NiteOwl

Part Two

Table of Contents

Table of Contents	1

1. NiteOwl and the Small Payloads Program Objectives	3

2. Top-level Science Requirements	4

3. Instrument	4

3.1 Imaging Spectrograph	4

3.1.1 Window, Entrance Baffles, and Optical Filter(s)	4

3.1.2 Transmission Grating	5

3.1.3 Objective Lens	5

3.1.4 CCD Detector	6

3.1.5 CCD Readout System	7

3.1.6 Estimate of Achievable Signal-to-Noise Ratio	7

3.2 Avionics	8

3.2.1 Video Camera for Attitude Determination	8

3.2.2 Global Positioning System Receiver	8

3.2.3 Compression Electronics	8

3.2.4 Telemetry system	8

3.2.5 Instrument Power Supply	8

4. Other Required Systems	9

4.1 Temperature Sensor	9

4.2 Chemiluminescent Ozonesonde	9

4.3 High-Altitude Deployment Parachute	9

5. Required Facilities	10

5.1 Available Facilities	10

5.1.1 ISAS Optics Laboratory	10

5.1.2 Physics and Engineering Physics Machine Shop	10

5.1.3 Chemistry Thermal Vacuum Facilities	10

5.1.4 Mechanical Engineering Vibration Facility	11

5.1.5 SCI-TEC Facilities	11

5.2 Other Required Facilities	11

5.2.1 Bristol Aerospace Limited Payload Test Facilities	11

5.2.2 Optical Flat-Field Calibration Facilities	11

6. Instrument and Payload Testing	11

6.1 Imaging Spectrograph Characterization and Calibration	11

6.2 Attitude Video Camera Testing and Characterization	12

6.3 Determination of Relative Orientation of Imaging Spectrograph and Attitude Video Camera	12

7. Launch and Operational Considerations	12

7.1 Launch Vehicle	12

7.2 Launch Window	13

7.3 Launch Support	14

8. Work Breakdown Structure and Schedule, including Management Plan	14

8.1 Work Breakdown Structure and Schedule for the NiteOwl Project	14

8.2 Work Breakdown Structure and Schedule for NiteOwl Phase A	15

8.3 Management Plan	17

8.3.1 Human Resources Deployment Plan	17

8.3.2 Project Monitoring and Control	17

9. Project Budget	18

9.1 Phase A	18

9.2 Phases B - E	18

10. Risk Analysis	21

10.1 Categories for Risk Analysis	21

10.1.1 Science	21

10.1.2 Pre-Launch	21

10.1.3 Launch	21

10.1.4 Payload Dynamics	21

10.1.5 Optical System	21

10.1.6 Electronic Systems	21

10.1.7 On-Board Data	22

10.1.8 Ground-Based Data	22

10.1.9 Post-Flight	22

10.2 Risk Model	22

11. Potential Benefits	23

References	25

NiteOwl

Part Two

1. NiteOwl and the Small Payloads Program Objectives

The NiteOwl project meets the Small Payloads Program objectives in several innovative ways.

The parachute-borne spectrographic images of ozone absorption taken while descending through the lower stratosphere and upper troposphere simulate the observations that could be acquired from a satellite in low Earth orbit (LEO). While a rocket borne experiment cannot provide global coverage, it is an important validation step toward a future micro-satellite experiment. These innovative and cost-effective measurements will provide specific data regarding ozone in the upper troposphere and lower stratosphere ( UTLS ) during the Arctic winter, with the spatial resolution required by current predictive ozone models

The NiteOwl project will provide ample opportunities for graduate students and, in some instances, undergraduate students to be involved in all stages of the project due to the type and scope of the instrument involved. The participation of eight graduate students in preparing the NiteOwl proposal is a clear indication that this work can be done, and done well, with young researchers. Graduate student participation will continue during the hardware specification, design and integration phases of the project. Subsequent data analysis and calculation of the ozone vertical and horizontal distributions require expertise from researchers in various disciplines such as software engineering, computer tomography, theory of inverse problems, atmospheric chemistry, geophysics of the upper and lower atmosphere, and image analysis. The project will demonstrate the synergy of a multidisciplinary team of university scientists working closely with an industrial partner.

The NiteOwl project is very important for the industrial partner, SCI-TEC Instruments Inc.. Currently, SCI-TEC manufactures world class optical instruments for ground-based monitoring of the ozone layer. SCI-TEC's participation will give the company an opportunity to extend their product line to include optical instrumentation for micro-satellite/satellite measurements of ozone concentration. More importantly, data obtained from orbit by the stellar occultation technique can be used to generate near-real-time ozone maps with regional, national, or global coverage. This is a first step for SCI-TEC toward the development of a high value-added data product and will strengthen their ability to compete internationally. Rocket experiments are also important for Bristol Aerospace Ltd. ( BAL ) and Akjuit Aerospace Inc. ( AAI ). Their participation in this project allows them to enhance their industrial capabilities in the manufacture and launch of rocket payloads.

The NiteOwl project will address key scientific requirements for an improved understanding of ozone trends and will also take a key step toward meeting future information needs of Canadians. All participants in the project recognize that improved ozone measurements are timely, and are an appropriate response to increasing public concern over ozone depletion. This phenomenon is of vital importance to Canada because of its vast Arctic and sub-Arctic regions. Global ozone monitoring by stellar occultation will make an important contribution to international efforts to understand the nature of ozone variations in the upper troposphere and lower stratosphere.

2. Top-level Science Requirements

The NiteOwl project will use the absorption of visible-wavelength starlight by ozone to obtain images from which column ozone densities between the imaging spectrophotometer and the stars observed can be determined to within 5%. The ozone distribution within a radius of 600 km will then be determined with 12% RMS uncertainty, with a vertical resolution of 3 km, a radial resolution of 200 km, and an azimuthal resolution of 10 , over a 45 azimuth sector.

