The Deep Space Network is a collection of antennas distributed around the world that allow us to keep in touch with our herd of extraterrestrial explorers. The complexes contain a mixture of 26-meter, 34-meter, and 70-meter antennas, all serving different functions.
Back when Jet Propulsion Laboratories had a sudden scramble to launch Explorer into orbit, they needed the ability track their new spacecraft on very short notice. In less than a month, they deployed portable radio tracking stations in Nigeria, Singapore, and California. These stations, the prototype for the Deep Space Network (DSN), received telemetry from the tiny probe and helped mission controllers track its orbit. The full Deep Space Network was launched shortly after the lunar and planetary exploration programs were centralized under NASA, reducing the operational overhead of setting up independent communication for each program.
The network consists of three Deep Space Stations (DSS) around the earth, providing communication and tracking for multiple spacecraft within the system every moment of every day. Each complex has at least four antennas, with a mix of large, parabolic dish antennas and ultra-sensitive receiving systems.
When dealing with such faint signals from so far away, amplifiers are absolutely essential. Alas, amplifiers do their job indiscriminately, so amplify background noise along with the signal. Even worse, the electronics add their own noise. Cooling the equipment to just a few degrees above absolute zero helps, as does encoding the signals to be very distinctly different than the radio static naturally emitted by nearly everything else in the universe.
The smallest antennas are 26 meters in diameter. Originally built to support the Apollo moon missions, these antennas are now used to track Earth-orbiting spacecraft that are 160 to 1,000 kilometers above the surface.
The antennas have an extremely special mounting system, allowing them to point extremely low on the horizon and pick up fast-moving orbiters. The antennas can crank around at a maximum of 3 degrees per second, allowing them to track the equivalent of one full rotation of an orbiting spacecraft every two minutes.
The largest antennas are 70-meters in diameter, with less than 2 centimeters deviation across its 3,850 square-meter surface area. They're so huge they weigh nearly 2.7 million kilograms, supported by a hydrostatic bearing assembly. A thin film of oil allows the antenna to glide around on a large steel ring.
The massive antennas were built to receive very weak signals and transmit very strong ones. The antennas were originally constructed in the 1960s, stretching a massive 64-meter diameter, before being upgraded in the 1980s to the present 70-meter diameter.
These antennas are starting to show their decades of use, wearing out.
The mid-sized 34-meter antennas come in two varieties: a high-efficiency antenna, and a beam waveguide antenna. Every site has one high-efficiency antenna, and at least one waveguide antenna. They're being constructed as replacements for the 70-meter antennas, whose colossal size makes them difficult to maintain and upgrade as technology changes.
The waveguide antennas have five additional precision radio frequency mirrors. These mirrors reflect radio signals along a tube into a climate-controlled below-ground room. This allows for reducing the amount of ambient noise from warm electronics, and simplifies upgrading, maintaining, and modifying equipment.
Using antennas in combination allows them to function as an array, functioning as a single large antenna. By collecting data over a larger area, arrays improve reception of weak signals. This is particularly useful when dealing with the distant signals from spacecraft in deep space.
The Deep Space Network first started using arrays in the early 1970s, with a prototype capturing data from the Voyager encounter with Jupiter and the Pioneer 11 encounter with Saturn. After learning how to best increase sensitivity, all three complexes networked their antennas into arrays to collect signals as Voyager encountered Saturn. By the time Voyager encountered Uranus in 1986, the Deep Space Network was able to link up to four antennas into an array. When Voyager reached Neptune in 1989, the network integrated signals from the Goldstone array and all 27 antennas in the Very Large Array in New Mexico.
These lessons were vital for the success of the Galileo mission to Jupiter in the late 1990s. The spacecraft had a crippled high-gain antennas, reducing how much data the spacecraft could transmit. But by arraying five antennas from three tracking stations in two continents, the Deep Space Network was able to triple the data transmission.
Each complex is shielded from interference by being located in hilly, bowl-shaped terrains. The original station locations were in California, Australia, and South Africa, spaced out longitudinally to ensure constant coverage. The South Africa location was abandoned in the 1970s due to the challenging political climate, replaced with a new station in Spain instead.
Here's a look at some of the stations, past and present.
The Hartebeesthoek complex is 600 kilometers southwest of Johannesburg, South Africa. Located 20 degrees away from Goldstone complex in California, the station completed the trio of antennas that are the backbone of the Deep Space Network.
In 1961, the 26-meter DSS-51 antenna was installed in Hartebeesthoek. The antenna came on-line just in time to help track the Ranger 1 lunar explorer. Considered about the shifting political environment in South Africa, NASA started looking for alternate locations for a replacement antenna at the same longitude. They found it in Spain. By 1974, changes in technology and flight requirements made the antenna obsolete, ending operations at the station.
The Madrid complex is actually located in Robledo de Chevala, not even 50 kilometers west-northwest of Madrid. The Madrid Complex grew, eventually including a pair of 34-meter beam waveguide antennas (DSS-54 and DSS-55), a 34-meter high efficiency antenna (DSS-65), and eventually DSS-66 after it was relocated from Fresnedillas, 5 kilometers southeast of Robledo de Chavela.
