Satellite watching or satellite spotting is a hobby which consists of the observation and tracking of artificial satellites that are orbiting Earth. [1] People with this hobby are variously called satellite watchers, trackers, spotters, observers, etc. Since satellites outside Earth's shadow reflect sunlight, those especially in low Earth orbit may visibly glint (or "flare") as they traverse the observer's sky, usually during twilight.
Amateur satellite spotting traces back to the days of early artificial satellites when the Smithsonian Astrophysical Observatory launched the Operation Moonwatch program in 1956 to enlist amateur astronomers in an early citizen science effort to track Soviet sputniks .[ clarification needed ] [2] The program was an analog to the World War II Ground Observer Corps citizen observation program to spot enemy bombers. [3] Moonwatch was crucial[ according to whom? ] until professional stations were deployed in 1958. The program was discontinued in 1975. [4] The people who had been involved continued to track satellites however and began to concentrate on satellites that had been omitted from the Satellite Catalog (deliberately), these satellites are from the US and other, allied, countries.
In February 2008 the front page of The New York Times hosted an article about an amateur satellite watcher Ted Molczan in relation to the story about falling American spy satellite USA-193. American officials were reluctant to provide information about the satellite, and instead, Ted Molczan, as the article says, "uncovers some of the deepest of the government’s expensive secrets and shares them on the Internet." [5] Molczan participates with a group of other sky-watchers who have created a "network of amateur sky-watchers and satellite observers" who focus on "spotting secret intelligence-gathering satellites launched by the United States, Russia and China." [6] As of 2017 [update] , the amateurs continue to make their sightings and analysis public on the internet via an electronic mailing list called SeeSat-L, [6] just as they had a decade earlier, since they began the practice in the previous century in days of the early internet. [5]
Prior to 2008, NASA's Orbital Information Group had been providing free information about over 10,000 objects in Earth orbit. Recently[ when? ] this was identified as a security threat,[ by whom? ] and a pilot program was launched in 2008 to replace the NASA OIG website with a US Air Force site (Space-Track.org) with somewhat more controlled access. [7] [ needs update ] The practice by the militaries of countries such as the United States to not distribute all of their satellite orbital data can be counteracted by the skills of satellite watchers, who can calculate the orbits of many military satellites. [6]
As the digital revolution continued to advance in the 2000s, many planetarium and satellite tracking computer programs to aid satellite spotting emerged. [1] In the 2010s, accompanied by the development of augmented reality (AR) technologies, satellite watching programs for mobile devices have been developed. [8] During the 64th International Astronautical Congress 2013 in Beijing a citizen science method to track satellite beacon signals by a Distributed Ground Station Network (DGSN) was presented. [9] [10] The purpose of this network at announcement was to support small satellites and cubesats projects of universities.[ needs update ]
In 2019, amateur sky-watchers analyzed the high-resolution photograph of an Iranian launch site accident tweeted by US President Trump and identified the specific classified spysat (USA-224, a KH-11 satellite with an objective mirror as large as the Hubble Space Telescope) that had taken the photograph, and when it was taken. [11] [12]
Satellite watching started by being done with the naked eye or with the aid of binoculars since predictions of when they would be visible was difficult; most low Earth orbit satellites also move too quickly to be tracked easily by the telescopes available to astronomers. It is this movement, as the satellite tracks across the night sky, that makes them possible to see. [11] As with any sky-watching pastime, the darker the sky the better, so hobbyists will meet with better success further away from light-polluted urban areas.
Today most observers use digital still cameras or video cameras; imagery is put into Astrometry software to generate the angles needed to generate "observations" that are used to calculate orbits of the satellites imaged.
Because geosynchronous satellites move slowly relative to the viewer [13] they can be difficult to find and were not typically sought when satellite watching. [14] However, with digital cameras it is easy to photograph most high-altitude satellites.