3. Instrument

3.1 Imaging Spectrograph

The imaging spectrograph ( ISG ), illustrated schematically in Figure 2-1, consists of two main optical elements: a transmission diffraction grating (§3.1.2) and an objective lens (§3.1.3). The collimated light from each star in the instrument field of view is dispersed by the diffraction grating into a spectrum, which is focussed onto a CCD detector by the objective lens. The objective lens defines the entrance pupil and hence the light grasp of the ISG , and is thus the element on which the requirement for 100:1 SNR (Part I, §2.3) places the most stringent demands (cf. §3.1.3). The other components of the ISG are the entrance window and baffles preceding the diffraction grating, which define the instrument field of view and minimize stray light incident on the grating, the optical filter which defines the wavelength passband, and the CCD detector which records the irradiance produced by each star. These two sections of the instrument are described in §3.1.1 and §3.1.4.

3.1.1 Window, Entrance Baffles, and Optical Filter(s)

The ISG will be enclosed in a box with a window defining the field of view, and surrounded by the payload aft bay skin section which is attached to the motor. The window will be uncovered when the payload separates from the motor near apogee. The size of the window will be determined by the distance from the window plane to the center of the transmission grating. This distance should be as large as possible, in order to reduce the vignetted portion of the sky from which stellar energy reaches the grating. Between the window and the diffraction grating a series of knife edge baffles will reject light from outside the field of view and minimize the amount of light reflected onto the grating from within the instrument. Finally, a stop between the objective lens and the CCD detector will eliminate internal reflection and scattering that would otherwise contaminate the image at the CCD.

Blocking filters will be used to define the limits of the wavelength passband of the NiteOwl ISG . These will reject wavelengths shorter than 400 nm and longer than 780 nm , in order to avoid spectral overlap on the CCD between adjacent orders of diffraction.

Because the launch site at SpacePort Canada (Churchill, MB) lies at the center of the statistical auroral zone, the ISG may view auroral emissions at times during the mission, even when viewing the prime target stars to the south. Certain airglow emissions from the upper atmosphere will also be seen. The emission wavelengths of primary concern are the [OI] emissions at 557.7 nm and 630.0 nm , as these lie near the center of the ozone Chappuis absorption and are prominent in the spectra of both the nightglow and the aurora. The wavelength passband options described in Table 2-1 have been considered. Option 1 is favoured but a final decision will be taken on the basis of detailed instrument modelling to be carried out in Phase A.

Table 2-1. Wavelength Passband Options for Imaging Spectrograph

Option	1	2	3
Filter Type	Bandpass: 400 - 780 nm	Notch: reject 557.7 nm and 630.0 nm	Bandpass: 560 - 620 nm
Number of Components	One bandpass or (one highpass + one lowpass)	Same as Case 1, with two notch filters	Same as Case 1
Advantages	Measure whole visible spectrum, no data lost	Reject only airglow and auroral spectrum; rejection bands mark wavelengths	Minimal background auroral contribution - "dark sky"
Disadvantages	Strong aurora may compromise data	Wide rejection bands and out-of-band "ripple"	Limited wavelength band (60 nm )

3.1.2 Transmission Grating

A transmission grating with a nominal ruled area of 100 × 100 mm and a ruling frequency of 75 lines/mm will be used to disperse the incident starlight. This results in a spectral resolution of 3.4 nm /pixel in first order, and spectral features wider than 8 nm will be resolved over the entire wavelength range of interest. The grating will be blazed at 530 nm in first order, giving as much as 78% transmission at that wavelength in the first order spectrum. Since the incoming light is perfectly collimated, the spectrum from each star will be dispersed over the entire aperture of the lens. Vertical dispersion will be obtained by aligning the grating rulings horizontally, to prevent payload spin (about the longitudinal axis) from degrading the spectral resolution. Space-qualified gratings meeting these specifications are available from Richardson Grating Laboratory.

3.1.3 Objective Lens

A 15 × 11.6 field of view on the sky has been selected for the ISG ; this permits the use of an entrance aperture large enough to image 3rd magnitude stars with 100:1 SNR, and is wide enough to keep a given star within the field of view during the entire 1-s exposure time, even while spinning at the nominal rate of 6 /s or 1 r.p.m. In the vertical dimension (i.e., that of wavelength dispersion), a field stop will limit the acceptance angle of the ISG to 11.56 , allowing the remaining 3.44 to be occupied by the first-order spectrum of a star seen at the edge of the field of view. In order to use the entire area of the square CCD detector (24.58 × 24.58 mm), the first order image of the longest wavelength (nominally 800 nm ), incident from the vertical limit of the field of view, will be focussed onto the last row of the CCD. Thus the objective lens will receive light rays over a 15 full field both horizontally and vertically.

The 15 field of view and the 24.58-mm size of the CCD determine the properties of the lens. The requirement that the zeroth -order image of a star at the vertical limit of the field of view be imaged at the edge of the CCD fixes the focal length at

Signal-to-noise ratio calculations (cf §3.1.6) indicate an entrance aperture of about 50 mm is required, so an f/# of 2.0 is indicated. Photographic lenses satisfying these requirements are readily available commercially, although photographic lenses are usually corrected for chromatic aberration only to about 700 nm . Procurement of a suitably-corrected lens may be costly. Various options have been considered, including modifying a video projection lens, and obtaining a custom-manufactured lens from Applied Physics Specialties. The most cost-effective approach will be taken.

3.1.4 CCD Detector

Light collected by the optics will be focussed onto a charge-coupled device (CCD) detector with the nominal specifications shown in Table 2-2. Data sheets and prices for suitable large-area CCD detectors have been obtained from Scientific Imaging Technologies, Inc. ( SITe ) and English Electric Valve ( EEV ) Canada. The specifications in Table 2-2 are those of the SITe SI -003A device.

In the event that a non- MPP CCD is selected for use, it will be important to cool the CCD to minimize dark current. This can be done by means of a cold finger thermally coupling the CCD to a radiator plate in the payload skin, which will conduct heat away from the CCD and reject it to the cold ambient environment.

Table 2-2. Nominal specifications for the CCD imager .

