Joshua Schoolcraft

Spacecraft data and relay management using delay tolerant networking

NASAs demonstration of the successful transmission of relay data through the orbiting Mars Odyssey, Mars Global Surveyor, and Mars Express by the Mars Exploration Rovers has shown not only the benefit of using a relay satellite for multiple landed assets in a deep space environment but also the benefit of international standards for such architecture. As NASA begins the quest defined in the Vision for Exploration with robotic and manned missions to the Moon, continues its study of Mars, and is joined in these endeavors by countries world-wide, landed assets transmitting data through relay satellites will be crucial for completing mission objectives. However, this method of delivery of data will result in increased complexity in routing and prioritization of data transmission as the number of missions increases. Also, there is currently no standard method among organizations conducting such missions to return these data sets to Earth given a complex environment. One possibility for establishing such a standard is for mission designers to deploy protocols which fall under the umbrella of Delay Tolerant Networking (DTN). These developing standards include the Bundle Protocol (BP) which provides a standard, secure, store and forward mechanism designed for high latency and asymmetric communication links and the Licklider Transmission Protocol (LTP) which is used to provide a reliable deep space link transmission service.

The Deep Impact Network Experiments - Concept, Motivation and Results

The first Deep Impact Network Experiment (DINET I) was performed by personnel at the Jet Propulsion Laboratory with the cooperation of the EPOXI project on the Deep Impact (DI) spacecraft. Using nine ground-based computers controlled from the Experiment Operations Center (EOC) in JPL’s Protocol Technology Lab (PTL) and the DI spacecraft, all connected via JPL’s interplanetary overlay network (ION) disruption-tolerant network (DTN) protocol implementation, the DINET I experiment successfully integrated and tested the first link of the interplanetary internet over the course of 27 days in 2008. The DTN concept allows for automated scheduling and routing of data through an overlay network that bridges smaller local networks. The accomplished technical goal of DINET I was to prove the capabilities of delay-tolerant networking protocols – specifically the Licklider transmission protocol (LTP) and bundle protocol (BP) – in an interplanetary operational environment. The accomplished strategic goal of DINET I was to provide a venue in which to simultaneously raise the JPL technology readiness level of ION and encourage mission project acceptance of DTN technology in space operations communications. A follow-on experiment with the Deep Impact spacecraft, DINET II, is planned by JPL and funded by NASA. DINET II has developed and will test new DTN capabilities such as key-based authentication, mixed-route file delivery, and improvements to DINET I software on the EPOXI ground-based testbed system with the addition of network nodes at JHU-APL, CU Boulder and the International Space Station.

The Deep Impact Network Experiment Operations Center Monitor and Control System

The interplanetary overlay network (ION) software at JPL is an implementation of delay/disruption tolerant networking (DTN) which has been proposed as an interplanetary protocol to support space communication. The JPL deep impact network (DINET) is a technology development experiment intended to increase the technical readiness of the JPL implemented ION suite. The DINET experiment operations center (EOC) developed by JPLs protocol technology lab (PTL) was critical in accomplishing the experiment. EOC, containing all end nodes of simulated spaces and one administrative node, exercised publish and subscribe functions for payload data among all end nodes to verify the effectiveness of data exchange over ION protocol stacks. A monitor and control system was created and installed on the administrative node as a multi-tiered Internet-based Web application to support the deep impact network experiment by allowing monitoring and analysis of the data delivery and statistics from ION. This monitor and control system includes the capability of receiving protocol status messages, classifying and storing status messages into a database from the ION simulation network, and providing Web interfaces for viewing the live results in addition to interactive database queries.

