UV Imager for Molniya Met Mission
MUVI – The FUV Imager on the Molniya Mission
-- Strawman -Eric Donovan‡ (PI), Trond Trondsen‡, Tuija Pulkkinen† and Anssi Malkki†
(‡) University of Calgary
(†) Finnish Meteorological Institute
Submitted to team members for Initial Consideration – June 23, 2005
Revised – July 21, 2006
Executive Summary: The Molniya mission Far Ultraviolet Imager (MUVI) would provide
global images with spatial resolution of better than 20 km over much of the northern hemisphere
auroral and polar cap regions for more than 60% of the time during the mission. This spatial
resolution is better than anything achieved to date, and in conjunction with established groundbased auroral imaging programs will provide the first systematic observations of the spatial and
temporal distribution of the aurora across all relevant spatial scales (global & tens of seconds
down to tens of meters and sub-second). The primary science drivers of this project are crossscale coupling, multi-scale processes, and natural complexity. As well, MUVI will achieve better
out-of-band wavelength rejection be a technology pathfinder for future twin-head imagers that
will separate the LBH-long and short auroral emissions. Finally, MUVI will provide the
traditional contextual information that is so widely used from other global imaging missions, and
complement other global observations, such as those from the international SuperDARN and
PolarDARN HF radar networks. Presently, MUVI is the only global imager proposed for flight in
the 2010 timeframe, and hence would fill an important gap in the ILWS mission lineup.
BRIEF HISTORY OF AURORAL IMAGING – SETTING THE STAGE ............................................ 2
MOLNIYA MISSION & FUV IMAGER – CONCEPT AND OVERVIEW .......................................... 5
GEOSPACE SCIENCE OBJECTIVES FOR MUVI ................................................................................ 9
TECHNICAL CONCEPT ..........................................................................................................................13
UVAI DESIGN CONCEPT ...........................................................................................................................13
SUGGESTED WORK SHARING – CANADA AND FINLAND ............................................................................18
ACKNOWLEDGEMENTS ........................................................................................................................18
UV Imager for Molniya Met Mission
Brief History of Auroral Imaging – Setting the Stage
Global auroral imaging began in the early 1970s with the Auroral Scanning Photometer
(ASP) on ISIS2 satellite (launched April 1, 1971). ASP used the satellite spin and its
orbital motion to provide the very first global auroral images (obtained in both 557.7 nm
and 130.4 nm once per orbit). The ISIS2 system was operated for almost 10 years and
yielded a number of discoveries, including the diffuse auroral oval [Lui et al., J. Geophys.
Res., volume 80, page 1795, 1975].
Since ISIS2, global auroral imaging has evolved significantly. Imagers on Kyokko, DE 1,
HILAT, and Polar Bear operated in the UV, allowing for the first time imaging of the
aurora on the dayside. Global imagers on Dynamics explorer and Viking allowed more
than one image per pass, with the Viking UV instrument providing an impressive cadence
of one image every 20 seconds. In fact, the Viking instrument utilized a combination of
UV filters, UV-reflective coatings, and a UV-sensitive image intensifier fiber-optically
coupled to a 256 by 256 pixel CCD to obtain short-exposure (1 second) simultaneous
global UV images in the LBH-short band and the LBH plus an extension into the part of
the spectrum including the 1304 Å OI line. Viking provided an exciting new picture of
the global time-evolving auroral distribution and new insights into the substorm dynamic
[see Henderson et al., Geophys. Res. Lett., volume 25, pages 3737-3740, 1998]. Images
from the two filters could be used to estimate energy deposition and the mean electron
energy, however resonant scattering and a requirement of knowing the O/N2 ratio
seriously limited the accuracy of these derived quantities.
