chipsat cosmic hot interstellar plasma spectrometer spacecraft julius-maximilians-universität...
TRANSCRIPT
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 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
• 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
Flag01111110
Address8 bit or 16 bit
Flag01111110
Control8 bit or 16 bit
Infon -Byte
FCS16 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 missionsFAST, 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/GSMonitor& ControlSystem
Ground Station
ITOS
Two-line Element
Download twiceper day
• Build PassSchedules
SOC
Pass supportrequest
Pass support request
1.pre-pass
Automation of Satellite Contact
SatTrack Suite
SatTrack/GSMonitor& ControlSystem
Ground Station
ITOS
Two-line Element
Download twiceper day
• Build PassSchedules
SOC
SENDPASSESFACILITYBERKELEY OBJECTRHESSI
2.pre-pass
SENDPASSESFACILITYBERKELEY
Automation of Satellite Contact
SatTrack Suite
SatTrack/GSMonitor& ControlSystem
Ground Station
ITOS
Two-line Element
Download twiceper day
• Build PassSchedules
SOC
incomingObject
• Corresponding time line of all events
• Configuration parameter
3.pre-pass
•read configuration file
Start pre-passconfiguration
Automation of Satellite Contact
SatTrack Suite
SatTrack/GSMonitor& ControlSystem
Ground Station
ITOS
Two-line Element
Download twiceper day
• Build PassSchedules
SOC
4.pre-pass
Request for individualpass support
Start pre-passconfiguration
Establishconnection
Automation of Satellite Contact
SatTrack Suite
SatTrack/GSMonitor& ControlSystem
Ground Station
ITOS
Two-line Element
Download twiceper day
• Build PassSchedules
SOC
5.duringpass
record telemetrydata
•Send commands•Received Data
Satellite
Automation of Satellite Contact
SatTrack Suite
SatTrack/GSMonitor& ControlSystem
Ground Station
ITOS
Two-line Element
Download twiceper day
• Build PassSchedules
SOC
6.post-pass
recorded data
spacecraft engineeringdata
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
INTERNETVPN
VPN
VPN
LAN
MCCserver
MCCclient
LANMCCclient
LAN
SpaceDevRouter
SpaceDevRouter
switch
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