Characteristic	Specification
Visible Pixel Array	1024 × 1024
Pixel Size	24 m × 24 m
Fill Factor	100%
Potential Well Depth	300,000 electrons
Quantum Efficiency	55% - 85%
Wavelength Sensitivity	400 nm - 900 nm
Imaging Size	24.58 mm × 24.58 mm
Resolution	14 bits/pixel
Exposure Time	1s (nominal)
Readout Rate	1 frame/s
Data Rate	16,777,216 bit/s

3.1.5 CCD Readout System

A custom CCD readout system will be required to meet the specifications on frame transfer speed, digitization precision, readout noise, power consumption, and overall payload mass and volume. Routes Inc. ( Kanata , ON) can modify the design for the OSIRIS readout system to meet the specifications for NiteOwl . As well, Prof. Gordon Walker and his colleagues in the Department of Geophysics and Astronomy, University of British Columbia, have expertise in the development of compact, low-power readout systems that can be adapted to space applications.

3.1.6 Estimate of Achievable Signal-to-Noise Ratio

The preliminary tomography simulations (§§2.1, 2.3.2) assumed a signal-to-noise ratio (SNR) of 100:1 for the count rate at a given wavelength. The preliminary optical design described above achieves this SNR for stars brighter than magnitude 3.0. The number of electrons deposited per CCD pixel at 600 nm (near the center of the Chappuis bands) is expressed by the following equation:

where	np	= number of accumulated photoelectrons corresponding to = 600 nm ;

= stellar radiance at 600 nm (nominally 567 photons cm-2 s-1 nm -1 for mv = 3.0) [Allen
1958];

A	= entrance aperture area (19.6 cm 2 for a 50-mm entrance pupil);

g	= 1st-order grating transmission efficiency at 600 n m (0.74);

= optics transmission coefficient at 600 n m (0.8, including passband filter);

d	= wavelength interval per pixel (3.5 n m);

e	= CCD quantum efficiency at 600 n m (assume 0.8);

d t	= exposure time (1 sec).

The SNR may then be written as

where	nd	= number of accumulated thermal recombination electrons (assume 280 e-);

nr	= RMS read noise (18 e-).

Both np and nd follow Poisson statistics, while nr is approximately gaussian with mean 0 and variance nr2 .

For simplicity, this calculation neglects two offsetting effects: blurring caused by payload spin, which reduces the SNR, and the increase in SNR which will result from deriving species column concentrations by fitting the measured spectrum with species absorption and scattering cross-sections over the full spectral range from 400 to 780 nm . To a first approximation, these effects will tend to cancel each other and allow the species column concentrations to be determined from the actual NiteOwl observations with a SNR of approximately 100:1 for 3rd-magnitude stars. For brighter stars the SNR will be correspondingly higher.

3.2 Avionics

3.2.1 Video Camera for Attitude Determination

An image-intensified analog video camera will be used to determine the viewing direction of the ISG . The orientation of the video camera with respect to the ISG will be precisely measured during payload integration. Star images acquired by the video camera during the mission will be correlated with a star database to resolve the orientation of the video camera, and identify the stars in the ISG field of view. BAL will supply a Xybion intensified camera of the same type as that used successfully in the GEMINI and OEDIPUS-C missions. The analog output of the camera will be downlinked over the telemetry antenna and captured by a dedicated receiving antenna on the ground. The knowledge base for accurate interpretation of the video data stream with high time resolution was developed at the University of Saskatchewan [ Moorhouse 1994] and is available for application to this mission.

3.2.2 Global Positioning System Receiver

A Global Positioning System (GPS) receiver is required to track the position of the instrument during the mission. The position of the payload must be known in order to associate a measurement with a specific three-dimensional position, and to facilitate payload recovery. Civilian use of GPS technology is normally limited to altitudes below 10 nautical miles (18.5 km) and flight speeds less than 600 knots (1100 km/hr), but these limitations can be defeated with appropriate authorization. BAL will provide a GPS position determination capability as part of the payload.

3.2.3 Compression Electronics

Lossless compression of the ISG data, with a ratio approaching 2:1, will be required in order to transmit all the data collected. This can be done by exploiting the expected redundancy in the images from the ISG , which will show horizontally blurred stellar spectra in which adjacent columns will differ little, if at all. Transmitting data by columns, and transmitting differences between adjacent columns when these can be represented in less than 8 bits, is expected to achieve significant savings in the total data rate. The image analysis and compression will be implemented with a digital signal processor (DSP).

3.2.4 Telemetry system

Standard S-band telemetry will be used. Three data channels will be required: a wideband link capable of 10 MHz bandwidth for the compressed ISG data, another wideband link with 2 MHz bandwidth for the AVC signal, and a narrow-band link for the GPS data as well as other housekeeping data. The ISG data will be encoded to RNRZ and pre-emphasized before reaching the transmitter. The analog AVC data will need no pre-conditioning. The GPS and housekeeping data will be encoded with a BAL single-board encoder. A radio frequency (RF) triplexer will be used to mix the three data channels noted above before applying them to the S-band antenna.

3.2.5 Instrument Power Supply

The power required by the instruments is estimated as 30 W at 28 Vdc and 1.07 A. This capacity is overrated by 25% to allow for a margin of safety. System power at 28 Vdc will be available on a bus from system batteries provided by BAL . We will provide power conditioning hardware to convert the system power to the voltage levels required by our instruments. Estimated power consumption is listed by device in Table 2-3.

Table 2-3. Instrumental power consumption

Device(s)	Power Consumption (W)
CCD and Readout System	5
Chemiluminescent Ozonesonde	7
Avionics	7
In Flight Payload Heating	5
Total Consumption	24
Overrated by 25%	30

4. Other Required Systems

4.1 Temperature Sensor

It is desirable to include a simple ambient temperature monitor in the payload to provide an independent atmospheric temperature reference. A thermistor-based sensor such as that used in the Super Loki Datasonde [ Schmidlin 1986] is proposed, as it is small, lightweight, proven, and well understood. Integration of the atmospheric density downward from apogee, using the measured temperature profile, will also provide a reliable pressure/density profile. This will be useful as a check on densities and temperatures inferred from measurements of the Rayleigh scattering component of the stellar irradiance attenuation.

