PANSAT - Worcester Polytechnic Institute · PANSAT power requirements. As for the data transmission model , ground station view time durations were obtained from the orbital model

WPI Nanosat 3 Program - Annual Report PANSAT

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PANSATPowder Metallurgy And Navigation Satellite

Annual Report

26 September 2003

Fred J. Looft, PIProfessor and Head

Electrical and Computer EngineeringWorcester Polytechnic Institute

Worcester, MA 01609

Submitted to:

Air Force Office of Scientific ResearchUniversity Nanosat Program - Nanosat 3

AFOSR F49620-03-1-0133


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TABLE OF CONTENTS

1. Synopsis .......................................................................................................................................................32. Program Startup...........................................................................................................................................3

Spring 2003 Start-Up.......................................................................................................................................4Student Selection.........................................................................................................................................4Summer Student Selection ..........................................................................................................................4Safety Exam.................................................................................................................................................4

SCR Teleconference ........................................................................................................................................43. Summer - 2003 ............................................................................................................................................5

Project Teams ..................................................................................................................................................5Materials and Structures..............................................................................................................................5System Design or Operational Scenario.....................................................................................................5Orbital Modeling .........................................................................................................................................6

Shot Workshop ................................................................................................................................................6Preliminary Design Review.............................................................................................................................7

4. Current PANSAT Activities .......................................................................................................................7Program Organization......................................................................................................................................7Design Teams ..................................................................................................................................................8

1. Power Systems ........................................................................................................................................82. Sensors.....................................................................................................................................................83. Communications - Tx/Rx/TNC ..............................................................................................................84a. Circularly-Polarized Single-Band Patch Antenna................................................................................94b. Ground Tracking Antenna ....................................................................................................................95. Navigation ...............................................................................................................................................96. TMR & UniProcessor ...........................................................................................................................107. Satellite Attitude Control ......................................................................................................................108. Bus Structure .........................................................................................................................................109. Thermal Analysis ..................................................................................................................................10

Innovative Technologies Under Development .............................................................................................11Satellite Fabrication Workshop.....................................................................................................................11

5. Summary and Conclusions........................................................................................................................11


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1. SYNOPSIS

This document summarizes the first eight months1 of activities associated with the WPI Nanosat-3 (N3)

development program proposed in response to a BAA by the AFOSR and AIAA for the development of a

nanosat that addresses specific scientific and educational objectives (University Nanosat Program,AFOSR BAA 2003-02) . Building on the strengths of the WPI faculty research and a rich thirty-yearhistory of projects based education, we proposed to have WPI undergraduate and graduate student teams,under the direct guidance of WPI faculty, develop a nanosat and that this nanosat be used as a vehicle to

investigate;

a. a GPS based navigation and orientation determination system

b. the use of a powder metallurgy (P/M) component design methods to develop the primary satellitebus structure

Within the context of the original proposal, the first year of development was to be focused on the

development of a fully functional prototype nanosat. This development effort was to be accomplishedthrough the integrated efforts of student teams. During the second year of the program, it was proposed

that a fully functional nanosat would be integrated and tested for space flight. Provided an opportunityexisted, the nanosat would then be scheduled for launch and a mechanism put in place to manage theevent.

The material that follows this brief introduction details what we have accomplished toward our first year

goals. In particular, we address i) what we accomplished during the first summer of activity (2003), ii)how we have organized our projects and student teams to focus on specific technology and operational

development areas, iii) the accomplishments of our students relative to required and optionalAFOSR/NANOSAT-3 program activities, iv) our current development efforts, and finally v) our plans forthe remainder of our first year development effort.

2. PROGRAM STARTUP

WPI (Worcester Polytechnic Institute) is unique in that all students are required to complete a significant

project component as one of their degree requirements. This project requirement (internally known as theMajor Qualifying Project, or simply MQP) will be referred to in this report as the Senior Project (SP)requirement. Unlike most colleges and universities where the SP is simply one design class used to

satisfy the ABET2 capstone design requirement for program accreditation, the WPI SP represents a fullthree courses of equivalent effort, typically during a student’s fourth year of study3.

Within the context of the WPI Nanosat program, the SP is being used as a basis for nanosat development.

