# Presentation: 782222

## LPT CANDOS Flight Summary

**Dave Israel/NASA/GSFC**
**David Zillig/QSS**

- STS-107 LPT Experiment

- March 4, 2003

## CANDOS Experiment

- The Communications and Navigation Demonstration on Shuttle (CANDOS) flew as an experiment on the FREESTAR Hitchhiker payload on STS-107.
- The LPT CANDOS Experiment operated from launch day, January 16, 2003 until completing its mission on January 31, 2003.  The experiment was a great success.  Data collected will be further analyzed and published in forthcoming papers, however the highlights and preliminary results are summarized herein.

**CANDOS Experiment**

- The CANDOS Experiment showcased the integrated communications and navigation functions of the Low Power Transceiver (LPT), a modular, software programmable, multi-band, multi-channel transceiver developed by NASA/GSFC and ITT Industries under sponsorship of the NASA Office of Space Flight

**The CANDOS Low Power Transceiver (LPT)     (1****st**** Generation-modified)**

- LPT CANDOS Flight Summary 3/04/03

- As  configured for the CANDOS Experiment, the LPT’s capabilities include:
-  Space Network Communications/TDRSS
-  Ground Network Communications/Ground stations
-  GPS Navigation – using GEODE software developed by GSFC Guidance, Navigation, and Control Center
-  Mobile IP and IP-in-space applications & flight ops software enhancements developed by the GSFC/CSC OMNI Project
-  Space-based Range Safety
-  On-orbit reconfiguration

**CANDOS Experiment**

- LPT CANDOS Flight Summary 3/04/03

## Communications And Navigation Demonstration on Shuttle (CANDOS) 

**TDRS-W **(171/174° W)

**TDRS-E **(41°/46° W)

**TDRS-Z **(275°W**)**

**Wallops Island Ground**
**Station**

**Merritt Island Ground**
**Station**

**HitchHiker Control Center Goddard Space Flight Center (GSFC)**

**White Sands Complex**

- HH Data Path

- S-Band
- LPT Com

- S-Band
- LPT Com

**Global Positioning System (GPS)**
**Constellation**

- S-Band
- LPT Com

- S-Band
- LPT Com

- S-Band
- LPT Com

**Dryden Flight **
**Research Center**
- (Range Safety Only)

- S-Band
- LPT Com

**NASA/JSC **
**(Shuttle I/F)**

- Orbiter Data Path

-  **GPS Navigation**
- GEODE Software
- On-board Navigation

**Space-Based Range Safety**
-  Simultaneous TDRSS & Ground Station Communications

**Space Network Communications**
-  TDRSS Data Relay Communications
-  Mobile-IP in Space Demonstration via TDRSS

**Ground Network Communications**
-  Direct-to-Ground Communications
-  Mobil IP in Space Demonstration via Ground Stations

**On-Orbit Reconfiguration**
-  Demonstrates ability to upgrade capabilities
- of Communications/Navigation Transceiver (LPT)
- while on-orbit

- CANDOS SN Data Path

- CANDOS GN Data Path

- IP Networks

- L-Band
- GPS Com

- TDRS
-  Space-to-Ground
- Links

- LPT CANDOS Flight Summary 3/04/03

## Space Network & Ground Network Communications Overview

**Space Network & Ground Network Communications Overview**

- CANDOS demonstrated the ability to close forward (command) and return (telemetry) communications links while on-orbit via:
-  Space-based data relay through the TDRSS MA/SMA and SSA Space Network (SN) Services
-  Direct-to-ground communications through Ground Network (GN) stations at Merritt Island, FLA and Wallops Island, VA

- LPT CANDOS Flight Summary 3/04/03

##  97 SN events were supported for just over 52 hours of total time

-  97 SN events were supported for just over 52 hours of total time
-  37 GN events were supported for 6 hours of total time
-  89% of events were fully successful
-  8 % partially successful
-  3 % unsuccessful
-  5 events outside of predicted field of view
- None of the unsuccessful events appear to be due to the LPT RF hardware.  The most likely explanation for most cases is hardware or software misconfiguration.
- (All 2-way GN and TDRSS communications events used Mobile IP to automatically route the data between the ASPC (CANDOS control center at GSFC) and the active SN & GN ground station.  This was the first time Mobile IP has been used on orbit)

