SUBMILLIMETRON project

Submillimeter Wave Cryogenic Telescope
for the Russian Segment of the International Space Station

Introduction
The objectives of the Submillmetron Project
Experiment configuration
Main parameters
Cryogenic Telescope parameters
Block diagram of the Cryogenic Telescope

Free flying variant
of the Submillimeter Wave Cryogenic Telescope

Submillimeter Wave Cryogenic Telescope
disposal on the Research Module.

Submillimeter Wave Cryogenic Telescope
for the Russian Segment of the International Space Station

The Submillimetron is the project of the space telescope for astronomical studies at the submillimeter and infrared wavelengths using facilities of the Russian segment of the International Space Station (ISS). The concept of Submillimetron telescope includes a 60 cm mirror telescope cooled to liquid helium temperature combined with a new type of supersensitive microbolometers arrays. This combination gives unique possibility to realize background limited sensitivity in the spectral minimum of the extraterrestrial background electromagnetic radiation around frequency 1 THz. This region is between peaks of galactic dust emission and extragalactic cosmic microwave background (CMB) measured by COBE satellite. The angular resolution about 1 arcmin and field of about 1o are similar to IRAS satellite survey, but more then order of magnitude better sensitivity about 10-18 W Hz-1/2 and another spectral region permits reveal in full sky survey sufficiently more new astrophysical objects. For following space missions FIRST, PLANK, IRIS these results will give useful complementary information of measurements with different angular resolution in another spectral regions. Next feature of the project is the concept of free flying instrument with periodic docking to ISS. Unlike to the usual concept of an autonomous mission this one gives possibility to combine low cost with reliability, refilling, repairment and maintenance. The initiative of the Project was done in Astro Space Center of the P.N. Lebedev Institute after discussions with NASA and JPL, supported later by the Russian Academy of Sciences. The proposal was undertaken to feasibility study in S.P. Korolev Rocket Space Corporation Energia and approved by the Russian Space Agency for the 2-d stage of ISS realization after years 2004 - 2005.
 

The objectives of the Submillmetron Project.

The objects of an astronomical study in submillimeter and infrared wavelengths are the "cold" components of the matter in the Universe (3oK radiation relic of Big Bang, extragalactic sources on the stage of star birth burst, dust in the Solar System, in the Galaxy). The primary goal is to conduct a submillimeter wave full sky survey, and to perform studies of the spectra of astronomical sources and their variability, to conduct cosmological studies (study of the anisotropy of the cosmic microwave background radiation and search for Lyman-alpha line at the epoch of recombination and secondary heating). The secondary goal is to provide a test bed to perform the technological experiments needed to develop follow-on projects.
 

Experiment configuration

The main configuration of the Submillimetron in the process of observation is free flying spacecraft (FFS) carrying telescope payload with deployed screens and fully active cryogenic systems. The FFS has docking equipment for work in conjunction to ISS on stages of delivery, deployment , and if necessary for refilling, repairment and maintenance. The FFS made on the base of Progress cargo-ship has also possibility to arrange auxiliary observing instruments, for example heterodyne instrument for high resolution spectrometry and interferometry with noncooling mirror up to 1.5 m. The orbit of the FFS can be distant enough from ISS to solve problems of contaminations and excessive infrared radiation and shadowing. Submillimtron telescope payload consists of Cryogenic Telescope with optics and cryogenics systems and Data Registration and Processing Unit with electronics and power supply systems.

Orbit: circular orbit at an altitude of approximately 444 km with a 51.6o inclination.
Delivery to initial ISS orbit: modified cargo-ship Progress

Payload: the Submillimeter Cryogenic Telescope

Data output: 1 Gbyte/day

The Cryogenic Telescope parameters are:

Diameter: D=0.6 m
Optical system: two-mirror Cassegrain
Cooling:

Wavelengths: Spectral bandwidth: 20 - 30% of the central wavelength.
Detector arrays: Sensitivity of the detectors: Angular resolution: Sensitivity of the telescope (integration time = 1 s)




Block diagram of the Cryogenic Telescope
ACS - Active Cooling System, 
            T=20K;
STR - Star Tracker, defines 
           pointing of the telescope;
HeII – superfluid helium vessel*)
           T=2K, cooling of primary 
            and secondary mirrors;
TPS - Telescope Pointing System;
FDB - Focal Dichroic 
            Beam-splitters assembly;
IDA- Infrared Detector Array;
SBA - Submillimeter Bolometer 
           Array;
CAU - Cool Amplifiers Unit;
mKC - milli-Kelvin Cooler 
            (T=100 mK);
TEA – Telescope Electronics 
           Assembly,
DRPU - Data Registration and 
             Processing Unit.


The participants of the Submillimetron project are: Interested collaborators are encouraged to contact Submillimetron team.

Last updated: 11 July 2000.
E-mail: f4agro@fy.chalmers.se