Satellite sensor maps global atmospheric ammonia emissions

7 July 2009
Using radiation measurements obtained by the MetOp satellite, scientists have produced the first complete map of global ammonia emissions – a pollutant of key environmental concern. The map, based on observations throughout 2008, shows inaccuracies in current ammonia inventories and identifies new hotspots.

Ammonia emissions contribute to a host of environmental problems, including soil acidification, reductions in biodiversity and the formation of atmospheric particulate matter, which has been linked to human health problems such as asthma. Yet despite its importance, many uncertainties remain about its global distribution.

Mapping ammonia is difficult, in part, because once emitted it only remains in the atmosphere for a short period. While in the atmosphere, however, it reacts with acid pollutants, such as nitric acid and sulfuric acid, to produce ammonium aerosol, which is believed to influence climate.

Lieven Clarisse and Pierre Coheur from the University of Bruxelles, Cathy Clerbaux from the French Scientific Research Centre (CNRS) and colleagues developed a methodology to be used with MetOp’s Infrared Atmospheric Sounding Interferometer (IASI) sensor that could isolate the signature of ammonia.

	Ammonia concentrations over Italy

By comparing the concentration map generated with IASI data obtained over a one-year period, which included more than a million measurements a day, with recent atmospheric models, the team was able to locate inconsistencies and identify ammonia hotspots across the globe.

Most of the hotspots appeared over agricultural regions in Europe, North America and Asia, as expected. However, the measurements taken from space over agricultural valleys, such as Italy’s Po Valley, Uzbekistan’s Fergana Valley and the US’s Snake River Valley in Idaho, were higher than the current inventories. The scientists also identified some sources in Central Asia that had not been included in current inventories.

Areas with biomass burning also had high ammonia emissions. For instance, increased ammonia concentrations were found over regions, such as Africa, Asia and South America, that had experienced a large number of fires.

Atmospheric ammonia is being increasingly recognised as a key pollutant that contributes to several environmental problems. In 1999 the UN Economic Commission for Europe (UNECE) set stringent reduction targets for ammonia to be obtained by 2010. However, reducing ammonia emissions has proved uncertain.

MetOp in orbit

Although more work is needed to detect low-level ammonia emissions from space, the techniques demonstrated by the team are very promising. With fine-tuning, Earth-observing satellites could provide the careful monitoring essential to ensuring these targets are met.

MetOp, launched in 2006, is the first of three meteorological satellites developed under a joint programme being carried out by ESA and the European Meteorological Satellite Organisation (EUMESAT). The IASI sensor was developed by CNES (the French space agency) in cooperation with EUMETSAT.

These new results, published online in Nature Geoscience in June, were obtained as part of a scientific project in response to a Research Announcement of Opportunity for MetOp, organised jointly by ESA and EUMETSAT. The support to scientific research by ongoing ESA programmes is important for developing and testing innovative methods with data from operational missions.

satellite

A satellite in polar orbit round the Earth. Satellites in polar orbit usually complete an orbit in two hours or less and as the Earth is rotating as they orbit, they cover a large part of the Earth's surface each day. Remote-sensing satellites, such as Landsat, are in polar orbit.

The British satellite Prospero continues to orbit the Earth every 100 minutes and will do so until 2040. With the correct equipment, the satellite's radio transmitter can still be heard broadcasting on 137.56 MHz.

Any small body that orbits a larger one. Natural satellites that orbit planets are called moons. The first artificial satellite, Sputnik 1, was launched into orbit around the Earth by the USSR in 1957. Artificial satellites can transmit data from one place on Earth to another, or from space to Earth. Satellite applications include science, communications, weather forecasting, and military use.

Space probes have been sent to natural satellites including the Earth's Moon, Mars's Deimos, and the moons of the giant planets Jupiter, Saturn, Uranus and Neptune.

At any time, there are several thousand artificial satellites orbiting the Earth, including active satellites, satellites that have ended their working lives, and discarded sections of rockets. The brightest artificial satellites can be seen by the naked eye. Artificial satellites eventually re-enter the Earth's atmosphere. Usually they burn up by friction, but sometimes debris falls to the Earth's surface, as with Skylab and Salyut 7.

Hundreds of millions of pieces of space junk, ranging from particles a millimetre across up to disabled satellites, are careering around the Earth. The US Space Command catalogues the larger items to make sure they are not mistaken for enemy missiles; currently about 10,000 items are listed.

Launch and mission

Soviet 40 copecks stamp, showing satellite's orbit.

