On the floor of the Spaceflight Operations Facility at NASA’s Jet Propulsion Laboratory there is a plaque that boldly proclaims: “The Center of the Universe.” With large screens on the wall displaying data being downloaded from various spacecraft across the solar system and engineers pouring over rows and rows of glowing screens in the darkened room, the Spaceflight Operations Facility resembles a scene from a science fiction film. It is a fitting description as this is the only place on Earth where we can communicate with robotic spacecraft in deep space.
NASA’s Jet Propulsion Laboratory (JPL) has been exploring the solar system and beyond for over 50 years now. It is home to the Deep Space Network (DSN), the network of large antennae across the planet that collect information from remote spacecraft for the Spaceflight Operations Facility.
The origins of the Deep Space Network can be traced to January 1958 when JPL was still part of the Unites States Army and used portable radio tracking stations in Nigeria, Singapore, and California to plot the orbit and collect telemetry data for the United States first satellite, Explorer 1. It took less than a month for these portable radio tracking stations to be erected. In December of that year, JPL was transferred to the newly formed NASA where they were assigned missions to explore the Moon and the solar system. In order to do this, a new network to communicate with remotely controlled spacecraft was created. This also eliminated the need for each mission to have to create its own network in addition to creating a spacecraft.
Communications between spacecraft and the Deep Space Network occurs via radio waves. Since planets, stars, galaxies, and various astronomical objects also emit radio waves, the DSN has performed the additional task of conducting radar and radio astronomy observations of the solar system and beyond. Radio waves are longer than light waves so the antennae must be much larger and visitors to each station are greeted with an impressive array of antennae dishes. As the distances spacecraft have travelled from Earth have increased, so have the size of the antennae.
Very Long Baseline Interferometry (VLBI) is a specialty of radio astronomy in which a pair of telescopes located thousands of kilometers apart simultaneously combine the signals they have received to measure the differences in time of the arrival of microwave signals. The resolution is proportional to the distance between the telescopes providing a very detailed description of a remote part of the universe. This can also be exploited to instantaneously provide positioning data of a spacecraft for navigation and interaction with astronomical bodies.
The Deep Space Network is able to maintain continuous contact with various spacecraft throughout the solar system and beyond with an array of 3 large radio antennae stations, each containing at least four large antenna dishes, situated 120º apart from each other around the planet. As the Earth rotates and one antenna looses contact, another will take over. Today, these antennae are situated in the United States (Goldstone, California), Australia (Canberra), and Spain (Madrid). Each complex houses 26, 34, and 70-meter antennae, each of which provides a specific function to the network. The data they download and uplink with JPL can be viewed online.
The 26-meter antennae are the smallest. They were built in the 1960s to provide support for the Apollo missions. Today, they are used to track spacecraft orbiting the Earth 160 to 1000 km above the surface. The mounting systems allow them to point low on the horizon and track rapidly moving spacecraft with the ability to move around at 3 degrees per second.
In order to receive faint signals and transmit strong signals to distant spacecraft, the 70-meter antennae were conceived. These massive antennae weigh approximately 2.7 million kg. The current 70-meter iterations were built in the 1980s to replace the 64-meter antennae that were built in the 1960s. While still in use, these antennae are starting to wear out. Due to their massive size, maintenance, repairs, and upgrades are difficult.
Due to the difficulty in maintaining and upgrading the 70-meter antennae with technological advances, the 34-meter antennae are being built as a replacement. There are two types of 34-meter antennae, a high efficiency and a beam waveguide antenna. Each station will have one high efficiency and one or more beam waveguide antennae.
Beam waveguide antennae are unique in that they have 5 precision radio frequency mirrors to reflect incoming radio signals across a tube to a room below ground, protecting the sensitive electronic components in a climate controlled environment rather than outdoors. This design is also a lot easier to maintain and upgrade.
The Deep Space Network will use antennae in combination, allowing the system to function as an array. Arrays can boost the reception of weak signals via the collection of data over a large area. This has proved to be useful in receiving signals from spacecraft on deep space missions. JPL has been using arrays since the 1970s starting with the Pioneer 11 and Voyager explorations of Saturn. By the time of the Galileo mission to Jupiter in the late 1990s, arrays were used to communicate with the spacecraft’s damaged antenna that was only capable of transmitting weak signals.