Specifically, every single student team and every design project that the WPI Nanosat Programencompasses is based on students using their nanosat design project to satisfy their SP designrequirement. A significant benefit to the WPI Nanosat program is that WPI students are use to working

on teams toward complex goals, have experience with detailed and high quality documentation

1 March - October, 20032 Accreditation Board for Engineering and Technology3 WPI operates on a quarter basis, the terms being labeled A-B-C-D with a fifth E term during the summer.


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development, and develop their course schedules and daily activities around group meetings, informationcollection, and other classical project work related activities.

Spring 2003 Start-Up

Student Selection

The WPI Nanosat projects program was announced during C term, 2003 with a broadcast solicitation for

students in the Mechanical and Electrical/Computer Engineering areas (ME, ECE) and Computer Science(CS). Subsequently, students applied to the program, were interviewed, and eventually selected to workon development teams that would start work in A term, 2003 (late August of 2003). In other words, in

spite of the grant being awarded and announced in early 2003, the bulk of the design and developmentwork could not actually start until August 2003, primarily because of WPI SP scheduling issues andbecause most students would not be around for the summer.

Summer Student Selection

Concurrent with fall student team member selection, three students were selected to start work on the

WPI Nanosat Project immediately after classes were over for the academic year (AY - May, 2003).These three paid summer students were;

Catherine Price ME senior, focus on structures, materials, design and analysis

David Belliveau ME senior, focus on structures, materials, design and analysis

Himanshu Agrawal ECE senior, focus on digital and analog design, signals and systems

In addition, a fourth student who was interested in completing his SD project for academic credit, and

hence not a paid summer student,

Nate Chenerack ECE senior, focus on systems, signals and design

was recruited. Specific summer activities completed by these, and other students, are described in detail

below.

Safety Exam

Immediately after the student selection process was completed, and prior to the end of the last quarter of

AY 2002-03 (D term), all WPI Nanosat-3 team members were contacted and assigned specific sections ofthe nanosat Safety Exam. Prof. Robert Labonte’ (ECE) coordinated the dissemination of exam sections,

the assignment of specific reading topics, and the collection of exam results. Once all exam sectionswere returned, Prof. Labonte’ and senior ECE student Himanshu Agrawal reviewed the exam answers,collated the material, and submitted the solutions to the AFOSR for grading. This exam was particularlydifficult for the WPI Nanosat Projects organization since this exam had to be administered prior to any

students actually working on any part of the WPI Nanosat Projects program.

SCR Teleconference

Also immediately prior to the end of D term, 2003, the four students who were selected for summeremployment and project development (Agrawal, Belliveau, Chenerack, Price) were asked to focus on the

SCR teleconference scheduled for April, 2003. These students were tasked with reading, studying andunderstanding the original WPI Nanosat-3 proposal, understanding all aspects of the proposed systemdesign, and becoming sufficiently conversant with the design and program objectives to be able to


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represent WPI during the SCR teleconference. Since the slides used for the SCR have been previouslyavailable to the AFOSR Nanosat 3 office, they will not be reproduced here. However, Appendix Icontains the comments received subsequent to our SCR.

3. SUMMER - 2003

Summer activates for the WPI Nanosat program started immediately after school was out in mid-May,

2003. The goals for the summer student teams were to;

• create an operational model of the satellite that could be used to develop operational and system

component design constraints,

• collect detailed technical information that would be needed to start the detailed design ofmechanical and electrical systems when classes started again in the fall,

• identify system and operational issues, problems and design constraints that would need to be

addressed prior to full system design,

• refine the proposed system technical and operational design based on the data and information

collected, and

• develop documentation and presentation materials needed for the August, 2003 Preliminary

Design Review (PDR).

Project Teams

To address the summer team goals, the summer students were loosely organized into technology or

information development teams. These teams, goals, objectives and summer accomplishments arebriefly described below.

Materials and Structures

Three students addressed the following topics.

• learn about powder metallurgy (PM) design and manufacturing techniques� visit a PM manufacturing facility, discuss manufacturing and PM processing with an engineer

at the PM facility

� develop an understanding of the material properties that any PM component would need toexhibit if used on the WPI nanosat

� develop a detailed understanding of the material properties of 6061-T6 aluminum as the “goldstandard” against which all PM structural components would be compared and judged.