**Space Network & Ground Network Communications**
**Preliminary Results**

- LPT CANDOS Flight Summary 3/04/03

## The LPT processes GPS signals using the civilian C/A codes, performs code and carrier phase measurements and maintains an estimate of time.  It also recovers and decodes each tracked GPS spacecraft’s ephemeris and almanac broadcasts.  In addition to characterizing the LPT’s GPS receiver, an extended Kalman filter is being used to estimate position and velocity (i.e., the state vector) of the Shuttle in real-time, demonstrating the capability of a spacecraft to determine its own state precisely enough to navigate autonomously.

**GPS Navigation Experiment                             Overview**

- LPT CANDOS Flight Summary 3/04/03

##  Four GPS experiment intervals occurred during the mission, each requiring a minimum of 2 hours of consecutive time without Shuttle attitude maneuvers

-  Four GPS experiment intervals occurred during the mission, each requiring a minimum of 2 hours of consecutive time without Shuttle attitude maneuvers
-  After starting each experiment, the navigation software automatically maintained track of the GPS constellation using the shuttle attitude, and did not require any operator intervention for the duration of the experiments
-  Position difference was within the 1-sigma uncertainty of the JSC vector for all comparisons except one, which was within 2-sigma
-  The Navigation Filter (GEODE) measurement residuals were generally well within ±20 m over each 2-orbit experiment, indicating that GEODE is meeting its performance expectations (20 m 1-sigma).

**GPS Navigation Experiment **
**Preliminary Summary of Results**

- LPT CANDOS Flight Summary 3/04/03

## GPS Navigation Experiment 

**Preliminary LPT-JSC Vector Comparisons**

| Orbit
Number | GPS
Experiment | Delta-Position
(m) | Delta-Velocity
(m/s) |
| --- | --- | --- | --- |
| 55 | 1 | 179 | 0.17 |
| 56 | 1 | 150 | 0.19 |
| 57 | 1 | 248 | 0.27 |
| 64 | - | 47 | 0.06 |
| 101 | 2 | 25 | 0.08 |
| 102 | 2 | 98 | 0.12 |
| 116 | 3 | 132 | 0.14 |
| 117 | 3 | 225 | 0.28 |
| 132 | 4 | 440 | 0.52 |
| 133 | 4 | 243 | 0.21 |

- One-sigma JSC vector uncertainty: 360 m position, 0.314 m/s velocity

- LPT CANDOS Flight Summary 3/04/03

## CANDOS GPS Experiment #4Measurement Residuals

**CANDOS GPS Experiment #4****Measurement Residuals**

- One-sigma residual = 13 m

- LPT CANDOS Flight Summary 3/04/03

## IP-in-Space & Mobile IP Experiment Overview

** ****Multicast Dissemination Protocol (MDP) – UDP based, reliable file transfers from space**
** ****Network Time Protocol (NTP) – UDP based spacecraft clock synchronization**
** ****UDP packets - real-time spacecraft telemetry**
** ****UDP packets – spacecraft blind commanding**
** ****Secure Shell (SSH) and Telnet – TCP based remote login to the spacecraft**
** ****Secure Copy (SCP) and FTP – TCP based reliable file transfer to and from the spacecraft **
** ****A highlight of the IP evaluations was the use of Mobile IP for automated route management to the Shuttle.  Mobile IP autonomously addressed IP packets, as required to route message traffic between the LPT on the Shuttle and the Hitchhiker control center at GSFC, regardless of the ground station or TDRSS data relay satellite through which they were communicating.  The changing communications paths as the Shuttle orbited provided an opportunity to evaluate Mobile IP and assess its potential for use in future space missions.**

