P19101: CubeSat Solar Sail
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Preliminary Detailed Design

Table of Contents

Team Vision for Preliminary Detailed Design Phase

What did your team plan to do during this phase?

What did your team actually accomplish during this phase?

Prototyping, Engineering Analysis, Simulation

Torque Test

Our plan was to test the torque needed to turn the Geneva cam to have the booms deploy but the Geneva cam kept locking up and we couldn't get any usable data. Not being able to get it to work added with the fact that it reduces torque instead of increasing it like the worm gear, led us to the decision to choose to use a worm gear instead of the Geneva cam.

Working with the Dev Kit

The CubeSat Development Kit from Pumpkin Space Systems, is a proprietary PCB design, which allows a collection of different processor models to be used with a signal modular motherboard. The processor version which was with the model we worked on was an MSP430F2618. This processor is a radiation hardened model with 116kB of FRAM and 8 kB of SRAM. While this processor is a high end model for a embedded processor, the turn away from this system is related to the Firmware of the motherboard. The Cubsatkit website notes that the kit only one development environment may be used when programming the MSP430 version of the kit. This software is known as CrossWorks for MSP430. However, the version of this software which is noted as running the kit is 1.4 while the most recent release is 3.1, indicating that there is likely a lack of support for more modern versions. In a similar vein, firmware drivers needed to connect to the motherboard is only compatible with older versions of windows (7 and older) meaning that unless a windows 7 system is immediately available, development is much more difficult. In the end, although the capabilities of the kit are enticing, the lack of easily accessible modern system support makes it a less than ideal candidate at this time.

Test Strength of Tape Measure with holes

We tested some tape measures to determine the loss of strength that might occur when putting holes along the length of them. This was done to determine the feasibility of adding holes along the booms as a method for tracking the deployment of the sail. We tested them using a hanging mass set. The masses were put in a hole at the end of a tape measures and the tape measures were slid slowly off the end of a table until the tape measures bent under the weight. The data collected can be seen in the table below. We concluded that the maximum distance in which the tape measures could support themselves didn't change much when holes were added, so putting holes in them should be fine.

Testing Data

Testing Data

Team Discussion and Design

How to deploy solar panels flap

We looked into several ideas on how to deploy the flaps the solar panels are on as can be seen below

Ideas for Solar Panel Deployment

Ideas for Solar Panel Deployment

Looking at the ideas there were some ideas we could eliminate so of the ideas right off the bat. The temperature reliant system would not be feasible because we don't know how long it will be in space before it needs to deploy. Also its orientation to the sun will effect the temperature on either side of the cubesat. We also could rule out straight springs since there is a maximum spring force amount allowed in cubesats. We ended up choosing the motor and string. For this idea a motor would sit on the one end of the cubesat. When activated the motor will turn and pull on four strings that will pull up the four sides of the cubesat that hold the solar panels. We picked this idea since we can control the speed and it will be easier to implement than some of the other ideas such as the clock spring idea. Also if the idea requires more torque it would be easy to just add a worm gear or another gear arrangement.

Meeting with Dubai Team

We meet with the Dubai team over video chat and talked about our projects and if there was any way to combine them. We were told they required 2U. We need 3U worth of equipment but i could be possible to combine the power system and micro controller cutting out 1U. This still leaves us a minimum size of 4U. Switching to a 6U now would require us to develop a whole new design.We decided to work on our own indiviual projects for now and maybe in the future they could be combined. A link to the meeting notes can be found here.

Seminar on Remote Sensing ISRO Applications

Per the advice of our SME Dr. Kurinec, we attended a lecture by Dr. Kumar, former head of the Indian Space Research Organization (ISRO), on remote sensing applications for developing countries such as India, with emphasis placed on the role on nano-satellites for these applications. The event helped increase project visibility and provide information on missions other countries and universities are undertaking for their nano-satellites.
Lecture Flyer

Lecture Flyer

Grant Application

Due to having low fund we decided to apply to the New York Space Grant Consortium. We filled out the form and attached our bill of materials below.

Drawings, Schematics, Flow Charts, Simulations

Power System

The power system PCB will consist of several functional blocks:
Power System Schematic

Power System Schematic

Power Sourcing

With Cooperation with SME Prof. Kurinec, the following PV panel assembly shown in the spec sheet has been identified with the following characteristics: -Light-weight -Tin -Shatter resistant -Durable -high-efficiency -GaAs cell -Radical Temperature Resistant -Rad-Hard -PCB Backing Provided
Alta PV Assembly Spec Sheet

Alta PV Assembly Spec Sheet

The following is also captured from a NASA study on nano-satellites encompassing the OTS sources of PV cells and assemblies, along with a sampling of respective efficiencies.

NASA Study on PV Sourcing

NASA Study on PV Sourcing

All information and data provided in the above image is taken directly from NASA source material at https://sst-soa.arc.nasa.gov/03-power.

Frame

Frame with folding solar panel sides

Frame with folding solar panel sides

Deployment mechanism for solar panel sides

Deployment mechanism for solar panel sides

Hinge with folding feet

Hinge with folding feet

View of feet in 'Launch' position

View of feet in 'Launch' position

Deployment

New solar sail deployment drivetrain

New solar sail deployment drivetrain

Pinions used to the motor closer to center

Pinions used to the motor closer to center

Bill of Material (BOM)

The up to date document can be found here.

Bill of Materials

Bill of Materials

Test Plans

High Altitude Balloon

Thermal

Prototype Battery Recharging

Vibrations

Design and Flowcharts

The up to date document can be found here

Flowchart

Flowchart

The following is a more detailed plan of the development life cycle during MSDII.

Semester Schedule

Semester Schedule

Risk Assessment

We updated our risk assessment which can be seen below. Most of the risks are the same the only main difference was the likelihood of the risks. We lowered several likelihoods such as sail getting tangled and not enough torque. Our redesign makes us more confident that we can accomplish these tasks. Our most important risk right now is "Can't get a big enough sail to really generate propulsion." We did decrease the likelihood of this since we are confident we can make a bigger sail than last years group did but it didn't decrease by much and this has very sever consequences.
Risk Assessment

Risk Assessment

A link to our current up to date document can be seen here.

Design Review Materials

Include links to:

Plans for next phase

For the next phase, in three weeks, we plan to finalize our design. All the mechanical and electrical systems will be completely designed. We will also continue to update the Bill of Materials.

Adam Stock

Kristin Angel

Jarrett Pischera

Brett Saxe

Nathan Lindberg


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