The next significant leap forward in global imaging came with the ISTP Polar satellite,
which carried two imaging packages. The Visible Imaging System [VIS; see Frank et al.,
Space Sci. Rev., volume 71, pages 297-328, 1995] consists of two cameras for nightside
auroral imaging in the visible wavelengths. The two cameras deliver images with
different spatial resolutions (~10 and ~20 km at apogee), and have produced images that
have been widely used in studies of magnetospheric dynamics [see, eg., McWilliams et
al., Annales Geophysicae, volume 19, pages 707-721, 2001; Nakamura et al., Annales
Geophysicae, volume 17, pages 1602-1610, 1999]. In addition to VIS, Polar carries a UV
imaging package (UVI for Ultraviolet Auroral Imager), which provides images of the
entire auroral oval for roughly half of the 18 hour Polar orbit. Polar UVI has also been
widely used in studies of global magnetospheric dynamics [see, for example, Sergeev et
al., Geophys. Res. Lett., volume 26, pages 417-420, 1999]. The nominal UVI spatial
resolution is 50 km at apogee, with an integration time of ~30 seconds and sensitivity of
50 R. This sensitivity is still the best ever achieved with a global imager.
In 2000, NASA launched the IMAGE satellite. This was the first space science satellite
with an instrument complement entirely devoted to remote sensing via optical and radio
means. IMAGE carried with it a global imaging “FUV” package consisting of three
instruments. One of the FUV instruments onboard IMAGE is the Spectrographic Imager,
one channel of which (the SI-12 channel) provides global proton auroral images every
two minutes (the satellite spin period). IMAGE this provides the first global picture of the
proton aurora, and thus of the electron and proton aurora.
UV Imager for Molniya Met Mission
Figure 1: left) ISIS II image of the global aurora obtained in 1971 (once per orbit);
middle) Viking image from April 1, 1986 (once every 20 seconds); right) IMAGE FUV
WIC
By the time IMAGE was flown, there had been great advances, and great achievements,
in global auroral imaging. Still, after 35 years of global imaging from space, there is a
surprising list of technical challenges that have either not been met, or have been done to
a degree that could be improved upon. Surpassing previous accomplishments or striking
out in new ways would facilitate new science. Two examples of technological
improvements that would facilitate exciting new science include better spatial resolution,
better wavelength isolation.
Better spatial resolution in global images would facilitate scientific advancement in the
study of cross-scale coupling and multi-scale processes. The aurora shows significant
structure on scales ranging from global (ie thousands of kilometers) down to tens of
meters and even smaller. Some of this structure is a manifestation of the global structure
of the magnetosphere and its significant plasma regions such as the Central Plasma Sheet
(CPS), lobe, and cusp. As well, structure also arises as a consequence of electrodynamics
involved in auroral acceleration. It is clear that the scales are related, as are the processes,
but it is not clear how. Furthermore, temporal evolution of features of various scale sizes
arises as a consequence of magnetospheric dynamics and the auroral electrodynamics. An
imaging program to systematically explore the spatio-temporal structure and evolution of
the aurora would allow for exciting studies of multi-scale processes, cross-scale coupling,
and even the emerging field of natural complexity. As illustrated in the figure at right,
such a program would involve ground-based observations of the smallest scales (tens of
meters to tens of kilometers) and fastest processes (< 30 second time scales), and would
not be possible without global auroral images with better spatial resolution than
previously obtained (ie., < 20 km resolution).
Isolation of parts of the auroral spectrum is an absolute necessity for the ultimate
quantification of the flux and characteristic energy of auroral electrons, which are in turn
essential to our ability to truly understand magnetosphere-ionosphere coupling, and
magnetospheric dynamics. It would be timely to prototype an auroral imager with the
capability to isolate parts of the auroral spectrum corresponding to LBH emissions in the
UV, with the objective being out of bandpass rejection sufficient to support inference of
characteristic energy and energy flux.
UV Imager for Molniya Met Mission
Figure 2: Cross-scale coupling, multi-scale processes, and natural complexity are evident
in the aurora. Structure arises spontaneously in this system, and understanding how that
structure arises is of fundamental importance to future progress in space physics.
Observations to support theoretical studies of the distribution of scales and its origins
must involve global imaging from space and simultaneous meso- and small-scale
imaging from the ground. Ideally, networks of ground instruments would provide subsecond observations of tens of meters scales, and several second observations of
kilometer to tens of kilometer scales. The ground-based observations would mesh
together with global imaging with better than 20 kilometer resolution and 30 second
cadence or better. The effectiveness of this strategy is contingent that the assumption that
small-scale fast processes are not organized on global scales.
