DESCANSO Performance Metrics
Deep Space Communications Capability
- The Profile of Deep Space Communications Capability chart (pdf) has been around for as long as we can remember. Joseph H. Yuen was the unofficial custodian of this plot in the late '70s and most of the '80s. A version of this plot was published in the Preface to Deep Space Telecommunications Systems Engineering, Joseph H. Yuen (editor), Plenum, New York, p. ix, 1983. This update from the 2002 version is by Jim Taylor and Abijit Biswas. The S-band, X-band, and Ka-band radio communications are unchanged, but optical communications are updated per current plans and expected developments.
- The Profile is the fruit of all at JPL who contributed to deep space communications. Credit belongs to everyone in JPL's deep space communications community. The flight projects and Deep Space Network (DSN) both played a major role.
- Revisions during the late 1980s and 1990s were done by folks in the Interplanetary Network Office (formerly TMOD, TDA, and DSN) and the Telecommunications Science and Engineering Division, including Nicholas A. Renzetti, James W. Layland, Lawrence L. Rauch, and many others. The version we started from for the 2002 revision is circa 1997. The 1997 version is included in "The Evolution of Technology in the Deep Space Network: A History of the Advanced Systems Program," J. W. Layland, and L. L. Rauch, TDA Progress Report 42-130, p. 33, August 15, 1997, and in Uplink-Downlink: A History of the Deep Space Network 1957-1997, Douglas J. Mudgway, NASA SP-2001-4227, p. 493, 2001.
- This 2015 revision was generated assuming that everything on the plot before 2002 is correct, and there is every reason to believe that this is true. The performance figures have been reconciled with the Voyager, Cassini, and Mars Reconnaissance Orbiter missions. On the performance curve, blue is for S-band and lower, black for X-band, red for Ka-band, and green for optical. Our effort here is to continue from the 2002 version, with special emphasis on optical.
- Every effort was made to list all the relevant data/references/information, etc., that we use. Radio capability from 2005 through 2030 is based on Mission Downlink Projections for High Capacity Ground Communications Study, Doug Abraham, Rev. C (JPL internal document), August 6, 2002, and on information received at JPL from Doug Abraham (Ka-band), William J. Hurd (large arrays), and James R. Lesh (optical communications). Optical capability through 2030 was reassessed in 2015 by Abijit Biswas, supervisor of the Optical Communications Systems group at JPL from information published by NASA’s Space Communications and Navigation (SCaN) office.
- Major advances in capability have occurred in both ground (G) and spacecraft (S/C) capability. Spacecraft mission events by year mark the milestones for those improvement steps. The Profile is displayed as an ever-increasing capability, as though each successive deep space mission or ground advance incorporated all of the capability that preceded it. The actual missions have imposed constraints other than link capability, especially in the faster-better-cheaper era of the early 2000s. Displaying every mission in this era would show some apparent decreases in capability, superimposed on the general upward trend.
- The data rates for high-definition television (HDTV), home television (TV), fast Internet, hi fi audio, and telephone as they are currently used (on Earth) are given for comparison purposes. The deep space communication capability today is nearly capable of sending data from Jupiter distance at the fast Internet data rate. Use of multi-station arrays at Ka-band could exceed the HDTV rate in a few years, and optical capabilities under the direction of SCaN could do even better than the planned Ka-band capability. The current deep space data rate capability of about 600 kbps from Jupiter is equivalent to 250,000 Gbps from geosynchronous orbit distance (about 36,000 kilometers, or 22,000 miles above the Earth). Another way to consider the comparisons is that an Earth satellite in geosynchronous orbit, such as those for relaying home TV signals and capable of transmitting 1 Gbps to the Earth, could transmit merely 2.29 bps to the Earth if that same satellite were at Jupiter.
Joseph Yuen and Jim Taylor