GATEWAY TO SPACE SPRING 2006 DESIGN DOCUMENT

Transcription

1 Colorado Space Grant Consortium GATEWAY TO SPACE SPRING 2006 DESIGN DOCUMENT Team Ram-Rod Written by: Aaron Gardiner Tyler Murphy Vivian Phinney Farheen Rizvi Ali Toltz April 18, 2006 Revision C

2 Revision Log Revision Description Date A Conceptual Design Review March 2, 2006 B Preliminary Design Review March 23, 2006 C Critical Design Review April 18, 2006 D Analysis and Final Report May 2, 2006 Page 2 of 23

3 Table of Contents 1.0 Mission Overview Design Management Budget Test Plan and Results Expected Results Launch and Recovery Plan Appendix...21 Page 3 of 23

4 1.0 Mission Overview Helios will be developed in order to test the effectiveness of two different brands of sunscreen (same SPF) when exposed to scattered light. Helios will determine the amount of protection provided by various SPF s of sunscreen to ultraviolet radiation in the atmosphere, providing important information to the general public about the effectiveness of sunscreen. The environment under which this experiment will be conducted is one which cannot be simulated on the earth except within a laboratory. The conditional temperatures, atmospheric pressures, and ultraviolet light in space will reveal the true effectiveness of sunscreen. Helios will log pressure data from a barometric switch. This data will be used in conjunction with the Ideal Gas Law and the Hydrostatic Equation to determine ascent and decent rates of the satellite. 2.0 Design 2. 1 Design Overview Helios measures the increasing intensity of UV light as a function of altitude during the duration of the flight. It allows for light to enter the satellite through a window made of fused silica onto a rotating plate of epoxy board. Two plates of fused silica containing different brands of sunscreens are embedded into the board. Light that passes through the sunscreen will then travel through a UV filter, which is located underneath the rotating epoxy board. Any UV radiation that passes through the UV filter will then hit a photodiode sensor, which will create a current proportional to the photons that hit it. The current that it produces will be read out by a uni-polar transimpedance amplifier circuit, creating a slowly varying DC output voltage, which will then be sent to a HOBO data logger. The epoxy board will rotate by means of an open-looped motor. The data received from light falling on a brass plate (black filter), which will output the least amount of voltage of any of the samples, will enable the frequency rate of the motor to be determined, which will provide a means to calibrate when the various samples were exposed to the ultraviolet radiation in the scattered light. The satellite will contain a camera mounted to a nylon wedge to optimize the angle of the photographs to take pictures of the Earth. The satellite will also utilize a Barometric Switch to detect and log the pressure as a function of altitude to later utilize, in addition to the collected relative humidity data, in calculating the ascent and descent rates of the satellite. 2.2 Design of Experiment Module The epoxy board rotates freely during the flight. It consists of five different filters as illustrated in the figure below. Page 4 of 23

5 Model of Rotating Disk 1. Sunscreen 1 Consists of an inexpensive sunscreen enclosed in fused silica (Kroger SPF 35) 2. Sunscreen 2 Contains an expensive sunscreen enclosed in fused silica (Neutrogena SPF 35) 3. Black (Brass) Does not allow any light to pass through Indicator for one complete rotation of the wheel 4. Red Leak Filter (OG515) Only allows red leak to pass through (section 2.6) Use red leak data to subtract its affects from the output of the photodiodes from the other samples 5. Blank (Fused Silica) Allows all wavelengths of light to pass through Accounts for any absorption by fused silica plates before the scattered light falls on the sunscreen samples 2.3 Ozone Effects on Experiment Page 5 of 23