System Design or Operational Scenario

The ECE and ME students who worked together to address system design and operational scenarios, were

focused on the following topics.

• develop a model to determine the power available from the sun for several different nanosatconfigurations� compare round, square, penta-, hexa-, and octagon shaped satellites for power generation� compare and study different types of satellite stabilization systems, with a focus on how they

affect power availability, antenna pointing (communication) issues, and heating/cooling.


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Orbital Modeling4

A single ECE student elected to work on his SP during this past summer. The purpose of this project

was to create an orbital simulation of a satellite which could be used as an aid in the preliminary designprocess of WPI’s nanosat that will compete as part of the University Nanosat student satellite designcompetition.

The first step in the preliminary design process of PANSAT was to create an orbital model. This model

was created using Satellite Tool Kit (STK), a commercial program that can be used to simulate a satellite

in orbit, given its classical orbital elements. Numerous reports were then generated by STK thatdescribed the satellite’s orbit and parameters associated with the orbit. The reports related to the orbitalmodel dealt with position acquisition in terms of latitude and longitude as well as ground station azimuthand elevation angles. This model also generated other useful reports that influenced the design of the

power and communication subsystem design.

The power model addressed the generation, storage, and distribution of PANSAT’s5 Electrical Power

System (EPS). This model was based on the use of solar cells for power generation and secondarybatteries for energy storage. Subsequently, a power budget was generated based on the proposedelectrical components for the satellite. Model results based on maximum eclipse and sunlight durationcalculations were then performed to determine the required area and efficiency of the solar cells to meet

PANSAT power requirements.

As for the data transmission model, ground station view time durations were obtained from the orbital

model to determine the amount of time that would be required to transmit data to Earth. The satellite wasmodeled for a period of one month, during which reports were generated that determined the minimum,maximum, and mean in-view time durations of the satellite from a particular point on the surface of the

Earth. A bit generation chart was also created that tallied the amount of the data that would be collectedfor the maximum time that the satellite was out-of-view from the ground station, which was used todetermine the amount of onboard memory necessary for this data collection.

The orbital model allowed the user to generate numerous useful reports that determine location and define

parameters for numerous subsystems. The model also allowed the user to generate two dimensionalground tracks of the satellites.

A copy of the final, complete project can be obtained from the following individuals.

Nathan Chenarak [email protected] (508) 792-9880

Fred J. Looft [email protected] (508) 831-5231

Shot Workshop

In June, 2003, four students were sent to the AFRL SHOT workshop. At this workshop, the WPI

students collaborated to develop a balloon launched satellite, and then participated in the launching,tracking and recovery of the balloon payloads. It was interesting to note that of all the teams that

participated in the workshop, only a few teams understood that the light sensing window of the camera

4 Material in this section was excerpted from Chenarak, N. “PANSAT Simulation - Executive Summary”, WPI ECE Dept. - E Term, 20035 Mid-Summer, the name of the WPI Nanosat Program was changed to PANSAT - for P o w d e r Metallurgy And Navigation SATellite.


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had to be open for viewing in addition to the lens front of the camera. Since the WPI students allowedfor light sensing on their payload, the pictures taken were quite spectacular. Thus, in addition to workingtogether in a team similar to what they do at WPI on a regular basis, the students were able to demonstrate

excellent results for their efforts.

Finally, we note that one of the students who participated in the SHOT workshop is currently working on

his senior design project at the Goddard Space Flight Center, in Greenbelt MD, designing an advancedballoon satellite payload control system known as “Simsat”.

SHOT Workshop (June, 2003) Balloon Sat Picture Taken by WPI Student Payload

Preliminary Design Review

The culmination of the summer student work was the preparation of the slides and presentation for the

Preliminary Design Review held in Logan Utah as part of the SmallSat conference, mid-August, 2003.Four students (R. Angilly, C. Price, H. Agrawal, D. Belliveau) presented the WPI PANSAT design andconcept slides during the PDR. The slides for the PDR are provided with this annual report as a separate

document.

4. CURRENT PANSAT ACTIVITIES

Program Organization

Currently, twenty-two students in the ME (design, thermal, aero) and ECE (communications, signals,

computers) are working on 8 student teams to develop different systems and components of the WPI


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PANSAT. These students started their team work in late August, 2003 and will continue to work on theirprojects until May, 2004.

