# Sounding rocket

A sounding rocket or rocketsonde, sometimes called a research rocket or a suborbital rocket, is an instrument-carrying rocket designed to take measurements and perform scientific experiments during its sub-orbital flight. The rockets are often used to launch instruments from 48 to 145 km (30 to 90 miles) above the surface of the Earth, the altitude generally between weather balloons and satellites; the maximum altitude for balloons is about 40 km (25 miles) and the minimum for satellites is approximately 121 km (75 miles).
Due to their suborbital flight profile, sounding rockets are often much simpler than counterparts built for orbital flight. Certain sounding rockets have an apogee between 1,000 and 1,500 km (620 and 930 miles), such as the Black Brant X and XII, which is the maximum apogee of their class. For certain purposes, sounding rockets may be flown to altitudes as high as 3,000 kilometers (1860 miles) to allow observing times of around 40 minutes to provide geophysical observations of the magnetosphere, ionosphere, thermosphere and mesosphere.

## Etymology

The origin of the term comes from nautical vocabulary to sound, which is to throw a weighted line from a ship into the water to measure the water's depth. The term itself has its etymological roots in the Romance languages word for probe, of which there are nouns sonda and sonde and verbs like sondar which means "to do a survey or a poll". Sounding in the rocket context is equivalent to "taking a measurement".

## Design

The basic elements of a modern sounding rocket are a solid-fuel rocket motor and a science payload. In certain sounding rockets the payload may even be nothing more than a smoke trail as in the Nike Smoke which is used to determine wind directions and strengths more accurately than may be determined by weather balloons. Or a sounding rocket such as the Nike-Apache may deposit sodium clouds to observe very high altitude winds. Larger, higher altitude rockets have multiple stages to increase altitude and/or payload capability. The freefall part of the flight is an elliptic trajectory with vertical major axis allowing the payload to appear to hover near its apogee. The average flight time is less than 30 minutes; usually between five and 20 minutes. The rocket consumes its fuel on the first stage of the rising part of the flight, then often separates and falls away, leaving the payload to complete the arc, sometimes descending under a drag source such as a small balloon or a parachute.
Sounding rockets have utilized balloons, airplanes and artillery as "first stages." Project Farside utilized a Rockoon composed of a 106,188-m3 (3,750-ft3) balloon, lifting a four stage rocket composed of 4 Recruit rockets as the first stage with 1 Recruit as the second stage, with 4 Arrow II motors composing the third stage and finally a single Arrow II as the fourth stage. Sparoair, air launched from Navy F4D and F-4 fighters were examples of air launched sounding rockets. There were also examples of artillery launched sounding rockets including Project HARP's 5", 7", and 15" guns, sometimes having additional Martlet rocket stages.