6 This experiment intends to test the true effectiveness of two sunscreens of equal sun protection factor (SPF) but differing commercial brand name. Because most of the UV light is absorbed by the ozone layer, the experiment will be conducted above the earth s atmosphere where effects of ozone are minimal. In this respect, the sunscreen will receive maximum UV radiation. 2.4 Sunscreen Data Data will be stored in the HOBO data logger in voltage form. The maximum amount of voltage that the HOBO can read is V. Since the photodiode is attached to the HOBO, its voltage needs to be in the same range. To do so, a feedback resistor is used with a high resistance (see appendix I for the method of calculation) to scale the changes in the current and ensure that the input voltage is always within V. 2.5 Photodiode Sensor Specification For this experiment, S photodiodes will be used. The plot below represents the performance of this sensor in response to different wavelengths of light. Figure 1: Figure shows the sensitivity of the S photodiode vs. wavelength of light. Its response to UV radiation ( nm) is approximately 0.12 Amperes/Watt. This sensor has a high UV sensitivity and is thus ideal for this experiment. 2.6 UV filter Specification In this experiment, a UG11 filter will be used. This filter allows significant amounts of UVA, UVB, UVC and red leak light to pass through. The plot below represents the transmittance of this filter to different wavelengths of light. Page 6 of 23

7 Figure 2: Figure illustrates the response of the filter to different wavelengths of light. It is most responsive to nm of light (UV light). This range is also consistent with the photodiode s range for response to the UV light. 2.7 Red Leak As inferred from Figure 2, UG11 filter also allows nm of light to pass through. This portion of the light spectra is referred to as the red leak. In this case, the expected UV light falling on the photodiode is over estimated. To discard the effects of the red leak on the amount of light falling on the photodiodes, a OG515 filter will be used. The plot below shows the performance of this filter for different wavelengths of light. Page 7 of 23

8 Figure 3: Figure shows the wavelengths of light that are able to pass through the OG515 filter. Only wavelengths greater than 500 nm can pass through. This data will be used to subtract the effects of red leak on the light falling on the photodiodes. 2.8 Hardware Overview: Final Parts List - 5 Fused silica plates o (a) To enclose the sunscreen within the epoxy board in order to prevent vaporization (b) minimize absorption of ultraviolet light due to the plate (c) use to create a window in the satellite to allow light in (d) one among 5 to act as a blank to account for absorption before light reaches sunscreen - Epoxy Board Disk o To rotate the various samples of sunscreen around the UV filter and photodiode sensors - UG11 UV Filter o To allow only ultraviolet light to pass through to the photodiode sensor - Red Leak Filter (OG515) o To account for red leak light falling on the photodiodes - Black (Brass) o To act as an indicator of one complete rotation of the epoxy board disk -Faraday Cage Page 8 of 23

9 o To contain the amplifier circuit and photodiodes - Photodiode Sensors (S ) o To detect photons passing through the sunscreen and UV filter, and create a proportional current that will pass through to the amplifier circuit - Uni polar Amplifier/Resistors o To create an amplifier circuit to detect the current created by the photodiodes, which produces a current read out proportional to the intensity of the photons. The current will pass through two separate feedback resistors (Rfeedback) which was calculated to be large enough to achieve a maximum dynamic range, and be sent to the U12 HOBO through two separate input voltage cables corresponding to the resistance they pass through (10kΩ/100kΩ). - First HOBO Data Logger H8 Series o External Temperature o Internal Temperature o Relative Humidity o DC Voltage output from the Barometric Switch - Second HOBO Data Logger U12 Series Provides a bit rate of 12 bit o DC Voltage output from the transimpedance amplifier circuit - Foam Core o To create the outer structure of the satellite - Heater o To maintain the internal temperature of the satellite above 0 Celsius throughout the duration of the flight -Insulation Foam o To help maintain the internal temperature of the satellite above 0 Celsius throughout the duration of the flight and provide protection to the various elements of the satellite -Nylon wedge o To mount the camera at a 4 degree angle relative to the plane of the bottom face of the satellite structure as calculated to optimize photograph of the Earth - Camera Mount Screw o To attach the camera the nylon wedge to stabilize the camera - Rotating Motor (9-18 VDC Hobby Motor) o 4-Speed Crank Axle Gearbox Page 9 of 23

