History of the Deep Space Network

The forerunner of the DSN was established in January 1958, when JPL, then under contract to the U.S. Army, deployed portable radio tracking stations in Nigeria, Singapore, and California to receive telemetry and plot the orbit of the Army-launched Explorer 1, the first successful U.S. satellite.^[1]

NASA (and the DSN by extension) was officially established on October 1, 1958, to consolidate the separately developing space-exploration programs of the US Army, US Navy, and US Air Force into one civilian organization.^[2]

Origin in the 1950s

On December 3, 1958, JPL was transferred from the US Army to NASA and given responsibility for the design and execution of lunar and planetary exploration programs using remotely-controlled spacecraft.

Shortly after the transfer NASA established the concept of the Deep Space Network as a separately managed and operated communications system that would accommodate all deep space missions, thereby avoiding the need for each flight project to acquire and operate its own specialized space communications network.

The DSN was given responsibility for its own research, development, and operation in support of all of its users. Under this concept, it has become a world leader in the development of low-noise receivers; large parabolic-dish antennas; tracking, telemetry, and command systems; digital signal processing; and deep space navigation.

1960s (Apollo Era)

To support the Apollo manned lunar-landing program NASA's Manned Space Flight Network (MSFN) installed extra 26-meter antennas at Goldstone; Honeysuckle Creek, Australia; and Fresnedillas, Spain. However, during lunar operations spacecraft in two different locations needed to be tracked. Rather than duplicate the MSFN facilities for these few days of use, in this case the DSN tracked one while the MSFN tracked the other.

This arrangement also provided redundancy and help in the case of emergencies. Almost all spacecraft are designed so normal operation can be conducted on the smaller (and more economical) antennas of the DSN (or MSFN). However, during an emergency the use of the largest antennas is crucial. This is because a troubled spacecraft may be forced to use less than its normal transmitter power, attitude control problems may preclude the use of high-gain antennas, and recovering every bit of telemetry is critical to assessing the health of the spacecraft and planning the recovery.

A famous example from Apollo was the Apollo 13 mission, where limited battery power and inability to use the spacecraft's high gain antennas reduced signal levels below the capability of the Manned Space Flight Network, and the use of the biggest DSN antennas (and the Australian Parkes Observatory radio telescope) was critical to saving the lives of the astronauts.

The Apollo program

Although normally tasked with tracking unmanned spacecraft, the Deep Space Network (DSN) also contributed to the communication and tracking of Apollo missions to the Moon, although primary responsibility was held by the Manned Space Flight Network. The DSN designed the MSFN stations for lunar communication and provided a second antenna at each MSFN site (the MSFN sites were near the DSN sites for just this reason).

Two antennas at each site were needed both for redundancy and because the beam widths of the large antennas needed were too small to encompass both the lunar orbiter and the lander at the same time. DSN also supplied some larger antennas as needed, in particular for television broadcasts from the Moon, and emergency communications such as Apollo 13.^[3]

From a NASA report describing how the DSN and MSFN cooperated for Apollo:^[4]

Another critical step in the evolution of the Apollo Network came in 1965 with the advent of the DSN Wing concept. Originally, the participation of DSN 26-m antennas during an Apollo Mission was to be limited to a backup role. This was one reason why the MSFN 26-m sites were collocated with the DSN sites at Goldstone, Madrid, and Canberra.

However, the presence of two, well-separated spacecraft during lunar operations stimulated the rethinking of the tracking and communication problem. One thought was to add a dual S-band RF system to each of the three 26-m MSGN antennas, leaving the nearby DSN 26-m antennas still in a backup role. Calculations showed, though, that a 26-m antenna pattern centered on the landed Lunar Module would suffer a 9-to-12 db loss at the lunar horizon, making tracking and data acquisition of the orbiting Command Service Module difficult, perhaps impossible.

It made sense to use both the MSFN and DSN antennas simultaneously during the all-important lunar operations. JPL was naturally reluctant to compromise the objectives of its many unmanned spacecraft by turning three of its DSN stations over to the MSFN for long periods. How could the goals of both Apollo and deep space exploration be achieved without building a third 26-m antenna at each of the three sites or undercutting planetary science missions?

The solution came in early 1965 at a meeting at NASA Headquarters, when Eberhardt Rechtin suggested what is now known as the "wing concept". The wing approach involves constructing a new section or "wing" to the main building at each of the three involved DSN sites. The wing would include a MSFN control room and the necessary interface equipment to accomplish the following:

1. Permit tracking and two-way data transfer with either spacecraft during lunar operations.
2. Permit tracking and two-way data transfer with the combined spacecraft during the flight to the Moon.
3. Provide backup for the collocated MSFN site passive track (spacecraft to ground RF links) of the Apollo spacecraft during trans-lunar and trans-earth phases.

With this arrangement, the DSN station could be quickly switched from a deep-space mission to Apollo and back again. GSFC personnel would operate the MSFN equipment completely independently of DSN personnel. Deep space missions would not be compromised nearly as much as if the entire station's equipment and personnel were turned over to Apollo for several weeks.

The details of this cooperation and operation are available in a two-volume technical report from JPL.^{[5] [6]}

1970s

There was a substantial expansion of the number of 64m and 26m antennas in the 1970s.[1]

In particular, NASA constructed additional 64-meter antennas at Tidbinbilla, Australia and Madrid, Spain, for moon missions support and Deep Space telecommunictions to Viking and Mariner craft.

The Hartebeesthoek Radio Astronomy Observatory was originally built in 1961 by NASA. Its role was as a tracking station for NASA craft operating beyond Earth orbit. It was also known as the Deep Space Instrumentation Facility (DSIF). Formally it is known as DSS-51 in the DSN station nomenclature. The facility was operated by the South African Council for Scientific and Industrial Research (CSIR) on behalf of NASA. The facility was removed from the Deep Space Network in 1974 and recommissioned as a radio astronomy facility.[2]

1980s

There were no moon missions after 1972. Instead, there was an emphasis on Deep Space exploration in the 1980s. A modernization programme was launched to increase the size of the 64m antennas. From 1982 to 1988 the three 64-meter antennas of the Mars subnet in Spain and Australia were extended to 70 meters.[3]

The average improvement in performance of the three DSS stations of the subnet was over 2 db in the X-band due to the modernization. This performance increase was vital for the return of science data during Voyager's successful encounters with Uranus and Neptune, and the early stages of its interstellar mission. The modernization also extended the useful range of communications for Pioneer 10 from about 50 astronomical units to about 60 astronomical units at S-band.

After the Voyager Uranus flyby, the DSN demonstrated the capability of combining signals from the radio astronomy antenna at Parkes, Australia, with the Network antennas at Tidbinbilla. This DSS subnet capability capability is now a standard part of network operation.

The Voyager encounter of Uranus in August 1989 presented an additional challenge for the Network. The DSN personnel negotiated with several radio observatories the option of combining signals with the deep-space stations.

By arrangement the Very Large Array (VLA) had agreed to equip the 27 antennas with X-band receivers in order to communicate with Voyager at Neptune. The coupling of the VLA with the Goldstone antenna subnet made possible significant science data return, particularly for imaging the planet and its satellite and for detecting rings around Neptune.

1990s (Galileo Era)

DSN provides emergency service to other space agencies as well. For example, the recovery of the Solar and Heliospheric Observatory (SOHO) mission of the European Space Agency (ESA) would not have been possible without the use of the largest DSN facilities.[4]

2000s (Cassini-Huygens Era)

See also

References