The control system of the Sputnik Rocket was tuned to provide an orbit with the following parameters: perigee height - 223 km (139 mi), apogee height - 1,450 km (900 mi), orbital period - 101.5 min.^[39] A rocket trajectory with these parameters was calculated earlier by Georgi Grechko,^[40] after completing the calculations over several nights on the USSR Academy of Sciences's mainframe computer.^[20]

The Sputnik Rocket was launched at 19:28:34 UTC, on 4 October 1957, from Site No.1 at NIIP-5.^[41] Processing of the information, obtained from the "Tral" system showed^[20] that the side boosters separated 116.38 seconds into the flight and the second stage engine was shut-down 294.6 seconds into the flight.^[39] At this moment the second stage with PS-1 attached had a height of 223 km (139 mi) above Earth's surface, a velocity of 7,780 m/s (25,500 ft/s) and velocity vector inclination to the local horizon was 0 degrees 24 minutes. This motion resulted in an orbit with initial parameters: perigee height - 223 km, apogee height - 950 km (590 mi), initial orbital period - 96.2 minutes.^[39]

After 314.5 seconds PS-1 separated from the second stage^[39] and at the same moment at the small "Finnish house" of IP-1 station Junior Engineer-Lieutenant V.G.Borisov heard the "Beep-beep-beep" signals from the radio receiver R-250. Reception lasted for two minutes, while PS-1 was above the horizon. There were many people in the house, both military and civil, and they were probably the first to celebrate the event.^[20][42] After 325.44 seconds a corner reflector on the second stage was opened, that also allowed measurement of its orbit parameters - like the working "Tral" system did.^[29]

The designers, engineers and technicians who developed the rocket and satellite watched the launch from the range.^[43] After the launch they ran to the mobile radio station to listen to signals from the satellite.^[43] They waited about 90 minutes to ensure that the satellite had made one orbit and was transmitting, before Korolyov called Khrushchev.^[44] The downlink telemetry included data on temperatures inside and on the surface of the sphere.

On the first orbit the Telegraph Agency of the Soviet Union (TASS) transmitted: "As result of great, intense work of scientific institutes and design bureaus the first artificial Earth satellite has been built".^[45] The Sputnik 1 rocket booster (second stage of the rocket) also reached Earth orbit and was visible from the ground at night as a first magnitude object following the satellite. Korolyov had intentionally requested reflective panels placed on the booster in order to make it so visible.^[44] The satellite itself, a small but highly polished sphere, was barely visible at sixth magnitude, and thus more difficult to follow optically. Ahead of Sputnik 1 flew the third object - the payload fairing, 80 cm (31 in)-long cone, i.e. a little bit bigger than the satellite.

Observational complex

The measurement complex at the proving ground for monitoring launch vehicle parameters from its start onward was completed prior to the first R-7 rocket test launches in December 1956. It consisted of six static stations: IP-1 through IP-6, with IP-1 situated at a distance of 1 km (0.62 mi) from the launch pad.^[20] The main monitoring devices of these stations were telemetry and trajectory measurement stations, "Tral," developed by OKB MEI. They received and monitored data from the "Tral" system transponders mounted on the R-7 rocket;^[23] an on-board system that provided precise telemetric data about Sputnik's launch vehicle. The data was useful even after the satellite's separation from the second stage of the rocket; Sputnik's location was calculated from the data on the second stage's location (which followed Sputnik at a known distance) using nomograms developed by P.E. Elyasberg.^[24]

An additional observational complex, established to track the satellite after its separation from the rocket, was completed by a group led by Colonel Yu.A.Mozzhorin in accordance with the General Staff directive of 8 May 1957. It was called the Command-Measurement Complex and consisted of the coordination center in NII-4 by the Ministry of Defence of the USSR (at Bolshevo) and seven ground tracking stations, situated along the line of the satellite's ground track. They were: NIP-1 (at Tyuratam station, Kazakh SSR, situated not far from IP-1), NIP-2 (at Makat station, Guryev Oblast), NIP-3 (at Sary-Shagan station, Dzhezkazgan Oblast), NIP-4 (at Yeniseysk), NIP-5 (at village Iskup, Krasnoyarsk Krai), NIP-6 (at Yelizovo) and NIP-7 (at Klyuchi).^[20][25] The complex had a communication channel with the launch pad. Stations were equipped with radar, optical instruments, and communication means. PS-1 was not designed to be controlled, it could only be observed. Data from stations were transmitted by telegraphs into NII-4 where ballistics specialists calculated orbital parameters. The complex became an early prototype of the Soviet Mission Control Center^[26]

Launch vehicle preparation and launch site selection

he two-stage R-7 rocket was initially designed as an ICBM by OKB-1. The decision to build it was made by the CPSU Central Committee and the Council of Ministers of the USSR on 20 May 1954.^[14] A special reconnaissance commission selected Tyuratam as a place for the construction of a rocket proving ground (the 5th Tyuratam range, usually referred to as "NIIP-5", or "GIK-5" in the post-Soviet time). The selection was approved on 12 February 1955 by the Council of Ministers of the USSR, but the site would not be completed until 1958.^[15] Actual work on the construction of the site began on 20 July by military building units. On 14 June 1956 Sergei Korolev decided to adapt the R-7 rocket to the 'Object D',^[16] that would later be replaced by the much lighter 'Object PS'.