Design Teams

The WPI PANSAT development program is organized into nine teams of students. In addition to each

team meeting with their advisor(s) to discuss individual project responsibilities, all teams meet at leastonce a week for program discussions and information sharing. At each meeting, one student is selected

to be the discussion facilitator while a second student is selected to be the group secretary. For allmeetings, notes are transcribed to electronic form and submitted to other group members within 24 hours.

Below, a summary of the goals and objectives of each current (Sept. 2003) PANSAT technology group is

described. A complete list of all team members, emails and their project assignments is provided inAppendix II.

1. Power SystemsGoals: The PANSAT power system is crucial to the operation of the satellite. The goal of this

project team is to design, develop, build and test a complete power system that meets thepower needs of the PANSAT over a projected one-year orbital lifetime.

Objectives: Specific objectives include the following.• use solar cells and the standard Nanosat-03 batteries for power source• include intelligent power management for battery charging, and solar cell sourcing• include mechanisms to monitor the power system performance, health and safety• include mechanisms to shunt power as necessary from or to specific power busses as

dictated by processor based algorithms for power management• include design factors that allow for failure of various components without the failure

of the full power system

2. SensorsGoal: The purpose of this project is to design the sensor subsystem for the WPI PANSAT.

The sensors subsystem will monitor the Health and Safety (H&S) of the satellite,and will include all electronics for the satellite magnetometer.

Objectives: The sensor subsystem will include sensors of two main types: health and safety(H&S) and experimental. The H&S sensors will measure and monitor thetemperature and voltage of other subsystem components such as radio electronicsand solar cells. The experimental sensors will include a magnetometer and will beused to verify components such as the on board GPS system.

The sensors will form the basis for a data acquisition system. At this point severalsensor subsystem approaches are under consideration: including sensor, signalconditioning, multiplexing, analog to digital conversion, and digital interface and anapproach that uses direct temperature to digital technology. The informationobtained through data acquisition will be transmitted to a ground based commandstation.

3. Communications - Tx/Rx/TNCGoal: The goal of this project is to design, implement, and test an end-to-end packet radio system

that supports up- and down-link of digital data via an interface to the PANSAT flight


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computer. Appropriate communication models, receivers, transmitters, coding schemes,communication protocols, antennas, tracking methods and command structure will bedeveloped and implemented. The system will be based on the use of Amateur Radiofrequencies and will require cooperation with the AMSAT organization to coordinateappropriate frequency allocations for the PANSAT. The system will provide end-to-endcommunications and will implement a ground station in addition to the radiocommunications system to be flown on PANSAT. The communications system will adhereto all applicable NASA and AFRL safety and part sourcing and tracking standards.

Objectives: • Digital, end-to-end communications system for command and data up/down-link• Low bit error rate• Amateur Satellite Service frequency allocation• Space flight qualified design and part selection• Minimal power consumption

4a. Circularly-Polarized Single-Band Patch AntennaGoals: The purpose of this project is to design a circularly polarized single-band patch antenna for

the WPI PANSAT.

Objectives: The primary objectives are to perform rigorous numerical simulations and design the singlepatch antenna including the effects of patch size and shape, substrate thickness, dielectricconstant, feed position and satellite as a coupled metal platform. The antenna is alsorequired to have a gain of 4.0-6.0 dB, a CP bandwidth of 50 kHz (3 dB axial ratio), and areturn loss of less than -10 dB within the CP beam width (3 dB) of 90° - 120°.

4b. Ground Tracking AntennaGoals: This project will consist of the design, construction, and performance verification of a

ground-based helical antenna for both PANSAT data transfer and uplink/downlinkcommunications. The pertinent performance specifications for a transmitting frequency of435-438 MHz, circular polarization, 30db gain, 100 degree half power bandwidth, and a CPbandwidth of 50kHz.

Objectives: The project is divided into three phases: design, construction, and performance verification.During the designing stage, the proposed designs’ operating characteristics andperformances are modeled and simulated, and a design would be chosen based on thesimulation results. This modeling and simulation process is aided by a software tool calledHFSS Ansoft. The next step is the construction of the antenna according to the chosendesign, followed by performance testing and verification.

