431-ICD-000094

Revision -

Effective Date: To be added upon CM Release

Expiration Date: To be added upon CM Release

Robotic Lunar Exploration Program

Lunar Reconnaissance Orbiter

Cosmic Ray Telescope for the Effects of Radiation (CRaTER) to Spacecraft Electrical

Interface Control Document (ICD)

June 2, 2005

CM FOREWORD

This document is a Lunar Reconnaissance Orbiter (LRO) Configuration Management (CM)-controlled document. Changes to this document require prior approval of the applicable Configuration Control Board (CCB) Chairperson or designee. Proposed changes shall be submitted to the LRO CM Office (CMO), along with supportive material justifying the proposed change. Changes to this document will be made by complete revision.

Questions or comments concerning this document should be addressed to:

LRO Configuration Management Office

Mail Stop 431

Goddard Space Flight Center

Greenbelt, Maryland 20771

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431-ICD-000094

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Signature Page

Prepared by:
______
Philip Luers
RLEP Avionics Systems
GSFC/NASA, Code 561
Reviewed by:
______
Mike Pryzby Date
LRO Spacecraft Systems Engineer
Swales Aerospace
Approved by:
______
Arlin Bartels Date
LRO Payload Manager
NASA/GSFC, Code 430 / ______
Craig Tooley Date
LRO Project Manager
NASA/GSFC, Code 430
______
TBD Date
CRaTER Project Manager
MIT / Lincoln Labs

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431-ICD-000094

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ROBOTIC LUNAR EXPLORATION PROGRAM

DOCUMENT CHANGE RECORD Sheet: 1 of 1

REV
LEVEL / DESCRIPTION OF CHANGE / APPROVED
BY / DATE
APPROVED
Draft 0

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Item No. / Location / Summary / Ind./Org. / Due Date /
1 / Section 1.2 / CRaTER Operational Description / CRaTER
2 / Figure 1-1 / CRaTER Block Diagram / CRaTER
3 / 2.3 / Drawing # for Reference Drawings / Philip Luers / Code 561
4 / Table 3-1 / CRaTER Power Allocation / Philip Luers / Code 561
5 / 3.1.1, Table 3-2 / CRaTER operating modes and current draw / CRaTER
6 / 3.1.2, Figure 3-2 / Switch designations for CRaTER, operational heater and survival heater, and accompanying figure / Philip Luers / Code 561
7 / 3.9.2 / 1 pps timing characteristics and timing diagram / Philip Luers / Code 561
8 / 3.9.4 / Operational heater sizes / Philip Luers / Code 561
9 / 3.9.5 / External interfaces, any required / CRaTER
10 / 3.10.1, 3.10.2 / Part Numbers, signal names, and pinouts for CRaTER power and housekeeping interface connectors / CRaTER
11 / 3.10.3 / Part number for CRaTER 1553 connector / CRaTER

Table 11. List of TBDs/TBRs

TABLE OF CONTENTS

Page

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LIST OF FIGURES

Figure Page

LIST OF TABLES

Table Page

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431-ICD-000094

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1.0  Introduction

1.1  Purpose

This document details the electrical interfaces between the Diviner Cosmic Ray Telescope for the Effects of Radiation (CRaTER) instrument and the Lunar Reconnaissance Orbiter (LRO) spacecraft. The interfaces described include the power and command and data handling (C&DH) interfaces.

1.2  Instrument Electrical System Overview

The CRaTER Instrument electrical system is comprised the CRaTER detectors and read-out electronics, a MIL-STD-1553 interface, and a low voltage power converter. A block diagram is shown in Figure 1-1. CRaTER will handle all of its own data processing requirements.

TBD -- Insert CRaTER electrical block diagram here.

Figure 11. CRaTER Block Diagram

TBD – Insert CRaTER operational description here.

1.3  Definitions and Terminology

In this document, a requirement is identified by “shall,” a good practice by “should”, permission by “may”, or “can”, expectation by “will”, and descriptive material by “is.”