UV Imager for Molniya Met Mission
Molniya Mission & FUV Imager – Concept and Overview
The proposal is to fly (at least) one FUV auroral imager on the proposed NASA Molniya
mission as a mission of opportunity. The auroral project would be a joint Canada-Finland
effort, involving researchers at the University of Calgary, the Finnish Meteorological
Institute (FMI), and engineers and technicians at industries in Canada and Finland.
Funding for the Molniya FUV imager would be provided by the Canadian Space Agency
(http://www.space.gc.ca/asc/index.html) and Tekes (http://www.tekes.fi/eng/), with work
(and cost) sharing to be established in the near future.
The proposed FUV imager on the Molniya mission provides us with an exciting
opportunity to fly an imager on a stabilized platform (allowing long integration time
relative to imaging cadence), with excellent pointing accuracy, and with a better
bandwidth allocation than has (to our knowledge) ever been available for an auroral
imager to date. As a consequence, the Molniya FUV Imager (MUVI) would be an
excellent opportunity to achieve better spatial resolution than previously achieved.
Relatively long integration times (of 20 seconds) will allow good SNR while not
compromising cadence (the objective is 30 seconds). Good bandwidth allows us to use a
CCD with more pixels and still retrieve the data. Pointing stability and state-of the art
mechanical, thermal, and opto-electronic engineering will allow us to capitalize of the
good SNR and pointing accuracy to achieve a nadir spatial resolution of ~15 km at
apogee.
The Molniya orbit would have a ~12 hour period and inclination of 63.4 degrees (which
achieves the Molniya objective of no precession of the line of apsides so that apogee will
always be at the highest latitude of the orbit). In Figure 3, we show 20 locations along the
Molniya orbit (as projected in the GEI YZ plane). In Figure 4, we show the distribution
of the spatial resolution of our proposed imager for geomagnetic latitudes above 40
degrees invariant for each of the 20 times identified in Figure 3. The orbit provides
excellent global coverage of the northern hemisphere auroral zone, with better spatial
resolution than has been achieved to date, for more than 60% of the orbit period.
While not essential to our immediate science objectives of exploring multi-scale
phenomena in space plasmas, we intend to use this opportunity to demonstrate that new
technologies will facilitate better out of bandpass rejection than has been previously
achieved. As such, MUVI is a technology pathfinder for future missions on which twinhead cameras will be flown for simultaneous two-wavelength imaging capable of
quantifying auroral electron characteristic energy and energy flux.
To summarize, we are proposing that MUVI be capable of providing better than 20 km
spatial resolution over much of the auroral zone for images at a cadence of 1 every 30
seconds. Note that our spatial resolution will be achieved with a 1024X1024 effective
CCD, obtained by instrument-level binning from a 2048X2048 pixel CCD. There is a
very real chance that soon-to-be-available photocathode material will greatly increase
the optical throughput, allowing us to achieve our desired SNR with global images with
better than 10 km resolution. Our initial concept for MUVI is described below.
UV Imager for Molniya Met Mission
Figure 3: The proposed satellite will be in a traditional Molniya-type orbit, with a 0.5
Sidereal day orbital period, and inclination (in GEI and also geographic) of 63.4 degrees.
This plot is a projection of such an orbit into the GEI YZ plane. The numbers in boxes
indicate 20 locations along the orbit for which we calculated the distribution of spatial
resolution of the proposed FUV auroral imager. Those results are shown in the following
figure. The 20 locations divide the orbit into equal time segments.
UV Imager for Molniya Met Mission
Figure 4: The distribution of spatial resolution for the 20 equally spaced times indicated
on Figure 3. Black indicates locations that are visible to the imager, but for which the
resolution is comparable to or worse than that of global imagers that have been
previously flown. We have restricted our attention to locations poleward of 40 degrees
magnetic invariant.
UV Imager for Molniya Met Mission
Figure 5: The distribution of spatial resolution for one time, enlarged and with contours
of constant magnetic latitude over-plotted. This figure corresponds to apogee. Note that
the spatial resolution is better than 20 km for the auroral zone (even in disturbed
conditions) across more than 8 hours of MLT.
