The microwave sounding unit (MSU) was the predecessor to the Advanced Microwave Sounding Unit (AMSU).
52-455: The MSU was first launched aboard the TIROS -N satellite in late 1978 and provided global coverage (from Pole to Pole). It carries a 4-channel microwave radiometer , operating between 50 and 60 GHz . Spatial resolution on the ground was 2.5 deg in longitude and latitude (about 250 km circle). There were 9 different MSUs launched; the most recent one on NOAA-14 . They provided measurements of
104-667: A larger launch vehicle for larger satellites, allowing the RCA to change the Janus design to a larger spin-stabilized spacecraft. The Janus project was renamed to Television Infrared Observation Satellite (TIROS) following the changes and the project was declassified. Development of the TIROS satellite payload was contracted to the Army Signal Corps Laboratories and $ 3.6 million was allocated to Air Force Systems Command for use of
156-411: A radiometer developed by Verner E. Suomi to measure Earth's energy budget . However, only the optical system was included in the first TIROS payload, TIROS-1 , launched on April 1, 1960, as the first U.S. satellite to carry a television camera. The originally planned instruments were included in the subsequent launches of TIROS-2 , TIROS-3 , and TIROS-4 over the following two years. Despite
208-541: A beginner". The Advanced Research Projects Agency (now DARPA ) initiated the TIROS program in 1958 and transferred the program to the National Aeronautics and Space Administration ( NASA ) in 1959. Participants in the TIROS program also included, United States Army Signal Research and Development Laboratory , Radio Corporation of America ( RCA ), the United States Weather Bureau Service ,
260-631: A committee chaired by William Welch Kellogg of the RAND Corporation with representatives from the U.S. Armed Forces, the U.S. Weather Bureau , the National Advisory Committee for Aeronautics , and the RCA was convened to discuss a satellite meteorological program and design objectives. The committee recommended that such a program should provide observations of cloud cover with television cameras at coarser and finer resolutions, accompanied by infrared measurements of Earth's radiation ;
312-455: A few hundred feet from the pad, blockhouse crews watching in stunned surprise at the upper stage motors burning on the ground. Cause of the mishap was quickly traced to a short between two diodes in a power inverter, which cut off power to the guidance system at liftoff and caused the Juno's engine to gimbal to full stop, flipping the vehicle onto its side before Range Safety action was taken. To prevent
364-480: A high-priority requirement by the U.S. government, the RCA shifted the goals of the Janus project towards meteorological applications, whose relaxed resolution requirements for cameras enabled smaller and lighter satellite systems. Accordingly, the resolution of the television cameras planned for Janus was lowered, relying on off-the-shelf refractive optics rather than the more sophisticated systems originally planned. The U.S. Army also granted an ARPA request to develop
416-537: A long data record and have been used for tracking atmospheric temperature trends (see: Microwave Sounding Unit temperature measurements ). TIROS Television InfraRed Observation Satellite ( TIROS ) is a series of early weather satellites launched by the United States , beginning with TIROS-1 in 1960. TIROS was the first satellite that was capable of remote sensing of the Earth , enabling scientists to view
468-460: A recurrence of this failure mode, improved coatings were used on the circuit boards in the booster. On 15 August 1959, the next Juno II was flown, carrying the Beacon satellite . While first-stage performance was nominal, the upper stages malfunctioned. One intended experiment on this mission was the ejection of four flares stowed in the interstage section which would be tracked and photographed during
520-543: A study for the RAND Corporation in 1951, concluding that a spaceborne television camera could provide worthwhile information for general reconnaissance. In 1956, the RCA received funding from the U.S. Army to develop a reconnaissance satellite program, initially called Janus, under the administration of the Army Ballistic Missile Agency (ABMA). The project remained under the administration of ABMA but
572-408: A total of 64 pictures taken at fixed 30-second intervals, equivalent to at most two orbits of data. Imaging capacity was increased to 96 pictures beginning with TIROS-9, and implementation of a clock system enabled for variable intervals between images. The camera shutters made possible the series of still pictures that were stored and transmitted back to earth via 2-watt FM transmitters as
