CHIPSat Cosmic Hot Interstellar Plasma Spectrometer Spacecraft Julius-Maximilians-Universität Würzburg S: Telematik in der Raumfahrt Prof. Dr. Schilling 11/20/2003 Gerd Weiß

Table of Contents A small Description Some technical Details Communication Architecture HDLC-Protocol Berkeley Ground System Chips Operation Result of using TCP/IP

Small Description I First Satellite in NASA´s University-class Explorer Program (UNEX) Spacecraft developed by SpaceDev Inc. Instrument developed at the Space Sciences Lab at UCB Launch on January 12 th, 2003 from Vandenberg Air Force Base as a secondary payload on a Delta II booster

Small Description II Purpose of the research: to measure extreme ultraviolet emissions from the interstellar medium Conducted at SpaceDev, later at UCB/SSL Generated data volume ca. 16 MB/day

Some Technical Details Mass for entire satellite less than 64 kg Dual-junction GaAs/InP/Ge solar arrays with nickel Fiber cadmium batteries provide the power of 40W Singelboard flight computer (Motorola PowerPC 750 CPU) WindRiver VxWorks RTOS

Communication Architecture Onboard redundant asynchronous RS-422 links S-band transceiver for RF communications HDLC point-to-point link to ground station Standard TCP/UDP/IP protocol stack layered within HDLC frames

HDLC - Protocol Works on Layer 2 (OSI-Model) Variable Info length Backward error correction Support Sliding-Windows Flag Address 8 bit or 16 bit Flag Control 8 bit or 16 bit Info n -Byte FCS 16 bit HDLC – frame:

Ground System (U.C Berkeley) 1999: operation center, satellite ground station established at U.C. Berkeley´s Space Sciences Laboratory - Mission Operation Center (MOC) - Science Operation Center (SOC) - Berkeley Ground Station (BGS) Serves three satellite missions FAST, RHESSI, CHIPS

Mission Operation Center (MOC) Tasks: -Mission planning -Mission control -Flight Dynamics Several software used like: -SatTrack Suite for flight dynamics -Integrated Test and Operation System (ITOS) for spacecraft command and control (used by HESSI and FAST -Mission Planning System (MPS) for command load generation (used by FAST mission) -Mission Control Center (MCC)

MOC – SatTrack Suite Developed by Bester Tracking Systems, Inc. Some features: Pass Scheduling and Orbit Event Analysis Batch Mode and Interactive Mode Client/Server Network Environment Message exchange in plain ASCII format

MOC - ITOS Runs on one machine or a cluster of machines receives data and sends commands to and from the spacecraft interface over an IP Ethernet connection distribute data via an IP Ethernet to other systems attached to the local area network Developed by the Hammers Company

Science Operation Center (SOC) Tasks: Science data processing, archival, distribution, access, retrieval Hardware: Sun Microsystemes, Linux- based workstations, Servers, a full automated CD-ROM production system

Berkeley Ground Station (BGS) 11-m parabolic reflector antenna Configuration completely automated Pre-pass station set-up begins 10 minutes prior to acquisition of Signal (AOS) Deconfiguration is completed 3 minutes after loss of signal (LOS)

Automation of Satellite Contact SatTrack Suite SatTrack/GS Monitor& Control System Ground Station ITOS Two-line Element Download twice per day Build Pass Schedules SOC Pass support request Pass support request 1. pre-pass

Automation of Satellite Contact SatTrack Suite SatTrack/GS Monitor& Control System Ground Station ITOS Two-line Element Download twice per day Build Pass Schedules SOC SENDPASSES FACILITY BERKELEY OBJECT RHESSI 2. pre-pass SENDPASSES FACILITY BERKELEY

Automation of Satellite Contact SatTrack Suite SatTrack/GS Monitor& Control System Ground Station ITOS Two-line Element Download twice per day Build Pass Schedules SOC incoming Object Corresponding time line of all events Configuration parameter 3. pre-pass read configuration file Start pre-pass configuration

Automation of Satellite Contact SatTrack Suite SatTrack/GS Monitor& Control System Ground Station ITOS Two-line Element Download twice per day Build Pass Schedules SOC 4. pre-pass Request for individual pass support Start pre-pass configuration Establish connection

Automation of Satellite Contact SatTrack Suite SatTrack/GS Monitor& Control System Ground Station ITOS Two-line Element Download twice per day Build Pass Schedules SOC 5. during pass record telemetry data Send commands Received Data Satellite

Automation of Satellite Contact SatTrack Suite SatTrack/GS Monitor& Control System Ground Station ITOS Two-line Element Download twice per day Build Pass Schedules SOC 6. post-pass recorded data spacecraft engineering data

CHIPS Operation Command and control by Mission Control Center (MCC) software (replaced ITOS and MPS) Clients and Server connected via a VPN While in contact, the CHIPS spacecraft acts as another node on this network CHIPS utilizes telnet and ftp for data and file transfer

Chipsat Data Flow INTERNET VPN LAN MCC server MCC client LAN MCC client LAN SpaceDev Router SpaceDev Router switch CHIPSat

Security VPN with multiple Internet Protocol Security (IPSec) tunnels Firewalls are used Only pre-authorized computers have access Computers are password protected Written details of architecture secure

Result of Using TCP/IP Packets dropped during transmission are simply retransmitted  poor link margin result in a lower throughput, no data are lost Standard products provide TCP/IP  reducing the costs for systems Latency is not increased significantly