The Minitrack Network, was the first U.S. satellite tracking network to become operational, in 1957. It was used to track the flights of Sputnik, Vanguard, Explorer, and other early space efforts. Minitrack was the progenitor of Spacecraft Tracking and Data Acquisition Network

Spacecraft Tracking and Data Acquisition Network

The Spacecraft Tracking and Data Network was established by NASA to satisfy the requirement for long-duration, highly-available space-to-ground communications...

 (STADAN) and the Manned Space Flight Network

Manned Space Flight Network

The Manned Space Flight Network was a set of tracking stations built to support the American space efforts of Mercury, Gemini, Apollo and Skylab...

 (MSFN).

Origins

When the proposals for satellites floated in the mid 1950s, the question of tracking them naturally arose. Three approaches were considered:

• Optical tracking
• Use of radar
  Radar
  Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
  
  
• A scheme from the United States Naval Research Laboratory
  United States Naval Research Laboratory
  The United States Naval Research Laboratory is the corporate research laboratory for the United States Navy and the United States Marine Corps and conducts a program of scientific research and development. NRL opened in 1923 at the instigation of Thomas Edison...
  
   (NRL) that measured angles using interferometry
  Interferometry
  Interferometry refers to a family of techniques in which electromagnetic waves are superimposed in order to extract information about the waves. An instrument used to interfere waves is called an interferometer. Interferometry is an important investigative technique in the fields of astronomy,...
  
  , based on work at the White Sands Missile Range
  White Sands Missile Range
  White Sands Missile Range is a rocket range of almost in parts of five counties in southern New Mexico. The largest military installation in the United States, WSMR includes the and the WSMR Otera Mesa bombing range...
  
  .

The optical and radar approaches did not require a cooperative target, but had the major problem of acquisition, or finding the target in the first place, since they had very small fields of view. The NRL proposal needed a transmitter on the target, but could easily measure a target anywhere in a wide field of view. The NRL proposal was accepted and turned into the basis of the Minitrack stations.

From a NASA history document:

In early April 1955,
Milton Rosen, John Mengel, and Roger Easton assembled informally
at NRL and generated a document entitled, "Proposal for
Minimum Trackable Satellite (Minitrack)." No date and no
authors are listed on this key report; but, according to
Rosen, it preceded only by a few days a more formal report
with the title, "A Scientific Satellite Program,"
April 13, 1955, and written by the NRL Rocket Development
Branch. Appendix B of this document was labeled, "The Minitrack
System" and was nearly identical to its predecessor of
a few days. The name "Minitrack" now appearing for the
first time on paper, was coined by John Mengel.

Development

The original proposal had only a single pair of stations. However, this was soon realized to be insufficient. From the NASA history:

Before the end of 1955, ideas changed drastically.
First, it was realized that a single pair of stations would
provide very limited geographical coverage, rendering data
acquisition difficult and the accumulation of orbital data
very slow. Four pairs of stations across the southern U.S.
were next proposed. The idea of a "radio fence" was implicit
in this suggestion; i.e., the creation of a long chain of
overlapping antenna patterns that the satellite must intersect
frequently. The trouble was that the planned orbital
inclination of the Vanguard satellite would keep it away
from the southern U.S. too much of the time. The next logical
step was the construction of a long north-south fence
that the satellite would pass through on almost every orbit.
But the Vanguard program could not financially support a
long chain of paired stations; besides, further thought
soon showed that complete orbital data could be computed
from angular (interferometric) tracking alone. These changes
in thinking manifested themselves in a report describing a
chain of nine single Minitrack stations strewn along the
75th meridian. To the regret of some engineers, ranging
and velocity-measuring capabilities were dropped.

The technical desirability of Minitrack stations on
foreign soil was one thing; more formidable were site negotiation,
site preparation, and logistics. The situation was
particularly acute in South American countries that were
sensitive about U.S. bases and where transportation and communication
facilities were primitive. Unfortunately, Minitrack
stations required radio-quiet spots which are usually
not coexistent with the also-desired communication links and
supply facilities.

[...]

The Site Selection Team had picked six South American
locations: Havana

Havana

Havana is the capital city, province, major port, and leading commercial centre of Cuba. The city proper has a population of 2.1 million inhabitants, and it spans a total of — making it the largest city in the Caribbean region, and the most populous...

, Panama, Quito, Lima, Antofagasta

Antofagasta

Antofagasta is a port city in northern Chile, about north of Santiago. It is the capital of Antofagasta Province and Antofagasta Region. According to the 2002 census, the city has a population of 296,905...

, and
Santiago; but who would undertake the imposing task of setting
up stations outside the United States proper? The U.S.
Army, by virtue of its IAGS experience, was the logical
choice. In September 1956, the Army Chief of Engineers
initiated construction at the six sites at the request of
NRL. More specifically, the task fell to the specially
created Project Vanguard Task Force of the Army Map Service.
It should be mentioned here that the South American sites,
though near large cities, were generally some distance from
modern facilities and their associated radio noise. The
isolation and primitive conditions caused logistics and operator
morale problems in early days.

The Minitrack sites in the continental U.S. were established
with greater ease. The Navy set up and operated
the Blossom Point and San Diego stations; the latter being
at the Brown Naval Auxiliary Air Station, near Chula Vista,
California, and operated by the Naval Electronics Laboratory

Naval Electronics Laboratory

The U.S. Navy Electronics Laboratory was created in 1945, with the consolidation of the Navy Radio and Sound Lab and its wartime partner, the University of California Division of War Research...