UV Imager for Molniya Met Mission
Geospace Science Objectives for MUVI
This is a brief description of the Molniya science objectives. In short, depending on if and
when Molniya flies, UVI imaging on Molniya would very likely be the only global
imaging at the time. MUVI would provide the typical and ever important global context
for essentially all other contemporaneous geospace observations. As witnessed by the
broad usage of imager data from Viking, Polar, and IMAGE, this in itself is a powerful
motivation for flying MUVI: in short, MUVI would facilitate system level science and
place other observations in important context. In addition, however, we would focus on
the following three science themes.
Cross-scale coupling, multi-scale phenomena, and natural complexity: MUVI would
have significantly better spatial and temporal resolution than ay previously flown global
imager. MUVI would fly at a time when there are extensive continent-scale networks of
ground-based imagers provided even higher time and space resolution over sub-global
regions. MUVI, in conjunction with these arrays, would provide a unique and new
perspective on the time evolving spatio-temporal structures in geospace, as projected and
manifested in the aurora. This would support new studies in cross-scale coupling, natural
complexity, and multi-scale phenomena.
Auroral electrodynamics (with SWARM and AMISR):
SWARM, AMISR,
NORSTAR and other projects offer up a new era of observations of auroral
electrodynamics. Global 10 second/15 kilometre observations at the same time would
provide the opportunity to use the SWARM, AMISR and other more in depth plasma and
field observations to address how local auroral processes fit into the global dynamic.
This is closely related to the first topic.
Substorms (With THEMIS and PolarDARN): MUVI would certainly fly during the
timeframe of THEMIS. While THEMIS will have unprecedented coverage of the auroral
region on the night side when THEMIS is also on the night side, global imaging with 10
second time resolution would add greatly to THEMIS. Here we point out just three
examples. First, when THEMIS apogee conjunctions are on the dayside, the Canadian
ground networks will also be on the dayside. THEMIS will at that time provide
unambiguous observations of the solar wind right upstream of both the bowshock and
magnetopause. Global imaging at the same time with 10 second/15 kilometer resolution,
in conjunction with these dayside observations, will lay the triggering question to rest
without question. Second, even when the THEMIS apogee conjunctions are on the
nightside, information about dayside, polar cap, and nightside open-closed boundary
dynamics during the substorm growth and expansive phases will be of crucial importance
to understanding the substorm cycle. MUVI and in particular PolarDARN will, taken
together, specify the high latitude convection and possibly even field-aligned current
pattern (for the latter see the section on field-aligned currents in Appendix B which is the
Donovan Advances in Space Research article on global imaging during ILWS). This in
turn will allow THEMIS observations to be interpreted with a firm understanding of the
larger convection process within which the substorm is evolving.
UV Imager for Molniya Met Mission
Figure 6: The distribution of spatial resolution for one time, enlarged and with FoVs of the
Canadian/US THEMIS ASIs (http://aurora.phys.ucalgary.ca/themis/themis_main.html) and
Finnish MIRACLE ASIs (http://www.ava.fmi.fi/MIRACLE/index.html) over-plotted. This figure
corresponds to apogee. Note that the spatial resolution is better than 20 km for the auroral zone
(even in disturbed conditions) across more than 8 hours of MLT. The ASI arrays provide
mesoscale observations with resolution down to ~1km. A “dense array” of ASIs (please see
http://aurora.phys.ucalgary.ca/norstar/norstar_main/doc/norstar_dense_array.pdf) is planned for
CGSM/NORSTAR. The dense array imagers will operate with FOVs overlapping the THEMIS
instruments, and provide spatial resolution down to several hundred meters, as well as
triangulation for height determination. Finally, the University of Calgary Portable Auroral Imager
(please see http://www.phys.ucalgary.ca/pai/) will provide 30 Hz observation with spatial
resolution down to tens of meters on a campaign basis.
UV Imager for Molniya Met Mission
Figure 7: The distribution of spatial resolution for one time, enlarged and with FoVs of the
northern hemisphere SuperDARN HF radars over-plotted. This figure corresponds to apogee.
Note that the spatial resolution is better than 20 km for the auroral zone (even in disturbed
conditions) across more than 8 hours of MLT. Global images such as those that MUVI would
provide, and synoptic convection maps from SuperDARN are arguably the only truly global
observations that we have in our arsenal. Taken together, these two data sets are a powerful tool.
