Gateway to Space ASEN/ASTR 2500November 9, 2007

Colorado Space Grant Consortium

GATEWAY TO SPACE

FALL 2007

DESIGN DOCUMENT

Team #1: Team Ramrod

Written by:

Daniel Armel, Michaela Cui, Andrew Grimaldi,

Kyle Kemble, Silvia Peckham, Chris Sawyer,

Kelsey Whitesell

October 16, 2007

Revision C

Revision Log

Revision / Description / Date
A / Conceptual Design Review / October 4, 2007
B / Preliminary Design Review / October 9, 2007
C / Critical Design / November 8, 2007
D / Analysis and Final Report / November 29, 2007

Table of Contents

1.0 Mission Overview………………………………………………………………………. 4

1.1 Mission Statement.……………………………………………………………… 4

1.2 Mission Background……………………………………………………………. 4

1.3 Result Predictions………………………………………………………………. 4

2.0 Requirements Flow Down………………………………………………………………. 5

3.0 Design.…………………………………………………………………………………... 7

3.1 RFP Compliance………………………………………………………………… 7

3.2 Design Discussion………………………………………………………………. 8

3.3 Components, Mass and Budget List……………………………………………..10

3.4 Design Drawings…………….………………………………………………….. 11

3.5 Functional Block Diagram……………………………………………………… 12

4.0 Management…………………………………………………………………………….. 14

4.1 Organizational Chart……………………………………………………………. 14

4.2 Mission Schedule………………………………………………….……………. 14

5.0 Budget…………………………………………………………………………………... 15

5.1 Mass Budget…………………………………………………………………….. 15

5.2 Mission Budget………………………………………………………………….. 16

6.0 Test Plan and Results……………………………………………………………………. 16

6.2 Test Results………………………………………………………………………18

7.0 Expected Results………………………………………………………………………….22

8.0 Launch and Recovery…………………………………………………………………….23

8.1 Launch and Recovery Plan……………………………………………………….23
1.0 Mission Overview

1.1 Mission Statement (M1)

The primary mission is to launch a small satellite in compliance with the RFP and Design Document to an altitude of thirty kilometers with other small satellites connected to a balloon launch vehicle, to quantitatively measure the amount of infrared radiation present at or below this altitude; and recover said vehicle to return accurate and comparable results.

1.2 Mission Background

Recently there has been significant interest in the possibility of taking images of space from stations in the upper atmosphere (‘near space’) at altitudes around 30 km above Earth. At this altitude, imaging instruments would be above the Earth’s weather and about 90% of the particles in its atmosphere, allowing for a wider range of wavelengths to be detected and for images to be significantly clearer than those taken from ground-based observatories. Cold temperatures in the upper-atmosphere also help reduce dark current in imaging devices like CCD cameras. Dark current is the current generated by heat that flows even when there are no photons entering a photosensitive device.

Infrared (IR) imaging also has advantages when taking images of near space. IR detectors are better at detecting cool objects, like forming and evolved starts. Interstellar gas is also more transparent at IR wavelengths (1 mm- 750 nm) than at visible wavelengths (750-400 nm). It is important to determine if there is sufficient infrared sky brightness in order to obtain high quality, clear infrared images from a platform based at approximate altitudes of 30 km.

This mission involves taking measurements of the IR radiation at altitudes in order to explore the benefits of orbiting satellites, blimps, or other vehicles in near space for imaging purposes.

The IR radiation recorded is expected to be noticeably greater thanthat on the ground. Theoretically, the radiation at higher altitudes is greater due to the lack of protective atmosphere in the case of near space altitudes and due to radiation reflection within the atmosphere.

2.0 Requirements Flow Down

From the mission statement (M1) listed in the mission overview, level 0 requirements include the mass and financial costs of the spacecraft; launch method, location, and time; target altitude for the spacecraft; and accuracy of the measurements taken by the spacecraft. Level 1 requirements include specific mission objectives derived from the level 0 requirements such as apportionment of the budget and general requirements for the mission. Level 2 requirements include specific requirements listed in the RFP, and more detailed requirements derived from level 1.