.
The stations downrange from Cape Canaveral

Cape Canaveral

Cape Canaveral, from the Spanish Cabo Cañaveral, is a headland in Brevard County, Florida, United States, near the center of the state's Atlantic coast. Known as Cape Kennedy from 1963 to 1973, it lies east of Merritt Island, separated from it by the Banana River.It is part of a region known as the...

 were set up in
cooperation with Great Britain and operated by the U.S. Navy
and Air Force. After deliberation over tracking requirements,
logistics, and support facilities, Antigua and Grand
Turk were finally chosen for downrange stations instead of
the initially planned Barbuda

Barbuda

Barbuda is an island in the Eastern Caribbean, and forms part of the state of Antigua and Barbuda. It has a population of about 1,500, most of whom live in the town of Codrington.-Location:...

 and Mayaguana

Mayaguana

Mayaguana is the most easterly island and district of the Bahamas. It is one of only a few Bahamian islands which retain their Lucayan names. The population of Mayaguana in the 2000 census was 259, amounting to an estimate 312 in 2010...

.

[...]

The Blossom Point station, just 56 km southeast of
Washington, went into operation in July 1956, and was soon
employed as a training headquarters for Minitrack operators
and as a test facility for Minitrack equipment. During the
IGY and after, many foreign nationals took the Minitrack
course at Blossom Point. In fact, the willingness of NRL
and NASA to employ and train foreign nationals at the Minitrack
and STADAN stations greatly eased the task of placing
U.S. facilities on foreign soil. Minitrack stations have
"earned their keep" many times over as non-political, nostrings-
attached representatives of the United States. 28

The full Minitrack network of ten stations was placed
in operation during October 1957, with the eleventh, at
Woomera, Australia, added a month later. It should already
be evident that the Minitrack network was not a static thing.
Stations were added and subtracted as the space program required.
Bigger satellites with more transmitter power made
stations such as Antofagasta redundant. Political harassment
in Cuba made it apparent as early as September 1957
that the Havana station would probably have to be moved.

Technical problems

Although a Minitrack station could measure the angles to the satellites very accurately, using this information to determine an orbit required additional work.

• The location of the station must be known very accurately. Prior to satellites, each continent had their own surveying coordinate system, and the relationship between these systems was not known accurately.
• The time at the station must be known accurately. The solution was to set up an accurate clock at each station, and calibrate it by comparing to the radio transmissions of WWV.
• Since more than one observation is needed to determine an accurate orbit, the data from each station must be sent to a central location for orbit determination. This was difficult since the stations were located in radio quiet areas, which therefore had little communications infrastructure. The US army pitched in and built new communications facilities for the stations.

Minitrack and sputnik

By October 1, 1957, Minitrack was complete except for
the checkout of some teletype links and the calibration of
some stations. Three days later, Sputnik i began crossing
the Minitrack fence every 96 minutes; but it was transmitting
at 20 and 40 MHz. Minitrack operators knew Sputnik I
was passing overhead but could not track it with 108-MHz
interferometers.

Sputnik I was transmitting in the amateur radio bands
and getting good publicity as hams all over the world picked
up the signals. Army radio engineers and many amateurs spent
the night of October 4 building and modifying their equipment
for Doppler tracking. Crude orbital data were available
within a day. At NRL, the minitrack team had already
begun to modify Minitrack for 40-MHz reception. Alerted by
radio announcements of the Sputnik launching, they burned
the midnight oil cutting 40-MHz dipoles and planning network
modifications. 40-MHz crosses were quickly installed at
Blossom Point, San Diego, and Lima; and, later, at Santiago
and Woomera. In several days, good tracking data were being
received. Sputnik 1 and Sputnik 2, in fact, gave Minitrack
good shakedown runs.

Midlife: 1958-1962

When the US satellites Explorer and Vanguard were launched a few months later, Minitrack was able to track them easily. This worked sufficiently well that the Minitrack interferometers also formed the basic tracking method of the succeeding STADAN network.

The last prime IGY Minitrack station went operational
at Woomera during October 1957. Outside of some minor shuffling
and addition of sites and the rebuilding of temporary
installations, no major changes were made to Minitrack until
the big 26-m paraboloidal antenna was installed at the new
Fairbanks site in May 1962. [...] During this period, the Minitrack network
easily tracked the few, relatively simple scientific
satellites that passed overhead. It was a time of intense
planning, research, and development as the Nation planned
space programs that would soon saturate Minitrack's capabilities.

Transformation into STADAN

As satellites grew bigger and more sophisticated, there were a number of problems that Minitrack could not handle well, and some capabilities that were not needed. These included:

• Satellites in polar orbits. This required new sites to track.
• Satellites in synchronous orbits. These have bearings that change slowly (or can be completely stationary). This makes angle tracking much less useful. What is needed in this case, especially for maneuvers of such satellites, is range and range rate. Minitrack could not make these measurements. A very similar situation exists for satellites are near apogee in eccentric orbits.
• A need for much larger data return bandwidths, and hence larger antennas. Nimbus was the first satellite that stressed this issue, as it began to return pictures rather than just basic telemetry.
• More, and more automated, telemetry and command facilities, as the number of satellites, and their sophistication, increased.
• Much less need for blind tracking. As the launch ranges improved their tracking, good orbital elements were available before the missile even left the range.

To meet these new needs, a number of fundamental changes were made to the Minitrack network.

• Site changes, closures, and additions.
• Adding larger 12 meter and 26 meter dishes at some sites.
• Adding the Goddard Range and Range Rate tracking equipment (GRARR).
• Adding new automatic tracking telemetry and command antennas (SATAN).
• Larger and more automated ground communication links between stations.

The resulting network was called the Spacecraft Tracking and Data Acquisition Network

Spacecraft Tracking and Data Acquisition Network

The Spacecraft Tracking and Data Network was established by NASA to satisfy the requirement for long-duration, highly-available space-to-ground communications...

, or STADAN.