Often referred to as the Goldstone Observatory, the Goldstone Deep Space Communications Complex (GDSCC) is located on the US Army’s Fort Irwin Military Reservation in California’s Mojave Desert. Operated by the Jet Propulsion Laboratory, it is named after a gold-mining ghost town located nearby. This location was chosen due to its distance from power lines and residing within a natural bowl shaped depression, providing shielding from any interference from commercial and radio transmissions. Construction began on its first antenna the Pioneer Deep Space Station (DSS-11) in 1958, now a National Historic Landmark. As of today, there are 5 antennae operating.
Opened in 1964 just in time to provide support for the Mariner 4 mission to Mars, the Canberra Deep Space Communication Complex (CDSCC) is operated and managed by the Commonwealth Scientific and Industrial Research Organization (CSIRO) and is located the Tidbinbilla valley, about 35 km outside of Canberra. Surrounding ridges that provide a shield against radio interference and located close to the growing city of Canberra made this an attractive location.
In 1966 the addition of a crewed spaceflight wing to provide assistance with the Apollo moon missions was initiated. Construction began in early 1969 on the 64-meter antenna (Deep Space Station 43), which would take four years to complete. This massive antenna was conceived to accommodate the increasingly large amounts of data and the greater distances spacecraft were travelling. A spacecraft’s lifetime could be increased, as its signal grew weaker the further it travelled from Earth. By 1970, a cafeteria and living quarters was added to support staff that lived on sight. It has a visitor’s center that is open daily. There are 4 antennae that support the DSN today.
The Madrid Deep Space Communications Complex (MDSCC) is actually located in Robledo de Chevala, Spain. The National Institute for Aerospace Technology, or the Instituto Nacional de Tecnica Aerospacial (INTA) in Spanish, operates it for JPL.
Originally located near Johannesburg, South Africa, the third site of the Deep Space Network was selected due to its location being ideal for receiving signals within an hour following a launch from Cape Canaveral, Florida. The political environment as a result of the repressive racial segregation under apartheid in South Africa in the 1960s had NASA looking for a new location on the same longitude. Thus the location near Madrid was chosen.
Construction began in 1964 and its first antenna became operational a year later. Today there are 4 antennae contributing to the Deep Space Network. In October 2019, the 34-meter Deep Space Station 56 antenna will begin to receive signals while the Deep Space Station 53 will begin to receive signals in October 2020.
An agreement between the Spanish and US governments under the Host Country Program, Spanish astronomers are given access to the antennae 3% of the time. The Astrobiology Center (NASA/INTA/CSIC) manages the Host Country Program. K-band and Q-band spectroscopy observations are mainly observed for this project.
Keeping track of the vast array of spacecraft means that the Deep Space Network operates 24 hours a day, seven days a week. There is a backup battery and 10 days of fuel to prevent any interruption in operations due to any blackouts or natural disasters. In the event of an evacuation, the emergency control center at Goldstone serves as an alternative location.
The DSN has been called upon during emergencies. The largest antennae at each station will be employed for each emergency just in case a troubled spacecraft may not be able to transmit and receive data at normal transmitter power and/or the orientation of a spacecraft’s antennae may reduce that ability. In the spirit of international cooperation, the DSN will provide this assistance for spacecraft in need from other space agencies.
Perhaps the most famous use of the DSN was during the Apollo 13 mission where an oxygen tank failed causing oxygen gas to be leaked into space. With the loss of oxygen, which was combined with hydrogen to create water and power, the crew was left with limited power to get home and reduced signal levels to reach the Manned Space Flight Network. The largest antennae of the DSN and the Australian Parkes Observatory radio telescope were able to bridge this gap and helped saved the lives of the three astronauts who very well may have been lost in space.
The Deep Space Network not only supports NASA spacecraft, it supports a wide range of spacecraft from various countries and space agencies around the world and is an example of international cooperation in the name of scientific advancement. Visitors to JPL are taken to the Spaceflight Operations Facility, which houses the Deep Space Network. It is one of the most popular sites to visit at the annual JPL Open House with hour-long wait times to tour the facility.