Tip Mass Presentation Anders Fornberg – Team Lead/Imaging

Tip Mass Presentation

• Anders Fornberg – Team Lead/Imaging

• Kate Worster– Power

• Siddharth Shetty – Comm

• Jen Getz & Terry Song – Structures

• Joshua Stamps – Thermal

Overall Mission of the tip-mass

• Main Mission

• Provide gravity-gradient stabilization for DINO

• Functions

• Capture and send pictures
• Deployment of FITS
• Deployment of Aero-fins
• DINO main module

Top-Level Requirements

• 5kg mass

• Tip-Mass shall not connect to DINO other than via the boom

• Separate power system
• Wireless communications from DINO to Tip-Mass module

• Tip-Mass shall meet all NASA safety requirements

General Layout of Tip Mass

Overall Tip Mass Subsystem Test Plan

• Proper operations of the tip mass when given specific commands

• Triggering of camera
• Resetting of camera’s memory
• Receiving image for camera’s memory
• Initialization of power save mode
• Return to non-power save mode
• Accomplished with software that simulates commands that the flight computer would send to the tip mass

• “Initial on” counter can initially activate the tip mass subsystem

• Accomplished by connecting counter to power subsystem and running multiple test to ensure reliability

COMM System Requirements

• Fast and reliable wireless link

• Transmit over 6 meter distance (tested over >33m distance successfully without packet loss)

• Utilizes 5 V DC power line

• RS-232 Compatible

TPS Options

• Infrared

• Very low range
• Line of sight required

• Bluetooth

• Recommended Receiver sensitivity: -70dBm
• Standard not as open as compared the IEEE 802.11
• Operates in license-free band

• IEEE 802.11b

• Open and widely used standard
• Recommended Receiver sensitivity: -90dBm (higher range)
• Operates in license-free band

Communication system

Features - WISER 2400

• Operates In the ISM band (2.4GHz – 2.495GHz), no FCC license required

• No driver on the host device is required for radio operation

• Independent of the operating system on the host equipment or device as long as a RS232 port is properly supported

• Industry standard IEEE 802.11b-compliant wireless interface; Interoperable Client radios from other vendors

Specifications-WISER 2400

• Frequency: ISM band (2.4GHz – 2.495GHz)

• Link Distance: ~6 meters in open space

• Voltage, current: 5v, max 480mA (in transmit mode)

• Data rate: Capable of supporting up to 115K baud (possible limitation on the digital camera side to transmit data)

• Weight : 3.7ounces:the radio with case,1.7 ounces is the weight of the case

• Antenna type: Integrated dipole antenna (omni-directional) with ~2dBi gain

Implementation details

• One Wiser unit will act as the Access Point and the other will play the role of a station

• ‘Beacon’ packets show supported data rates of 1,2,5.5,11 Mbps

• Cap on the serial interface; a 9600 baud rate is currently set (default value), which can be increased up to 115K

Agilent Tool

Radio test results

Link Budget

• Free space loss in space

• Lp(dB)= 92,45 + 20log10 F+20 log10d 

• For 10m L~ 60dB at 2.45GHz and ~70dB for 30m

• Power at Rx (20m)= 14dBm + 2dBm – 70dB + 2dB = -52dBm ( > Receiver sensitivity of -80dBm)

Power Drain

• Beacons transmitted at 100msec intervals by Access Point (Infrastructure mode)

• Effective time of transmission of beacon frames ~ 3.8sec per hour

• Power drain in Receive mode higher ~250mA

• Support for power-save mode available

• Circuitry to cut off power at times of ‘No use’

Future tests

• Exhaustive radio test to be carried out by attaching the wiser units behind isogrids to simulate actual working conditions and also takes into account the orientation of units

• Throughput calculations to be performed using programs to transfer bulk data over these units and observing the transmit success rate

Requirements on other TM systems

• Equipment

• 4 A-hr NiCad Cells @ 1.2V ea.