4.2 Chemiluminescent Ozonesonde

To provide in situ validation for the ozone profile inferred optically, it is desirable to include a chemiluminescent ozonesonde [ Hilsenrath and Kirschner 1980] in the payload. The device is cylindrical, 10.5 cm in diameter and 51 cm long, weighing 2.4 kg. This instrument uses the chemiluminescence reaction between ozone and rhodamine -B to measure the ozone concentration in situ . Ambient air is sampled by a self-pumping technique as the sonde descends through the atmosphere. The reliability and accuracy of this technology have been tested on many flights. The vertical resolution of the ozonesonde is comparable to or less than that of the ISG (1.1 km at 60 km; less than 100 m below 40 km), and the detector provides sufficient sensitivity for accurate measurements of ozone from 65 km down to 20 km altitude.

4.3 High-Altitude Deployment Parachute

The instrument must rotate as it descends to ensure data are acquired from the desired range of azimuths. The payload descent rate and spin rate will be determined by local atmospheric conditions and parachute characteristics. The descent rate and spin rate within the ozone layer are critical to the acquisition of an adequate data set for tomographic reconstruction. The descent rate and spin rate above the ozone layer must be low enough to allow unocculted spectral data to be obtained for each star, so that the instrument will indeed be self-calibrating. Spin parachutes are an existing technology, and the literature [ Silbert 1983] suggests that such parachutes provide a constant number of revolutions per distance fallen. In order to obtain the target 1 km vertical resolution for observations of a given star within the ozone layer, the instrument must rotate at least once per km at altitudes below 30 km. Estimates based on data from Silbert [1983] suggest a spin rate of 4.5 rpm near 70 km altitude, where the descent speed is highest. This is the maximum spin rate at which spectral data will have to be acquired.

5. Required Facilities

5.1 Available Facilities

Several major facilities within the University of Saskatchewan and at SCI-TEC Instruments, Inc. are available to provide instrumentation and expertise for fabrication, testing and calibration. The Institute of Space and Atmospheric Studies ( ISAS ) has a fully equipped optics laboratory where wavelength calibration of the ISG can be carried out. The Department of Physics and Engineering Physics has a machine shop whose staff have successfully completed numerous instrumentation development projects. The Department of Chemistry has facilities to create a low-temperature, low- pressure environment suitable for simulating conditions in the stratosphere, to allow thermal-vacuum testing of the various components. The Department of Mechanical Engineering has a vibrational testing facility which could be used to simulate the conditions to which the NiteOwl instruments will be exposed during launch.

5.1.1 ISAS Optics Laboratory

The ISAS Optics Laboratory is fully equipped with equipment for generating, manipulating, and measuring light at wavelengths from the near UV to the near IR. Of particular value to this project is a scanning 1-m Ebert -Fastie monochromator, which can be used for acceptance testing of the CCD detector and the grating as well as characterizing the response of the entire optical system to light as a function of wavelength and angle of incidence.

5.1.2 Physics and Engineering Physics Machine Shop

The machine shop in the Department of Physics and Engineering Physics is available for mechanical fabrication and assembly. This facility is staffed by three highly qualified machinists, who are Canadian Interprovincial Journeymen Machinists and fully accredited Canadian Instrument Makers. Because they are employed by the Department, fabrication services can be provided at highly competitive rates. Recent work has included the preparation of space research instruments meeting very tight tolerances, for NASA projects and the Odin satellite.

5.1.3 Chemistry Thermal Vacuum Facilities

Instrument testing before launch must simulate the cold near-vacuum of the mesosphere to ensure proper instrumental operation at the expected low temperatures and pressures, and to verify that heat absorbed by the CCD can be radiated to space efficiently enough to cool the CCD and reduce dark current. The expected conditions can be simulated readily using facilities in the Department of Chemistry. A bell jar large enough to house the instrument, evacuated with a fore pump, can be used to reduce the pressure to 2×10-3 torr, the expected pressure 5 km above apogee. A plywood enclosure constructed around the jar, lined with 15 cm thick styrofoam and cooled by a controlled flow of nitrogen gas boiled off from a dewar at 77K , can be cooled easily to the 200 -250K ambient temperatures found throughout the stratosphere and mesosphere. The interior of the bell jar can be appropriately blackened to absorb the thermal radiation from the CCD radiator plate.

5.1.4 Mechanical Engineering Vibration Facility

A Brüel & Kjær vibration exciter with a stroke of 0.75 in and a maximum head speed of 50 in/s can be used for vibration testing at oscillation frequencies up to 4 kHz. The product of loading mass and peak acceleration that can be produced is 143 kg g or 1400 kg m s-2. This will allow vibration testing of the NiteOwl instruments, but not the whole payload, at vibration levels characteristic of launch conditions.

5.1.5 SCI-TEC Facilities

SCI-TEC can provide facilities, resources, and services including ordering, receiving, and storage for instrument parts; the use of computers for instrument control and data analysis; Brewer ozone spectrophotometer data for reference and correlation with data received from the NiteOwl experiment; space for instrument assembly and storage; and a machine shop. Pre-flight instrument testing can be undertaken using SCI-TEC's dark room, optical tables, laser alignment jigs, gas calibration unit (capable of ozone generation), and calibrated light source. It may be possible to conduct ozone absorption tests with SCI-TEC's resources.

5.2 Other Required Facilities

5.2.1 Bristol Aerospace Limited Payload Test Facilities

BAL have facilities for conducting electrical, mechanical, thermal, and vacuum tests on rocket payloads. Electrical tests that will be required include those for electrical compatibility and electromagnetic interference. Mechanical tests will include those for payload spin balance and vibration tolerance. Payload operation can be tested under conditions of temperature or pressure representative of those expected during flight.

5.2.2 Optical Flat-Field Calibration Facilities

In order to exploit the self-calibrating nature of the stellar occultation experiment with a multi-
element detector, it is necessary to obtain an accurate characterization of the relative spectral response of each detector pixel. In order to ensure that suitable facilities for this purpose are available, a line item for the procurement or use of such facilities is included in the Direct Materials budget.

6. Instrument and Payload Testing

6.1 Imaging Spectrograph Characterization and Calibration

The ISG will have to be characterized in terms of the sensitivity of the instrument to light of different wavelengths and in terms of the effect of the optics on the path taken through the instrument by light of various wavelengths and at various angles of incidence. This work is expected to require some 18 person-weeks of effort at a cost of $58K . The per-pixel relative sensitivity of both the CCD and the ISG as a whole as functions of wavelength will be measured with the ISAS 1-m monochromator. This instrument can be used to produce monochromatic light over the entire passband of the NiteOwl ISG with a spectral resolution of less than 0.1 nm , if required.