## Development history

The earliest sounding rockets were liquid propellant rockets such as the WAC Corporal, Aerobee, and Viking. The German V-2 served both the US and the USSR's R-1 missile as sounding rockets during the immediate Post World War II periods. During the 1950s and later inexpensive surplus military boosters such as those used by the Nike, Talos, Terrier, and Sparrow came to be used. Since the 1960s rockets specifically designed for the purpose such as the Black Brant series have dominated sounding rockets, though often having additional stages, many from military surplus.
The earliest attempts at developing sounding rockets were in the Soviet Union. While all of the early rocket developers were concerned largely with developing the ability to launch rockets some had the objective of investigating the stratosphere and beyond. The All-Union Conference on the Study of Stratosphere was held in Leningrad (now St. Petersburg) in 1936. While the conference primarily dealt with balloon Radiosondes, there was a small group of rocket developers who sought to develop "recording rockets" to explore the stratosphere and beyond. Amongst the speakers at the conference was Sergey Korolev who later became the leading figure of the Soviet space program.
Specifically interested in sounding rocket design were V. V. Razumov, of the Leningrad Group for the Study of Jet Propulsion. A. I. Polyarny working in a special group within the Society for Assistance to the Defense, Aviation and Chemical Construction of the U.S.S.R in Moscow designed the R-06 which eventually flew but not in the meteorological role.
The early Soviet efforts to develop a sounding rocket were the earliest efforts to develop a sounding rocket and ultimately failed before WWII. P. I. Ivanov built a three-stage which flew in March 1946. At the end of summer 1946 development ended because it lacked sufficient thrust to loft a sufficient research payload.
The first successful sounding rocket was created at the California Institute of Technology, where before World War II there was a group of rocket enthusiasts led by Frank Malina, under the aegis of Theodore von Kármán, known amidst the people of the CIT as the "Suicide Squad." The immediate goal of the Suicide Squad was exploring the upper atmosphere which required developing the means of lofting instruments to high altitude and recovering the results. After the start of WWII the CIT rocketry enthusiast found themselves involved in a number of defense programs, one of which, deemed Corporal, was intended to produce a bombardment guided missile the Corporal. Eventually known as the MGM-5 Corporal it became the first guided missile deployed by the US Army.
During WWII the Signal Corps created a requirement for a sounding rocket to carry 25 pounds (11 kg) of instruments to 100,000 feet (30 km) or higher. To meet that goal Malina proposed a small Liquid-propellant rocket to provide the GALCIT team necessary experience to aid in developing the Corporal missile. Malina with Tsien Hsue-shen (Qian Xuesen in Pinyin transliteration), wrote "Flight analysis of a Sounding Rocket with Special Reference to Propulsion by Successive Impulses." As the Signal Corps rocket was being developed for the Corporal project, and lacked any guidance mechanism, it was Without Attitude Control. Thus it was named the WAC Corporal. The WAC Corporal served as the foundation of Sounding Rocketry in the USA. WAC Corporal was developed in two versions the second of which was much improved. After the war the WAC Corporal was in competition for sounding mission funding with the much larger captured V-2 rocket being tested by the U.S. Army. WAC Corporal was overshadowed at its job of cost-effectively lifting pounds of experiments to altitude, thus it effectively became obsolescent. WAC Corporals were later modified to become the upper stage of the first two staged rocket the RTV-G-4 Bumper.
Captured V-2s dominated American sounding rockets and other rocketry developments during the late 1940s. To meet the need for replacement a new sounding rocket was developed by the Aerojet Corporation to meet a requirement of the Applied Physics Laboratory and the Naval Research Laboratory. Over 1,000 Aerobees of various versions for varied customers were flow between 1947 and 1985.$^{:57}$ One engine produced for the Aerobee ultimately powered the second stage of the Vanguard (rocket), the first designed for the purpose Satellite Launch Vehicle, Vanguard. The AJ10 engine used by many Aerobees eventually evolved into the AJ10-190 which formed the Orbital Maneuvering System of the Space Shuttle.
The Viking (rocket) was intended from the start by the Navy not only to be a sounding rocket capable of replacing, even exceeding the V-2, but also to advance guided missile technology. The Viking was controlled by a multi-axis guidance system with gimbled Reaction Motors XLR10-RM-2 engine. The Viking was developed through two major versions. After the United States announced it intended to launch a satellite in the International Geophysical Year (1957-1958) the Viking was chosen as the first stage of the Vanguard Satellite Launch Vehicle. The last two Vikings were fired as Vanguard Test Vehicle 1 and 2.
During the post WWII era the USSR also pursued V-2 base sounding rockets. The last two R-1As were flown in 1949 as sounding rockets. They were followed between July 1951 and June 1956 by 4 R-1B, 2 R-1V, 3 R-1D and 5 R-1Es, and 1 R-1E (A-1). The improved V-2 descendant the R-2A could reach 120 miles and were flown between April 1957 and May 1962. Fifteen R-5Vs were flown from June 1965 to October 1983. Two R-5 VAOs were flown in September 1964 and October 1965. The first solid-fueled Soviet sounding rocket was the M-100. Some 6640 M-100 sounding rockets were flown from 1957 to 1990.
Other early users of sounding rockets were Britain, France and Japan.
Great Britain developed the Skylark (rocket) series and the later Skua for the International Geophysical Year.
France had begun the design of a Super V-2 but that program had been abandoned in the late 1940s due to the inability of France to manufacture all components necessary. Though development of the Veronique (rocket) began in 1949, it was not until 1952 that the first full scale Veronique was launched. Veronique variants were flown until 1974. The Monica (rocket) family, an all solid-fueled which was pursued in a number of versions and later replaced by the ONERA. series of rockets.
Japan was another early user with the Kappa (rocket). Japan also pursued Rockoons.
The People's Republic of China was the last nation to launch a new liquid-fueled sounding rocket, the T-7. It was first fired from a very primitive launch site, where the "command center" and borrowed power generator were in a grass hut separated from the launcher by a small river. There was no communications equipment- not even a telephone between the command post and the rocket launcher. The T-7 led to the T-7M, T-7A, T-7A-S, T-7A-S2 and T-7/GF-01A. The T-7/ GF-01A was used in 1969 to launch the FSW satellite technology development missions. Thus the I-7 led to the first Chinese satellite, the Dong Fang Hong 1 (The East is Red 1), launched by a DF-1. Vital to the development of Chinese rocketry and the Dong Feng-1 was Qian Xuesen (Tsien Hsue-shen in Wade Guiles transliteration) who with Theodore von Kármán and the California Institute of Technology "Suicide Squad" created the first successful sounding rocket the WAC Corporal.
By the early 1960s the sounding rocket was considered established technology.