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#1732854583378624-551: The Earth Radiation Budget Satellite (ERBE) and SBUV/2 . The search and rescue (SAR) system became independent, utilizing a special frequency for transmission of data to the ground. Juno II Juno II was an American space launch vehicle used during the late 1950s and early 1960s. It was derived from the Jupiter missile, which was used as the first stage. Solid-fueled rocket motors derived from
676-512: The MGM-29 Sergeant were used as upper stages, eleven for the second stage, three for the third stage, and one for the fourth stage, the same configuration as used for the upper stages of the smaller Juno I launch vehicle. On some launches to low Earth orbit the fourth stage was not flown, allowing the launch vehicle to carry an additional nine kilograms of payload. Development of the Juno II
728-594: The Thor launch vehicle. Before signing the National Aeronautics and Space Act that created the National Aeronautics and Space Administration (NASA), President Dwight D. Eisenhower determined that NASA should handle meteorological satellite development. Edgar Cortright , the ARPA committee overseeing the TIROS project, arranged the transfer of TIROS to NASA's Goddard Space Flight Center on April 13, 1959. The acquisition of
780-680: The United States Naval Photographic Interpretation Center (NPIC), the Environmental Science Services Administration (ESSA), and the National Oceanic and Atmospheric Administration (NOAA). The TIROS project emerged from early efforts examining the feasibility of surveillance from space for meteorology and intelligence gathering which began in the U.S. as early as the late 1940s. The Radio Corporation of America conducted
832-507: The equator , providing coverage of the Earth between 55°N and 55°S. Concurrent improvements in the Thor-Delta launch vehicle selected for the TIROS program permitted increases in the orbital inclination of later payloads. The following four satellites from TIROS-5 through TIROS-8 had a higher inclination of 58°, expanding satellite coverage to 65°N–65°S. TIROS-9 and TIROS-10 achieved full coverage of
884-470: The temperature of the troposphere and lower stratosphere until 1998, when the first AMSU was deployed. AMSU provides many more channels and finer resolution (about 50 km). Table 1 lists some characteristics of the MSU. The radiometer's antenna scans underneath the satellite through nadir , and its polarization vector rotates with the scan angle. In the table, "vertical polarization near nadir" means that
936-551: The E-vector is parallel to the scan direction at nadir, and "horizontal polarization" means the orthogonal direction. Table 1 Radiometric characteristics of the Microwave Sounding Unit The MSU was used by NOAA for meteorological analyses in combination with two infrared instruments, and sometimes alone, for post-analysis of weather events and other atmospheric phenomena such as waves. MSU and AMSU together provide
988-436: The Earth from a new perspective: space. The program, promoted by Harry Wexler , proved the usefulness of satellite weather observation, at a time when military reconnaissance satellites were secretly in development or use. TIROS demonstrated at that time that "the key to genius is often simplicity". TIROS is an acronym of "Television InfraRed Observation Satellite" and is also the plural of "tiro" which means "a young soldier,
1040-484: The Earth's daylight side with near-polar orbital inclinations of 98° with respect to the equator. The orientations of the first eight TIROS satellites and their orbits constrained the observable portion of Earth's sunlit side, relying on orbital precession over the course of several months to cover areas in both the Northern and Southern hemispheres. As of June 2009, all TIROS satellites launched between 1960 and 1965 (with
1092-525: The Improved TIROS Operational System (ITOS), was developed and launched in the 1970s, combining the capabilities of the two types of ESSA satellites and serving in an operational capacity. Unlike the preceding TIROS generations, the ITOS spacecraft featured three-axis stabilization . Later ITOS satellites included additional instruments and improved versions of the preceding instruments, including