The stellar occultation experiment as performed by the ISG is self-calibrating, provided the relative instrument sensitivity as a function of wavelength and position on the CCD is known with high precision. Knowledge of these characteristics renders an absolute calibration of the instrument unnecessary and affords considerable savings in calibration difficulty, time, and expense.

6.2 Attitude Video Camera Testing and Characterization

BAL will supply a tested AVC for integration into the experiment. Prior to integration, the spectral sensitivity and limiting (stellar) magnitude of the AVC will be determined. The spectral sensitivity test will be performed with a collimated light source of known wavelength.

This test should be preceded by a simple functional test in which the camera views the clear night sky from a dark location on a moonless night, to allow a quick assessment of the image quality and the number of detected stars. A key requirement is to determine the mapping from the ( r ) object space of the attitude video camera to the ( xy ) image space. This can be accomplished most simply by suitable analysis of the starfield video data discussed above.

6.3 Determination of Relative Orientation of Imaging Spectrograph and Attitude Video Camera

The orientation of the Imaging Spectrograph ( ISG ) with respect to the Attitude Video Camera (AVC) will have to be evaluated before launch. Note that it is not necessary to align the two subsystems precisely to a known relative orientation. It is only necessary to determine what the relative orientation is. It is proposed to do this in three stages. During payload assembly the two subsystems can be coarsely oriented during systems integration. During initial testing of the payload optical tests can be performed (using facilities in the ISAS Optics Laboratory) to determine whether the coarse orientation specification was met. During final verification of the payload, and during testing of the Attitude Video Camera, determination of the orientation angle between the two subsystems can be performed at night using known star patterns.

7. Launch and Operational Considerations

7.1 Launch Vehicle

The launch vehicle will be the Orion, an U.S. vehicle. This single stage, unguided, fin stabilized rocket with a 14'' diameter and a 110'' length can reach an altitude of 80 km with a 55 kg payload. This rocket uses a two-phase burn: the first phase provides an acceleration up to 15 g for a few seconds, and the second phase provides 6-8 g acceleration. The total burn time is approximately 32 seconds. Three nominally canted fins provide a spin rate of four revolutions per second at burnout. The expected mass distribution, shown in Table 2-4, indicates a weight problem. However, an enhanced version of the Orion with greater thrust may be available, which could resolve the problem. Failing this, a heavily ballasted Black Brant V could be used.

Table 2-4. Expected Payload Mass Distribution

Item	Mass (kg)
Payload skin section	18 .6
Separation system	9 .1
Nose cone	10 .0
Parachute	12 .2
Despin hardware	2 .3
Telemetry system	12 .6
Experiment	10 .9
Total	75 .7

The 'Experiment' item includes all required on-board systems: optics, power supply, batteries, and mounting structure. The estimated vehicle cost is $70,000. In order to use the Orion, an End User Agreement will be negotiated with the US Navy, as has been done in the past for projects with Canadian government sponsorship.

7.2 Launch Window

In determining an optimal launch window, the positions of the sun and moon as well as the distribution of stars on the celestial sphere must be taken into account. To minimize contamination by scattered light, ground-based astronomical observations are usually carried out when the sun is at least 12 below the horizon, and the moon is also down. A conservative approach was adopted, namely, requiring these conditions to hold from apogee (nominally 80 km altitude). The corresponding depression angles at ground level are 21 and 9 for the sun and moon, respectively.

Between October 1, 1998 and February 28, 1999, there are five periods of ten to thirteen days when these conditions are met for at least six hours each night. Table 2-5 lists these times, along with the length of the longest dark period in each month, and the range of local sidereal times ( LST ) covered during each period.

Table 2-5. Launch Windows Between October 1, 1998 and February 29, 1999

Launch Campaign Dates	Maximum Dark Period	LST range (hrs)
17-27 Oct 1998 (11 d)	9 hr 10 min	21.27 - 6.95
14-26 Nov 1998 (13 d)	10 hr 50 min	22.11 - 09.76
13-25 Dec 1998 (13 d)	11 hr 40 min	23.68 - 12.16
11-22 Jan 1999 (12 d)	11 hr 10 min	01.92 - 13.84
10-19 Feb 1999 (10 d)	9 hr 30 min	04.72 - 14.84

A very favourable sector for star observations at southern azimuths occurs during the December - February launch windows at 9h30m - 10h00m LST . Over a 45 range of azimuths centered at 220 azimuth, seven stars of magnitude 3.0 or brighter are distributed within ±6 of the local horizon (see Figure 2-2).

A Brewer ozone spectrophotometer will be used to measure ozone total column densities and profiles before and after the mission, to provide further validation for the measurements derived from the NiteOwl data. Provided that the moon is at least 20 above the horizon for one hour while the sun is at least 12 down, total column ozone can be measured using moonlight on the night of the mission. Thus it would be ideal to pick a launch date when the moon either sets before the launch or rises after the launch. Failing this, validation measurements can be obtained during the daylight hours bracketing the launch.

7.3 Launch Support

Launch support will be provided jointly by AAI and BAL . This will include transportation of the rocket and payload to the launch site; facilities and personnel for rocket and payload processing, assembly, and testing; technical expertise and facilities for the launch itself; tracking and telemetry systems implementation; decommutation and storage of the flight data; and post-flight recovery of the payload.

By the spring of 1998 AAI expect to have available two 5-m antennas for payload tracking and telemetry acquisition. These antennas provide 38 dB gain at S-band frequencies, which is adequate to record telemetry from a 2 W transmitter at ranges up to 370 km.

Data from the three links telemetered to the ground will be recorded with time stamps on magnetic tape by AAI and decommutated after the mission. AAI will provide the decommutated data in permanent form, e.g., recorded on CD-ROM.

Post-flight recovery of the payload is highly desirable but will be complicated by the long parachute time of the payload, which creates trajectory dispersion problems. The land area surrounding Churchill is sparsely populated but heavily wooded, and this could complicate the actual recovery of the payload. Monthly mean zonal winds in the stratosphere over Churchill are strongly eastward, making it probable that the payload will land on the ice of Hudson Bay. GPS data during descent and a low-power beacon on board the payload will be used to locate and recover the payload promptly after completion of the mission.