Although to the observer low Earth orbit satellites can move at a similar speed as high altitude commercial aircraft, individual satellites can be faster or slower; they do not all move at the same speed. Individual satellites never deviate in their velocity (speed and direction). [15] They can be distinguished from aircraft because satellites do not leave contrails and do not have red and green navigation lights. They are lit solely by the reflection of sunlight from solar panels or other surfaces. A satellite's brightness sometimes changes as it moves across the sky. Occasionally a satellite will 'flare' as it changes orientation relative to the viewer, suddenly increasing in reflectivity. [16] Satellites often grow dimmer and are more difficult to see toward the horizons. [1] Because reflected sunlight is necessary to see satellites, the best viewing times are for a few hours immediately after nightfall and a few hours before dawn. Given the number of satellites now in orbit, a fifteen-minute session of sky watching will generally yield at least one satellite passing overhead.
There are many satellite watcher clubs, which collect observations and issue awards for observations according to various rules. [1]
Amateur astronomy is a hobby where participants enjoy observing or imaging celestial objects in the sky using the unaided eye, binoculars, or telescopes. Even though scientific research may not be their primary goal, some amateur astronomers make contributions in doing citizen science, such as by monitoring variable stars, double stars, sunspots, or occultations of stars by the Moon or asteroids, or by discovering transient astronomical events, such as comets, galactic novae or supernovae in other galaxies.
A satellite or artificial satellite is an object, typically a spacecraft, placed into orbit around a celestial body. Satellites have a variety of uses, including communication relay, weather forecasting, navigation (GPS), broadcasting, scientific research, and Earth observation. Additional military uses are reconnaissance, early warning, signals intelligence and, potentially, weapon delivery. Other satellites include the final rocket stages that place satellites in orbit and formerly useful satellites that later become defunct.
Lacrosse or Onyx is a series of terrestrial radar imaging reconnaissance satellites operated by the United States National Reconnaissance Office (NRO). While not officially confirmed by the NRO or the Government of the United States prior to 2008, there was widespread evidence pointing to its existence, including one NASA website. In July 2008, the NRO itself declassified the existence of its synthetic aperture radar (SAR) satellite constellation.
The night sky is the nighttime appearance of celestial objects like stars, planets, and the Moon, which are visible in a clear sky between sunset and sunrise, when the Sun is below the horizon.
Satellite flare, also known as satellite glint, is a satellite pass visible to the naked eye as a brief, bright "flare". It is caused by the reflection toward the Earth below of sunlight incident on satellite surfaces such as solar panels and antennas. Streaks from satellite flare are a form of light pollution that can negatively affect ground-based astronomy, stargazing, and indigenous people.
The United States Space Surveillance Network (SSN) detects, tracks, catalogs and identifies artificial objects orbiting Earth, e.g. active/inactive satellites, spent rocket bodies, or fragmentation debris. The system is the responsibility of United States Space Command and operated by the United States Space Force.
A balloon satellite, sometimes referred to as a "satelloon", is inflated with gas after it has been put into orbit.
Ajisai is a Japanese satellite sponsored by NASDA, launched in 1986 on the maiden flight of the H-I rocket. It is also known as the Experimental Geodetic Satellite (EGS), as it carries the Experimental Geodetic Payload (EGP).
The Moon is the largest natural satellite of and the closest major astronomical object to Earth. The Moon may be observed by using a variety of optical instruments, ranging from the naked eye to large telescopes. The Moon is the only celestial body upon which surface features can be discerned with the unaided eyes of most people.
Operation Moonwatch was an amateur science program formally initiated by the Smithsonian Astrophysical Observatory (SAO) in 1956. The SAO organized Moonwatch as part of the International Geophysical Year (IGY) which was probably the largest single scientific undertaking in history. Its initial goal was to enlist the aid of amateur astronomers and other citizens who would help professional scientists spot the first artificial satellites. Until professionally staffed optical tracking stations came on-line in 1958, this network of amateur scientists and other interested citizens played a critical role in providing crucial information regarding the world's first satellites.
Systems Tool Kit, often referred to by its initials STK, is a multi-physics software application from Analytical Graphics, Inc. that enables engineers and scientists to perform complex analyses of ground, sea, air, and space platforms, and to share results in one integrated environment. At the core of STK is a geometry engine for determining the time-dynamic position and attitude of objects ("assets"), and the spatial relationships among the objects under consideration including their relationships or accesses given a number of complex, simultaneous constraining conditions. STK has been developed since 1989 as a commercial off the shelf software tool. Originally created to solve problems involving Earth-orbiting satellites, it is now used in the aerospace and defense communities and for many other applications.