2.0  Documentation

2.1  Applicable Documents

2.1.1  NASA Documents

431-ICD-000008 LRO Electrical Systems Interface Control Document (ICD)

431-RQMT-000045 Radiation Requirements for the Lunar Reconnaissance Orbiter

2.1.2  Non-NASA Documents

TIA/EIA-422 Electrical Characteristics of Balanced Voltage Digital Interface Circuits (formerly known as RS-422)

2.2  Reference Documents

431-ICD-000104 CRaTER Data ICD

2.3  Reference drawings

431-TBD Diviner Power Harness Drawing

431-TBD Diviner Data Harness Drawing

431-TBD Diviner Safe/Arm Plug Drawing

431-TBD Diviner Mechanical Drawing

3.0  LRO Electrical System Requirements

The CRaTER instrument shall adhere to the following requirements stated in the LRO Electrical Systems ICD. Where this document conflicts or differs with the LRO Electrical Systems ICD, this document shall take precedence.

3.1  Power

The LRO Power subsystem shall supply a single 1 Amp (A) switched power service for the CRaTER instrument.

Table 31. CRaTER Power Consumption

PARAMETER NAME / VALUE
CRaTER Steady State Power, current best estimate / 6 W
CRaTER Peak Power, current best estimate / 9 W
CRaTER Peak Power Allocation / TBD W

3.1.1  Power Profile

The CRaTER instrument operates in modes. The following charts illustrate the nominal power/current draw while in each mode.

Table 32. CRaTER Operational Modes

MODE / TYPICAL POWER (W) / OPERATING CURRENT (A) / MODE DESCRIPTION
Operating Power (solar storm) / TBD / TBD / For example: All High-Voltage (HV)power supplies turned on, heaters turned on, assumes 70% efficient low voltage power converters
Operating Power (nominal) / TBD / TBD / For example: Only digital electronics in standby mode on, assumes 70% efficient low voltage power converters

3.1.2  Instrument Power Specifications

The instrument power system shall comply with the User (Subsystem) requirements stated in section 3.1.3 of the Electrical Systems ICD (431-ICD-000008). The specifications in this section apply to voltage seen at the CRaTER end of the interface between the instrument and the spacecraft. Any deviations to the specification must be waived by the LRO Project and identified in this ICD.

Insert Power Interface Diagram Here (TBD).

Figure 32. CRaTER Instrument Power Interface.

3.2  System Grounding Requirements

The CRaTER Instrument shall comply with the System Grounding requirements as stated in section 3.2.1 – 3.2.6.2 of the LRO Electrical Systems ICD (431-ICD-000008). Any deviations to the specification must be waived by the LRO Project and identified in this ICD.

3.3  EMI/EMC Requirements

The CRaTER Instrument shall comply with the Electromagnetic Interference (EMI)/ Electromagnetic Compatibility (EMC) requirements as stated in section 3.3 of the Electrical Systems ICD 431-ICD-000008. The CRaTER shall be off from launch to launch vehicle separation. Any deviations to the specification must be waived by the LRO Project and identified in this ICD.

3.4  Data and Signal Interfaces

The CRaTER Instrument shall comply with the Data and Signal Interface requirements as stated in section 3.4 of the Electrical Systems ICD (431-ICD-000008). Any deviations to the specification must be waived by the LRO Project and identified in this ICD.

3.5  Multipaction and Corona

The CRaTER Instrument shall comply with the Multipaction and Corona requirements as stated in section 3.5 of the Electrical Systems Interface ICD (431-ICD-000008). Any deviations to the specification must be waived by the LRO Project and identified in this ICD.

3.6  Design For Radiation

The CRaTER instrument shall meet its performance requirements with acceptable degradation due to radiation induced effects. The LRO radiation requirements are contained within the Radiation Requirements Document for the Lunar Reconnaissance Orbiter (431-RQMT-000045).

3.7  Charging and Discharging Requirements

The CRaTER Instrument shall comply with the Charging and Discharging requirements as stated in section 3.7 of the Electrical Systems Interface ICD (431-ICD-000008). Any deviations to the specification must be waived by the LRO Project and identified in this ICD.

3.8  Harness Requirements

The CRaTER Instrument shall comply with the Harness requirements as stated in section 4.0 of the Electrical Systems Interface ICD (431-ICD-000008). Any deviations to the specification must be waived by the LRO Project and identified in this ICD.

3.9  Inter Component Communications

3.9.1  CRaTER 1553

The CRaTER Instrument shall comply with the electrical interface as stated in section 3.4.1.1 of the Electrical Systems ICD (431-ICD-000008). Any deviations to the specification must be waived by the LRO Project and identified in this ICD.

The CRaTER Instrument shall utilize a connector compatible with the LRO 1553 harness which uses a Trompeter PL3155AC connector on M17/176-00002 cable.

