A retrorocket is a rocket engine providing thrust opposing the motion of a vehicle, thereby causing it to decelerate. They have been used in spacecraft, with more limited use in short-runway aircraft landing. New uses are emerging in the 2010s for retro-thrust rockets in reusable launch systems. Rockets were fitted to the nose of some models of the DFS 230, a World War II, German Military glider; this enabled the aircraft to land in more confined areas than would otherwise be possible during an airborne assault. Another World War II development was the British Hajile project, initiated by the British Admiralty's Directorate of Miscellaneous Weapons Development. A request from the British Army as a method to drop heavy equipment or vehicles from aircraft flying at high speeds and altitudes, the project turned out to be a huge disaster and was forgotten after the war. Although some of the tests turned out to be successful, Hajile was too unpredictable to be used in conventional warfare, by the time the war drew to a close, with no chance to put the project into action, it was shelved.
Soviet experiments used this technique, braking large air-dropped cargos after a parachute descent. To ensure clean separation and prevent contact, multistage rockets may have small retrorockets on lower stages, which ignite upon stage separation. Meanwhile, the succeeding stage may have ullage rockets, both to aid separation and ensure good starting of liquid-fuel engines; when a spacecraft in orbit is slowed sufficiently, its altitude decreases to the point at which aerodynamic forces begin to slow the motion of the vehicle, it returns to the ground. Without retrorockets, spacecraft would remain in orbit for years until their orbits slow, reenter the atmosphere at a much date. Therefore, it is critical that spacecraft have reliable retrorockets. Due to the high reliability demanded by retrorockets, Mercury spacecraft used a trio of solid fuel, 1000 lbf thrust retrorockets strapped to the heat shield on the bottom of the spacecraft that fired for 10 seconds each. One was sufficient to return the spacecraft to earth.
Gemini used four rockets, each 2,500 pounds-force, burning for 5.5 seconds in sequence, with a slight overlap. These were mounted in the retrograde section of the adapter module, located just behind the capsule's heat shield. Operation Credible Sport, a plan put forward by the US government in 1979 to rescue the hostages in Iran resulted in the construction of two modified Lockheed C-130 Hercules, designated YMC-130H, which featured retro-rockets to allow it to perform short landings; as part of the plan, these aircraft would land in the Shahid Shiroudi Stadium near the US Embassy in Tehran and use the retrorockets to come to a stop. One aircraft was destroyed in a crash during a test flight without any fatalities, the plan was scrapped that year; the Apollo program did not require retrorockets for lunar flights, as the flight from the moon was directed to fly the spacecraft directly back to earth, not enter orbit. However, the flights in earth orbit for tests required retrorockets, so the large, versatile Service Propulsion Module on the Service Module was used to decelerate the spacecraft.
The Space Shuttle would use a similar multipurpose engine for reentry. However, retrorockets were used to back the S-IC and S-II stages off after their respective shutdowns during the rocket's journey from the launch pad at the Kennedy Space Center to Earth Parking Orbit; the Space Shuttle Orbital maneuvering system provided the vehicle with a pair of powerful liquid-fueled rockets for both reentry and orbital maneuvering. One was sufficient for a successful reentry, if both systems were to fail, the reaction control system could slow the vehicle enough for reentry. Retrorockets are used in landing spacecraft on other astronomical bodies, such as the Moon and Mars, as well as enabling a spacecraft to enter an orbit around such a body, when otherwise it would scoot past and off into space again; as pointed out above the main rocket on a spacecraft can be re-oriented to serve as a retrorocket. The Soyuz capsule uses small rockets for the last phase of landing. New uses; the SpaceX reusable rocket launching system uses one to three of the booster main engines, following second stage separation in the launch sequence, in order to decelerate the first stage for controlled-descent tests through the atmosphere and over-water simulated-landing testing.
Launch vehicle first stages in the first sixty years of spaceflight have been destroyed after a single use by atmospheric reentry and high-speed impact in the ocean. An earlier test vehicle, the Grasshopper v1.0, began low-altitude, low-velocity return-to-Earth landing tests in late 2012 using a Merlin 1D main engine to reduce descent speed for vertical landing. SpaceX' intent is to develop and refine the technology, over a period of several years, to achieve full and rapid reusability of the first stage by 2015, with complete launch vehicle reusability, including the second stage, to be worked on following that as "part of a future design architecture."