10 o Provides high torque to rotate the epoxy board disk - Camera o To take and photographs of the Earth during flight Timer Circuit o To send a signal to actuate the camera at constant, controlled intervals - Barometric Switch o To detect and log pressure as a function of altitude, which will later be utilized, in addition to relative humidity rates, to determine the ascent/descent rates of the satellite -Voltage Regulator Circuit o To regulate the voltage input for the motor - Two Voltage Input Cables o To connect various electrical components of the satellite to the HOBO Data Logger. One will be used with the Barometric Switch and one with the amplifier circuit V Alkaline Batteries o To provide power to the 555 timer circuit -4.1V Nokia BL 5c Battery o To provide power to the amplifier circuit and the rotating motor - 9V Lithium Battery o To provide power to the heater - 3 Switches o To turn on the power to each electrical components of the satellite externally on launch day 2.9 Subsystem and Overall System Requirements Page 10 of 23

11 2.10 Design Drawings and Illustrations: Transimpedance amplifier circuit Model of Experiment and Circuitry Page 11 of 23

12 Design and Dimensions of Overall Outside and Inside Satellite Structure Page 12 of 23

13 Functional Block Diagram Page 13 of 23

14 3.0 Management 3.1 Organizational Chart Team Member Duties: 3.2 Schedule: February DEADLINES: Tuesday 2/14: Proposal Due Thursday 2/16: CoDO Slides Due Wednesday - 2/1 Friday 2/3 Wednesday 2/8 Wednesday 2/15 Saturday 2/18 Tuesday 2/28 Team Meeting: Discuss design Team Meeting: Freeze design Team Meeting: Integrate slides for CoDR and work on Proposal Team Meeting: Practice CoDR presentation Final list for hardware Meeting with Dr. Harder: Finalize schematics for Rev. A Award announcement in class March DEADLINES: Thursday 3/2: Design Doc. Rev. A Due Tuesday 3/23: CDR Slides Due Design Doc. Rev. B Due Wednesday 3/1 Thursday 3/2 Friday, - 3/3 Saturday 3/4 Team Meeting: Update on hardware progress Acquire all known hardware Shop seminar to all acquire access to machine shop Get sample rates from HOBO (Tyler & Vivian) Build Barometric Switch Voltage Divider Circuit Get Preliminary Design proposal for the camera mechanism Build first structural prototype Laser Cutter ITLL Page 14 of 23

15 Monday 3/6 Friday 3/10 Sunday 3/12 Wednesday 3/15 Design layout of the Epoxy Board Structure Finalize Dimensions of mirror Finalize mass budget Meeting at LASP with Dr. Harder: work on power supply diagram Second structural prototype built Finalize design for insulation Team Meeting: Amp. Circuit built Decision on Faraday Cage (mass?) Saturday 3/18 Team Meeting: CDR slides and Rev. B Integrate Amp. Circuit with Photodiodes in Faraday Cage Finalize subject of motor, order Wednesday 3/22 Team Meeting: Integrate teams slides for CDR Finish Design Doc. Rev. B Saturday 3/25 Work on Optical Interrupter Circuit Circuits Lab Tuesday 3/28 Work on Optical Interrupter Circuit more Finalize the Power Subsystem Thursday 3/30 Machine Shop: Finish insulation April DEADLINES: Tuesday 4/18: Design Doc. Rev. C Bring All Hardware Thursday 4/20: Launch Readiness Review Presentation and slides DUE Early Turn-In (EXTRA CREDIT) Friday 4/21: Satellite DUE 1:30 pm Saturday 4/22: Launch Day (leave by 5:30am) Saturday 4/1 Monday 4/3 Wednesday 4/5 Saturday 4/8 Sunday 4/9 Wednesday 4/12 Friday 3/14 Saturday 3/15 Machine Shop: Attach Faraday Cage to motor Finish building insulation Team Meeting: Decide whether or not to drop the Optical Interrupter Circuit discuss options Drop Test: Bridge in ITLL and down stars in DLC Whip Test: hang and swing Team Meeting: Rebuild insulation Discuss Cold Test Final Integration Cold Test #1: 8-10:30pm Cold Test #2: 2:30-5am Work on final adjustments post-cold test Fix Power system Prep for Cold Test#3 Cold Test #3 Page 15 of 23