8. Work Breakdown Structure and Schedule, including Management Plan

8.1 Work Breakdown Structure and Schedule for the NiteOwl Project

A top-level work breakdown structure and schedule for the entire NiteOwl project is given in Figure 2-3, outlining the major tasks required in each phase of the work. The planned duration of the project, from the start of work on Phase A to the completion of the data validation after the mission, is 468 days, or about 21.6 months. This includes a waiting period of one month after the Preliminary Design Review before the decision to proceed to launch is received. If work begins on April 7, 1997, the Mission Readiness Review will be held in December1998 and launch can occur in January 1999.

8.2 Work Breakdown Structure and Schedule for NiteOwl Phase A

A fully-detailed work breakdown for Phase A is shown in Figure 2-4. We have estimated 7 months for Phase A activities, which will include the required preliminary design studies as well as a detailed specification and description of all aspects of the experiment. The design studies will address many issues common to both the parachute-borne version of the NiteOwl experiment and the follow-on satellite experiment.

8.3 Management Plan

8.3.1 Human Resources Deployment Plan

The NiteOwl Team consists of a number of highly qualified personnel from the University of Saskatchewan and the project's industrial partner, SCI-TEC Instruments, Inc., as previously described in the Science Team section of Part One. Four graduate students in science and engineering will take part in the project, and financial and other management responsibilities will be undertaken by appropriately qualified graduate management students under the supervision of Prof. M.J. Painter of the College of Commerce. The detailed task descriptions of the students are provided below. With the exception of student 3 ( J.A. Steele), graduate students have not yet been selected.

Student 1 (Electrical Engineering) will be registered in an M.Sc . program under the supervision of Prof. R.J. Bolton, with support from a graduate fellowship. During Phase A this student will work on electrical/electronics aspect of the experiment, including data compression methods and their implementation in digital circuits.

Student 2 (Mechanical Engineering) will be registered in an M.Sc . program under the supervision of Prof. J.D. Bugg , with support from a graduate fellowship. The student will study parachute and payload dynamics and perform structural and thermal modelling of the experiment in Phase A.

Student 3 (Mechanical Engineering) will be registered in a Ph.D. program under the supervision of Prof. A.T. Dolovich , with support from an NSERC Postgraduate Scholarship. The student will be involved in synthetic data preparation, algorithm development, and the spin rate and data rate trade-off studies during the Experiment Modelling in Phase A, and will work on tomographic analysis of synthetic data during the remaining phases. The tomographic analysis of the NiteOwl data set will form part of this student's Ph.D. dissertation.

Student 4 ( Engineering Physics) will be registered in an M.Sc . program under the supervision of Dr. D.P. Steele, with support from a graduate fellowship. The student will be involved in most aspects of the Experiment Modelling activity, and in work on the optics and detector system within the Experiment Specification and Description, both in Phase A.

Student 5 (College of Commerce) will be registered in the MBA program and will work under the supervision of Dr. M.J. Painter, with support from a graduate scholarship. The student will serve as Assistant Project Manager ( APM ), assisting with the financial and human resources management of the project.

Students 1, 2, and 4 will also gain hands-on experience at SCI-TEC as term employees during portions of Phase B, the implementation, integration, testing, and calibration of the instrument. In addition, these students will have limited involvement in the Launch Operations, Phase D.

8.3.2 Project Monitoring and Control

Close oversight and control on both budget and human resources must be applied, to ensure the project schedule and budget are met. During the Detailed Scheduling activity of Phase A the Critical Path for the remainder of the project will be identified. Time overruns in Critical Path tasks risk delaying the entire project. The APM will have responsibility for monitoring the progress of the project overall, and each task in particular, to ensure all tasks are proceeding on schedule. The APM will work closely with the PI (and the responsible persons with each subcontractor) to anticipate scheduling or budget difficulties. In cases of anticipated time or cost overruns during the project, the APM will report the situation to the PI, who will decide with the science team and SCI-TEC how to resolve the situation with the least adverse impact on both the science objectives and the project budget.

Contingency periods with appropriate levels of effort have been built into the schedule outlines above, to provide a 10% cushion in time and personnel costs.

9. Project Budget

9.1 Phase A

A detailed budget for Phase A of the project is set out in Table 2-5. The labour item for the Investigator Organization corresponds to full-time support for the Principal Investigator for the duration of Phase A. A further breakdown of the labour item for SCI-TEC is provided in Table 2-6, which breaks down the project labour costs by phase and participant.

Table 2-5. Detailed budget for Phase A.

Phase A Budget
Investigator Organization	Labour	$ 54,096
Equipment	$ 17,000
Communications	$ 300
Travel and Living	$ 2,400
SCI - TEC Instruments, Inc.	Labour	$ 27,316
Travel and Living	$ 2,400
Bristol Aerospace Limited	Engineering	$ 76,169
Total for Phase A	$ 179,681

9.2 Phases B - E

Tables 2-6(a-d) on the following pages provide budget estimates for all phases of the project.

Table 2-6(a). Budget estimates for labour costs for all phases of the NiteOwl project.

Labour	Salary/Month	Phase A	Phases B-E	Total Salary
Investigator Organization
Principal Investigator Salary	$ 4,333	$ 29,392	$ 62,166	$ 91,558
( + Benefits @ 11.5%)	$ 500	$ 3,391	$ 7,173	$ 10,564
Overhead (65% of PI salary + benefits)	$ 3,142	$ 21,313	$ 45,078	$ 66,391
Total IO Labour Cost	$ 7,975	$ 54,096	$ 114,417	$ 168,513
Table 2-6(a) (continued).

