The first scientific results of the experiments have been analysed and were shared at the symposium, as follows:
MEDET, Material Exposure and Degradation Experiment (CNES, ONERA, University of Southampton, ESA)
The experiment aimed to evaluate the effects of the complex low orbit space environment on material properties and to investigate material degradation due to contamination. Preliminary analysis of the material degradation data shows the relative trends in the material behaviour and ageing/degradation mechanisms (yellowing, erosion from atomic oxygen…). During 2010 the analysis of the in-orbit results will be complemented with ground-based measurements (environment simulation, calibration, chemical analysis, physical and optical properties).
TRIBOLAB, a multipurpose facility for testing tribology properties of materials in space
TriboLAB was designed to measure lubrication effects under microgravity conditions. Two types of tests were performed: Pin On Disk (POD) tests and Ball Bearing (BB) tests. Though the analysis of the data is still ongoing, the first results from the POD tests showed that the behaviour of the lubricants under microgravity and vacuum conditions in orbit is similar than on Earth, with transferred material from the coated disk to the mating surface (ball). The main friction coefficient and the maximum endurance of the coating in orbit were similar to the ones obtained on Earth in a commercial tribometer.
DOSTEL, Advanced Dosimetric Telescope (DLR Institute of Flight Medicine)
The experiment was designed for monitoring the cosmic radiation environment outside the International Space Station (ISS) and the comparison of these data with measurements obtained from inside the ISS. Preliminary results showed that dose rates outside the ISS are a factor of around 2 times higher than inside. These data will be compared with the results obtained from previous similar experiments already sent to space such as DOSIS and MATROSHKA and used to build overall radiation models.
EXPOSE-E, a set of five experiments for photobiology and exobiology research (Kayser-Threde, under ESA contract)
This multi-user facility accommodates a box-shaped structure including three trays hosting a suite of organic experiment samples in the following disciplines: photo processing, photobiology and exobiology. Furthermore EXPOSE-E also accommodated temperature sensors and active (R3D) and passive dosimeters (DOSIS/DOBIES) to measure solar radiation in four channels and cosmic ionizing radiation. This data obtained is used for the interpretation of the evolution of the various organic samples during their space exposure and also to run the EXPOSE-E Mission Ground Reference experiment, in which a similar set of samples in a ground laboratory are exposed to the same conditions as the samples in space The de-integration and distribution of the samples took place in December 2009. The LIFE experiment shows that the lichen Xanthoria elegans is still vital after one and a half years of exposure to LEO-conditions. The post-flight analysis of all the EXPOSE-E samples is currently on-going and as soon as the EXPOSE-E MGR is finished, the space and ground experiment results will be compared.
DEBIE-2, a micrometeoroid and orbital debris detector (Patria Finavitec, under ESA contract)
This standard low-resource instrument provided in-situ real-time data for space debris modelling. DEBIE-2 collected valuable data on sub-millimetre micro-meteoroids and space debris population and its variation with time and position. A first analysis of potential impact events has been performed. DEBIE2 data are highly dominated by noise events. False events on DEBIE-2 are mainly due to the ISS plasma and thermal environment and ISS operations (e.g. Shuttle docking/undocking). Background noise filtering based on the timing between the different signals has already been applied on the data sets, but more refined filtering is needed. Currently 931 events are filtered as potential impact events in the period Jan-Sep. 2009, with a significant higher amount of impacts on the zenith sensor than on the ram and starboard sensors.
FIPEX, Flux (Phi)-Probe-Experiment, an Atomic Oxygen Detector (University of Dresden)
The sensor development and miniaturisation was proven to be very successful. The results showed that there is an increase of Atomic Oxygen (AO) soon after local sunrise and just before local sunset when the ISS is travelling along the orbit respectively from S to N and from N to S, reaching a peak when crossing the Equator. The levels of AO decrease as the ISS continues the orbit to higher latitudes. The level reaches its minimum when the ISS exits the night phase.
PLEGPAY, Plasma Electronic Gun Payload for Plasma Discharge (Thales Alenia Space, under ASI contract)
The objective of the PLEGPAY experiment was to study spacecraft/space environment interactions in LEO with reference to electrostatic charging/discharging phenomena. A set of four experiments were designed however the execution of experiments 1 and 4 were forbidden for safety reasons in 2008 at the early stage of investigation activity, limiting the overall scientific achievements. However, the first runs of experiment 1 in 2008 demonstrated the capability of the PLEGPAY plasma contactor device to control the potential of a very large spacecraft such as the ISS through the biasing of the plasma contactor. Furthermore experiment 2 demonstrated the capability to lock the ISS potential around zero by small current emission and the PLEGPAY Langmuir Probe measurements were found to match the independent floating potential measurements made by the NASA Floating Potential Measurement Unit (FPMU).
EuTEMP, an autonomous multi-channel temperature recording unit (Efacec)
This unit successfully recorded temperature data throughout the EuTEF transfer phase, i.e. inside the Shuttle cargo bay and during the installation on Columbus. The measured and recorded values were downloaded during the commission held in February 2008.
MEDET: (Material Exposure and Degradation Experiment) Past experiments, with degradation measurements only, have not always exhibited real in-space degradation effects as samples are often cured by oxygen in the air after their return. Moreover, the degradation dynamics, combined effects and saturation processes are not fully understood. Ground based simulation experiments have been performed, which are often very complex arrangements. It is however known, that the simultaneous existence of atomic oxygen, thermal cycles and micro-meteorites are much more serious than each environment alone.
The effect of a combination of space environmental temperatures and radiation on the material in question are investigated - an environment overall, that can not very well be imitated on Earth
PLEGPAY: (Plasma Electron Gun Payload) The PLEGPAY facility has a few basic components in order to generate the data expected from it. The main question is focused around electrostatic charging and discharging of gases in low Earth orbit on large space structures, identifying a potentially fatal problem for spacecraft electronics. The most effective technology for avoiding unwanted and uncontrolled events is based on hollow cathode technology which consists of a cavity closed at one end. This is essentially the system that PLEGPAY provides for controlled experiments with variations in gas flows.
TRIBOLAB: The Tribology Laboratory instrument aims to test solid and lubricant systems in space, which have proven to be ideal candidates on ground, in particular the effects of microgravity, vacuum and launch, as well as ISS environment and collateral radiation effects. The instrument hosts three different experiments:
- Fluid lubricant experiment on test and verification of labyrinth seal and vent design;
- Tribological evaluation of coatings and surface treatment
- Evaluation of thermal sprayed solid lubricant coatings
The two technical instruments are:
EuTEMP: Records the environmental temperature at all times. It has measured the temperature profile during the ascent to orbit on the STS-122 flight, during the transfer to Space Shuttle Discovery's cargo bay during STS-128 and for one day inside the cargo bay.
EVC: The Earth Viewing Camera is a technology demonstrator, testing the usability of commercial digital cameras for usage in space. It has been taking photos of Earth during the stay.