16 Sunday 3/16 Cold Test #4 Wednesday 4/19 Thursday 4/20 Team Meeting: Any final adjustments Prepare for LRR presentation Early turn in May DEADLINES: Tuesday 5/2: Final Presentation Due Saturday 5/6: Design Doc. Rev. D Due 4.0 Budget Mass and Cost: Components Mass (g) Cost ($) 1 Structure (foam core) 123 provided (instructor) 2 Foam Insulation 34 provided (instructor) Experiment Disk with filters 3 (epoxy) 33 provided (LASP) 4 Motor and Perf Board 47 5 Barometric Switch 66 provided (LASP) 6 Faraday Cage, UV Filter provided (LASP) and Amplifier Circuit 71 provided 7 HOBO H8 15 (instructor) 8 HOBO U12 (and software) 20 $200 provided 9 3 Switches 12 (instructor) 10 Camera with Film and Battery 140 provided (instructor) Timer Circuit 28 provided (instructor) 12 Voltage Regulator Circuit 8 provided (LASP) 5 x $10.00 = 13 9 V Battery (Lithium) (5) 37 $ V Nokia Battery 22.5 provided (team) provided 15 Heater 16 (instructor) V Battery 34 provided (instructor) 17 Battery Connector 2 provided (instructor) 18 Wiring Miscellaneous $50.00 Total $300 Page 16 of 23

17 5.0 Test Plan and Results Design Test Overview: I. Temperature Test a. Helios was tested to ensure that its internal temperature will remain above 0ºCelsius by placing it in a foam cooler with dry ice in it for two hours (a simulated duration of the flight). b. The following plot represents the internal temperature of the satellite for 2.5 hours. The internal temperature remained above 0ºC at all times during the test. Figure 3: The temperature remains above 0ºC at all times during the test. Page 17 of 23

18 Figure 4: Plot shows the outside temperature dropping from 30º C to -20º C. II. Motor Test a. Helios was tested to ensure that the motor spins the experiment disk for the entirety of the flight in the cold environment. b. The experiment was placed in a cold environment (simulated utilizing dry ice) for 2.5 hours. The motor was tested with a 4.1V battery. The motor was found to still have been spinning at the end of the test. c. The test results demonstrated that the 4.1V battery will successfully run the motor through the duration of the flight. III. Weight Test a. Helios was tested to see if total weight remained below or equal to the allotted 775 grams, by weighing the final product in the ITLL. IV. Structure Test (Drop) a. Helios was tested to ensure the sturdiness of the structural design by dropping it off the bridge in the Engineering Center (bridging the DLC to the ITLL). b. The structure endured no damage during this test. c. The test results demonstrated that the designed structure will be able to endure a freefall and impact. We are confident in our structure's design, as the structure endured no damage during this test. Page 18 of 23

19 V. Structure Test (Kicking Down Stairs) a. Helios was tested to ensure the sturdiness of the structural design by kicking it down the stairs, and ensuring that the payload withstands any stress. Kicking it down the stairs simulates any stress that the satellite will endure during the impact of landing. b. The structure endured minimal damage during this test. The aluminum rod which runs through our structure to encase the nylon string during flight was bent at both ends. Also, the shape of one wall of the structure was affected as all of the weight within the structure shifted into it. c. The test results demonstrated that the designed structure is sturdy enough to withstand impact. We are confident in our structure s design as it withheld and remained completely sealed after this structural test. VI. Whiplash Test a. Helios was tested to ensure that the string will remain attached during the duration of its flight by whipping it around by its string for approximately 60 seconds to ensure the structure can withstand the stress. b. The structure endured almost no damage during this test. The aluminum rod which runs through the structure was slightly bent at both ends. Otherwise, the structure remained wholly intact. c. The test results demonstrated that the designed structure can endure the whipping of the nylon string during flight as it incurred minimal damage during this test VII. Optics Test a. Helios was tested to ensure a proper image can be obtained during flight without interference from the outer structure or the insulation. b. The camera and 555 timer were placed within the satellite. Power to the 555 timer was activated, and the camera took pictures approximately every 2 minutes and 40 seconds. The images were developed, and when studies revealed minimal interference from the satellite structure and a clear and focused image. c. The test results demonstrated that the optical systems on the satellite will function properly, and the images will not suffer from interference from the satellite structure nor insulation. 6.0 Expected Results I) Barometric Switch The barometric switch will allow us to calculate the altitude that the satellite is at every second. To do this, we will mark down the switches initial position before launch and use this point to count our data from. The data will be in the form of logical highs and logical lows, corresponding to when the wiper of the barometric switch were touching a contact and off a contact. Each contact it touches corresponds to a predetermined pressure, which Page 19 of 23