## Advantages

Sounding rockets are advantageous for some research because of their low cost (often using military surplus rocket motors), relatively short lead time (sometimes less than six months) and their ability to conduct research in areas inaccessible to either balloons or satellites. They are also used as test beds for equipment that will be used in more expensive and risky orbital spaceflight missions. The smaller size of a sounding rocket also makes launching from temporary sites possible, allowing field studies at remote locations, and even in the middle of the ocean, if fired from a ship.
Sounding rockets have been used for the examination of atmospheric nuclear tests by revealing the passage of the shock wave through the atmosphere. In more recent times, sounding rockets have been used for other nuclear weapons research.

## Applications
### Meteorology

Weather observations, up to an altitude of 75 km, are done with rocketsondes, a kind of sounding rocket for atmospheric observations that consists of a rocket and radiosonde. The sonde records data on temperature, moisture, wind speed and direction, wind shear, atmospheric pressure, and air density during the flight. Position data (altitude and latitude/longitude) may also be recorded.
Common meteorological rockets are the Loki and Super Loki, typically 3.7 m tall and powered by a 10 cm diameter solid fuel rocket motor. The rocket motor separates at an altitude of 1500 m and the rest of the rocketsonde coasts to apogee (highest point). This can be set to an altitude of 20 km to 113 km.

### Research

Sounding rockets are commonly used for:
* Research in aeronomy, the study of the upper atmosphere, which requires this tool for in situ measurements in the upper atmosphere.
* Ultraviolet and X-ray astronomy, which require being above the bulk of the Earth's atmosphere.
* Microgravity research which benefits from a few minutes of weightlessness on rockets launched to altitudes of a few hundred kilometers.
* Remote sensing of Earth resources uses sounding rockets to get an essentially instant synoptic view of the geographical area under observation.

### Dual use

Due to the high military relevance of ballistic missile technology, there has always been a close relationship between sounding rockets and military missiles. It is a typical dual-use technology, which can be used for both civil and military purposes. During the Cold War, the Federal Republic of Germany cooperated on this topic with countries that had not signed the Non-Proliferation Treaty on Nuclear Weapons at that time, such as Brazil, Argentina and India. In the course of investigations by the German peace movement, this cooperation was revealed by a group of physicists in 1983. The international discussion that was thus set in motion led to the development of the Missile Technology Control Regime (MTCR) at the level of G7 states. Since then, lists of technological equipment whose export is subject to strict controls have been drawn up within the MTCR framework.