For example, the radars can measure the electric field and the vorticity of the convection pattern,
while the optical imagers can be used to infer the conductivities and conductivity gradients MUVI
would provide global images overlapping the SuperDARN. This information allows one to (in
principal) infer the global distribution of FACs (G. Sofko – personal communication).
UV Imager for Molniya Met Mission
Figure 7: The distribution of spatial resolution for one time, enlarged and with FoVs of the
northern hemisphere incoherent scatter radars over-plotted. This figure corresponds to apogee.
Note that the spatial resolution is better than 20 km for the auroral zone (even in disturbed
conditions) across more than 8 hours of MLT. MUVI and ISR coordinated studies will explore
cusp dynamics, reconnection at the open-closed field line boundary, and other processes.
UV Imager for Molniya Met Mission
Technical Concept
MUVI would provide better than 20 km spatial resolution over much of the northern
hemisphere auroral zone with the ability to resolve features with 10 Rayleigh emission
rate, in a 20 second exposure. As our primary objectives are exploration of multi-scale
phenomena and demonstration of wavelength isolation, we will likely fly only one UV
imager on the Molniya mission. Below, we provide our initial concept for the imager.
Please note that we will be utilizing a 2048X2048 pixel CCD and binning down to
1024X1024. This is necessitated our sensitivity requirement (~10 R for SNR=1), and the
desire to keep the aperture and f/# both small (to facilitate a relatively compact
instrument). If this mission goes forward, there is a very real possibility that new
photocathode mater1als will greatly increase the QE, and hence allow us to go after
higher frame rates with the same spatial resolution, or better spatial resolution (ie., utilize
the full 2048X2048 CCD) with the same frame rate. Further, if mass, power, and
bandwidth allocations permit, it would not be unreasonable to fly a two-head imager and
attempt to achieve the wavelength separation in the LBH. In other words, if technical
budgets permit, we would argue to attempt to produce quantitative energy flux and
characteristic energy maps over and above our primary technical objective of achieving
the best spatial resolution to date.
UVAI Design Concept
The design of the UVAI imager(s) is motivated by a desire to record snapshots of auroral
dynamics with high temporal resolution under nighttime as well as fully sunlit conditions.
An intensified FUV CCD-based imager with fast optics will be developed. Such a design
allows each image pixel to be exposed simultaneously, giving true snapshot ability as
well as high temporal resolution. Considering the high spatial resolution requirement, this
will place certain demands on the satellite platform pointing stabilization performance.
The image-forming section of each camera is comprised of a fast, off-axis all-reflecting
telescope with three spherical mirrors. This type of reflecting telescope is very compact,
is fully corrected for spherical aberration, coma, and astigmatism. Moreover, it has
excellent resolution over most of its field of view and has a high throughput in the far
ultraviolet part of the spectrum. MUVI would have a field of view of 25 degrees by 25
degrees (subject to the impact that wide FOV would have on the baffles). This field of
view must be unobstructed by booms or other protrusions that would scatter sunlight into
the optical system and causing possible damage to the detector. Adequate baffling will
be implemented, and a reusable aperture door is planned.
FIGURE FROM ROUTES
Figure 9: MUVI optical design: Three mirror concept.
UV Imager for Molniya Met Mission
Special proprietary dielectric multilayer mirror coatings (Torr et al., 1995) will be used.
These have very low reflectivity in Visible and Near-UV region, and are manufactured
for high reflectivity in the LBH-short or LBH-long wavelength region, as required. The
three reflecting surfaces on which to deposit such coatings will help us achieve the
required 10E10 out-of-band rejection, for a imager sensitivity of 10 Rayleighs in a 10second exposure. In addition, there is a BaF2 window in front of the detector, which
provides the short wavelength cut-off. A CsI (solar blind) MCP photocathode provides
additional long wavelength cut-off at about 200 nm. A high level of cleanliness is
required during handling, installation and testing. UVAI optical components must not be
exposed to environments exceeding 100,000 particles per cubic foot, greater than 0.5
microns in size [TBC]. All parts must be protected from contamination during shipping
and handling. A sealed aperture door will provide some measure of protection of the
filters and coatings.