The Luna programme called Lunik or Lunnik by western media, was a series of robotic spacecraft missions sent to the Moon by the Soviet Union between 1959 and 1976. Fifteen were successful, each designed as either an orbiter or lander, accomplished many firsts in space exploration, they performed many experiments, studying the Moon's chemical composition, gravity and radiation. Twenty-four spacecraft were formally given the Luna designation; those that failed to reach orbit were not publicly acknowledged at the time, not assigned a Luna number. Those that failed in low Earth orbit were given Cosmos designations; the estimated cost of the Luna programme was about $4.5 billion. Luna 1 missed its intended impact with the Moon and became the first spacecraft to fall into orbit around the Sun. Luna 2 mission hit the Moon's surface, becoming the first man-made object to reach the Moon. Luna 3 rounded the Moon that year, returned the first photographs of its far side, which can never be seen from Earth.
Luna 9 became the first probe to achieve a soft landing on another planetary body. It returned five black and white stereoscopic circular panoramas, which were the first close-up shots of the Lunar surface. Luna 10 became the first artificial satellite of the Moon. Luna 17 and Luna 21 carried the Lunokhod vehicles. Another major achievement of the Luna programme, with Luna 16, Luna 20 and Luna 24, was the ability to collect samples of lunar soil and return them to Earth; the programme returned 0.326 kg of lunar samples. The Luna missions were the first space-exploration sample return missions to rely on advanced robotics. Luna 15 designed to return soil samples from the lunar surface, underwent its mission at the same time as the Apollo 11 mission. Neil Armstrong and Buzz Aldrin were on the lunar surface when Luna 15 began its descent, the spacecraft crashed into a mountain minutes later. While the programme was active, it was Soviet practice not to release any details of missions which had failed to achieve orbit.
This resulted in Western observers assigning their own designations to the missions, for example Luna E-1 No.1, the first failure of 1958 which NASA believed was associated with the Luna programme, was known as Luna 1958A. NASA identified a spacecraft which it referred to as Luna 1966A as having launched on 30 April 1966, a spacecraft referred to as Luna 1969B as having launched on 15 April 1969, a spacecraft referred to as Luna 1970B as having launched on 19 February 1970; when details of Soviet launches were disclosed, no launches of Luna spacecraft were found to have occurred on those dates. Luna Luna-Glob Soviet moonshot Soviet space program Lunar and Planetary Department Moscow University Luna Series Profile by NASA's Solar System Exploration Encyclopædia Britannica, Luna Space Probe Soviet Luna Chronology Soviet Lunar Images Exploring the Moon: Luna Missions
Oceanus Procellarum is a vast lunar mare on the western edge of the near side of the Moon. It is the only one of the lunar maria to be called an "Oceanus", due to its size: Oceanus Procellarum is the largest of the maria, stretching more than 2,500 km across its north-south axis and covering 4,000,000 km2, accounting for 10.5% of the total lunar surface area. Cosmonaut Alexei Leonov proposed renaming the Ocean of Storms to the Ocean of Gagarin to the United Nations in 1968, the year Gagarin died in a jet crash. Like all lunar maria, Oceanus Procellarum was formed by ancient basaltic flood volcanic eruptions that covered the region in a thick, nearly flat layer of solidified magma. Unlike the other lunar maria, Oceanus Procellarum may or may not be contained within a single well-defined impact basin. Around its edges lie many minor bays and seas, including Mare Nubium and Mare Humorum to the south. To the northeast, Oceanus Procellarum is separated from Mare Imbrium by the Carpathian Mountains.
On its north-west edge lies the 32 km wide Aristarchus ray crater, considered as the brightest feature on the Near side of the Moon. The more-prominent ray-crater Copernicus lies within the eastern edge of the mare, distinctly with its bright ray materials sprawling over the darker material. On the northern edge of Oceanus Procellarum lies Sinus Roris. There are several hypotheses about the origin of Oceanus Procellarum and a related asymmetry between the near and far sides of the Moon. One of the most is that Procellarum was a result of an ancient giant impact on the near side of the Moon; the size of the impact basin has been estimated to be more than 3,000 kilometers, which would make it one of the three largest craters in the Solar System. The impact happened early in the Moon's history: at the time when magma ocean still existed or just ceased to exist, it deposited 5–30 km of crustal material on the far side forming highlands. If this is the case, all impact related structures such as crater rim, central peak etc. have been obliterated by impacts and volcanism.