The first launch of an R-7 rocket (8K71 No.5L) occurred on 15 May 1957. The flight was controlled until the 98th second, but a fire in a strap-on rocket led to an unintended crash 400 km from the site.^[17] Three attempts to launch the second rocket (8K71 No.6) were made on 10-11 June, which failed due to a mistake made during the rocket's assembly.^[18] The unsuccessful launch of the third R-7 rocket (8K71 No.7) took place on 12 July.^[17] During the flight the rocket began to rotate about its longitudinal axis and its engines were automatically turned off. The packet of stages was destroyed 32.9 seconds into the flight. The stages fell 7 km (4.3 mi) from the site and exploded.^[19]

The launch of the fourth rocket (8K71 No.8), on 21 August at 15:25 Moscow Time,^[17] was successful. Its head part separated, reached the defined region, entered the atmosphere, and was destroyed at a height of 10 km (6.2 mi) due to thermodynamic overload after traveling 6,000 km. On 27 August TASS the USSR issued a statement on the launch of a long-distance multistage ICBM. The launch of the fifth R-7 rocket (8K71 No.9), on 7 September^[17] was also successful, but the head part was also destroyed in the atmosphere,^[19] and hence needed a long redesign to completely fit its military purpose. The rocket, however, was already suitable for scientific satellite launches and this "time-out" of the rocket's military exploitation was used to launch the PS-1 and PS-2 satellites.^[20]

On 22 September a modified R-7 rocket, named Sputnik Rocket (Russian: ракета-носитель Спутник) and indexed as 8K71PS, with the satellite PS-1, arrived at the proving ground and preparations for the launch began.^[21] As the R-7 was designed to carry the much heavier Object D, its adaptation to PS-1 reduced its initial mass from 280 to 272.83 short tons (250 to 250 metric tons) and its mass at launch was 267 short tons (242 metric tons); its length with PS-1 was 29.167 metres (95 ft 8.3 in) and the thrust was 3.90 MN (880,000 lb_f)

Satellite construction project

The history of the Sputnik 1 project dates back to 27 May 1954, when Sergei Korolev addressed Dmitry Ustinov, then Minister of Defense Industries, proposing the development of an Earth-orbiting artificial satellite. Korolev also forwarded Ustinov a report by Mikhail Tikhonravov with an overview of similar projects abroad.^[5] Tikhonravov emphasized that an artificial satellite is an inevitable stage in the development of rocket equipment, after which interplanetary communication would become possible.^[6] On 29 July 1955 the U.S. President Dwight Eisenhower announced, through his press secretary, that the United States would launch an artificial satellite during the International Geophysical Year (IGY).^[7] A week later, on 8 August the Presidium of the Central Committee of the CPSU approved the idea of creating an artificial satellite.^[8] On 30 August Vasily Ryabikov – the head of the State Commission on R-7 rocket test launches – held a meeting where Korolev presented calculation data for a spaceflight trajectory to the Moon. They decided to develop a three-stage version of the R-7 rocket for satellite launches.^[9]

On 30 January 1956 the Council of Ministers of the USSR approved practical work on an artificial Earth-orbiting satellite. This satellite, named "Object D", was planned to be completed in 1957-58; it would have a mass of 1,000 to 1,400 kg (2,200 to 3,090 lb) and would carry 200 to 300 kg (440 to 660 lb) of scientific instruments.^[10] The first test launch of "Object D" was scheduled for 1957.^[6] According to that decision, work on the satellite was to be divided between institutions as follows:^[11]

• USSR Academy of Sciences was responsible for the general scientific leadership and research instruments supply
• Ministry of Defense Industry and its main executor OKB-1 were assigned the task of creating the satellite as a special carrier for scientific research instruments
• Ministry of Radiotechnical Industry would develop the control system, radio/technical instruments and the telemetry system
• Ministry of Ship Building Industry would develop gyroscope devices
• Ministry of Machine Building would develop ground launching, refueling and transportation means
• Ministry of Defense was responsible for conducting launches