A micro-channel plate (MCP) image intensifier placed at the focal surface of the camera
is illuminated by the FUV image formed by the all-reflecting optics. Rather than an open
intensifier as was used in the VIKING UV Imager, a closed (i.e., sealed) design is
employed in order to avoid contamination of sensitive elements (e.g., photocathode) and
saturation due to ambient electron fluxes.
The sealing is accomplished by placing a BaF2 filter as a window in front of the
photocathode. For structural reasons, the windows must be relatively thick. 2.5 mm of
BaF2 will be used in order to provide the short wavelengths cut-offs. Once a photon
passes through the window, it impinges upon a photocathode material (CsI) designed to
be photoemissive over a particular wavelength region. The CsI photocathode is
deposited directly on the front surface of the MCP.
Once a photoelectron is confined to a MCP pore, it is accelerated by a potential of 5 kV
to produce a cascade of electrons out from the rear of the MCP. This acceleration is
necessary for the electrons to traverse an aluminium coating overlaid on a P43 phosphor.
The purpose of the coating it to shield the subsequent optical chain from light which
penetrates (without photoconversion) the MCP. P43 is baselined in spite of its low
efficiency (30% of P20) because of its particularly fast decay time (> 100 ns). This is
required because of the high spin rate of the spacecraft: since a pixel (a resolution
element on the ground) sweeps through the field of view at a fairly high rate, it is
required that the response of the phosphor due to one pixel must be sufficiently decayed
before the next pixel arrives. Once the electrons strike the phosphor, photons are
produced. These photons are then fibre-optically coupled to the CCD.
The baselined CCD is a 2048 x 2048 pixels chip, yielding a ~8 km resolution from
apogee, for a 25 degree field of view. However, our current plan is to bin down to
1024X1024 pixels. This is necessitated to achieve our required sensitivity. The CCD will
not require a mechanical shutter. The CCD needs to be operated at some stabilized
temperature below 0 degrees C in order to reduce thermal noise. This is accomplished by
using a radiator that faces directly towards Earth, supplemented by low-power active
cooling (or heating) from a TEC. This solution provides for best control of the CCD
UV Imager for Molniya Met Mission
temperature at a fairly low power and mass penalty. Another solution is to use a radiator
at the back of the spacecraft and having the spacecraft attitude control ensure that the
radiator never sees the sun. This is attractive in terms of required radiator area, but could
be heavy, depending on final spacecraft topology. These issues will have to be revisited
at the appropriate time. The power figures given in [Table 2] includes provision for some
low-power active cooling. Temperature sensors will be mounted at strategic places, and
temperature will be continuously monitored.
MUVI will be controlled by the Electronics box, the MUVIE. MUVIE will be DSP or
FPGA based, depending on the results of upcoming radiation dosage modeling. The
controller provides bias voltages, three phase clock signals to the CCD parallel and serial
registers, signal processing to extract and digitize (16 bits, via a dual-slope integrator) the
CCD output signal, and a fast serial interface (e.g., asynchronous RS-422) to the
spacecraft main data handling unit. There will be built in a capability to command the
imagers into a variety of operational modes (frame rates, binning, CCD gain, etc). In
future two-imager designs, the electronics box will control both imagers.
The design of the dual-slope integrator and clock drivers are optimized for fast settling
time. This is not strictly necessary for the Molniya mission, however it is consistent with
our secondary objective of technology pathfinding for future missions, including
missions on spinning platforms. Aside: [As the electronics unit (and the preamp) will
have more than sufficient speed, it is possible to continuously clock the CCD and thus
generate images greater in extent than the 2048 rows of the CCD. This allows us to
exceed the 25 degree field of view in the scan plane. Thus, a full 360 degree image could
in principle be generated, highly useful for in-orbit sensitivity and spatial calibrations
using stars. By utilizing 2 x 2 binning, signal to noise ratio can be increased during
operational modes where some spatial resolution can be sacrificed.]
In case of radiation-induced upsets, internal program memory and registers can be
reloaded from EDAC protected memory periodically, as signalled by a watchdog timer.