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#17328545833781144-401: The Juno II. The conversion of the booster for LEO launches also threw off the calibration of the spinning tub third stage which was designed for the tiny Pioneer probes and not the larger Explorer satellites. At this time, NASA had four Juno IIs remaining in their inventory. The review board predicted that two of them would launch successfully, but recommended that there was no reason not to fly
1196-486: The TIROS Operational System (TOS) beginning in 1966. Nine ESSA satellites were launched during 1966–1969. The odd-numbered ESSA satellites provided meteorological data to national meteorological services while television images from the even-numbered ESSA satellites could be received from simple stations globally through an Automated Picture Transmission (APT) system. A third generation of TIROS satellites, named
1248-432: The TIROS project from ARPA by NASA was seen as a means to provide good publicity and validate the existence of the nascent civilian agency. The agency treated the project as an experimental testbed rather than as an operational aid or as a platform for taking scientific observations. The United States Weather Bureau and Department of Defense Weather Services favored operational use of early TIROS data. This tension led to
1300-736: The Very High Resolution Radiometer. In 1978, RCA completed the first spacecraft in the TIROS-N series, the fourth generation of TIROS satellites. These offered a new suite of instruments including the Advanced Very-High-Resolution Radiometer (AVHRR). Later TIROS-N satellites, beginning with NOAA-E in 1983, had higher data-handling capacity and carried new instruments on a slightly larger spacecraft bus ; these satellites were collectively known as Advanced TIROS-N (ATN). NOAA-N Prime (later designated NOAA-19)
1352-465: The atmosphere. A malfunction in a propellant depletion circuit was found to be the cause of the failure, although the exact nature of it could not be determined. The circuit was redesigned afterwards. Pioneer 4 launched successfully on 3 March 1959, making for the only first-generation U.S. lunar probe to accomplish all of its mission goals, as well as the sole successful U.S. lunar probe until 1964. After Pioneer 4, NASA shifted their lunar efforts to
1404-515: The axis of rotation of TIROS-1 to oscillate . A magnetorquer was introduced on TIROS-2 and maintained through TIROS-8 to allow 1.5° changes in the spacecraft attitude per orbit by gradually varying the spacecraft's own magnetic field. A more robust magnetic system, named the Quarter Orbit Magnetic Attitude Control System, was introduced on TIROS-9, allowing for quicker and finer attitude control and enabling changes in
1456-399: The base plate and aligned parallel to the spacecraft's axis of rotation . The lack of attitude control on the first generation of TIROS meant that Earth was only in the field of view of the cameras for a portion of the satellite orbit, with the satellite holding a fixed orientation relative to space for its entire service lifetime by design. Interaction with Earth's magnetic field caused
1508-462: The beginning. The main differences between the Juno II and Jupiter were stretched propellant tanks for increased burn time (the first stage burn time was approximately 20 seconds longer than on the Jupiter), a reinforced structure to support the added weight of upper stages, and the inertial guidance system replaced with a radio ground guidance package, which was moved to the upper stages. The Juno II
1560-445: The bigger Atlas-Able booster and decided instead to utilize the Juno II for Earth orbital launches. By removing the fourth stage, the payload capacity was nearly doubled. The attempted launch of an Explorer satellite on 16 July 1959 failed dramatically when the Juno II lost control almost immediately at liftoff, performing a cartwheel before the range safety officer sent the destruct command. The almost fully fueled booster crashed
1612-479: The booster, leading to low interest and apathy among those in the program. The JPL team who developed the Juno II had originally only intended it for the Pioneer lunar probes and their interest started waning as soon as NASA began Earth orbital launches with the vehicle. Even worse, most of the design team had been disbanded and its members reassigned to other projects, making it difficult to obtain technical information for
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1664-426: The boosters since they had already been bought and paid for. Their assumptions proved correct. Explorer 8 was launched successfully on 3 November 1960, with the next attempt on 24 February 1961 a failure. A control cable came loose during ascent and wrapped itself around the spinning third-stage tub, damaging the upper stages and payload. Second-stage ignition occurred on time, but the third stage did not ignite and
