand the space environment for mission durations often lasting well above 10 years. This paper outlines the space environmental test campaign performed to qualify novel and advanced polymer foils to reduce blanket mass and replace export-controlled materials. Complete multilayer insulation layups were irradiated; these were composed of thicker outermost layers of the reference material Kapton®, a white polyimide and an alternative, conductive black polyimide and up to seven thin internal, aluminized or polyethylene terephthalate and polyethylene naphthalate layers separated by nonwoven spacers. One sample set consisted of polyether-ether-ketone foil and internal vacuum-deposited-aluminum-coated polyether-ether-ketone layers. Materials were exposed to ultraviolet, electrons and protons simulating a 15-year geostationary orbit mission. Absorptance was measured at various stages in situ during the exposures, and emittance was measured ex situ at the beginning and end of the test. With tensile testing, exposure influence on foil mechanical properties was determined and compared with pristine and reference materials. Although the white polyimide was sensitive to ultraviolet and showed strong degradation after ultraviolet and proton exposure, degradation of all other materials was within expected limits and compatible to state-of-the-art foils.

Force limited vibration testing applied to the CASSIOPE spacecraft

CASSIOPE is a small Canadian spacecraft carrying two payloads: the enhanced polar outflow probe payload consisting of eight scientific instruments, and the Cascade payload, a high-speed Ka-band communication technology demonstrator. As part of the environmental test campaign, the spacecraft was subjected to sine vibration testing for qualification, and to random vibration testing for workmanship verification. The force limited vibration (FLV) approach was utilized for the random vibration tests. The control strategy for the random tests combined force and response limiting. For the lateral axes, the rms value of the input force was reduced by more than 60%, primarily from force limiting at the fundamental frequencies of the spacecraft. The input specification was notched by as much as 20 dB at the fundamental frequency. For the thrust axis, the rms value of the input force was reduced by 50%, primarily because of response limiting. The large amount of input notching observed for the CASSIOPE spacecraft, t...