5. NavigationGoals: The goal of this project is to develop a GPS based satellite navigation and orientation

determination system for use onboard the WPI PANSAT. Spacecraft attitude systemsusually consist of two components; the vehicle orientation sensors for examplemagnetometers, horizon sensors, sun sensors, gyroscopes, and star trackers; and activeattitude control actuators for example control momentum gyros, reaction wheels, offsetthrusters, and magnetic torque rods. GPS provides attitude and attitude rate data toactuators for real-time, autonomous attitude determination and control. The elimination ofdifferent sensors reduces cost, complexity, power requirements and weight of the entiresystem. This makes GPS a useful tool for small satellite applications where there arepower, weight and complexity limitations.


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Objectives: The GPS subsystem on the satellite will determine the position, velocity and attitude(azimuth, pitch and yaw) for PANSAT. The data collected and the measurements made bythe GPS subsystem will be part of the telemetry that will be transmitted back to the groundstation. The attitude measurements made by the GPS subsystem will be used by the activeattitude control system so that the satellite is pointing in the right direction at all times. TheGPS subsystem on PANSAT will obtain a position accuracy of 25 meters, azimuthaccuracy of 0.5 degrees and pitch/roll accuracy of 0.5 degrees.

6. TMR & UniProcessorGoals: The goal of this project is to research, design, develop, build and test a triple-modular-

redundant processor that exhibits extremely high reliability in a LEO environment.

Objectives: Specific objectives include very low power, small size, low mass, a design that allows theuser to elect to use one, two or three processor, but with all three based on EDC memoryand high reliability components, and a significant number of IO ports.

7. Satellite Attitude ControlGoals: The goal of the Attitude Determination and Control System (ADCS) portion of the

PANSAT project is to provide a system with which to stabilize the nanosat. To do this, theteam will research a variety of methods for satellite stabilization. Research on the differentstabilization methods will include, determining how each works, the effectiveness of eachmethod, and results of use on other satellites. After researching these methods, the teamwill assess the positive and negative aspects using a detailed value analysis. From the valueanalysis, a stabilization method will be chosen, which will in turn be specifically designed,prototyped, analyzed, and tested specifically for the nanosat. Additionally, the team willdesign a mechanism to deploy the three global positioning system (GPS) antennae and aboom to which a magnetometer will be fixed.

Objectives: Specific objectives for the ADCS team are listed below.• Research different satellite stabilization methods• Design and build prototype stabilization system• Test, analyze, and iterate design

8. Bus StructureGoals: A satellite bus is one of the most crucial safety and structural items to be designed. The

PANSAT bus structure is unique in that it is to be built using powder metallurgy (PM)techniques. The goal of this project team is to i) design a PM bus structure, ii) thoroughlyanalyze the PM structure using standard software based analysis tools, iii) develop amanufacturing methodology for the structure, iv) build at leat two of the structures and v)destructively test at least one of the structures built.

Objectives: Specific objectives include the following.• work with the WPI Powder Metallurgy Research Center (PMRC) to create a

manufacturable design• work with PMRC industrial members to select an appropriate power for the structure• develop a design that can be easily replicated• develop a design that meets all NASA safety and design requirments, to at least the

same extent that an identical structure built from 6061T6 alumnimum would.

9. Thermal AnalysisGoal: Thermal analysis will be performed on all components, systems and integrated stuctures.


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Objectives: • create a methodology for thermal analysis.• develop a clear understanding of thermal issues related to sun and shadow heating and

cooling, respectively• create a thermal model that accurately predicts the flow of thermal energy through the

structure and from component to component based on an evolving structural,mechanical, and integrated design

• use the thermal analysis tools and the integrated design to evolve the design to meetspecific thermal, structural and intergrated design requirements.

Innovative Technologies Under Development

The following innovative technologies are under development by various members of the PANSAT teams

described above.

GPS Orientation A three receiver GPS system, each with its own antenna, is being developed to

determine satellite orientation. The receiver logic software is being modified toallow for high resolution signal phase measurements.

PM Bus Structure Several students are working to develop a hybrid PM / Aluminum satellite bus

structure. PM components will be used for the side structure of the satellite

while aluminum will be used for top/bottom plates, joint members, and internalcomponent support structures.

