NASA Tests e-VLBI concept from the Madrid Deep Space Network to JPL Thom Stone Principal Computer Scientist CSC-NASA Ames Research Center

Deep Space Network and eVLBI What is “electronically linked-Very Long Baseline Interferometry” and why do we need it? What is the DSN and how is it connected now? Our testing, why, when how Results Conclusions and suggestions Data from deep space - The future

What is e-VLBI eVLBI is the process of using high speed networks to connect radio telescopes separated by large distances ( s of km) instead of the traditional method of recording onto magnetic tape and shipping the recorded data to a central correlator In other words several radio telescopes dispersed over the planet are tied together over high speed networks to form one big telescope.

Arecibo radio telescope (Puerto Rico) World’s largest single- dish radio telescope 305m diameter, 40K perforated aluminum panels

e-VLBI Tried over European networks successfully 2007 Requires the high available bandwidth of a advanced commercial or research network Main application is tracking spacecraft and other objects in deep space (triangulation) Requires exacting time synchronization between telescopes (10 13 sec.) Logical method for creating large array

What is the NASA Deep Space Network (DSN)? Three arrays of radio telescopes (dish antenna) spread around the world to give maximum sky coverage Used to contact spacecraft beyond earth orbit both NASA and International TDRSS satellites are used to communicate to spacecraft in Earth orbit

Deep Space Network Ground Stations: Near Barstow California in the Mojave desert Outside of Madrid Spain In Parks Australia

Why the DSN Each station has many antenna including one 70 meter to: –Send Beatles songs to other star system –Tracking, commanding, and receiving data from spacecraft (NASAs and International partners) outside of Earth orbit. Some are light hours away –Some radio Astronomy

Current DSN connectivity Minimal Internet connectivity at each site even though they are near major high speed research networks(as well as commercial networks) Use leased lines and tapes to move data to NASA centers and then on to researchers

NREN-Madrid-JPL Test Took place in December 2006 after several months of discussion and design Goal was to form eVLBI between Madrid and Goldstone DSN stations with a Beowolf cluster (JVC) at JPL as correlator Object was to demonstrate that data now sent on tapes to JPL could utilize HPREN (High Performance Research and Education Networks) instead (faster, and better) Cooperation between JPL, ARC, REDIRIS, and the DSN Up to a terabyte a day can be generated in Madrid

JPL Correlator (Beowulf Cluster)

Limiting Factors There is only an E1 link (2 Mb/sec) between Madrid DSN and REDIRIS the Spanish HPREN in downtown Madrid The default route to JPL from RedIRIS is via commercial network not NREN’s 1 Gbps link The software/hardware (MARK-5 system) used to make tapes was not set up for high speed transmission of the data

Test Set Up A “Mark-5” computer, used to generate files from data received from the antenna from spacecraft was moved to the REDIRIS operations center on a Gigabit LAN segment Success criteria was to prove that 1/2 Tbyte could be moved in 18 hours or less (about mbits per second with TCP average) A Route was set up between the Mark-5 computer at REDIRIS to the Columbia Supercomputer UDP and TCP tests were performed between hosts –Between hosts on the same LAN segment –Between hosts on the wide area –Using the Mark-5 software

Mark-5 connected to RedIRIS LAN (1 Gbps) RedIRIS connects to GEANT (European backbone) 1 Gbps GEANT Spain to GEANT France to transatlantic cable (10 Gbps) GEANT to Abilene (10 Gbps) Abilene to NREN (10 Gbps) NREN would need to set up route from RedIRIS to machine at JPL for real test 40km Madrid to RedIRIS: work in progress Route

Test Results Used IPERF etc. for testing Able to get up to 800 Mbps UDP with a few errors from Spain (RedIRIS) to ARC. Less loss ARC->Spain Got Mb/sec TCP depending on time of day without optimization Unable to move files using MARK-5 software

Conclusion and Suggestions This is a viable concept, data can be moved faster and cheaper Improvement can be made with Jumbo Frames and multi-stream or other fast TCP Host tuning is a must A great candidate application for scavenger (less than best effort) service

What’s Up European VLBI up and working 40 KM Link from Madrid DSN to RedIRIS not funded even though pricing cheaper than low speed point to point to JSC/JPL Reason is funding and distrust of IP networks by some in NASA Whole DSN in need of upgrade to support future space exploration

What’s Next Keep requesting funding for high speed links to HPRN from all three DSN sites New NASA lunar endeavors will require higher data rates and faster access to data sooner rather than later

Un-Indicted Coconspirators "Garcia Miro, Cristina"

Un-Indicted Coconspirators " Fernando Aragon" "Cristina Garcia Miro" "Raul Alonso" "Charles J. Naudet” “Tom Kuiper” Ken Freeman, Ray Gilstrap, Hugh Lamaster at ARC Others at Madrid DSN and JPL

Thank you Questions? Comments? Thom Stone NASA Ames Research Center / CSC nasa.gov