The MIT Computation Center was organized in 1956 as a 10-year joint venture between the Massachusetts Institute of Technology and IBM to provide computing resources for New England universities. As part of the venture, IBM installed an IBM 704, which remained at MIT until 1960.
USA-193, also known as NRO Launch 21, was a United States military reconnaissance satellite launched on 14 December 2006. It was the first launch conducted by the United Launch Alliance (ULA). Owned by the National Reconnaissance Office (NRO), the craft's precise function and purpose were classified. On 21 February 2008, it was destroyed as a result of Operation Burnt Frost.
Walter Scott Houston was an American popularizer of amateur astronomy. He wrote the "Deep-Sky Wonders" column in Sky and Telescope magazine from 1946 to 1993.
International Observe the Moon Night is an annual public outreach event sponsored by the Lunar Reconnaissance Orbiter mission, the Solar System Exploration Division at NASA's Goddard Space Flight Center, and other NASA and astronomical organizations that encourages observation, appreciation, and understanding of the Moon and its connection to planetary science and exploration. Everyone on Earth is invited to join the celebration by hosting or attending an event or participating as a lunar observer — and uniting on one day each year to look at and learn about the Moon together. First organized in 2010, there are usually over 500 events annually in over 40 countries, hosted by universities, observatories, NASA Centers, schools, museums, parks, libraries, and amateur astronomers. Some events are offered both in person and via internet streaming video. The date is selected to enhance visibility of lunar topography.
USA-224, also known as NROL-49, is an American reconnaissance satellite. Launched in 2011 to replace the decade-old USA-161 satellite, it is the fifteenth KH-11 optical imaging satellite to reach orbit.
Prowler was an American reconnaissance satellite launched aboard Space ShuttleAtlantis in 1990 to study Soviet satellites in geosynchronous orbit. The government of the United States has never acknowledged its existence, however it has been identified by amateur observers and through leaked information.
Operation Phototrack was among the programs quickly organized in the United States, after the Soviet earth satellite Sputnik 1 was launched on 4 October 1957, to fill the temporary tracking gap until the Baker-Nunn cameras specially designed to optically track U.S. satellites became operational. It was also referred to as the "Independent IGY Tracking Coordination Program".
An orbital pass is the period in which a spacecraft is above the local horizon, and thus available for line-of-sight communication with a given ground station, receiver, or relay satellite, or for visual sighting. The beginning of a pass is termed acquisition of signal (AOS); the end of a pass is termed loss of signal (LOS). The point at which a spacecraft comes closest to a ground observer is the time of closest approach (TCA).
Torch, 9/1956, p. 1, Annual Report of the Smithsonian Institution for the year 1957, p. 8, 74
the satellite spotters who, needing little more than a pair of binoculars, a stop watch and star charts, uncover some of the deepest of the government's expensive secrets and share them on the Internet. Thousands of people form the spotter community. Many look for historical relics of the early space age, working from publicly available orbital information. Others watch for phenomena like the distinctive flare of sunlight glinting off bright solar panels of some telephone satellites. Still others are drawn to the secretive world of spy satellites.
a small community of amateur satellite trackers was far more interested in the picture than the words. These individuals use backyard telescopes to watch satellites whizzing across the sky, and they know where most of them are—even classified ones like USA 224. 'They're super bright in the sky and are easy to find,' says Michael Thompson, a graduate student in astrodynamics at Purdue University who spots satellites in his spare time. Once a satellite is seen, it's relatively easy to work out exactly where it will be at any point in future. 'Using math to calculate an orbit is really easy,' he says.
Since the trajectories of classified satellites are not published by the Department of Defense, Langbroek had to rely on orbit data collected by a global network of amateur spy-satellite hunters. This community obsessively documents the movements of classified objects in space, often using little more than binoculars, a stopwatch, and a basic knowledge of orbital mechanics. But despite the low-tech observation techniques, their predictions of satellite movements are often accurate to within a few seconds. ... This is the first time in three and a half decades that an image has become public that reveals the sophistication of US spy satellites in orbit.