TMR A fault tolerant, triple modular redundant (TMR) processor system is being

developed for nanosat use. The objective is to develop a system that can bequickly configured for fault tolerant uniprocessor or fault tolerant, high reliabilitytriple voting processing implementation.

COM Antennas Several different very low profile patch antenna designs are being designed,

modeled, built and tested for use on the WPI PANSAT. These antennas arebeing designed for use in the 430MHz communications band and, to date, exhibita 75o beam width and 6db of center gain.

Stability Systems Two different semi passive nanosat stabilization systems are being explored for

development. First, a modular “Weitzman” type gravity gradient boom system is

being explored as one method for satellite stabilization. Second, an “echo”permanent magnet based, reconfigurable stabilization system is underconsideration.

Satellite Fabrication Workshop

WPI is planning on sending two ECE students and two ME (aerospace, thermal) students to the Sandia

AFRL satellite fabrication course on October 17, 2003.

5. SUMMARY AND CONCLUSIONS

The timeline for the WPI PANSAT development is approximately as follows.

October 16, 2003

• subsystem designs considered, trade offs performed, final design proposed

• subsystem components ordered


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• all interface specifications agreed upon

• weight, balance, power - best guess specified

• operational scenario specified

December 20, 2003

• subsystems designed and analyzed

• component level subsystem construction started

• preliminary results

• detailed documentation in preparation

March 5, 2004

• full subsystems completed, full testing in progress

• system documentation in final preparation

• integrated testing initiated

May 1, 2004

• full integrated testing of benchtop satellite prototype

• full system documentation

• full subsystem documentation


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Appendix -I-

SCR Comments

A. University Nanosat Program System Concept Review

Date: April 25, 2003University: Worcester Polytechnic Institute

Originator: L. Cox Org: GSFC Code 591 GNC Systems Engineering BranchIssue/Comment: There are significant mission design/decisions that need to be made (at the system andsubsystem level; GN&C attitude control systems, orbit definition, C&DH, thermal, etc.) prior to the PDRphase. Education component is extremely sparse. Unclear how this is/will be addressed.Action Requested: Gaining an understanding of your mission’s overall requirements (science,technical, education, etc.) is a start and will help. Describe your education focus in more detail – howstudents will be included/involved in university project.

Originator: L. Niemeyer Org: GSFC Code 540 Mechanical Systems CenterIssue: Powder Metallurgy for primary structure: Be aware that the use of powder metallurgy for theprimary structure will require additional (prohibitive?) cost and effort to meet reliability/fracturerequirements for the launch vehicle.Action Requested: Since the use of powder metallurgy is not associated with the science goals, it shouldonly be considered for secondary, contained parts.

Originator: M. Urban Org: GSFC Code 546 Carrier Systems BranchIssue: Powdered Metal Structure will likely have a large overhead for qualification; similar to CastStructures. A large component of this overhead will be driven by the concern over intrinsic flaws in thestructure and possible propagation of these flaws. This assertion should not discourage the experimentersfrom pursuing a powdered-metal structure or even descoping the application of powdered metal. On thecontrary, it would be extremely useful to exercise the system both to determine the actual requirementsfor powdered metal qualification and to establish metrics for cost/benefit trades to quantitatively comparepowdered metal to other material options.Action Requested: Provide a detailed preliminary structural qualification plan addressing the potentialliabilities of powdered metal structures, NASA requirements for structural qualification and mappingthese liabilities/requirements into the elements of the test plan.Consider: Means of flaw detection (e.g. etching, dye penetration, x-ray)Correlation of flaw propagation models (e.g. FLAGRO) to powdered metal; either bydedicated test or history Life cycle fatigue testingIssue: Experimenters assume a spin release of their satellite at a preferred attitude. Some of the deliveryoptions available to them (e.g. AFRL MSDS) do not control release attitude, and many do notaccommodate a spinning release (e.g. HH PES, HH SHELS, AFRL MSDS, ESPA). It appears there’s nomission-driven requirement for attitude control, just attitude knowledge to correlate the GPS attitudesolution to a known reference.Action Requested: Consider an uncontrolled satellite. As I understand the requirements and objectives,this mission can be accomplished by having coarse attitude sensors (e.g. magnetometers and coarse sunsensors) and adequate solar cells on all surfaces to remain power-positive at arbitrary attitude.If this approach is unsatisfactory, the experimenters will have to trade the probability of access (i.e.“getting a ride”) against the launch vehicle services required (e.g. controlled release attitude, spin-up) toachieve mission success.Issue: Li+ batteries are potentially more difficult to qualify on the shuttle due to the hazards associatedwith battery charging and energy/toxic material release due to dead short. These hazards can be mitigated


