Outline of presentation to Akjuit Aerospace:

- basic idea: measure ozone column density from parachute-borne

				NITEOWL

Nightsky Imaging Tomography Experiment to Measure Ozone with Starlight

Faculty, staff, and students from five departments across three
faculties at the University of Saskatchewan, together with SCI-TEC
Instruments Inc. of Saskatoon, are preparing a response to the CSA AO
for the Small Payloads Program. We propose to measure the night-time
stratospheric ozone distribution in three dimensions at sub-Arctic
latitudes, by applying tomographic reconstruction techniques to
horizontal column ozone data acquired by multiple payloads descending
through the stratosphere. The column ozone data will be obtained by
measuring the absorption by ozone of visible starlight in the Chappuis
bands. 

We propose to fly identical experimental payloads on up to three Orion
sounding rockets, to be launched concurrently along a North-South
baseline running through SpacePort Canada at Churchill Rocket Range.
Each of the payloads will include a compact imaging spectrograph with
CCD detector for visible wavelength observations, a GPS receiver for
real-time inertial position information, onboard data selection and
compression circuitry, high-speed telemetry equipment capable of
sustained 10 Mbps transmission to the ground, and payload recovery
equipment in the form of a parachute for high-altitude deployment. After
reaching the 80 km apogee the payloads will be despun from 4 rps to less
than 0.1 rps (ideally 1 rpm) and deployed below parachutes.

During the descent phase from apogee to approximately 40 km altitude the
spectrographs, viewing horizontally through the side of the payloads,
will observe stars and measure their spectra in the absence of ozone
absorption and other attenuation processes (Rayleigh scattering, NO2
absorption, aerosol acattering). Subsequent observations of these stars
from within the ozone layer will allow the column ozone concentrations
along the lines of sight to the stars to be measured from the fractional
absorption of the starlight in the Chappuis band region (450 - 750 nm
wavelengths). Stars will be observed in many directions from a range of
altitudes as the slowly rotating payload descends through the
stratosphere. These observations, taken from up to three experiments
along three descent paths through the stratosphere, can be inverted to
yield the horizontal and vertical distributions of ozone over a large
geographic area enclosing the payload trajectories.

Stars will be observed over a 5-10° field of view, with a low-resolution
blazed transmission grating dispersing the collimated light from each
star into a bright first order spectrum adjacent to the zeroth order
star image. A fast lens will focus the light onto the large-format CCD.
Spectrograph images will be transmitted to ground, along with real-time
GPS-determined inertial positions, with onboard data selection and/or
compression as needed to allow the required data volume to be
transmitted ove a 10 Mbps telemetry link. The possibility of limited
onboard data storage for redundancy is being investigated. Data will be
telemetered from apogee to impact or loss of signal, in the hope of
measuring ozone in the troposphere as well as the stratosphere. The
requirement to recover the expensive payloads constrains the available
launch azimuths, and the relatively mild (6-8g) acceleration of the
Orion vehicle creates a vulnerability to wind weighting even as it
reduces the mechanical stresses on the payload components.

While a primary launch site at CRR is assumed, tomography considerations
favour additional launches at remote sites such as Gillam, Eskimo Point,
Rankin Inlet or Chesterfield Inlet. The cost, logistical, and regulatory
issues involved in launches from these sites will determine whether, and
where, additional launches are planned. Among the costs are those of
providing the needed sets of ground support equipment, including that
for TM reception and recording. Full tape backup of the TM is envisaged.
The additional costs of establishing temporary launch facilities at
remote sites may preclude one or both additional launches, although the
science impact of losing both remote launches would be significant.
Another consideration is the difficulty of securing the required
licenses for a remote launch, which may vary from site to site.

In order to submit a fully compliant proposal to CSA we will require
letters from all major subcontractors in the proposed activity,
detailing the services they would provide and the cost of those
services. This would include, in Akjuit's instance, the number of nights
of launch readiness you would provide within the stated cost, as well as
the cost per night thereafter. It is our hope that, after our meeting in
November, Akjuit Aerospace will be in a position to prepare and provide
such a letter, to be appended to our proposal. The proposal must be
complete in every respect by December 13th in order to receive all
required signatures before the University closes for Christmas.