**IP-in-Space & Mobile IP Experiment Overview**

- LPT CANDOS Flight Summary 3/04/03

## TDRSS Ground Terminal

**TDRSS Ground Terminal**

**MILA & Wallops Ground Stations**

- LPT CANDOS Flight Summary 3/04/03

##  All operations were conducted according to the GSFC IT Security Branch approved CANDOS security plan.

-  **All operations were conducted according to the GSFC IT Security Branch approved CANDOS security plan.**
** ****Mobile IP utilized on all two-way SN and GN passes. **
**Packet routing  established automatically and securely using the standard Mobile IP protocol that comes with Cisco routers **
** ****Automatically setup IP routing tunnels for SN & GN stations as the Shuttle came into view**
** ****The standard off-the-shelf IP stack built into the on-board COTS operating system supported all data communications. Standard HDLC packet framing was used on all links.**
** ****Blind commanding using UDP-based command uplink **
** ****Turned transmitter on using UDP command over static IP tunnel**
**Real time telemetry delivered using UDP**
** ****Reliable file delivery from CANDOS payload to POCC (navigation system logs, comm system logs) and from POCC to CANDOS payload (stored commands, data files, software updates) using both TCP/IP based 2-way file transfer protocols - Secure Copy Protocol (SCP) and one and 2-way UDP-based Multicast Dissemination Protocol (MDP)**

**IP-in-Space & Mobile IP Experiment** **Preliminary Results**

- LPT CANDOS Flight Summary 3/04/03

## IP-in-Space & Mobile IP Experiment    Preliminary Results (Cont’d)

**IP-in-Space & Mobile IP Experiment    Preliminary Results (Cont’d)**

-   On-board clock synchronization to ground time standard using Network Time Protocol (NTP)
-  Autonomous on-board message data routing demonstration
-  Secure LPT commanding from, and reliable file delivery to, a remote site (NASA/MSFC)
-  Multiple simultaneous secure sessions between the POCC and the spacecraft conducting commanding & reliable file transfers
-  Multi-station reliable file transfers (automatic resumption after handover)
-  File delivery across one-way links with application-level Reed Solomon coding

- LPT CANDOS Flight Summary 3/04/03

## The CANDOS Space-Based Range Safety Experiment demonstrated the use of the NASA/TDRSS as the space-based platform to support the range safety activities of the Eastern Range (ER), Western Range (WR) as well as  missile ranges, future spaceports and other remote launch locations. A single geosynchronous TDRSS spacecraft can provide coverage from launch vehicle liftoff to main engine cutoff, while the TDRSS constellation can provide continuous coverage throughout ascent, orbital operations, and landing. 

- The CANDOS experiment demonstrated the LPT as a fast-acquisition, multi-channel transceiver with S-Band and L-Band frequency inputs to simultaneously receive commands from a launch-head ground station (simulated by the Dryden ground station) and from TDRSS and position data from GPS and transmit the position and range safety data back at S-Band through TDRSS and the launch-head station.

**Space-Based Range Safety Experiment         Overview**

- LPT CANDOS Flight Summary 3/04/03

## SN Launch Range Coverage

**Typical East**
**Coast Launch**
**Area**

**Typical West**
**Coast Launch**
**Area**

**East Coast TDRS**
**Coverage Footprint(s)**

**West Coast TDRS**
**Coverage Footprint(s)**

**SN Launch Range Coverage**

- LPT CANDOS Flight Summary 3/04/03

##  12 Range Safety events total

-  5 Dryden-only events for 29 min 30 sec
- 1 TDRSS-only event for 15 min
-  6 Dual Dryden/TDRSS events for over 20 minutes of dual coverage time
-  All events were successfully able to close the link and flow error-free packet data.
-  Post-flight analysis is required to confirm the range safety events were conducted with a link margin of 9 dB.  Initial data indicates that most passes exceeded the 9 dB link margin.
- (The Dryden pass on January 16, 2003 was the first time a TDRSS forward link signal was successfully uplinked directly to an orbiting spacecraft from a ground station)

**Space-Based Range Safety Experiment**
**Preliminary Results**

- LPT CANDOS Flight Summary 3/04/03

## On-orbit Reconfiguration

**On-orbit Reconfiguration**

- As a demonstration of the ability to update the communications and navigation functionality of future radiation tolerant DSP and FPGA-based transceivers on-orbit, a modified version of the LPT’s DSP firmware was uploaded and commanded to re-boot the experiment.
-  Two on-orbit reconfigurations of the LPT Digital Signal Processing (DSP) were performed
-  The first reconfiguration tested the method by reloading the currently operating code to demonstrate the on-orbit process
-  The second reconfiguration included a file transfer of new DSP firmware from the ground which was subsequently installed in the LPT.  The new firmware included minimal code modifications, but it was verified to be installed and working during the following TDRSS events.

