Workshop on Project Submillimetron

Participants

Program

• Project Submillimetron. Development of a Submillimeter Cryogenic   Telescope (SCT) for the International Space Station.  Vladimir Gromov, Vladimir Kurt, Claude Meny;
• Development of Hot-Electron Microbolometers for SCT.

Leonid Kuzmin, Michael Tarasov;
• Scientific Space Platform. Possible heterodyne and/or IR instruments in addition to SCT.

Grigori Goltsman, Alexey Semenov, Valery Koshelets;
• Complementarity of the Submillimetron to other projects. Possible collaboration with other projects in technologies
•   and science. Vladimir Gromov, Claude Meny.
• Possibilities of submillimeter balloon experiments with support of the Russian Aerostat commission. Vladimir Kurt
• Cryogenics of the SCT. IRAS-like design or active cooling? Lionel Duband.

Conclusions

1. The Submillimetron project is accepted for implementation by S.P. Korolev Rocket Space Corporaton Energia (RSCE message).
2. In response to the Call for Ideas the proposals was applied and are under consideration by Swedish National Space Board (SNSB): Imaging  Arrays of Superconducting Detectors,

Submillimeter Space Telescope for Photometric Sky Survey "Submillimetron" .
3. A cryogenic concept of the telescope was updated. It based on storage of amount liquid helium enough for telescope cooling without active cooling of intermedium screens at level about 20 K. A design of updated cryostat arrangement inside of the free flying spacecraft was made. A concept was presented for discussion on workshop.
4. The importance of the scientific objectives of the Submillimetron is sufficiently raised after recent discovery of observational evidence of the reionization in early Universe. Photometric measurements of large (z>1) redshifts of galaxies in sky survey should give enough statistics for determination of star formation process in early Universe.
5. Development of Hot-Electron Microbolometers for SCT: A CC-NHEB sensitivity has been measured (Tarasov). NEP=7.5 10^-18 W/Hz^1/2  at temperature 0.256K  with amplifier noise 3 nV/Hz^1/2. A measured noise of detector is 0.5 nV/Hz^1/2, so detector's NEP=1.2*10^-18 W/Hz^1/2 for amplifier voltage noise < 0.35 nV/Hz^1/2 or current noise < 300 fA/Hz^1/2(for R_source~ 1 kOhm).
6. Development of readout system: A SQUID sensitivity 40 fA/Hz^1/2 has been measured (Kalabukhov).
7. Available  noise level for semiconductor noncooled amplifier is ~ 0.33 nV/Hz^1/2, for f >0.1 Hz (a corner frequency for the 1/f noise). (Zakosarenko).
8. Submillimeter sky-survey projects Submillimetron, ELISA and Planck have high degree of complementarity. Targets for experiments are: Submillimetron - extragalactic point sources, ELISA - galactic plane, Planck - cosmic background inhomogenities. Complemantarity of experiments in mutual calibration and separation of foreground sources. Only joint measurement cover a full range of sky sources brightness.
9. The proposals on development of bolometers array  to SNSB should be applied in May 2002 in responce to the Call for Projects in Remote Sensing, Atmospheric Research, Space Physics, Astronomy, Research under Microgravity, and other areas of space research.
10. Scientific Space Platform (SSP): The flexible structure of the SSP and large vacant volume allow to perform many different scientific experiments. The SSP should be extremely efficient for simultaneous sky-survey in for infrared photometry, medium and high-resolution spectral line survey, for Earth remote sensing and low temperature physics experiments. The SSP can be a testbed for components of future space missions like cooling systems, heterodyne instruments, a readout systems for imaging array of sensors, on-chip electron cooling and other systems.
11. Type of instruments discussed was: an astronomical spectrometer on base of hot-electron bolometer mixer (HEB), atmospheric/astronomical spectrometer on base of superconducting integrated receiver (SIR), and infrared photometer. Concrete detailed data should be supplied during June-July 2002 for feasibility study of these instruments in frame of SSP for following instruments:

a) A promising receiver for 400-600 GHz region is a SIR system designed, fabricated and experimentally studied by joint team from IREE /Russia and SRON/Netherlands (Koshelets);
b) HEB heterodyne mixer receiver for 1-3 THz region (Goltsman);
c) High-sensitive photometer for IR region using photon counter (Semenov).
12. Foreground fields for collaboration in technologies are: test of Submillimetron bolometers in ELISA or/and post-ELISA experiments, test of Hershel bolometers in ELISA and Submillimetron experiment, SQUID electronics.
13. Very fruitful should be scientific collaboration of Submillimetron and CESR-ELISA-Planck teams for bolometer developments, astronomical tasks and data analysis, ISM low-temperature nanoparticle theory.
14. Passive cryogenics of Submillimetron (IRAS/ISO-like design) should be more reliable in manufacturing and in use than active cooling.
15. Submillimeter balloon experiments with support of the Russian Aerostat commission (Kurt) are possible for flight over Russia (500 kg, 25-35 km), and over Antarctics  (50 kg, 10-15 km).