Salary/Day	Phase A	Phases B-E	Total Salary
Industrial Partner 1,2
Sniezek (Vice-President R/D/E)	$ 360	$ 6,300	$ 2,520	$ 8,820
Ivanov (Senior Research Engineer)	$ 336	$ 672	$ 32,760	$ 33,432
Johnston (Senior Research Scientist)	$ 336	$ 7,728	$ 18,144	$ 25,872
James (Programmer/Analyst)	$ 336	$ 0	$ 1,680	$ 1,680
Rosen (Electrical Engineer)	$ 304	$ 8,816	$ 43,776	$ 52,592
Wilson (Mechanical Engineer)	$ 304	$ 3,800	$ 44,992	$ 48,792
CAD (Technician)	$ 240	$ 0	$ 5,520	$ 5,520
Term EE (Student 1)	$ 260	$ 0	$ 39,650	$ 39,650
Term ME (Student 2)	$ 260	$ 0	$ 32,500	$ 32,500
Term EP (Student 4)	$ 260	$ 0	$ 38,220	$ 38,220
Total Industrial Partner Labour Cost	$ 27,316	$ 259,762	$ 287,078
Total Labour Cost	$ 81,412	$ 374,179	$ 455,591
Notes:
1. Salaries are unburdened cost, rather than burdened cost.
2. Industrial partner contributions include $301,182 in foregone profit, as well as undetermined costs for lost opportunities, usage of facilities and equipment, and Brewer spectrophotometer data.

Table 2-6(b). Budget estimates for material costs for the NiteOwl project.

Material	Unit Cost	Units	Total Cost
Experiment Components
Baffles, stops, cold finger	$ 7,000	1	$ 7,000
Optical filters	$ 5,000	1	$ 5,000
Transmission grating	$ 6,000	1	$ 6,000
Objective lens	$ 40,000	1	$ 40,000
CCD (engineering grade + scientific grade)	$ 62,000	1	$ 62,000
Readout controller	$ 35,000	1	$ 35,000
Other electronics	$ 20,000	1	$ 20,000
Temperature sensor	$ 1,000	1	$ 1,000
Ozonesonde	$ 5,000	1	$ 5,000
Mechanical structure	$ 15,000	1	$ 15,000
Miscellaneous supplies	$ 3,000	1	$ 3,000
Total Material Cost	$ 199,000

Table 2-6(c). Budget Estimates for Equipment Costs for the NiteOwl project.

Equipment
Data Reduction Equipment
Computer and Peripherals	$ 15,000
Interactive Data Language™ software	$ 2,000
Optical Calibration Equipment	$ 40,000
Total Equipment Cost	$ 57,000

Table 2-6(d) Budget Estimates for Supply and Service costs for the NiteOwl project.

Supplies and Services	Total Cost
Payload Contractor
Phase A	$ 76,169
Phase C	$ 771,204
Vehicle
Orion vehicle and retrofit	$ 70,000
Tail assembly	$ 166,300
Launch
Travel and Living	$ 8,000
Shipping	$ 3,000
Payload Contractor (Phases D + E)	$ 207,994
Launch Contractor	$ 309,700
Sub-total of Launch Cost	$ 528,694
Meeting Expenses
Travel and Living	$ 17,300
Instrument Calibration
User Fees for ISAS Optics Lab	$ 1,200
Travel and Living	$ 100
Communication	$ 900
Total Supplies and Services Cost	$ 1,631,867
Material	$ 199,000
Equipment	$ 57,000
Labour	$ 455,591
Total Budget Cost	$ 2,343,458

10. Risk Analysis

This section presents a risk analysis of the various subsystems associated with the instrument and the mission. The reliability of these subsystems will, for the most part, be determined by the sub- contractors involved in the implementation of each component.The entire payload will undergo acceptance tests appropriate to determine the suitability of the systems and subsystems. These will be undertaken in cooperation with the subcontractors involved and the industrial partner.

10.1 Categories for Risk Analysis

10.1.1 Science

The major concern here, and one that will have a major impact on the success of the project, is overlooking some aspect(s) of the experiment that would lead to failure. This can be mitigated by close scrutiny of all aspects of the experiment as well as by external review. Possible areas of concern are: incorrect assumptions, error in modelling, and error in simulation.

10.1.2 Pre-Launch

Since a number of the subsystems will be sub-contracted, it is important to monitor closely the specification, delivery, and documentation associated with these subsystems. This is included in the management plan for the project. A major mitigating consideration is that the launch window can be over a number of days each month allowing (to some extent) delivery dates to slip. This will, however, increase the cost of launch. Possible areas of concern are: failure to meet schedule, faulty design, payload weight overrun, destructive testing, and incomplete documentation

10.1.3 Launch

The launch of the payload will be coordinated by BAL and AAI . They will be responsible for all aspects of the launch operation and initial manual tracking/capture. Possible areas of concern are: vehicle failure, manual tracking failure, bad weather, and safety conditions.

10.1.4 Payload Dynamics

The payload must be decelerated by parachute and have a stable flight (spin rate <1 rpm below 30 km altitude; swing amplitude < 5°). Areas of concern are: de-spin, parachute deployment, and stabilization against pendulation .

10.1.5 Optical System

The optical system may become damaged or misaligned during launch. The mounting and alignment of this system will have to be checked during manufacture and assembly. Possible areas of concern are: g-forces, vibration, and the contamination of grating and/or optics.

10.1.6 Electronic Systems

This will include the power supply, power converter, data compression hardware, and miscellaneous monitoring circuitry. Possible areas of concern are: incorrect power estimates, incorrect interfaces, physical failure, EMI , thermal problems, GPS subsystem failure, and antenna failure. Outside expertise will be accessed wherever appropriate.

10.1.7 On-Board Data

The major component of this system is the data compression hardware subsystem. Since this will not be a commercially available unit, past performance of the system is not available for analysis. Areas of concern are: inadequate compression ratio.

10.1.8 Ground-Based Data

Aspects of this area include telemetry, data recovery and data storage. Areas of concern are: power failure, software failure, recorder failure, and antenna failure.

10.1.9 Post-Flight

This aspect is related to the recovery of the payload. Possible areas of concern are: loss of on-
board data storage (if used), and loss of payload.

10.2 Risk Model

In determining the "risk" involved with each of these mission aspects, the following areas of risk were considered, with the associated definitions of level of risk:

System Risk Level - depends on knowledge and experience with each particular system;

Low:	Use of flight qualified system, well understood considerations and methods;

Medium:	Possibility of error, incorrect specification;

High:	New systems, inexperience, inherent risk.