Level / Designation / Requirement / References
0 / O1 / The spacecraft shall be a BalloonSat with mass at or below 800 grams and total financial costs at or below $200 in compliance with the RFP. / M1
O2 / The spacecraft shall be launched from Windsor, Colorado and recovered on November 10, 2007. / M1
O3 / The spacecraft shall be configured to attach to a variable position on a string, with 10 other satellites, connected to the balloon launch vehicle. / M1
O4 / The instruments of the spacecraft shall remain intact and functional during a 90 minute ascent to an altitude of 30 km and a 45 minute descent including landing. / M1
O5 / The spacecraft and design document shall meet all other requirements stated in the RFP template. / M1
S1 / The payload shall record the number of infrared light particles during a 90 minute ascent within an altitude range of 0 and 30 km. / M1
S2 / The payload shall incorporate no less than two additional systems of radiation measurement for comparison analysis. / M1
1 / O1.1 / The mass and financial budget shall be divided proportionally among the structural, circuit and science components. / O1
O1.2 / The financial budget shall allow for the purchasing of spare parts. / O1
O2.1 / All systems of the spacecraft shall be completed and tested by November 3, 2007. / O2
O2.2 / The team shall provide A vehicle to travel to the launch and landing site and recover the spacecraft after launch. / O2
O3.1 / The spacecraft shall be secured to a string provided by the balloon launch vehicle over the entire 135 minute flight without severing the string at any point. / O3
O3.2 / The spacecraft shall not hinder the functionality of other satellites attached to the balloon launch vehicle in any way. / O3
O4.1 / The spacecraft shall be functional at exterior temperatures at or above -20 degrees Celsius. / O4
O4.2 / The structure of the spacecraft and the circuitry of the payload shall remain intact after colliding with the ground at a force equal to 15 times the force of gravity. / O4
O4.3 / The structure of the spacecraft shall support and enclose the main circuitry of the payload and all instruments which do not require direct contact with the exterior environment. / O4
O4.4 / The components of the spacecraft shall each be provided with the minimum voltage required to operate over the entire 135 minute flight. / O4
O5.1 / All RFP template requirements shall be satisfied in the design document. / O5
O5.2 / All RFP template requirements shall be satisfied in the construction of the satellite. / O5
S1.1 / The payload shall measure wavelengths between 1mm and 750 nm / S1
S1.2 / The payload shall additionally measure infrared particles within a 30mm radius from distant sources in space. / S1
S2.1 / The payload shall additionally record digital photographs of the exterior environment. / S2
2 / O1.1.1 / All structural components of the BalloonSat shall not exceed a total mass of 400 grams and a total cost of $75.00. / O1.1
O1.1.2 / All onboard circuitry excluding the scientific instruments shall not exceed a total mass of 180 grams and a total cost of $50.00. / O1.1
O1.1.3 / All scientific equipment shall not exceed a total mass of 220 grams and a total cost of $75.00. / O1.1
O2.1.1 / The spacecraft shall survive a drop test, cold test, whip test, photodiode calibration test, and functional test of each subsystem. / O2.1
O2.2.1 / The recovery vehicle shall be an all wheel vehicle capable of travelling off road at approximate 500 miles. / O2.2
O3.1.1 / The harness shall be composed of a nonmetal cylinder with smoothed edges. / O3.1
O3.2.1 / The payload shall include no functional radio devices of any kind. / O3.2
O4.1.1 / Internal temperature of the spacecraft shall remain above 0 degrees Celsius at all times during flight. / O4.1
O4.4.1 / 54 volts shall be divided among the various components of the spacecraft in order to insure that the minimum voltage required is supplied to the components at all times during the flight. / O4.4
O5.1.1 / Only metric units shall be utilized in the proposal document. / O5.1
O5.1.2 / A final report shall be submitted along with a video documenting the design, construction, and post-launch of the mission. / O5.1
O5.2.1 / The structure of the satellite shall consist of foam core siding, thermal blanket, and aluminum substructure. / O5.2
O5.2.3 / The cable harness shall be nonmetal. / O5.2
O5.2.4 / Lithium ion batteries shall be used as opposed to alkaline batteries because they have less mass and are more robust at cold temperatures. / O5.2
O5.2.5 / The HP E427 digital camera shall be used to compare the altitude and photodiode data with visible light photographs. / O5.2
O5.2.6 / The H.O.B.O. data logger shall be implemented along with an external temperature probe and cable. / O5.2
O5.2.7 / Contact information and a United States flag shall be prominently displayed on the exterior of the satellite. / O5.2
O5.2.8 / No living organisms shall be harmed in the making of, or implemented in the final design of the satellite. / O5.2

3.0 Design

3.1 RFP Compliance

  1. Only metric units shall be utilized in the proposal document.
  2. An additional science payload has been implemented involving the testing of sky brightness during the ascent of the balloon using a photodiodes measuring light above 750 nm.
  3. The photodiodes shall be housed at opposite extremities of the satellite allowing the cold fingers to be exposed to the outside environment.
  4. Plastic tubing provided in the kit shall be implemented to run through the center of the satellite to be used as the cable harness connecting the satellite to the launch vehicle.
  5. The structure of the satellite shall consist of the following:

a. Foam core siding

b. Thermal Blanket

  1. Lithium Ion batteries shall be used as opposed to alkaline batteries because they have less mass and are more robust at cold temperatures.
  2. Team Ramrod shall contact EOSS to obtain altimeter data from their payload.

