Engineering topics

Johnston, D. W. H.

Publications and source records attributed to Johnston, D. W. H..

7 records

NASA NTRS1981

Radio frequency interference protection of communications between the Deep Space Network and deep space flight projects

The increasing density of electrical and electronic circuits in Deep Space Station systems for computation, control, and numerous related functions has combined with the extension of system performance requirements calling for higher speed circuitry along with broader bandwidths. This has progressively increased the number of potential sources of radio frequency interference inside the stations. Also, the extension of spectrum usage both in power and frequency as well as the greater density of usage at all frequencies for national and international satellite communications, space research, Earth resource operations and defense, and particularly the huge expansion of airborne electronic warfare and electronic countermeasures operations in the Mojave area have greatly increased the potential number and severity of radio frequency interference incidents. The various facets of this problem and the efforts to eliminate or minimize the impact of interference on Deep Space Network support of deep space flight projects are described.

Johnston, D. W. H.↗

NASA NTRS1978

Pioneer mission support

Ongoing Pioneer project operations (Pioneers 6 through 11) are briefly mentioned. The DSN prelaunch preparations and launch operations for the Pioneer Venus orbiter are described in detail, along with a brief update on the Pioneer Venus multiprobe launch and encounter preparations.

Johnston, D. W. H.↗

NASA NTRS1977

Viking mission support

Statistics listing the Deep Space Network tracking and command support and the discrepancy report status for 1 January through 28 February 1977 are presented in tables. The initial Viking extended mission period of normal DSN support, following the nonstandard operations during the solar conjunction period is included. Operational testing subsequent to the MK III data system installations at DSS 12, 44, and 62 during this period are also discussed.

Johnston, D. W. H.↗

NASA NTRS1977

Viking mission support

The relatively quiet Viking On Board Science & Telemetry period from November 15, 1976, through December 31, 1976, is discussed, when Mars and the Viking spacecraft were in the Solar conjunction period. The period therefore presented the Viking Radio Science Team with a unique opportunity to utilize the DSN and Viking spacecraft to exercise their experiments with nonstandard station configurations, without the usual command and telemetry constraints.

Johnston, D. W. H.↗

NASA NTRS1977

Viking mission support

Deep Space Network support for the four Viking spacecraft during October and November 1976 is summarized. The period covers the last portion of the prime mission which officially terminated on 15 November 1976 and the start of the Viking extended mission on that date. November also covered the Mars-Sun-Earth superior conjunction period with the rapid degradation of RF link performance resulting in the tapering off and termination of telemetry data coincident with a rapid increase in radio science experiment activity. The various radio science experiments are described in detail and the computer aided countdown program utilized by the tracking stations during the Viking mission is also described.

Johnston, D. W. H.↗

NASA NTRS1976

Viking mission support

The most significant Viking Mission events supported by the DSN during August and September 1976 are reported. Intermediate Data production and DSS support are also summarized for this period. Viking DSN Discrepancy Report activity for the period January 1975 through September 1976 is also included.

Johnston, D. W. H.↗

NASA NTRS1976

Viking mission support

Deep Space Network support is summarized for the two Viking missions to Mars and the Mars orbit insertions of Vikings 1 and 2 and the landing of Viking 1. Special procedures were employed during these critical events to minimize interruptions to the telemetry data return due to spacecraft data mode and attitude changes.

Amorose, R. J.↗