Transcript SOC - Universität Würzburg

Julius-Maximilians-Universität
S: Telematik in der Raumfahrt
Würzburg
Prof. Dr. Schilling
CHIPSat
Cosmic Hot Interstellar Plasma Spectrometer
Spacecraft
11/20/2003
Gerd Weiß
Table of Contents
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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 12th, 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
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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
HDLC – frame:
Flag
01111110
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Address
Control
Info
8 bit or 16 bit 8 bit or 16 bit n -Byte
Works on Layer 2 (OSI-Model)
Variable Info length
Backward error correction
Support Sliding-Windows
FCS
Flag
16 bit
01111110
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:
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Mission planning
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Mission control
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Flight Dynamics
Several software used like:
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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
Developed by the
Hammers Company
• 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
Science Operation Center (SOC)
Tasks:
Science data processing,
archival, distribution,
access, retrieval
Hardware:
Sun Microsystemes, Linuxbased 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
Two-line Element
1.
pre-pass
SatTrack Suite
Monitor& Control
System
SatTrack/GS
Pass support
request
Download twice
per day
• Build Pass
Schedules
SOC
Pass support request
ITOS
Ground Station
Automation of Satellite Contact
Two-line Element
2.
pre-pass
SatTrack Suite
Monitor& Control
System
SatTrack/GS
SENDPASSES
FACILITY
BERKELEY
Download twice
per day
• Build Pass
Schedules
SOC
ITOS
Ground Station
SENDPASSES
FACILITY
BERKELEY OBJECT
RHESSI
Automation of Satellite Contact
Two-line Element
3.
pre-pass
SatTrack Suite
Monitor& Control
System
•read configuration file
SatTrack/GS
incoming
Object
Download twice
per day
• Build Pass
Schedules
SOC
ITOS
Start pre-pass
configuration
Ground Station
• Corresponding
time line of all
events
• Configuration
parameter
Automation of Satellite Contact
Two-line Element
4.
pre-pass
SatTrack Suite
SatTrack/GS
Monitor& Control
System
Download twice
per day
• Build Pass
Schedules
SOC
Request for individual
pass support
Ground Station
Start pre-pass
configuration
ITOS
Establish
connection
Automation of Satellite Contact
5.
during
pass
Two-line Element
SatTrack Suite
SatTrack/GS
Monitor& Control
System
Download twice
per day
• Build Pass
Schedules
SOC
Satellite
ITOS
Ground Station
record telemetry
data
•Send commands
•Received Data
Automation of Satellite Contact
Two-line Element
6.
post-pass
SatTrack Suite
SatTrack/GS
Monitor& Control
System
Download twice
per day
• Build Pass
Schedules
SOC
ITOS
Ground Station
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
MCC
client
MCC
LAN
SpaceDev
Router
switch
VPN
server
LAN
MCC
client
VPN
INTERNET
CHIPSat
VPN
LAN
SpaceDev
Router
switch
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