• Charge time 14-16hrs or 1hr

• MAX1672 DC/DC Power Converter

• Structure to contain and support battery

• Fuse, derated; appropriate-sized wires, also derated

• FET’s or relays for inhibit switching

Power Safety and Operations

• Safety

• Two-fault tolerant battery inhibit system

• No shunt diodes

• Battery case must contain any leaks and prevent shorts in the battery

• Fuse must be provided on ground leg of battery

• System will be un-powered until TM separation from DINO

• Launch with fully charged battery
• Need shunt diodes on ea. cell
• All cell vents must be oriented upward during launch

Power System Requirements

• Tip Mass Electrical Power System (TM-EPS) must provide 5V regulated line to TM subsystems

• 802.11b wireless transceiver
• Digital Camera

• TM-EPS must provide power for at least 180 minutes

• Will need to image on at least 3 different orbits
• Boom deployment
• FITS deployment
• Aero-fin deployment

• TM-EPS will meet all NASA safety requirements

• TM-EPS will share as many components as possible with DINO main S/C

• Inhibits and monitors must be able to be verified from Ground Support Equipment (GSE)

TM-EPS Block Diagram

Power System Overview

Power System Action Items

Power Tip Mass Test Plan

• Proper power levels to each subsystem

• Communication’s wiser 2400 unit is given a controlled 5 Volt line
• Imaging’s Jam-Cam is given a controlled 5 Volt line
• Accomplished using a multi-meter and slightly varying the input voltage to simulate noise

• Inhibits are operating properly

• Receives and can initialize power save mode

• Software that simulates a “power save” command given to power by the FPGA

• Receives and can initialize non-power save mode

• Software that simulates a “non-power save” command given to power by the FPGA

Science TP Sub-System Requirements

• Take clear pictures of FITS and Aero-Fins Deployment and main DINO module

• Serial connection to FPGA Chip

• Powered by 5 Volt line

• Pass all NASA specification on materials

• No ABS material

Trade Study (Jam-Cams in Tip-Mass)

Canon Powershot S-10 for Tip-Mass

Trade Study Review

• Due to the boom redesign the tip-mass structure will be positioned closer to the main module. This will require a less resolution camera. Also, because of the faster deployment of such a design, storage time is not such an issue.

• The ability of the S-10 to use serial and USB could allow for use in main satellite as well as tip mass module.

• S-10 is a better camera all around except that there are a lot of unknowns

Tip-Mass Camera Decision

• Jam-Cams will be the primary camera at this point

• Will do a dual development with the jam-cams and the Canon S-10

• In the process of purchasing one S-10 to do ABS plastic detection

Preliminary Command list for Science

• All of Jam-Cams operations can be controlled through the serial Port

• Camera Power (on/off)

• Camera Trigger (take picture)

• Receive images

• Clear Memory

• Ping Camera

FPGA Board

Test Plan and future studies

• Reliable serial connection to FPGA board

• Program to test commands given to Jam-Cam

• Test image quality at 6 meters with bright background

• ABS plastic testing on S-10 with help from main science team

Structures Design Requirements

• Total Mass: 5 kg

• Components Mass (estimates):

• Batteries (including structure): 500-600g
• Camera (w/o case): 68 g
• Comm (w/o case): TBD
• Top Half of the Lightband Deployment System: 2.1 kg
• Internal Deployment System:
• Mechanism to deploy: 1.0 kg
• Attachment Tether: ~1.0 mg
• Internal/External Support Boxes:
• Constructed of 6061 Aluminum
• Density: 2698.79064 kg/m3
• Ballast will be used as necessary to meet mass requirements.

Structures Design Requirements

• Total Volume: 420.5 in3

• Bottom Plate will have a half inch lip to decrease tension and increase stability.

• Interior Dimensions (estimates):

• Battery Box: TBD
• Camera Box: TBD
• Comm Box: TBD
• Boom Deployment System Box: 3.5” x 4.0” x 4.0”

• Center of Mass must be along the z-axis

• The boom is parallel to the z-axis
• The length of the boom is 6 meters long

Structures Design Detail

• The main design driver is the mass requirement

• The 5kg mass limit is critical in designing every component

• Maximizing interior space without failing to meet the design requirements

• Hexagon shape has been selected due to its large volume capacity

Structures Design Detail

Subsystem Test Plan for Tip-Mass

• COMM

• Transmit and receive from both FPGA and flight computer

• Structures

• Keep on improving the design to optimize structural performance meanwhile meeting mass requirement
• Testing will be done in coordination with the main satellite

• Science

• Image quality for objects at 6 meters (~60 feet)
• Proper communications with FPGA

• Power

• All system power test to ensure 2 hour operation

Issues and Concerns

• STR

• Protection for internal components, necessary?
• Exceeding the mass requirement is still possibly an issue

• COMM

• Power drain due to continuous “beacon” transmission

• PWR

• Effects on power from tether to boom (if any)
• MOPS counter vs. switch for initial power on

• SCI

• Non-ABS material with Canon S-10
• Complications of redesigning camera selection