One piece of evidence in support of this hypothesis is concentration of incompatible elements and low calcium pyroxene around Oceanus Procellarum. Procellarum may have been formed by spatially inhomogeneous heating during the Moon's formation; the GRAIL mission, which mapped the gravity gradients of the Moon, found square formations resembling rift valleys surrounding the region beneath the lava plains, suggesting the basin was formed by heating and cooling of the lunar surface by internal processes rather than by an impact, which would have left a round crater. Other hypotheses include a late accretion of a companion Moon on the far side; the latter postulates that in addition to the present Moon, another smaller moon was formed from debris of the giant impact. After a few tens of millions of years it collided with the Moon and due to a small collisional velocity piled up on one side of the Moon forming what is now known as far side highlands; the robotic lunar probes Luna 9, Luna 13, Surveyor 1 and Surveyor 3 landed in Oceanus Procellarum.
Luna 9 landed southwest of Galilaei crater in 1966. Luna 13 landed southeast of Seleucus crater in 1966. Surveyor 1 landed north of Flamsteed crater in 1966, Surveyor 3 landed in 1967. During the Apollo program, flight operations planners were concerned about having the optimum lighting conditions at the landing site, hence the alternative target sites moved progressively westward, following the terminator. A delay of two days for weather or equipment reasons would have sent Apollo 11 to Sinus Medii instead of ALS2—Mare Tranquillitatis; the manned Apollo 12 mission landed in Oceanus Procellarum, with astronauts Pete Conrad and Alan Bean on board. Their landing site, within 300 meters of Surveyor 3, has become known as Mare Cognitum
Lunar Orbiter 3
The Lunar Orbiter 3 was a spacecraft launched by NASA in 1967 as part of the Lunar Orbiter Program. It was designed to photograph areas of the lunar surface for confirmation of safe landing sites for the Surveyor and Apollo missions, it was equipped to collect selenodetic, radiation intensity, micrometeoroid impact data. The spacecraft was placed in a cislunar trajectory and injected into an elliptical near-equatorial lunar orbit on February 8 at 21:54 UT; the orbit was 210.2 by 1,801.9 kilometres with an inclination of 20.9 degrees and a period of 3 hours 25 minutes. After four days of tracking the orbit was changed to 55 by 1,847 kilometres; the spacecraft acquired photographic data from February 15 to February 23, 1967, readout occurred through March 2, 1967. The film advance mechanism showed erratic behavior during this period resulting in a decision to begin readout of the frames earlier than planned; the frames were read out until March 4 when the film advance motor burned out, leaving about 25% of the frames on the takeup reel, unable to be read.
A total of 149 medium resolution and 477 high resolution frames were returned. The frames were of excellent quality with resolution down to 1 metre. Included was a frame of the Surveyor 1 landing site, permitting identification of the location of the spacecraft on the surface. Accurate data were acquired from all other experiments throughout the mission; the spacecraft was used for tracking purposes until it struck the lunar surface on command at 14.3 degrees N latitude, 97.7 degrees W longitude on October 9, 1967. Lunar Orbiter Image Recovery Project Exploration of the Moon Lunar Orbiter 1 Lunar Orbiter 2 Lunar Orbiter 4 Lunar Orbiter 5 NSSDC Lunar Orbiter 3 page DESTINATION MOON: A history of the Lunar Orbiter Program 1976 Lunar Orbiter Photo Gallery - Mission 3 at the Lunar and Planetary Institute
Luna 11 was an unmanned space mission of the Soviet Union's Luna program. It was called Lunik 11. Luna 11 was launched towards the Moon from an Earth-orbiting platform and entered lunar orbit on 27 August 1966; the objectives of the mission included the study of: lunar gamma and X-ray emissions in order to determine the Moon's chemical composition. This subset of the “second-generation” Luna spacecraft, the Ye-6LF, was designed to take the first photographs of the surface of the Moon from lunar orbit. A secondary objective was to obtain data on mass concentrations on the Moon first detected by Luna 10. Using the Ye-6 bus, a suite of scientific instruments replaced the small lander capsule used on the soft-landing flights; the resolution of the photos was 15 to 20 meters. A technological experiment included testing the efficiency of gear transmission in vacuum as a test for a future lunar rover. Luna 11, launched only two weeks after the U. S. Lunar Orbiter, entered lunar orbit at 21:49 UT on 27 August.
