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Embry-Riddle Aeronautical University Molly Stagnitti, Anthony Pritchard, Kriszelda Menez
October 26, 2012 1
Kriszelda Menez
2
RockSat-C 2013
CoDR
“Project PHIDO’s mission is to design, build, and launch an
optical instrument to determine how the intensity of UV radiation
changes with altitude in order to deduce an ozone density profile
of the atmosphere.”
Mission Requirements:
Form a photometer design from its desired function while
adhering to rocket constraints
Construct, calibrate, and test the instrument
Validate the device by rocket flight and data collection
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RockSat-C 2013
CoDR
Expect to correlate UV intensity to ozone density as a
function of altitude in order to compare the profile to
previous data and current models
The design will benefit future senior design teams at
Embry-Riddle Aeronautical University by serving as a
viable prototype for a student CubeSat-mounted
photometer
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RockSat-C 2013
CoDR
Ozone (O3) is a gas made up of oxygen atoms that naturally
occurs in the Earth’s upper atmosphere
Ozone in the Earth’s stratosphere absorbs ultraviolet (UV)
radiation from the sun that would otherwise damage biological
organisms
By accurately monitoring UV absorption within the stratosphere, it
is possible to maintain records of this region’s ozone density and
distribution
5
RockSat-C 2013
CoDR
Countless previous studies have measured the atmosphere’s ozone density profile. NASA predicts the atmospheric ozone density to continue to decrease. Retrieved from http://www.espo.nasa.gov/solveII/implement.html
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RockSat-C 2013
CoDR 7
Altitude: 60km
Ozone
Density≈0
t≈933 s
Splash Down
Altitude: 95 km
Instrument Power Up
Begin Useful Data
Collection
t=0 s
Altitude: 95 km Apogee
End of Useful Data
Altitude≈110-
120km
Altitude: 52 km
Altitude: 75 km
Chute Deploys
t≈489.2 s
Altitude: 75 km
Terrier Burn: t≈5.2 s
Coast: t≈9.8 s
Orion Burn:
t≈25.4 s
End Data Collection
Shortly after
Apogee
RockSat-C 2013
CoDR 8
Altitude (km)
0—15 <.5—1
15—25 1—5
25—35 4—1
35—55 1—≈0
Kriszelda Menez Molly Stagnitti
9
RockSat-C 2013
CoDR 10
PMT
Detector
Pre-Amp/
Discriminator
Photomultiplier Tube
Counter Data
System
Data Storage/
Control System
Data System
Batteries HV Supply DC/DC
Converter
Electrical Power System
Wallops Flight
Facility Payload
Interface
RockSat-C 2013
CoDR 11
Data/Power
System
Mirror Mirror
Housing
Detector
Housing
Plates
RockSat-C 2013
CoDR 12
236.22mm
241.3
mm
There are 3
Plates. Each
plate has a
height of
6.35mm
22.25mm
67.53mm
62.99mm
RockSat-C 2013
CoDR 13
Microcontroller and Data Processing
1) Signals are sent via the Optical system in the form of electrical
counts.
2) A processor records the counts as they are collected.
3) The processor converts the number of counts to a binary number
every period of time.
4) The binary numbers are then stored in a storage device.
RockSat-C 2013
CoDR 14
Interface Name Brief Description Potential Solution
STR/PLT1 This top plate that has the electrical power system mounted to it will then be mounted onto the canister top plate.
The plate will be secured using bolts.
EPS-DS/PLT1 The electrical power system and data system which includes our DC-DC converters, batteries and data system will all be placed in a housing unit that is mounted to our top plate.
The housing unit is made of aluminum. Exact dimension of the housing unit will be determined by the CDR. Four bolts at the corners of the housing secure it to the plate.
MR/PMT
The mirror will enclosed within its own housing unit to make sure that all the light is focused into the PMT housing unit. The mirror housing unit will be attached to the PMT housing unit.
The mirror housing unit will be mounted to the PMT housing unit using four small bolts.
PMT/PLT2
The detector consists of an aluminum housing unit and its bottom will be mount to a second plate deck rigidly. The PMT/high voltage supply will be secured within the housing.
Bolts will secure the housing. RTV-11 will secure the PMT/high voltage within the detector.
PLT3/STR There will be a third plate attached to the second plate using metal rods. This third plate is used to mount the whole system to the bottom plate of the RockSat-C canister.