- LPT CANDOS Flight Summary 3/04/03

## Educational Outreach

**Educational Outreach**

- Ten different schools and organizations provided “test files” for use during the CANDOS experiment
-  These files included pictures, drawings, or signatures of students from places as close as local Maryland & Virginia schools and as far away as England.
- http://ipinspace.gsfc.nasa.gov/CANDOS/outreach/

- LPT CANDOS Flight Summary 3/04/03

## The CANDOS experiment provided the on-orbit demonstration of six payload objectives: TDRSS Communications, GN Communications, GPS Navigation, On-Orbit Reconfiguration, Space Based Range Safety, and Mobile IP – capabilities anticipated to be needed to enable the next generation of space missions. The first generation Low Power Transceiver (LPT) flown on STS-107 demonstrated a flexible hardware and software platform to meet those future needs.

- All experiment primary and secondary goals were met or exceeded and all data downloaded prior to the tragic loss of STS-107 and crew during landing on February 1, 2003.

**Conclusions**

- LPT CANDOS Flight Summary 3/04/03

## CANDOS Flight Configuration

- LPT CANDOS Flight Summary 3/04/03

## CANDOS Low Power Transceiver (Modified 1st Gen LPT)

|  |  |
| --- | --- |

- CANDOS Low Power Transceiver (Modified 1st Gen LPT)

- LPT CANDOS Flight Summary 3/04/03

## Slide 23

- LPT CANDOS Flight Summary 3/04/03

- LPT CANDOS Flight Summary 3/04/03

## CANDOS IP Station Network

- LPT CANDOS Flight Summary 3/04/03

## End-to-End Data Flow

**Async**
**serial**

**Sync**
**serial**

**LPT**

**Applications**

**Frame Relay**
**HDLC**
**framing**

**RS-422**

**Coding**
**Modulation**

**RF**

**Sync**
**serial**

- RS-232

**Xmit/**
**Rcvr**

**GPS**

**Data**

**Sync**
**serial**

**Ether-**
**net**

**IP**
**Network**

**Frame Relay**
**HDLC**
**framing**

**RS-422**

**Modulation**

**RF**

**LPT Processor & Transceiver**

**Ground Station**
**Router**

**End User**

**Ether-**
**net**

**CPU**
**(Linux)**

**Network driver**

**IP**

**IP**

**IP**

**CPU**

**UDP**

**TCP**

**UDP**

**TCP**

**GRID**

**Coding**

- LPT CANDOS Flight Summary 3/04/03

## GRID Channel Functional Block Diagram

- Router Interface (RS-530)

- Station  Interfaces (RS-422 or TTL)

- Prototype GRID (“GLT”) to be used for CANDOS

- LPT CANDOS Flight Summary 3/04/03

## CANDOS Space Network Station Implementation

- GRID Transmit Functions
- DCE Clock Source
- Scrambler
- Differential Encoder
- Convolutional Encoder
- GRID Receive Functions
- De-scrambler
- The GLT was controlled via a computer connected to the Closed IONET

- Low Rate Data Switch 320x320 (WSC)

- CANDOS Router

- WSC/GSFC NISN Closed IO-NET (WSC)

- MDM
- GSFC & JSFC
-  (WSC)

- J8

- J9

- FWD
- &
- RTN

- GRID GLT

- FWD
- &
- RTN

- FWD
- &
- RTN

- LPT CANDOS Flight Summary 3/04/03

## CANDOS Ground Network Station Implementation

- GRID Transmit Functions
- Scrambler
- GRID Receive Functions
- De-scrambler

- RF Uplink

- RF Downlink

- WPS/GSFC NISN Closed IO-NET (WPS)

- NCPS

- Wide Band
- S-Band Receiver

- S-Band HPA

- Bitsync

- CANDOS Router

- GRID GLT

- LPT CANDOS Flight Summary 3/04/03