TELIS (TErahertz and submm LImb Sounder) is a cooperation between European institutes, DLR, RAL, and SRON, to build a three-channel balloon-borne heterodyne spectrometer for atmospheric research. Many atmospheric trace gases have their rotational transitions in the sub millimeter and THz range, yielding a very rich spectrum. Limb sounding results in very accurate vertical profiles.
All three TELIS receivers will operate simultaneously. The 500 GHz channel is developed by RAL and will produce vertical profiles of BrO, ClO, O3, and N2O. The 1.8 THz channel is developed by DLR and will mainly target the OH radical, and will also measure HO2, HCl, NO, NO2, O3, H2O, O2, and HOCl. Finally the 550 - 650 GHz channel is developed by SRON and IREE and will measure profiles of ClO, BrO, O3 and its isotopologues, HCl, HOCl, H2O and its isotopologues, HO2, CO, NO, N2O, HNO3, CH3Cl, and HCN.
TELIS will fly on the MIPAS-B2 gondola. The two instruments together will yield the most complete set of stratospheric constituents. The qualification flight is foreseen in the winter of 2006/2007.
The TELIS instrument serves as a test bed for many novel cryogenic heterodyne technology: novel low-noise cryogenic heterodyne mixer detectors, novel low-noise cryogenic intermediate-frequency amplifiers, novel back-end spectrometer. In the presentation these technologies will be discussed and compared with 'conventional' technology as applied in the Microwave Limb Sounder (MLS) on EOS-Aura, launched in 2004. Emphasis will be on the science and technology of the channel developed by SRON. It contains a Superconducting Integrated Receiver (SIR), which combines on a 4x4 mm2 chip the low-noise Superconductor-isolator-Superconductor (SIS) mixer and its quasi-optical antenna, a superconducting phase-locked Flux Flow Oscillator (FFO) acting as Local Oscillator (LO) and SIS Harmonic Mixer (HM) for FFO phase locking. Latest test results and retrieval simulations will be presented.