The plate will be secured using bolts. This plate will help ensure that the second plate holding the PMT housing and mirror housing unit are at the correct height of the optical port.
RockSat-C 2013
CoDR 15
Requirement Verification Method Description
The payload must demonstrate the ability
to filter and detect the UV-b band of
atmospheric radiation.
Demonstration The photometer will return data which
corresponds closely to the amount of
known UV-b photon intensity at the tested
altitude.
The amount of data points discriminated
should correlate to the local UV-b photon
density during flight.
Analysis The known rate of change of UV-b
photons vs. altitude should be compared
to the change of the amount of data points
received by the instrument. Differences
should be explainable (as error or as
unforeseen changes in ozone density).
The full system shall fit within a Rocksat-C
canister and adhere to mass/centroid
requirements.
Inspection Calculations and weight measurements
should prove this adherence.
The payload must pass a low
pressure/vacuum test as well as a vibration
test.
Test The instrument will undergo a low
pressure/vacuum test at ERAU in order to
demonstrate its ability to resist EPS arcs.
At wallops, the system will show its ability
to maintain structural integrity during
marginal vibration tests.
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Molly Stagnitti
RockSat-C 2013
CoDR
The power system was designed to be simple yet effective in order to maintain the following: Cost: This system will consist of 3 NiMH batteries of 9 volts each. With having only 3
batteries in the system at high voltages the cost of supplies goes down.
Size & Mass: The small mass and volume of the RockSat-C canister call for a simplistic housing unit for the power system. This housing unit will also contain the components of data collection, ie. the microcontroller and data storage system.
Data Collection: The power system and data collection system will need to control the detector so that it can lower its power-input when it is close to the sun so that the PMT is protected
17
RockSat-C 2013
CoDR 18
NiMH Batteries: Being used because it is inexpensive, reliable and has been used in past RockSat-C missions by other teams
Length: 26.5mm
Height:48.5mm
Width: 17.5mm
Weight: 42g
Advantages: These batteries can easily be replaced
RockSat-C 2013
CoDR 19
DC-DC Converters: Two NPH15S series converters from C&D Technologies
One has a nominal input voltage of 24 V, an output voltage of 5.1V and an
output current of 3.0A. This is 81% efficient
The second has a nominal input voltage of 24V, an output voltage of 15.1V
and an output current of 1.0A. This is 87% efficient.
Advantages: These converters are cheap and relatively efficient
The microcontroller and data system box are being supplied by Team
Science and will fit inside the power system housing unit.
RockSat-C 2013
CoDR 20
144.46mm
176.21mm
0.875mm
1. Circuit Board:
76.2x76.2x3.175
2. Batteries
H: 46.41mm
L: 26.62mm
W: 17.50mm
3. DC-DC Converters
H: 50.01mm
L: 10.01mm
W: 24.99mm
1
2 2
2 3
3
RockSat-C 2013
CoDR 21
Co
ns
eq
ue
nc
e
PS.RSK.1
PS.RSK.2 PS.RSK.3
Possibility
PS.RSK.1: The whole system will not be functional if the batteries run out of
power before data has been collected
PS.RSK.2: If connections are disrupted by vibration testing or launch conditions
then data cannot be collect
PS.RSK.3: If it is unable to properly control the power to the detector system it
will destroy our PMT
22
Kriszelda Menez
RockSat-C 2013
CoDR
The detector subsystem was designed to be simple yet effective in order to optimize the following drivers:
▪ Cost: This system will consist of a PMT, a high voltage supply and a pre-amp/discriminator. The overall cost will depend on the parts that optimize the optical system.
▪ Size & Mass: The housing for the system will be the largest and most heavy component within the design. The placement of the housing will be determined based on the specifications of the optical system components.
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RockSat-C 2013
CoDR
We will be using the R7154 PMT within this subsystem. High sensitivity solar blind photocathode (160nm-320nm)
28mm (1-1/8 inch) diameter, Side-on type, 45g
24
Advantages: This PMT was chosen because it operates within the range of wavelengths we will be observing. Also, it fits best into the previously built housing component.
RockSat-C 2013
CoDR
The pre-amp/discriminator circuit will be placed in a compartment on the side of the detector housing.
The high voltage supply will also be placed in a compartment on the side of the detector housing. This compartment is exactly opposite of that of the pre-amp/discriminator
Both components will be covered and secured.
The exact parts have not yet determined.