By July 1956 the draft was completed and the scientific tasks to be carried out by a satellite were defined. It included measuring the density of the atmosphere, its ion composition, corpuscular solar radiation, magnetic fields, cosmic rays, etc. Data, valuable in creating future satellites, were also to be collected. A ground observational complex was to be developed, that would collect information transmitted by the satellite, observe the satellite's orbit, and transmit commands to the satellite. Such a complex should include up to 15 measurement stations. Due to the limited time frame, they should have means designed for rocket R-7 observations. Observations were planned for only 7 to 10 days and orbit calculations were expected to be not quite accurate.^[12]

Unfortunately, the complexity of the ambitious design and problems in following exact specifications meant that some parts of 'Object D', when delivered for assembly, simply did not fit with the others, causing costly delays. By the end of 1956 it became clear that plans for 'Object D' were not to be fulfilled in time due to difficulties creating scientific instruments and the low specific impulse produced by the completed R-7 engines (304 sec instead of the planned 309 to 310 sec). Consequently the government re-scheduled the launch for April 1958.^[6] Object D would later fly as Sputnik 3.

Fearing the U.S. would launch a satellite before the USSR, OKB-1 suggested the creation and launch of a satellite in April-May 1957, before the IGY began in July 1957. The new satellite would be simple, light (100 kg or 220 lb), and easy to construct, forgoing the complex, heavy scientific equipment in favour of a simple radio transmitter. On 15 February 1957 the Council of Ministers of the USSR approved this, providing for launching the simplest version satellite, designated 'Object PS'.^[13] This version also facilitated the satellite to be visually tracked by Earth-based observers while in orbit, and transmit tracking signals to ground-based receiving stations.^[13] Launch of two satellites PS-1 and PS-2 with two R-7 rockets (8K71) was allowed, but only after one or two successful R-7 test launches.

Sputnik 1

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Major contractors	OKB-1, Soviet Ministry of Radiotechnical Industry
Mission type	Atmospheric studies
Satellite of	Earth
Orbits	1,440
Launch date	19:28:34, October 4, 1957 (UTC) (1957-10-04T19:28:34Z) (22:28:34 MSK)
Launch vehicle	Sputnik Rocket
Mission duration	3 months
Orbital decay	4 January 1958
COSPAR ID	1957-001B
Home page	NASA NSSDC Master Catalog
Mass	83.6 kg (184.3 lb)
Orbital elements
Semimajor axis	6,955.2 km (4,321.8 mi)
Eccentricity	0.05201
Inclination	65.1°
Orbital period	96.2 minutes
Apoapsis	7,310 km (4,540 mi) from centre, 939 km (583 mi) from surface
Periapsis	6,586 km (4,092 mi) from centre, 215 km (134 mi) from surface

This metal arming key is the last remaining piece of the first Sputnik satellite. It prevented contact between the batteries and the transmitter prior to launch. Currently on display at the National Air and Space Museum.

Sputnik 1 (Russian: "Спутник-1" Russian pronunciation: [ˈsputnʲɪk], "Satellite-1", ПС-1 (PS-1, i.e. "Простейший Спутник-1", or Elementary Satellite-1)) was the first Earth-orbiting artificial satellite. It was launched into a low altitude elliptical orbit by the Soviet Union on 4 October 1957, and was the first in a series of satellites collectively known as the Sputnik program. The unanticipated announcement of Sputnik 1's success precipitated the Sputnik crisis in the United States and ignited the Space Race within the Cold War.

Apart from its value as a technological first, Sputnik also helped to identify the upper atmospheric layer's density, through measuring the satellite's orbital changes. It also provided data on radio-signal distribution in the ionosphere. Pressurized nitrogen, in the satellite's body, provided the first opportunity for meteoroid detection. If a meteoroid penetrated the satellite's outer hull, it would be detected by the temperature data sent back to Earth.

Sputnik-1 was launched during the International Geophysical Year from Site No.1, at the 5th Tyuratam range, in Kazakh SSR (now at the Baikonur Cosmodrome). The satellite traveled at 29,000 kilometres (18,000 mi) per hour, taking 96.2 minutes to complete an orbit, and emitted radio signals at 20.005 and 40.002 MHz^[1] which were monitored by amateur radio operators throughout the world.^[2] The signals continued for 22 days until the transmitter batteries ran out on 26 October 1957.^[3] Sputnik 1 burned up on 4 January 1958 as it fell from orbit upon reentering Earth's atmosphere, after traveling about 60 million km (37 million miles) and spending 3 months in orbit.^[4]