1716-567: The early success of TIROS, early difficulties with handling TIROS data and political pressure to develop an operational weather satellite system based around a second spacecraft in development, Nimbus . However, delays and the high cost of the Nimbus program ultimately led to TIROS-based spacecraft serving as the United States' fleet of operational weather satellites. The second generation of TIROS satellites, designated as ESSA , fulfilled this role as
1768-592: The environment. The naming of the satellites can become confusing because some of them use the same name as the over-seeing organization, such as "ESSA" for TOS satellites overseen by the Environmental Science Services Administration (for example, ESSA-1 ) and "NOAA" (for example, NOAA-M ) for later TIROS-series satellites overseen by the National Oceanic and Atmospheric Administration. The first ten TIROS satellites, beginning with
1820-468: The exception of TIROS-7) were still in orbit. The Advanced TIROS-N (ATN) spacecraft were similar to the NOAA-A through -D satellites, apart from an enlarged Equipment Support Module to allow integration of additional payloads. A change from the TIROS-N through NOAA-D spacecraft was that spare word locations in the low bit rate data system TIROS Information Processor (TIP) was used for special instruments such as
1872-715: The first generation, the scope of the TIROS project evolved from an initially experimental to a semi-operational stature. Following TIROS-1, the engineering and mission design of successive TIROS spacecraft were intended to resolve shortcomings observed in earlier iterations. The spacecraft bus for the first generation of TIROS spacecraft were drum-shaped 18-sided right prisms spanning about 42 in (1,100 mm) in diameter and 19 in (480 mm) in height. Made of aluminum alloy and stainless steel, each spacecraft weighed around 270 lb (120 kg). The satellites were powered by nickel–cadmium batteries , which in turn were charged by 9,200 solar cells mounted throughout
1924-563: The formation of the Panel on Operational Meteorological Satellites, an interagency group, in October 1960 to ascertain the objectives of an operational meteorological satellite program. The initial TIROS mission design called for three satellites. Each satellite was to carry a two-lens optical television system built by the RCA, an improved infrared scanning system drawn from the Vanguard 2 spacecraft, and
1976-498: The goal of the first meteorological satellites would be to trial experimental television techniques, validate sun- and horizon-based sensors for spacecraft orientation , and collect meteorological data. While Janus was in development, Herbert York , the Director of Defense Research and Engineering , moved Department of Defense reconnaissance satellites out of the purview of the U.S. Army. With meteorological satellites flagged as
2028-411: The ground station network. Some of the early TIROS spacecraft also included a five-channel medium resolution infrared scanning radiometer and a low resolution radiometer. The five-channel radiometer allowed for observations of both daytime and nighttime cloud cover. Data were transmitted via four antennas protruding from the spacecraft base plate, with a single receiving antenna mounted at the center of
2080-403: The launch of TIROS-1 in 1960 and ending with the launch of TIROS-10 in 1965, were polar orbiting spacecraft developed and operated under the aegis of NASA. Each spacecraft had design lifetimes of six months, with a new spacecraft launch every six months. The primary goal of the first TIROS satellites was to trial the use of spaceborne television camera systems for imaging cloud cover. During
2132-481: The launch. However, things went awry when the flare ejection failed to take place on schedule. The control system also malfunctioned and drove the upper stages into the Atlantic Ocean instead of orbit. It was concluded that one of the flares deployed inside the interstage section instead of outside like it was intended to, causing the guidance compartment to depressurize and cause loss of vehicle control. Explorer 7
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2184-461: The payload into the Atlantic Ocean. In mid-1960, with only two successful launches in six attempts, a NASA board conducted a thorough reevaluation of the Juno II as a launch vehicle. The failures were mostly traced to isolated component failures that occurred as a result of inadequate testing and checkouts. This was blamed on the program being close-ended, with no further plans for development of