25
RockSat-C 2013
CoDR 26
Light
PMT
HV Supply
Pre-amp/
Discriminator
The PMT will be secured
using RTV11, which is a
white, two component, low
viscosity potting compound
that cures at room
temperature to a soft pliable
rubber. The excellent
electrical properties make it a
candidate material for both
high and low voltage
electrical assemblies.
Cushions against mechanical
shock and vibration.
http://www.mgchemicals.com/products/rt
v-
silicones/potting-compounds/rtv11/
RockSat-C 2013
CoDR 27
Co
ns
eq
ue
nc
e
DS.RSK.1 DS.RSK.2
Possibility
DS.RSK.1: The whole system will not be functional if the HV supply fails before data has been collected DS.RSK.2: If the PMT breaks during vibration testing or launch conditions then data cannot be collected
28
Anthony Pritchard
RockSat-C 2013
CoDR
The optical system was designed for simplicity and effectiveness in order to optimize the following drivers:
Cost & time: A simple system with few components is cost effective
and minimizes construction/calibration time
Size & mass: Volume, mass, and centroid constraints of the Rocksat-C canister promote a small optical system placed along the center vertical axis
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RockSat-C 2013
CoDR 30
Data collection: The optics and detector must be effective enough to accurately detect a short wavelength given a limited light input source
Prototype: The optical system which is being tested during this experiment is a main aspect of the future CubeSat photometer. The prototype requirements similarly include optimal simplicity and effectiveness of the optical system
Multiple optical systems were considered. The system that most
completely fulfilled all of the above requirements was a single 90 degree 50.8x25.4 mm off-axis parabolic mirror with aluminum coating centered on the optic and center vertical axes. This mirror focuses light through a UV band-pass filter and onto a PMT photocathode.
RockSat-C 2013
CoDR 31
Advantages of each aspect of the optical system:
Single mirror: (1) Low mass and volume (2) Easy calibration (3) Simple
construction (4) Prototype purposes
90 degree mirror: (1) Simplifies alignment of mirror and detector housing centroid on canister center vertical axis
50.8x25.4 mm mirror: (1) 50.8 mm (2 inch) diameter just marginally spans the 1.5 inch cylinder of light coming in from infinity through the optical port of the canister along the optic axis (2) 25.4 mm PFL is small enough so that the EFL and y-offset allow the focal point to fall on the photocathode comfortably (*Note: Currently, a trade study is being conducted on PMT size and its affect on mirror dimensions)
RockSat-C 2013
CoDR 32
Off-axis parabolic mirror: (1) Off-axis allows all of the source light to be focused on the detector without the detector system interfering with the optics (2) Partial parabola focuses all light to single point which is best for count detection sensitivity and discrimination (4) Prototype purposes
Aluminum coating: (1) Low cost (2) Sufficient reflectivity for UV wavelengths
Centering: (1) Optimal light collection (2) Centering of mass centroid
UV band-pass filter: (1) Reduces irrelevant photons (2) Prototype purposes
PMT Detector: (1) Maximum sensitivity (2) Prototype purposes
RockSat-C 2013
CoDR
Although multiple precautions will be taken to reduce the risks involved with the optical system, a few risks are associated with it. The main consequence of the following risks are the failure to collect sufficient and reliable data.
Disruption of calibration during flight
▪ Causes: Excessive g’s not accounted for during testing; Damage caused by vibration tests at Wallops
Inability to transmit enough UV-b photons from the ground to 60km
▪ Causes: Aggregate transmittance is too low for UV-b; UV-b intensity is too low near ground level
Inability to sufficiently filter the correct wavelength
▪ Cause: Insufficient filtering by UV filter
33
RockSat-C 2013
CoDR 34
Optic Axis
Central Vertical Axis
90°Off-Axis
Parabolic Mirror
UV Filter
PMT Detector
Housing
RockSat-C 2013
CoDR 35
Con
seq
uen
ce
OS.RSK.1
OS.RSK.3 OS.RSK.2
Possibility
OS.RSK.1: Calibration will be disrupted if launch conditions exceed integrity of
optical system structure
OS.RSK.2: Sufficient photons will not be transmitted to the detector if optical
system transmittance is too low for the amount of available UV photons
OS.RSK.3: The wavelength of choice will be not be properly singled out if the UV
filter is not effective enough at this wavelength.
36
Anthony Pritchard
RockSat-C 2013
CoDR 37
Due to cost and time constraints, prototypes are not intended to be constructed (unless a part fails, we can consider that a prototype).