## Operators and programs

* Andøya Space Center in Norway operates two sounding rocket launch sites, one at Andøya and one at Svalbard. Has launched sounding rockets since 1962.
* Poker Flat Research Range is owned by the University of Alaska Fairbanks.
* The British Skylark sounding rocket programme began in 1955 and was used for 441 launches from 1957 to 2005. Skylark 12, from 1976, could lift 200 kilograms (440 lb) to 575 kilometres (357 mi) altitude.
* The British also developed the Falstaff sounding rocket as a part of the Chevaline program. There were eight launches between 1969 and 1979 from the Woomera Test Range, Australia.
* Cedar, a program of the Haigazian College Rocket Society, Ceadar 8 crossed the Karman line
* ISRO's VSSC developed the Rohini sounding rockets series starting in 1967 that reached altitudes of 500 km
* Delft Aerospace Rocket Engineering from the Delft University of Technology operates the Stratos sounding rocket program, which reached 21.5 km in 2015.
* Exela Space Industries is developing the Aims-1 sounding rocket that will launch to 100 km in 2035.
* Evolution Space operates the Gold Chain Cowboy sounding rocket with launch to 124.5 km on April 22, 2023.
* The Australian Space Research Institute (ASRI) operates a Small Sounding Rocket Program (SSRP) for launching payloads (mostly educational) to altitudes of about 7 km.
* Indian Institute of Space Science and Technology (IIST) launched a Sounding Rocket (Vyom) in May, 2012, which reached an altitude of 15 km. Vyom Mk-II is in its conceptual design stage with an objective to reach 70 km altitude with 20 kg payload capacity.
* The University of Queensland operates Terrier-Orion sounding rockets (capable of reaching altitudes in excess of 300 km) as part of their HyShot hypersonics research.
* Iranian Space Agency operated its first sounding rocket in February 2007.
* UP Aerospace operates the SpaceLoft XL sounding rocket that can reach altitudes of 225 km.
* TEXUS and MiniTEXUS, German rocket programmes at Esrange for DLR and ESA microgravity research programmes.
* Astrium operates missions with sounding rockets on a commercial basis, as prime contractor to ESA or the German Aerospace Centre (DLR).
* MASER, Swedish rocket programme at Esrange for ESA microgravity research programmes.
* MAXUS, German-Swedish rocket programme at Esrange for ESA microgravity research programmes.
* Pakistan's SUPARCO launched Rehbar series of sounding rockets, based on American Nike-Cajun series of rockets, from 1962 to 1971.
* REXUS, German-Swedish rocket programme at Esrange for DLR and ESA student experiment programmes.
* The NASA Sounding Rocket Program.
** NASA routinely flies the Terrier Mk 70 boosted Improved Orion, lifting 270–450-kg (600–1,000-pound) payloads into the exoatmospheric region between 97 and 201 km (60 and 125 miles).
* The JAXA operates the sounding rockets S-Series: S-310 / S-520 / SS-520.
* United States/New Zealand company Rocket Lab developed the highly adaptable Ātea series of sounding rockets to carry 5–70 kg payloads to altitudes of 250 km or greater, launched once on 30 November 2009.
* The Meteor rockets were built in Poland between 1963 and 1974.
* The Kartika I rocket was built and launched in Indonesia by LAPAN on 1964, becoming the fourth sounding rocket in Asia, after those from Japan, China and Pakistan.
* The Soviet Union developed an extensive program using rockets such as the M-100, the most used ever; its successor by its successor state, Russia, is the MR-20 and later the MR-30.
* Brazil has been launching its own sounding rockets since 1965. The largest and most current family of rocket are the Sonda, which are the R&D basis for Brazil's soon-to-be-launched VLS satellite launcher. Other rockets include the VSB-30
* The Paulet I rocket was built and launched in Peru by The National Commission for Aerospace Research and Development (CONIDA) on 2006, becoming the first sounding rocket of the country and the third rocket in South America, after those from Brazil and Argentina.
* The Experimental Sounding Rocket Association (ESRA) is a non-profit organization based in the United States which has operated the Intercollegiate Rocket Engineering Competition (IREC) since 2006.
* ONERA in France launched a sounding rocket named Titus, developed for observation of the total solar eclipse in Argentina on November 12, 1966. Titus was a two-stage rocket with a length of 11.5 m, a launch weight of 3.4 tons, and a diameter of 56 cm. It reached a maximum height of 270 kilometers. It was launched twice in Las Palmas, Chaco during the eclipse, in collaboration with the Argentine space agency CNIE.
* German Aerospace Center's Mobile Rocket Base (DLR MORABA) designs, builds and operates a variety of sounding rocket types and custom vehicles in support for national and international research programs.
* Interstellar Technologies is a Japanese company that is developing the experimental MOMO sounding rocket.