While the Madrid complex is located at Robledo de Chavela, it originally had 26-meter antennas at nearby Cebreos and Fresnedillas.
The Cebreos antenna was built 20 kilometers west-southwest of Robledo de Chavela. The antenna was retired in 1981, then found a new life in 2005 when the European Space Agency (ESA) repurposed the station with a 35-meter antenna. This new antenna is the second in the Deep Space Antenna station, DSA-2.
The antenna at Fresnedillas, 5 kilometers southeast of Robledo de Chavela, was originally constructed as part of the primary Manned Space Flight Network that tracked the Apollo missions in the late 1960s and early 1970s. It was later repurposed for the Spaceflight Tracking and Data Network. By 1987, a combination of obsolete technology and budget restrictions led to the antenna's retirement.
The 26-meter antenna was constructed as a replacement for DSS-51 in politically-charged South Africa, selected to fill the same longitudinal position in the trio. The antenna came online just in time for the Mariner 4 mission, helping transmit the first images of the Martian surface captured during the flyby.
Additional equipment was added in 1968 to provide backup communications for the manned space flight Apollo program. The entire antenna was upgraded and converted to a 34-meter antenna in 1980, before finally retiring from use in 1999.
The antenna currently functions as part of Proyecto Academico con el Radio Telescopio de NASA en Robledo (PARTNeR), an education program that allows students and astronomy associations to remotely control the antenna.
Madrid Deep Space Communications Complex started with just DSS-61, but later the massive 64-meter DSS-63 antenna joined the complex. Completed in 1973, the first signals it received were from the Pioneer 10 encounter with Jupiter, followed by the Mariner 10 encounter with Venus. But soon even 64-meters was too small. In 1987, the antenna was upgraded to 70-meter diameter, to hear Voyager call home when encountering the outer planets.
The Goldstone complex is located on the U.S. Army's Fort Irwin Military Reservation, 72 kilometers northeast of Barstow, California. The location was picked as a small, established community on government property, in low hills, and near the rocket research program at the Jet Propulsion Laboratory.
The very first antenna built for the Deep Space Station was the 26-meter antenna in Goldstone, California, constructed for the Echo program in 1960. The antenna captured signals transmitted from Holmdel, New Jersey, that was bounced off a 100 foot balloon orbiting the Earth. By the summer of 1962, it was moved 10 kilometers to the southern edge of the complex.
In 1994, the antenna was decommissioned and converted into a radio telescope which is still used for educational purposes. It is now the Goldstone Apple Valley Radio Telescope, a telescope accessible for K-12 students to operate from their classrooms.
The first of the 64-meter antennas went online just in time to track the Mariner 4 spacecraft. This marked the reacquisition of the Mariner 4 craft, which had been lost by the smaller tracking antenna after the Mars flyby in 1965. This gave it the enduring nickname, The Mars antenna. It was upgraded to its current 70-meter diameter in 1988 in order to track Voyager 2 during its Neptune encounter.
The antenna has participated in some of the most iconic space missions, including Pioneer, Cassini, and the Mars Exploration Rovers. It heard Armstrong's, "That's one small step for a man. One giant leap for mankind," and bounced its radar off planets, asteroids and comets to help image them.
The 26-meter antenna at Goldstone was built in 1967 as part of the Manned Space Flight Network. It originally provided tracking for the Apollo antenna, earning the nickname the Apollo Antenna, and later joined the Deep Space Network in 1985. Unlike the other 26-meter telescopes, it didn't require being relocated during the upgrade, instead just getting new fiber optical cables to connect it to the Signal Process Center.
The Canberra complex is located 40 kilometers southwest of Canberra near the Tidbinbilla Nature Reserve. The location was picked because it's roughly 120 degrees west of California, so fit the plan for three equidistant complexes.
As the massive 70-meter antennas are aging out, they are being replaced by smaller 34-meter antennas. They're easier to maintain, and, when arrayed in groups of four, equal the performance of the larger antennas. The first is in Canberra Deep Space Communications Complex in Australia.
The 26-meter diameter antenna in Woomera is also called Island Lagoon. While the Australians had been working with the British in the 1950s, the 1960 construction project was the first Australian antenna built by NASA. The antenna was used during the Ranger and earlier Mariner missions, before being retired in 1972.
The 26-meter diameter antenna was built in 1964 to support deep space probes like Mariner 4, with additional Manned Space Flight Network equipment to provide backup for the Apollo missions. The station was upgraded in 1980 to a 34-meter diameter to transmit and receive messages from Voyager's Saturn encounter. It was retired in 2000.
Canberra's 64-meter antenna came online in 1973, allowing spacecraft to travel further as weaker signals still be received. It was upgraded to 70-meter diameter in 1987, making it the largest steerable antenna in the Southern Hemisphere.
The 26-meter antenna was constructed in 1967 to receive data from the Apollo lunar missions. Arrayed with Parks and Tidbinbilla, this antenna received the first picture from the surface of the Moon in 1969. The antenna was transferred to the Canberra Deep Space Communications Complex and renamed DSS-46 in the early 1980s.