The HP E427 digital camera shall be used to compare the altitude and photodiode data with visible light photographs.

  1. The H.O.B.O. data logger shall be implemented along with an external temperature probe and cable.
  2. Contact information and a United States flag shall be prominently displayed on the exterior of the satellite.
  3. No living organisms shall be harmed in the making of, or implemented in the final design of the satellite.
  4. The satellite shall be in working condition within one week of launch on November 10th, 2007.
  5. A final report shall be submitted along with a video documenting the design, construction, and post-launch of the mission.

3.1 Design Discussion

The satellite known as Alpha Omegashall consist of a three-dimensional trapezoidal figure. This trapezoid will be comprised of two sections. The middle section is a cube with a volume of 2744 cm3, and the outer section is a block shaped as isosceles triangles with areas of 1372 cm3. Each of the triangular section will house a photodiode, circuitry, and cold finger.

The center cube shall be the main compartment of the satellite containing the essential electronics. The siding of the entire structure will utilize a triple-layer method. The outer most layer shall be comprised of foam core to prevent contamination of the inner workings of the satellite. The second layer shall be made of a Mylar blanket to reflect IR radiation emitted from the inside of the satellite. Along with multiple passive thermal systems used during the flight, an active system will be used as well. This system will consist of three resistors mounted separately on three of the inner walls to produce heat for the satellite during flight where temperatures are expected to approach -80o Celsius.

There will be one photodiode in place for the sky brightness test. Itwill collect sky brightness data via the photocurrent from a photodiode at wavelengths above 750 nm, in the near IR and IR spectrum. The wavelength of light collected by the diode shall be controlled using a #25 Wratten gel filter. The photodiode will be mounted at the focus point of a convex lens placed 19 cmfrom the opening of the telescope tube. This lens will serve to focus light from the atmosphere onto the photodiode and will also serve to define the field of view for the photodiode. The schematic for the photometer is shown:

Photons received by the photodiode will induce a current that will flow through the circuit above, grounded to apower source consisting of two 12 volt batteries. An integrating capacitor with convert the current input induced by photons activating P-N junctures on the photodiode into a voltage output. That output will be amplified by the two op-amplifiers into a readable value. A diode clamp (not shown in the schematic) will be used to bring the control the voltage output, keeping it between 0 and 5 V, the output readings compatible with the Basic Stamp.The Basic Stamp sends a voltage to the reed relay that prompts the relay to empty the capacitor. The rate of change of the voltage output (V) over time (s) is the photocurrent (A) flowing through the photodiode. Photocurrent is related to sky brightness (luminosity) by the following equation:

L = ((4 f2) / (π A d2 k)) I

where f is the distance from the calibrating pinhole camera to the photodiode, A is the active area of the photodiode, d is the diameter of the calibrating pinhole, k is the sensitivity of the diode in amperes/watt, and I is the photocurrent.

Power for the craft will come in the form of lithium ion batteries. These batteries hold more power in a smaller package, thus reducing the weight. As the temperature drops with therise in altitude, traditional alkaline batteries falter in their performance while lithium batteries maintain their levels of performance for longer periods of time at the same temperatures.