The Deep Impact Network Experiment Operations Center

Delay/Disruption Tolerant Networking (DTN) promises solutions in solving space communications challenges arising from disconnections as orbiters lose line-of-sight with landers, long propagation delays over interplanetary links, and other phenomena. DTN has been identified as the basis for the future NASA space communications network backbone, and international standardization is progressing through both the Consultative Committee for Space Data Systems (CCSDS) and the Internet Engineering Task Force (IETF). JPL has developed an implementation of the DTN architecture, called the Interplanetary Overlay Network (ION). ION is specifically implemented for space use, including design for use in a real-time operating system environment and high processing efficiency. In order to raise the Technology Readiness Level of ION, the first deep space flight demonstration of DTN was performed using the Deep Impact (DI) spacecraft. Called the Deep Impact Network (DINET), operations occurred during Autumn 2008. An essential component of the DINET project was the Experiment Operations Center (EOC), which generated and received experiment communications traffic as well as “out-of-DTN band” command and control traffic, archived DTN flight test information in a database, provided display systems for monitoring DTN operations status and statistics (e.g., bundle throughput), and supported query and analyses of the data collected. This paper describes the DINET EOC and its value in the DTN flight experiment and potential for further DTN testing. The DINET EOC housed ground nodes that produced and consumed “payload” data that was relayed through the DTN router on board the DI spacecraft. The EOC also controlled the topology among the nodes, altering the connectivity to test DTN functionality. An additional node in the EOC acted to perform administrative functions, and contained the Monitor and Control System to view experiment health and concurrently collect and analyze the data delivery status and statistics. The software diagnostic messages and protocol diagnostic messages issued by network nodes were collected analyzed and stored into a database in real-time. The DINET EOC was located within the JPL Protocol Technology Lab (PTL). The PTL provides connectivity to other NASA centers and external entities, and is itself a node in the larger DTN Experiment Network (DEN). The DINET EOC is envisioned to become a general tool in this broader context of experimental testing of DTN across a geographically dispersed user community.

MarCO: Interplanetary Mission Development on a CubeSat Scale

Shortly after JPL’s Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) mission launches, separates, and commences its cruise phase, two CubeSats will deploy from the launch vehicle’s upper stage and begin independent flight to Mars (Fig. 1). During InSight’s entry, descent, and landing (EDL) sequence, these twin Mars Cube One (MarCO) spacecraft will fly 3500 km above the Martian surface, recording and relaying InSight UHF radio data to the Deep Space Network (DSN) on Earth [1].

Adapting a Large-Scale Multi-Mission Ground System for Low-Cost CubeSats

The majority of todays CubeSat fleet consists of Earth-orbiting missions that mostly use existing ground systems developed by universities because of availability, simplicity, and low-cost. The Interplanetary NanoSpacecraft Pathfinder In Relevant Environment (INSPIRE) mission is a revolutionary CubeSat mission that will launch a pair of CubeSats into deep space to study the feasibility of CubeSats beyond low-Earth orbit. This uncovers a new set of systems and software engineering challenges to the development of a robust and reliable ground system in a low-cost environment. In this paper, we discuss the approach to these challenges by using the Jet Propulsion Laboratorys (JPL) Advanced Multimission Operation System (AMMOS) Ground Data System (GDS) as well as the methodologies used to engineer the flight system to work with an existing ground system developed for large-scale missions. Specifically we will focus on the command and telemetry subsystem of AMMOS, the Multimission Data Processing and Control System. We conclude with a retrospective on the challenges encountered and a brief discussion on our efforts to provide AMMOS to support future deep space CubeSat missions.

Deploying the Robot Application Programming Interface Delegate via second-generation IP-over-DTN

The Robot Application Programmer Interface Delegate (RAPID) is a pipeline designed for telerobotic operations in the Human Exploration Technology (HET) Program. As human spaceflight missions become more ambitious and far reaching (for example, long duration operations on board ISS or around near-Earth asteroids), traditional telerobotic technology becomes expensive, unwieldy and difficult to scale. We present a RAPID deployment architecture that leverages the advantages of COTS internetworking infrastructure while enjoying many of the benefits of space-optimized Delay/Disruption Tolerant Network (DTN) technology. DTNTAP is a multi-platform second-generation IP over DTN implementation with performance and usability improvements over its predecessor. Selected results from functional and performance tests are presented and new capabilities are described.

Reconfigurable protocol sensing for space-based applications

In this paper, we present sensing performance using an architecture for a reconfigurable protocol chip for space-based applications . We examine three common framing standards and present the sensing performance of these standards and their decorrelation statistics. We also examine the impact over lossy links. Finally, we describe a process flow for development of this sensor mechanism