The CRaTER Instrument shall comply with the data and protocol requirements as stated in the CRaTER Data ICD (431-ICD-000104).

3.9.2  CRaTER 1 Pulse Per Second (pps)

The CRaTER Instrument shall accept the LRO SC 1 pps pulse, an RS-422 signal with the following characteristics:

TBD rise time

TBD duty cycle

TBD fall time

TBD stability

TBD: Insert 1 pps diagram here.

Figure 33. CRaTER 1 pps timing

The 1 pps RS-422 differential signal shall adhere to the electrical terminations as given in the Electrical Characteristics of Balanced Voltage Digital Interface Circuits (TIA/EIA-422).

3.9.3  CRaTER Thermistors

The CRaTER instrument shall provide two (2) thermistors to be read by the LRO spacecraft. Both thermistors shall be internal to the CRaTER instrument with electrical interface on the housekeeping connector below. The locations of these thermistors are defined in the CRaTER Thermal ICD.

3.9.4  CRaTER Operational Heaters

The LRO spacecraft shall provide and power TBD (quantity) TBD amp/watt/ohm heaters mounted on the CRaTER instrument. Local thermostats shall control these heaters to maintain survival and operational temperatures. The locations of these heaters are defined in the CRaTER Thermal ICD.

Power for the CRaTER operational heaters shall be through the LRO spacecraft instrument operational heater bus.

Power for the CRaTER survival heaters shall be through the LRO spacecraft instrument survival heater bus.

3.9.5  External Interfaces

LRO shall provide test points and other external interfaces to support the component integration, anomaly investigation, environmental testing, and launch site operations.

TBD – is this required?

3.9.5.1  CRaTER SAFE-ARM FUNCTIONS

Not Applicable. CRaTER does not have any GSE/SAFE/ARM connectors.

3.9.5.2  CRaTER GSE/SAFE/ARM PLUGS AND CONFIGURATIONS

Not Applicable. CRaTER does not have any GSE/SAFE/ARM connectors.

3.10  Connector/Pin Out Definition

3.10.1  CRaTER Power Connector

Table 33. CRaTER Power Connector

Power Interface Connector (Designation J1)
15-POSITION HIGH-DENSITY PIN (LVPS BOARD-EDGE) P/N: TBD /
Pin
No. / Description / AWG / Type / Mate /
1 / NC
2 / +VCC / PSE
3 / +VCC / PSE
4 / NC
5 / NC
6 / NC
7 / -VCC / PSE
8 / -VCC / PSE
9 / CASE

3.10.2  CRaTER Housekeeping Connector

Table 34. CRaTER Housekeeping Connector

Power Interface Connector (Designation J2)
9-POSITION HIGH-DENSITY PIN (LVPS BOARD-EDGE) P/N: TBD /
Pin
No. / Description / AWG / Type / Mate /
1 / +1PPS / C&DH
2 / NC
3 / NC
4 / +THERM_1 / C&DH
5 / +THERM_2 / C&DH
6 / -1PPS / C&DH
7 / NC
8 / -THERM_1 / C&DH
9 / -THERM_2 / C&DH

TBD: this is a notional connector selection and notional pinout.

3.10.3  CRaTER 1553 Connector

The CRaTER Instrument shall utilize a TBD part # connector compatible with the LRO 1553 harness which uses a Trompeter PL3155AC connector on M17/176-00002 cable.

Appendix A. Abbreviations and Acronyms

Abbreviation/ Acronym / DEFINITION
A / Ampere
AWG / American Wire Gauge
C&DH / Command and Data Handling
CMO / Configuration Management Office
EMC / Electro-Magnetic Compatibility
EMI / Electro-Magnetic Interference
FPGA / Field Programmable Gate Array
GSE / Ground Support Equipment
GSFC / Goddard Space Flight Center
HV / High Voltage
ICD / Interface Control Document
IKI / Institute for Space Research
LRO / Lunar Reconnaissance Orbiter
LVPS / Low Voltage Power Supply
PPS / Pulse Per Second
PSE / Power Systems Electronics
RLEP / Robotic Lunar Exploration Program
SPG / Single Point Ground
SSPC / Solid-State Power Control
TBD / To Be Determined
TBR / To Be Resolved
VDC / Volts Direct Current
V p-p / Volts peak-to-peak

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