20 we can find post-flight on a calibrated chart specific to the device. Knowing the pressure and the Temperature (another input to the HOBO), we can calculate the air density. This information can then be used in the Hydrostatic Equation to determine the change in altitude as a function of pressure, which as previously calculated was a pressure or time. This will then translate into a distance traveled over one second, i.e. assent and descent rates. II) Transimpedence Amplifier Circuit The amplifying circuit will be used to measure the amount of UV light that the samples are exposed to. In order to do this we will use a UG11 filter that allows the UV light to pass through and filters out almost all other light. The one error that this filter has is that it allows a significant amount of red leak through. To compensate for this error, we will be comparing all of the data points from the other filter to an OG515 filter which blocks UV and allows the red leak to pass through. By subtracting the measurement of the red leak filter from the other, we will know the magnitude of the UV light. III) HOBOs The HOBOs that we are using are the supplied H as well as a U The reason that we are using the higher HOBO model is that the data that we will be measuring over the amplifying circuit will have small changes between data points. By using a HOBO with a higher bit data recording level, the data will be more precise. 7.0 Launch and Recovery 7.1 Launch Plans On April 22 nd, 2006, the members of Team Ram-Rod will depart for Windsor Colorado in 3 different automobiles. Upon arrival, Team Ram-Rod will use the three external switches to activate the power sources to the various electrical components of the satellite just before launch. The first switch will activate the rotating motor and amplifier circuit. The second switch will activate the heater. The third switch will activate the 555 timer circuit. This will ensure that the power in the satellite does not begin dissipating until the actual launch and is therefore not wasted. To ensure the safety of our team members and others present, Team Ram-Rod will follow all safety guidelines outlined and use a great deal of common sense. Protective eyewear will be worn when working with circuitry, if necessary, at the launch site. One team member will be running with the satellite in hand as the balloon is released. This team member will make sure to continue running until the satellite is airborne. Page 20 of 23

21 7.2 Recovery Plans All members of Team Ram-Rod, with the exception of Tyler Murphy, will attend the recovery. Aaron Gardiner will actively chase the balloon satellite, and Vivian Phinney, Allison Toltz, and Farheen Rizvi will follow. Upon recovering the satellite, great care will be taken to ensure the continued safety of the valuable internal components. The experimental data contained within the HOBO Data Logger U12 Series will be analyzed by means of the accompanying software. The film in the camera will be developed to examine the photographs taken. The barometric switch will also be analyzed in order to obtain the changing pressure over time information. The internal temperature, external temperature, and humidity data, stored in the second HOBO Data Logger H8 Series, will be analyzed by means of the accompanying software. 8.0 Appendix I Method for Calculation the Resistance of the Feedback Resistor Plot 1: UG11 filter performance under exposure Page 21 of 23

22 Plot 2: Solar Irradiance1 Plot 3: S Photodiode Performance under light Determine from plot 1 wavelength at maximum filter transmission (320 nm, 80%) Full Width Half Maximum (FWHM) of UG11 filter Determine from plot 2 Page 22 of 23

23 Irradiance (watts/m2 nm) Consider 80% Irradiance reaching photodiode due to absorption by UG11 filter Not looking at direct sun Irradiance intensity is 100 times less Actual Irradiance = 0.008*Irradiance Determine area of photodiode (4.1 mm diameter) Calculate number of watt falling on the photodiodes from area and FWHM Compute amount of current produced per watt from plot 3 Calculate the value of resistor (in Ω) from V = IR Page 23 of 23