1. ISS Institutional DTN Overview for CCSDS
Adam Schlesinger
NASA – JSC
October 30, 2013

2. Institutional DTN Objectives
Develop an ISS DTN Architecture for flight, ground, and test/simulation systems (includes MSFC, MCC-H, and SCTF/SDIL)
Increase reliability of payload data transfers between ISS and remote payload control centers during AOS/LOS transitions
Increase automation of Payload Developer (PD) requests for data transfers
Alleviate extensive support to plan payload transfers around AOS/LOS and operator required transfers
Use standard, publicly available protocols, avoiding the use of costly custom protocol implementations
Upgrade SWRDFSH file transfer application to use CFDP over DTN, improving bandwidth efficiency and enhancing QoS
Note: Targeting March 2015 for on-orbit availability 3

3. ISS System Implementation Architecture
Two nodes onboard on SSC File Servers accessible by both Payloads and Operations Users
One serves as Operations Primary and Payloads Backup
One serves as Payloads Primary and Operations Backup
Nodes will be ION
Two nodes at MCC-H
One Primary and One Backup for Operations
Two nodes at MSFC-HOSC
One Primary and One Backup for Payloads
Nodes will be DTN2
Note: MCC-H and MSFC-HOSC nodes will provide additional redundancy for Payloads and Operations 3

4. Current Payload Operations
Uplink/Downlink request via HOSC support
Entire files have to be re-transmitted when transfer errors occur
Manual transfer by operations required for file transfers across AOS/LOS
24x7 continuous support operations to ensure access to science data
Recorded data requires operators to initiate playback
Custom file transfer protocols utilized. Currently each payload, tool, support equipment uses a custom method or protocol to transfer data reliably between on-orbit and ground 3

5. DTN Benefits For Payloads
Provides capability for Payload Developers (PDs) to automate operations and ensure science delivery with little regard for link or facility outages
PDs can request files for up/down link without HOSC support
HOSC and ISS DTN nodes will store user file uplinks/downlinks and forward bundles as Ku-band becomes available
HOSC DTN node will also store user telemetry and forward it to the PD site when it comes back online
Reduce PD real-time support to access and downlink science data
DTN stores data during LOS and automatically initiates transfer upon AOS
A download transfer can span Ku-Band AOS periods without any special scheduling or scripting
Reduces need for duplicate storage and extra retrieval actions
Reliable data transfer for ISS during LOS/AOS cycles
Automatic verification of bundle receipts, retransmissions reduced
When transmission errors occur only the bundles that have errors are retransmitted
Maximizes use of bandwidth by reducing the amount of data that has to be retransmitted
Allows PDs to use DTN protocols for their own applications (streaming, telemetry, etc.)
Efficient use of downlink stream through DTN Quality of Service (QoS) / prioritization
Tolerance for high network latency 3

6. Current and Future Use Cases for ISS DTN
Current Users of DTN on ISS:
Various “developmental” DTN configurations have been in use on ISS in support of payload activities for several years
DTN is currently being used in support of the following Payloads
BioServe Commercial-Grade Bioprocessing Apparatus (CGBA)
DARPA Synchronized Position Hold Engage and Reorient Experimental Satellites (SPHERES) Smartphone
ESA Quickstart and OPSCOM I
Additional Payloads discussing use of DTN include:
Multiple User System for Earth Sensing (MUSES)
GRC SCaN TestBed – CoNNeCT
ESA’s METERON (Multi-Purpose End-To-End Robotic Operation Network) – OPSCOM II
HET Surface Telerobotics
JAXA interest in collaborating with NASA to implement Kibo DTN Project
Hyperspectral Imager for the Coastal Ocean Experiment Payload (HREP)
Other payloads are interested based upon availability for service to be implemented 3

7. DTN Example Benefits for Specific Payloads
Potential Benefits Provided by DTN
MUSES
Automated and bandwidth efficient file transfers of bulk data (HD video and files)
SCaN TestBed
Automated, reliable and bandwidth efficient transfer of data in the presence of short passes for the direct-to-ground link
ESA METERON/OPSCOM II
Reliable transfer of command and control plans for robots and prioritized streaming of situational awareness video
Human Exploration Telerobotics
JAXA Kibo
Automated, reliable and bandwidth efficient data transfer using DRTS as well as interoperability with NASA assets using a standard protocol
HREP
Automated, bandwidth efficiency and prioritized file transfers of bulk data (hyperspectral images)
Note: The bandwidth efficiency of each individual payload using DTN allows for more available bandwidth and more science return for all payloads 3

8. Summary
The implementation of DTN on ISS will provide a standard method of communication for payloads that is reliable, autonomous and more efficient than current techniques, resulting in better utilization and more science return from ISS
The use of DTN by payloads will significantly ease PD development of both onboard and ground communication systems and could reduce payload operator costs