Taking Saratoga from Space-Based Ground Sensors to Ground-Based Space Sensors

The Saratoga transfer protocol was developed by Surrey Satellite Technology Ltd (SSTL) for its Disaster Monitoring Constellation (DMC) satellites. In over seven years of operation, Saratoga has provided efficient delivery of remote-sensing Earth observation imagery, across private wireless links, from these seven low-orbit satellites to ground stations, using the Internet Protocol (IP). Saratoga is designed to cope with high bandwidth-delay products, constrained acknowledgement channels, and high loss while streaming or delivering extremely large files. An implementation of this protocol has now been developed at the Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO) for wider use and testing. This is intended to prototype delivery of data across dedicated astronomy radio telescope networks on the ground, where networked sensors in Very Long Baseline Interferometer (VLBI) instruments generate large amounts of data for processing and can send that data across private IP- and Ethernet-based links at very high rates. We describe this new Saratoga implementation, its features and focus on high throughput and link utilization, and lessons learned in developing this protocol for sensor-network applications.Comment: Preprint of peer-reviewed conference paper accepted by and to appear at the IEEE Aerospace 2011 conference, Big Sky, Montana, March 201

NEMO Experiments

Viewgraphs on Network Mobility (NEMO) experiments are included

CLEO and VMOC: enabling warfighters to task space payloads

CLEO, the Cisco router in low Earth orbit, is a secondary experimental payload onboard the UK-DMC disaster-monitoring consortium remotesensing small satellite built by Surrey Satellite Technology Ltd (SSTL). That router in space, its mobile networking capabilities, and the satellite's imaging capabilities have been proven as part of a demonstration and evaluation of VMOC, the Virtual Mission Operations Center, a joint US governmental/DoD initiative using Nautilus Horizon software from General Dynamics. The combination of the CLEO and VMOC initiatives together provides a framework to define, test, and field a 'system of systems ' based on the Internet Protocol (IP), capable of supporting secure distributed mission operations of IP-based platforms and sensors. VMOC is an Internet-enabled secure application that provides a user-friendly interface which enables both trained and untrained operators in the field to access database satellite imagery, and allows users to task and command space assets. VMOC receives live telemetry from the UK-DMC satellite via multiple Internet-enabled ground stations and uses high-order, emerging Internet standards for web services to request SSTL's own mission planning system schedule Earth images to be taken by the UK-DMC satellite. VMOC accesses the CLEO router onboard the UK-DMC satellite via SSTL's own ground station in Guildford, UK, and via Universal Space Network's ground station at North Pole, AK. The primary VMOC server is located in the AF Center for Research Support (CERES) on Schriever AFB, CO, with a backup VMOC server located at NASA Glenn Research Center in Ohio. The Home Agent for mobile routing to CLEO through any ground station, providing a permanent point of contact for access, is also located at NASA Glenn. For the demonstration the Army Space Support Element Toolset was deployed to Vandenberg AFB, CA, which served as the field location and Internet access site during testing and evaluation of VMOC and CLEO

An Interoperability Consideration in Selecting Domain Parameters for Elliptic Curve Cryptography

Elliptic curve cryptography (ECC) will be an important technology for electronic privacy and authentication in the near future. There are many published specifications for elliptic curve cryptosystems, most of which contain detailed descriptions of the process for the selection of domain parameters. Selecting strong domain parameters ensures that the cryptosystem is robust to attacks. Due to a limitation in several published algorithms for doubling points on elliptic curves, some ECC implementations may produce incorrect, inconsistent, and incompatible results if domain parameters are not carefully chosen under a criterion that we describe. Few documents specify the addition or doubling of points in such a manner as to avoid this problematic situation. The safety criterion we present is not listed in any ECC specification we are aware of, although several other guidelines for domain selection are discussed in the literature. We provide a simple example of how a set of domain parameters not meeting this criterion can produce catastrophic results, and outline a simple means of testing curve parameters for interoperable safety over doubling

Using Light-Emitting Diodes for Intersatellite Links

Abstract We examine the utility of Light-Emitting Diodes (LEDs) for short-range intersatellite links (ISLs), and compare and contrast LEDs with existing laser technologies used for long-distance ISLs. A hypothetical low-end LE

Saratoga: a Delay-Tolerant Networking convergence layer with efficient link utilization

Abstract—Saratoga is a lightweight transport protocol based on the User Datagram Protocol (UDP/IP). Saratoga was developed by Surrey Satellite Technology Ltd (SSTL) for file transfers of imaging data recorded onboard the Internet-Protocol-based Disaster Monitoring Constellation (DMC) satellites, and has been in operational use from low Earth orbit since 2004. Saratoga focuses only on efficient communication to the next hop when link connectivity is available, by filling the link with packets sent at line rate. This ensures that as much data as possible is transferred to the peering node during a twelveminutes-or-less pass over a satellite ground station. Saratoga uses a minimal bandwidth-efficient negative acknowledgement mechanism to ensure reliable data transfer. We examine how Saratoga can be adapted to serve as an efficient convergence layer for Delay-Tolerant Networking (DTN), by transferring DTN bundles as well as files. This will allow DTN networks to increase efficiency of communication across briefly-available disrupted links – for long-distance deep space links as well as for short-distance terrestrial mobile ad-hoc networks