Millimetron project
1. Objectives.
2. Principal scientific and technical parameters of the
observatory.
3. Main systems of the instrument complex.
Figure 1. General view.
Figure 2. Block diagram.
1. Objectives
The project assumes creation of an international space observatory - the
interferometer "Earth - Space - Space" in order to perform of astronomical
investigations in millimeter, submillimeter and infrared regions with extremely
high sensitivity (to a few nanoJanskies units of flux density in continuum
spectrum) and extremely high angular resolution (to a parts of microsecond
of arc or, possibly, nanosecond). Owing to last years research, it was
established that in interval 0.4 - 10 mm there is an absolute minimum of
brightness temperature of spectrum of electromagnetic radiation of far
cosmos. In region 0.25 - 0.5 mm there is a deep minimum of the value vIv
,
where
Iv - spectral density of background intensity at frequency
v. This phenomenon opens a unique possibility to create
a
space telescope with a mirror of 12m diameter , which will be equivalent
in sensitivity to ground-based radio-telescope with solid aperture 3km
diameter at 2cm wavelength, and in interferometric mode (with ground-based
telescope or with similar space element ) will permit to reach an angular
resolution thousand times higher than resolution of ground-based interferometer
with ultimate base at the same wavelength.
Diapason of millimeter - submillimeter waves is poor explored, but
contains reach and important information for cosmology and extragalactic
astronomy, physics of Galaxy and galactic objects. It’s a unique possibility
to observe in this spectral region a number of stars in combination with
enormous angular resolution, to discover and investigate other planetary
systems. At these wavelengths it is very small effect of radiation scattering
due to interstellar plasma fluctuations, therefore it will be possible
to obtain images of ultracompact objects, to measure with ultrahigh resolution
their coordinates and moving. This diapason is extremely perspective both
for researching in continuum and in atomic and molecular lines, for polarimetric
measurements and for objects variability monitoring.
2. Principal scientific and technical parameters of the
observatory.
Creation of the observatory assumes space launch of two satellites of "Spectrum"
type with automatically deployable mirror telescopes having diameter 12
m. It’s desirable to rise accuracy of satellite orientation (rms = 1"),
to reach scientific payload power consumption to 2.5 kW, and to enhance
working time to 5-10 years.
There are the following possible modes of observatory functioning:
single-beam and multi-beam investigations in continuum spectrum, in spectral
lines, and for polarization measurements in millimeter, submillimeter and
infrared region;
interferometer "Earth - Space" in millimeter region;
interferometer "Space - Space" in millimeter and submillimeter region.
The work on creation of radio-observatory is based on the experience of
creation and investigations of the largest ground-based radio-telescopes,
and very-long-base interferometers, and on space interferometers projects
"Radioastron" and "VSOP", infrared, submillimeter, and radio space missions
IRAS, ISO, and COBE, and also missions,
being prepared for launch before year 2005 - SMIM,
SIRTF,
MAP, COBRAS/SAMBA and FIRST. "Millimetron" project sufficiently exceeds
mentioned missions in all main parameters. In accordance with preliminary
considerations, it is possible to realize main requirements to space designs:
-
the main mirror of telescope with 12 m diameter is similar in design with
mirror of projects "Radioastron" and is maintained at temperature of 3
K by a system of radiation cooling and by cryogenic machine, accuracy of
surface rms = 10 mkm;
-
the optical system of Cassegrain type with flat periscopic tertiary mirror
for guidance control;
-
the telescope works in bolometric single or multi-beam mode in region 3-3000
mkm, diffraction limit is realized for wavelength more than 250 mkm;
-
diapason 0.3-20 mm used for interferometry "Earth - Space" with participation
of the largest ground-based radio-telescopes;
-
diapason 0.2-3 mm used for interferometry "Space - Space" between two satellites;
-
front-end devices of receivers and bolometers use deep cooling (down to
0.1 K);
-
an accuracy of orientation and stabilization rms=0.3" is achieved by adjustment
of tertiary mirror;
-
bandwidth of transmitting information for interferometric mode up to 1
(10) GHz with ability of real-time data-reduction;
-
the orbit of a space-craft No 1 : period - about 9 days, perigee
- 75 000 km, apogee - 300 000 km; the orbit is subjected to of systematic
disturbances by Moon, and consequently ensures the obtaining of high quality
images for any sky objects;
-
space-craft No 2 must be launched 2 - 3 years later than No
1 into a similar or higher orbit depending on results of investigations
made during this time.
3. Main systems of instrument complex
Main systems of the instrument complex are:
-
the bolometric multi-beam system (~ 100 beams) for sky mapping in region
0.2 - 3 mm in continuum spectrum;
-
the spectropolarimetric system for investigations of objects in region
0.2 - 3 mm with resolution v/Dv
~ 3 ;
-
the spectropolarimetric system of high resolution
up to v/Dv =3·106 in
region 0.2 - 3 mm;
-
radio-interferometric channels of the system "Earth - Space", region 0.3-
20 mm;
-
radio-interferometric channels of the system "Space - Space", region 0.2
- 3 mm;
-
the spectropolarimetric system of high resolution up to v/Dv
=3·106 in region 3 - 300 mkm;
-
the on-board system of high accuracy base frequencies and time.
Technical parameters of the observatory permit to realize a scientific
program of unique investigations of all main types of astronomical objects:
discovery and research of great number of young stars, planet systems,
and even single planets, their origin and evolution, search of evidence
of life in the Universe;
investigation of most dense regions of the Galaxy (compact gas-dust complexes,
globules), investigation of complex organic instances in interstellar medium;
investigation of relativistic stages of stellar evolution including supernova
explosions, white dwarfs, neutron stars, and black holes of stellar mass;
investigation of the structure and evolution of a region around the supermassive
black hole in the Center of our Galaxy, similar and more power objects
in other galaxies, processes of acceleration and interaction of superenergetic
particles, generated by cosmic accelerators in these regions;
detection of galaxies on stages of their originating, research of their
following evolution, including investigation of evolution of stellar, gas-dust
components of missing mass;
investigation of early evolution stages of the Universe from recombination
moment to beginning of stars and galaxies formation.;
determination of fundamental cosmological constants and investigation of
nature of missing mass, study of fundamental properties of space, time
and vacuum;
high-precision astrometry for determination of distances and proper motions
of stars and extragalactic objects;
search for new types of astronomical objects.
The sensitivity permits to investigate on the observatory any of more than
10 billions sky sources.
Figure 1. General view.
Figure 2. Block diagram.
If you have comments or corrections for this document, please send
them via E-mail to gro@asc.rssi.ru
Best experienced with 
Proposal on creation of space observatory "Millimetron"
within the framework of Federal Space Program of Russia during the period
until 2015.
Astrospace Center LPI RAS,
Moscow 1996