All systems will be tested as possible throughout the design process
After canister is complete with the optical, detector, and EPS systems finished, we will test the payload in a low-pressure/vacuum test to ensure no electrical arcing will occur.
38
Molly Stagnitti
RockSat-C 2013
CoDR
Predicted Mass: 20+/-.1 lb (with necessary ballasts)
Predicted Volume: Will roughly occupy 265 in3 cylinder. Individually, the instrument’s devices will roughly occupy a total of 70 in3
Activation: Expect at-launch activation
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RockSat-C 2013
CoDR 40
Team Leader Team Phido Molly Stagnitti
Science Team Greg Shinaberry
Dan McIlveen Alena Thompson
Faculty Advisor Dr. Matthew Zettergren
Sponsor Florida Space Grant
Consortium
Member Team Phido Anthony Pritchard
Member Team Phido Kriszelda Menez
Data/Software Greg Shinaberry
Dan McIlveen Alena Thompson
STR Molly Stagnitti
Kriszelda Menez
OPTICS Anthony Pritchard
PMT/PS Molly Stagnitti
Anthony Pritchard Kriszelda Menez
Main Faculty Advisor Dr. Peter Erdman
RockSat-C 2013
CoDR
Date Event
10/5/2012 Conceptual Design Review (CoDR) Due
10/9/2012 Conceptual Design Review (CoDR) Teleconference
10/17/2012 Earnest Payment of $1,000 Due
10/17/2012 Online Progress Report 1 Due
10/26/2012 Preliminary Design Review (PDR) Due
11/9/2012 Preliminary Design Review Teleconference
11/15/2012 Finalize All Design Aspects
11/16/2012 Critical Design Review (CDR) Due
11/28/2012 Critical Design Review Teleconference
11/29/2012 Order Parts
41
RockSat-C 2013
CoDR 42
Date Event
1/15/2013 Begin Testing on Subsystems
1/18/2013 Online Progress Report 1 Due
2/15/2013 Individual Subsystem Testing Reports Due
2/18/2013 First Payment Due
2/28/2013 Finish construction of all parts, make sure testing in finalized
3/01/2013 Begin Payload Subsystem Integration
3/12/2013 Online Progress Report 2 Due
3/29/2013 Payload Subsystem Integration and Testing Report Due
4/08/2013 Final Payment Due
4/20/2013 Calibrate payload with canister
4/26/2013 First Full Mission Simulation Test Report Presentation Due
RockSat-C 2013
CoDR 43
PS STR DET OP
•Order Materials
•Work Request Into
Shop
•Input subsystems
• Conduct vibration
testing
• Order Materials
•Work Request Into
Shop
•Implement into
structure
•Testing of detector
•Order Materials
•Work Request Into
Shop
•Implement into
structure
•Testing of optics
•Schematics
•Schematic Review
•First Revision of
Boards
•Testing of boards
RockSat-C 2013
CoDR 44
Estimated Travel Costs (4 people)
Expenses Total Costs
3 rooms ($120/day) $3600
Per diem (for 4 is $50/day) $2500
Transportation (Fuel expenses round trip)
$400
Launch Support through RockSat C Program: $12,000
RockSat-C 2013
CoDR 45
Estimated Instrument Costs
Item Cost
Photometer Detector $3700
Parabolic Mirror $350
Flat mirror for calibration system $2200
High voltage power supplies $500
Low voltage DC-DC converters $500
Ultra Violet interference filters $250
Machining and Materials $1200
Misc. printed circuit boards and electronic components
$500
Flight batteries $200
Total with Travel & Launch Support: $27,900
46
Anthony Pritchard
RockSat-C 2013
CoDR 47
By the CDR, we want to finalize all design aspects Must first:
Settle choice of wavelength with team OASIS
▪ Decide upon PMT (28mm or 13 mm) ▪ Decide upon mirror (50.8x25.4 mm or 50.8x38.1 mm)
▪ Finalize Power Requirements/Battery Sizing
Decide upon particular microcontroller
Finish physical model in CATIA and optical model in Code V
RockSat-C 2013
CoDR 48
0
5
10
15
20
25
0 50 100 150 200 250 300 350 400
% T
ran
smit
tan
ce
Wavelength (nm)
RockSat-C 2013
CoDR 49
Retrieved from http://tid.uio.no/ozone/plott/spectrum_thumb.png