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by use of the dead bus option (it looks like that’s the experimenter’s intent) and by destructive testing ofbatteries from the same lot as the flight battery.Action Requested: If commercial Li+ batteries are used, purchase only from a manufacturer whoprovides “lot” information on their batteries and purchase enough batteries to do destructive testing onbatteries from the same lot as the flight batteries.

Originator: T. Michalek Org: GSFC Code 545 Thermal Engineering BranchIssue/Comment: The kind of simple, passive thermal control indicated in the presentation can be veryeffective (and in some sense, almost necessary) for a small spacecraft such as this. However, such athermal design is very dependent on the attitude of the spacecraft with respect to the sun. This willfollow, to some extent, with considerations of the output of the solar array, but you may find the thermaldesign as sensitive as the solar array output, if not more so. So you must definitely keep the temperaturesin mind as you work through the attitude control strategy.

B. AFRL NS-3 SCR Presentation Comments:

General Comments (all Universities)• Pressure vessels are strongly discouraged. We will soon be posting sealed container system

guidance on the UNS web page.• The use of Lithium-Ion batteries is subject to increased Shuttle Safety scrutiny. We will soon be

posting battery / electrical system guidance on the UNS web page.• Previous Nanosat Universities had difficulty in effectively joining their primary structure panels to

achieve the required stiffness. Make sure your primary satellite structure is properly connected.• Please have students present all future program presentations.• The preferred orientation for satellite deployables is through the separation system. This allows for

containment of the deployable in the event of inadvertent activation.• The ICU Launch System does not currently provide the capability to spin-up the nanosatellite.

AFRL is investigating the possibility of providing a satellite spin-up capability.• Based on previous University Nanosat Program experience, software development represents an

extremely high schedule risk.

Worcester Polytechnic Institute (25Apr03)• Limit the application of the powder metallurgy to component boxes – not primary structure• Baseline design includes Li-Ion batteries - see general comments above• Only planning for 1 month of operations, should be 6-12 months• Baseline of multiple deployment mechanisms (i.e. booms) - see general comments above• Software to be fully designed by students – based on previous Nanosat Program experience this

represents an extremely high schedule risk - see general comments above• How will satellite spin-up be achieved? - see general comments above


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Appendix -II-PANSAT Project Teams and Advisors

Power System (Emanuel, Labonte')Kate Farb-Johnson katefj@wpiIrma Servatuius imets@wpi

Sensors (Looft)David Laventure-George davelg@wpiAndrew Hermann hermanna@wpi

Communications - Tx/Rx/TNC (Looft, Labonte')Isaac Waldron iwaldron@wpiMuhammad Assad massad@wpi

Communications - Antennas (Makarov)Andy Li a-li@wpiNobel Mathew nobel@wpiMahima Sehti mahima@wpi

Navigation (Michalson)Josh Holwell holwell@wpiAndrew Coonradt coonradt@wpiHimanshu Agrawal himanshu@wpi

TMR & UniProcessor (Michalson)Ryan Angilly rangilly@wpiMitch Lauer mdlauer@wpiDan Debiasio debiasio@wpi

Satellite Attitude Control (Labonte', Looft)Matt Benvenutti mbenven@wpiNate Cambray noc@wpi

Bus Structure (Looft, Apelian)Dav Belliveau davedude@wpiCatherine Price floyde@wpiSid Rupani sidrup@wpiKyle Fuller kyle@wpi


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Appendix -III-

PANSAT Reference Design

A reference design for the WPI PANSAT is provided through he PDR slides presented at the August,

2003 design review. Those slides are provided as a separate document with this report.

Documents

PANSAT - Worcester Polytechnic Institute · PANSAT power requirements. As for the data transmission model , ground station view time durations were obtained from the orbital model