2236-459: The satellite approached one of its ground command points. After transmission, the tape was erased or cleaned and readied for more recording. TIROS-8 served as a test run of the new APT system, allowing images to be readily broadcast and received without dependence on onboard storage. Subsequent TIROS spacecraft maintained the APT system accompanied by improvements to both the onboard system and expansion of
2288-507: The satellite failed to reach orbit. Explorer 11 launched successfully on 27 April 1961, an event that raised NASA's morale during a mostly disastrous month characterized by Project Mercury failures and the Soviet launch of a man into space . On 24 May 1961, the final Juno II lifted from LC-26A carrying another ionospheric beacon satellite. The instrument unit lost power following first-stage separation, resulting in no second-stage ignition and
2340-403: The sides of the spacecraft. The TIROS spacecraft were designed to spin at 8–12 rpm to maintain spin stabilization. Pairs of solid-propellant rockets mounted on the base plate of the instrument housing could be fired one pair at a time to increased the rotation rate by 3 rpm to counteract degradation in the spin rate. The cameras on the first eight TIROS satellites were also located on
2392-567: The spacecraft spin axis by up to 10°. The cameras on TIROS-9 were affixed radially on the sides of the spacecraft rather than the base plate. This "wheel" configuration, in contrast to the "axial" configuration of the preceding TIROS spacecraft, allowed more frequent imagery of the Earth. The first generation of TIROS satellites carried two 0.5 in (13 mm) diameter Vidicon line-scan cameras , typically with different fields of view supporting different angular resolution . The magnetic tape recorder on early iterations of TIROS could store
2444-431: The top plate. Each of the first ten TIROS missions were planned to take circular Sun-synchronous orbits with an altitude of about 400 nmi (740 km; 460 mi); over-performance of the second stage of TIROS-9's launching system resulted in the errant placement of that spacecraft in an elliptical orbit. The first four TIROS satellites were launched into circular orbits with an inclination of 48° with respect to
2496-447: Was extremely fast due to being completely built from existing hardware. The project began in early 1958 and the first vehicle flew at the end of the year. Chrysler was responsible for the overall contract, while Rocketdyne handled the first stage propulsion and Jet Propulsion Laboratory handled the upper stage propulsion. The first three Juno IIs were converted Jupiter missiles, however all remaining boosters were built as Juno IIs from
2548-567: Was scheduled for launch in the last week of September 1959, but a Jupiter missile test on an adjacent pad failed just after liftoff on 15 September 1959 and the Juno II suffered minor damage from flying debris. This was quickly repaired and the launch performed successfully on 13 October 1959. Explorer 7 would be the last Juno II launch from LC-5 as the pad was then permanently reassigned to Project Mercury . On 23 March 1960, another Explorer satellite failed to reach orbit when one second-stage motor failed to ignite, causing imbalanced thrust that sent
2600-519: Was the last spacecraft in the TIROS series, launching in February 2009. TIROS continued as the more advanced TIROS Operational System (TOS), and eventually was succeeded by the Improved TIROS Operational System (ITOS) or TIROS-M , and then by the TIROS-N and Advanced TIROS-N series of satellites. NOAA-N Prime ( NOAA-19 ) is the last in the TIROS series of NOAA satellites that observe Earth's weather and
2652-587: Was transferred to the Advanced Research Projects Agency (ARPA, now DARPA ) in 1958. The contract called for the development of a spacecraft to be launched using the Jupiter-C launch vehicle, which was eventually revised to the Juno II launch vehicle. Janus and Janus II, prototype satellites without directional stability and a single onboard camera, were built as part of the project. In May 1958,
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#17328545833782704-477: Was used for ten satellite launches, of which six failed. It launched Pioneer 3 , Pioneer 4 , Explorer 7 , Explorer 8 , and Explorer 11 from Cape Canaveral Launch Complex 5 and Launch Complex 26B . The first launch of a Juno II, Pioneer 3 on 6 December 1958, suffered a premature first-stage cutoff, preventing the upper stages from achieving sufficient velocity. Pioneer 3 could not escape Earth orbit, but transmitted data for some 40 hours before reentering
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