More drastic failures may require a re-initialization from on-board EPROM. The
instrument input power supply voltage will be +28VDC ± 6V. The instrument will
survive indefinite application of input voltages between 0 and +40V, with no damage.
Our concept is based on the following technical specifications, which include selfconsistent aperture, f/#, FoV, sensitivity, and spatial resolution.
UV Imager for Molniya Met Mission
Data Rate
Spatial
Resolution
Signal to Noise
Optical
Parameters
Optical
Efficiency
Exposure
Table 2: Initial Optical Design Parameters
Rows on square CCD
Total FoV [degrees]
Angular pixel FoV [degrees]
Exposure time [seconds]
Cadence [seconds]
Mirror reflectivity
Resulting reflectivity, 3 reflections
Intensifier window transmission
Photocathode QE [conventional technology]
MCP efficiency
Total of above [throughput]
Aperture [cm^2]
Diameter [mm]
Assumed MCP diameter [mm]
f/#
Pixel Omega [square pixels]
Radiance-kR conversion factor
Calculated Sensitivity [counts/kR/s]
Counts/R/pixel/exposure
Noise Equivalent Signal [R/exp]
Good SNR
Brightness for good SNR [R/exp]
1 RE [m]
Satellite Apogee [Re]
Derived Altitude [km]
Full Earth angle from above altitude [deg]
Auroral Oval subtends from alt [km]
Nadir resolution at apogee [km]
Bits per pixel
Total bits/image
telemetry rate-no compression [Mbits/s]
telemetry rate-no compression [Mbits/s]
1024
25
0.024
20.0
30.0
0.85
0.61
0.96
0.15
0.55
0.049
6
27.6
40
3.3
1.82E-07
7.96E+07
4.217
0.084
11.858
3.0
107
6.38E+06
7.1
38918.00
16.19
1031
16.6
12
1.26E+07
0.42
0.14
Several parameters can still be adjusted according to the overall needs of other payload
instruments, platform capabilities, and available detector technologies
1.
2.
3.
4.
5.
Range of possible orbits
Field of View range (note that 25 degrees is a practical maximum)
Detector (CCD) type and format
Type of high-speed interface to main Molniya data handling unit
Active or passive cooling of the CCD
UV Imager for Molniya Met Mission
Estimated (February 2005) payload resource requirements are listed in Table 2. These
are preliminary "guesstimates" that will need to be adjusted according to final design
options that will be selected. The spacecraft design must ensure that the combined
conducted and radiated emissions from all sources will not adversely affect the correct
scientific operation of MUVI or degrade the performance of elements of the spacecraft
bus subsystems.
Table 2: Initial MUVI Technical Budget
Mass UVAI (per imager)
Mass UVAI-E (Electronics box)
Dimensions MUVI
Dimensions MUVIE
Power MUVI
Power UVAMC-E
Data rate, per image
Data rate, total
Temperature Limits
2.5 kg
3.0 kg
25 x 24 x 15 cm
20 x 20 x 10 cm
4 Watts
3 Watts:
(see table 1)
function of cadence
Survival, non-operational: -40 C to +60 C
Operational: -25 C to +40 C (electronics)
-25 C to +20 C (cameras)
UV Imager for Molniya Met Mission
Suggested Work Sharing – Canada and Finland
The UV instrument package would be a University of Calgary and FMI collaborative
project. Development of the imager(s) would be carried out by UCalgary and the
Canadian prime industrial partner would likely be Routes Astro Engineering, with
potential contributions from other companies. Our goal would be to have this work be
viewed by the CSA as an international opportunity and have the CSA fund this Canadian
involvement. The FMI contribution would be the electronics box and data processing
units, plus development of necessary algorithms to operate the Calgary heritage
instrument from a non-spinning platform. FMI work would be funded by Tekes.
Acknowledgements
This letter of intent addresses an opportunity that arose as a direct consequence of work
on the CSA funded Ravens Concept Study. The technical information included in this
document was developed with funding from the Ravens Concept Study Contract, and was
adjusted by the PI (Eric Donovan) to meet the needs to the Molniya mission proposal and
engineering study. The work on the figures and technical information was supported by
the Ravens Concept Study Contract.