3.3 Components, Mass and Budget Table

Structural Engineering & Thermal / Components / Description / Quantity / Mass / Cost
Frame & Siding / Foam Core / The outer layer of defense, protects from the elements / 2 sheets / 50 grams / --
Aluminum / Substructure / 2 sheets / 75g / $25
Thermal / Mylar / Radiation Insulator / 2 sheets / 2g / $4.13
Heaters / Active Thermal System / 3 / 10g / --
Harness / Connecting Tube / Vertically mounted tube / 1 units / 5g / --
Connecting Plugs / Acrylic stoppers for the connecting tube / 2 units / 5g / --
Command & Data Handling / Data Logging / H.O.B.O / Temperature & Humidity Detector / 1 unit / 83g / --
BASIC Stamp / Data storage & processing / 1 unit / 15g / $50
Timing Circuit / 555 Timer / Timer For Camera / 1 unit / 26g / --
Power / Batteries / Lithium 9 Volt; Provide power for satellite / 6 units / 204g / --
Science / Photodiodes / Photodiode / Capture photons and convert into voltage values / 2 units / 120g / --
Lens / Convex lens fitted above the photodiode / 2 units / 10g / --
Filter / Ultraviolet & Infrared / 2 units / 10g / --
Cold Finger / Metal plate that wicks heat away from the photodiode / 2 units / 10g / --
Science Circuit / Resistor & Amplifier / 2 units / 10g / $20
Protective Tubing / Housing for photodiodes / 2 units / 10g / --
Cameras / HP E427 Camera / Photography / 1 unit / 137g / --
Total Mass and Cost / 784 grams / $99.13

3.4 Design Drawings

3.5 Functional Block Diagram

3.6 Subsystem and Overall System Requirements

Subsystem / Component / Requirements
Structure / Main Structure /
  • A main structure shall exist such that the wings of the spacecraft shall connect to two of its opposing sides barring the top and bottom
  • The main structure of the space craft shall house all components of the spacecraft barring the photometers, temperature sensor, and two of the heaters

Wings /
  • Wings shall exist such that they enclose the main structure on two of its opposing sides barring the top and bottom
  • The wings shall remain fastened to the main structure of the spacecraft at all times
  • The wings shall house all launch switches used on the spacecraft
  • The wings shall allow for easy access to the main circuitry of the spacecraft
  • The wings shall be secured at all times during flight with a locking mechanism

Foam Core /
  • Foam core material shall house all components of the spacecraft barring the connector tube, and temperature sensor

Mylar /
  • The mylar shall house all components of the spacecraft within the foam core
  • The mylar shall reflect 80% of IR radiation from the heaters

Harness /
  • A harness shall be mounted vertically at the center of the spacecraft
  • The harness shall be able to maintain structural integrity when 9 Newtons of force is applied to it vertically
  • The string shall be securely fastened to the harness such that no part of the string moves vertically within the boundaries of the harness
  • The string shall remain intact on all points

CDH / Power /
  • All power shall be supplied by lithium ion batteries
  • The total voltage for all circuits shall be kept at a minimum of 54 volts
  • At least 9 volts of power shall be provided to all electrical and scientific components within the space craft barring the HOBO, and Camera
  • All components shall be grounded to the negative leads of the batteries or to a common ground
  • No components shall be grounded to the frame
  • All electrical wiring shall be insulated and kept at the minimum length possible

Switches /
  • There shall be a circuit switch for each external power source of the spacecraft
  • All switches shall remain on the same side of the main structure

Basic Stamp /
  • The Basic Stamp shall be supplied with a minimum of 5 volts at all times during the flight
  • The Basic Stamp shall take in analog voltage values as input
  • The Basic Stamp shall convert analog voltage values to interpretable data
  • The Basic Stamp shall contain onboard memory

HOBO /
  • The HOBO shall be configured two weeks before launch to begin recording during the flight
  • The HOBO shall remain isolated from all external power sources and switches during the flight
  • The HOBO shall be calibrated to take in data for the entire flight as frequently as possible
  • The HOBO shall measure internal humidity, the temperature of the photometers and external temperature during the flight
  • The HOBO shall have 3 volts of power at all times during the flight

Heating Resistors /
  • The heating circuit shall be supplied with 12 volts at all times during the flight
  • Temperatures within the spacecraft shall remain above 0 at all times during the flight

555 Timer /
  • The 555 Timer shall be supplied with a minimum of 12 volts at all times during the flight
  • The 555 Timer shall connect to and control a modified digital camera
  • The timer shall send a signal to the camera to take a picture every 45 seconds during the flight

Science / Photometer /
  • The temperature of the photometer shall be both measurable and at or below -60 degrees Celcius at all times during the 135 minute flight
  • The photometer shall be supplied with 12 volts at all times during the flight
  • The mouth of the telescope shall never face directly into the sun
  • The photometer shall be calibrated to 1 degree of accuracy

Camera /
  • The camera shall be configured to run on a digital signal provided by the 555Timer
  • The camera shall record stable photographs during the flight
  • The camera shall record photographs at intervals of 45 seconds

4.0 Management