Probability of Occurrence - depends on how successful each subsystem has been in past missions;

Low, Medium or High based on past experience, reliability and input from team leaders.

Impact on Mission - depends on how a problem with each subsystem affects the mission;

Low:	Threatens optimal success;

Medium:	Threatens schedule or acceptable success;

High:	Threatens cost or minimum success.

Difficulty in Mitigating - depends on whether a problem with the subsystem in question can be resolved and what else can be done if this is not possible;

Low:	Well understood approach to minimize/identify/correct problem;

Medium:	Some opportunity to minimize/identify/correct problem;

High:	No opportunity to minimize/identify/correct problem.

Based on the assessment of each system, an aggregate averaging was used to rank each mission aspect according to the risk level associated with it. The assessments are summarized in Table 2-7 below, which ranks the mission aspects in order of decreasing risk.

The launch and the vehicle dynamics pose the greatest risk. However, if the payload survives the launch and is put in a position to begin taking data, the success of the mission seems assured.

Table 2-7. Risk Analysis of Various Aspects of NiteOwl Mission

Mission Aspect	System Risk Level	Probability of Occurrence	Impact on Mission	Difficulty in Mitigating
Launch
Invalid initial trajectory	High	Medium	High	High
Vibration impairs structural integrity	High	Medium	High	High
Vehicle Dynamics
Despin system failure	High	Medium	High	High
Parachute deployment failure	High	Medium	High	High
Optical System
Instrument optical misalignment	Medium	High	High	Medium
Stray light in instrument	Medium	High	High	Low
On-Board Data Handling
Data compression hardware failure	Medium	Medium	Medium	High
Antennae failure	Medium	Medium	High	High
Electronic Systems
Instrument turn-on failure	Medium	Medium	High	Medium
Subsystem interfaces not correct	Medium	High	Medium	Low
Ground-Based Data Handling
Antennae failure	Medium	Medium	High	Low
Power failure	Medium	Medium	High	Low
Science
Faulty instrument design	Medium	Low	High	Low
Incorrect scientific assumptions	Medium	Low	High	Low
Pre-Launch
Inadequate testing	High	Medium	Medium	Low
Parts unavailable or not received	Medium	Medium	Medium	Low
Post Flight
Vehicle unrecoverable	High	Low	Low	Low

11. Potential Benefits

Ozone layer research is important to all humans and especially to Canadians. In particular, the ecosystems and people of the Canadian North will be adversely affected by depletion of Arctic ozone. The NiteOwl project provides a low cost opportunity to measure ozone densities in northern Canada using Canadian expertise and equipment.

The most important spin-off of NiteOwl will be the development of a microsatellite -based instrument which will be used to measure local and global ozone distributions in near real-time; such a capability is essential if ozone depletion continues. With this capability, individuals will have the opportunity to "see" the ozone layer on television and at an Internet web site or obtain daily reports via newspapers and radio. Because of the health risks associated with ozone layer depletion, such rapid dissemination of information is important. Providing this information should be a high priority for publicly financed research.

The NiteOwl project and launch will also enhance the efforts made by Akjuit Aerospace Inc. towards re-establishing and expanding SpacePort Canada (Churchill, MB) as a key international launch site for satellites and sounding rockets.

Canadian industry will benefit. SCI-TEC Instruments, Inc. will gain research and development work on ozone monitoring instrumentation at very nominal cost, while exploring the feasibility of developing a microsatellite -based ozone monitor, a value-added data product, and a market for the product.

Graduate education in space science will benefit. The NiteOwl project involves graduate students at every stage, giving them first hand experience in all aspects of the conduct of scientific investigations. The graduate school experience and post-graduation employment opportunities of the participating students will be significantly enhanced. In particular, students will have the opportunity to work as term employees with SCI-TEC during Phase A, thus obtaining first hand experience in Canadian industry. This will benefit Canadian university space science in several ways: stronger links between scientists and industry, a demonstrated capacity to produce employable graduates, and more advanced technological support from industry.

Communication of the potential benefits of the NiteOwl project has already begun. A recent front page article in "On Campus News" (published by the University of Saskatchewan Office of Public Relations) featured the NiteOwl mission concept and the involvement of the industrial partner, and highlighted the unique aspect of having graduate students help develop the proposal. An Internet website is being developed to provide up-to-date progress reports and to communicate the results and benefits of the project. Presentations on the science and technology of the NiteOwl project will be made at appropriate conferences, and the results of the project will be published in scholarly journals (cf. Part One, §6).

The history of the NiteOwl project will be incorporated into a computer-based education initiative at the University of Saskatchewan. As part of the College of Engineering's Innovative Teaching and Learning Center , a PowerPoint -based set of materials (including Internet web pages) will document the development procedures used for the NiteOwl science and intrumentation . This will allow the formal system design process followed by the NiteOwl team to be presented to a fourth-year electrical engineering design class as an example of real-world engineering design.

Finally, the high level effort to educate the general public on the project will continue. For this purpose the science team will take advantage of existing programs such as the Western Space Education Network and the Canadian Space Resource Centre, Innovators in the Schools, University of Saskatchewan Engineering Summer Sci-Fi Camp and Spectrum, and the University of Saskatchewan University to the People program. Several members of the science team have participated in these programs in the past (see their personal data forms for details). In addition, during Phase A the plan is to explore the possibility of developing a videotape presentation chronicling the experiences of the graduate students in the project, and the final outcome of the NiteOwl project. With the success of the project, contacts will be made with radio and television networks to disseminate the outcome and expected benefits.

References

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Hilsenrath , E., and P.T. Kirschner , Recent assessment of the performance and accuracy of a chemiluminescent rocket sonde for upper atmospheric ozone measurements, Rev. Sci. Instrum , 51, 1381-1389, 1980.

Moorhouse , P., An attitude video camera using stellar images for the GEMINI experiment, M.Sc . thesis, Univ. of Saskatchewan, Saskatoon, 1994.

Schmidlin , F.J. , Rocket techniques used to measure the middle atmosphere, Handbook for Middle Atmosphere Program, 19, ed. R.A. Goldberg, 1-29, 1986

Silbert , M.N. , Deployment of a spin parachute in the altitude region of 260,000 ft., J. Spacecrafts and Rockets, 20, 11-
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