NASA Tests e-VLBI concept from the Madrid Deep Space Network to JPL

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

2. 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

3. What is e-VLBI • eVLBI is the process of using high speed networks to connect radio telescopes separated by large distances (100-1000s 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.

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

5. 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 (1013 sec.) • Logical method for creating large array

7. 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

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

9. 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

10. 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

12. 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

13. JPL Correlator (Beowulf Cluster)

14. 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

15. 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 60-100 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

16. Route • 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

17. 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 60-90 Mb/sec TCP depending on time of day without optimization • Unable to move files using MARK-5 software

18. 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

19. 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

20. 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

21. Un-Indicted Coconspirators "Garcia Miro, Cristina" <CGMiro@mdscc.nasa.gov>

22. Un-Indicted Coconspirators " Fernando Aragon" FAragon@mdscc.nasa.gov "Cristina Garcia Miro" CGMiro@mdscc.nasa.gov "Raul Alonso" <RAlonso@mdscc.nasa.gov> "Charles J. Naudet” Charles.J.Naudet@jpl.nasa.gov “Tom Kuiper” kuiper@jpl.nasa.gov John.E.Clark@jpl.nasa.gov Ken Freeman, Ray Gilstrap, Hugh Lamaster at ARC Others at Madrid DSN and JPL

23. Thank youQuestions? Comments? Thom Stone NASA Ames Research Center / CSC thom.stone @ nasa.gov