Transmittance, Reflectance and Emission Spectroscopy of Meteorites from the IV to the IR Spectral Range

In the last decade the Planetary Emissivity Laboratory (PEL) of DLR in Berlin has provided spec-tral measurements of planetary analogues from the visible to the far-infrared range for comparison with remote sens-ing spacecraft/telescopic measurements of planetary surfaces [1-5]. Bi-directional reflection, transmission and emis-sion spectroscopy are the techniques we used to acquire spectral data of target materials. In fall 2015 we started upgrading our laboratory set-up, adding a new spectrometer, three external sources, and new detectors and beamsplitters to further extend the spectral range of measurements that can be performed in the laboratory. Reflecting the wider scope of measurement capabilities the facility was renamed to Planetary Spectros-copy Laboratory (PSL). Two FTIR instruments are operating at PSL, in an air-conditioned room. The spectrometers are two Bruker Ver-tex 80V that can be evacuated to ~.1 mbar. One spectrometer is equipped with aluminum mirrors optimized for the UV, visible and near-IR, the second features gold-coated mirrors for the near to far IR spectral range. Apart from the mirrors the two instruments are identical, and can therefore share the collection of detectors and beamsplitters we have in our equipment to cover a very wide spectral range. The instruments and the accessory units used are fully automatized and the data calibration and reduction are made with software developed at DLR[4]. By using several pairings of detector+beamsplitter we can perform spectral measurements in the whole spectral range from 0.2 to 200 μm

Measuring the Spectral Properties of Candidate Mineral Sources of the Venus Radar Anomalies

Radar mapping of the surface of Venus shows areas of high reflectivity (low emissivity) in the Venusian highlands at altitudes between 2.5-4.75 kilometers. The origin of the radar anomalies found in the highlands remains unclear. Previous experimental research investigated possible materials under simulated Venusian atmospheric and surface conditions, with special emphasis on the combined effect of pressure and temperature, and chemical composition. The results of these studies identified candidate source materials for the radar anomalies. In order to fully be considered a true source candidate the material must have spectroscopic measurements comparable to those measured on the surface of Venus where the high temperature affects spectral characteristics of minerals. The spectroscopic measurements of the previously identified candidate minerals were made at the Planetary Spectroscopy Laboratory (PSL) of DLR in Berlin in an effort to identify the anomaly source. The spectroscopic measurements were made with a FTIR Bruker Vertex 80V evacuated to ~.1 mbar and using several pairings of detector+beamsplitter to cover the spectral range from 0.2 to 20 µm. Each sample was poured in a stainless steel reflectance cup and measured fresh. Successively each cup was heated (via an induction system) in vacuum (0.07 mbar) at 400°C for 8 hours and measured again in the UV+VIS+MIR spectral range. Three consecutive cycles of heating and measuring reflectance were performed to account for spectral variations arising from the thermal processing of the samples. Heating the samples directly inside the reflectance cups allows to measure every time exactly the same surface, exposed to increasing levels of thermal processing. Results from this study are expected to further constrain the source of the Venus radar anomalies