Parameters were 160 x 1,193 kilometers. During the mission, the TV camera failed to return usable images because the spacecraft lost proper orientation to face the lunar surface when a foreign object was lodged in the nozzle of one of the attitude-control thrusters; the other instruments functioned without fault before the mission formally ended on 1 October 1966 after the power supply had been depleted. Zarya - Luna programme chronology
Baikonur Cosmodrome Site 31
Site 31/6 at the Baikonur Cosmodrome, in Kazakhstan, is a launch site used by derivatives of the R-7 Semyorka missile. From 2011 onwards, it was supposed to be the launch site for manned Soyuz missions to the International Space Station, when launches switched from the Soyuz-FG carrier rocket to the Soyuz-2, unable to use the launch pad at Site 1/5. However, Site 1/5 has undergone modifications that allow the manned ISS missions to be launched from it. Only few manned missions to the International Space Station are launched from Site 31/6, when Site 1/5 is unavailable, it was first used on 14 January 1961, for an R-7A ICBM test mission. It is used for commercial Soyuz-FG/Fregat missions, Soyuz-2 launches. In the 1970s and early 1980s, several manned missions were launched from the site. Gagarin's Start "Baikonur LC31". Encyclopedia Astronautica. J. K. Golovanov, "Korolev: Facts and myths", Nauka, 1994, ISBN 5-02-000822-2. ISBN 5-217-02942-0. I. Ostashev, Korolyov, 2001.. Korolev. Yangel." - M. I. Kuznetsk, Voronezh: IPF "Voronezh", 1997, ISBN 5-89981-117-X.
Notes of a military engineer" - Rjazhsky A. A. 2004, SC. first, the publishing house of the "Heroes of the Fatherland" ISBN 5-91017-018-X. "Rocket and space feat Baikonur" - Vladimir Порошков, the "Patriot" publishers 2007. ISBN 5-7030-0969-3 "Unknown Baikonur" - edited by B. I. Posysaeva, M.: "globe", 2001. ISBN 5-8155-0051-8
Luna 9, internal designation Ye-6 No.13, was an unmanned space mission of the Soviet Union's Luna programme. On 3 February 1966 the Luna 9 spacecraft became the first spacecraft to achieve a soft landing on the Moon; the lander had a mass of 99 kilograms. It used a landing bag to survive the impact speed of 22 kilometres per hour, it was a hermetically sealed container with radio equipment, a program timing device, heat control systems, scientific apparatus, power sources, a television system. Luna 9 was launched by a Molniya-M rocket, serial number 103-32, flying from Site 31/6 at the Baikonur Cosmodrome in the Kazakh Soviet Socialist Republic. Liftoff took place at 11:41:37 UTC on 31 January 1966; the first three stages of the four-stage carrier rocket injected the payload and fourth stage into low Earth orbit, at an altitude of 168 by 219 kilometres and 51.8 degrees inclination. The fourth stage, a Blok-L fired to raise the orbit's perigee to a new apogee 500,000 kilometres, before deploying Luna 9 into a elliptical geocentric orbit.
The spacecraft spun itself up to 0.67 rpm using nitrogen jets. On 1 February at 19:29 UT, a mid-course correction took place involving a 48-second burn and resulting in a delta-V of 71.2 metres per second. At an altitude of 8,300 kilometres from the Moon, the spacecraft was oriented for the firing of its retrorockets and its spin was stopped in preparation for landing. From this moment the orientation of the spacecraft was supported by measurements of directions to the Sun and the Earth using an opto-mechanical system. At 74.885 kilometres above the lunar surface, the radar altimeter triggered the jettison of the side modules, the inflation of the air bags and the firing of the retro rockets. At 250 metres from the surface, the main retrorocket was turned off by the integrator of an acceleration having reached the planned velocity of the braking manoeuver; the four outrigger engines were used to slow the craft. 5 metres above the lunar surface, a contact sensor touched the ground triggering the engines to be shut down and the landing capsule to be ejected.
The craft landed at 22 kilometres per hour The spacecraft bounced several times before coming to rest in Oceanus Procellarum west of Reiner and Marius craters at 7.08 N, 64.37 W on 3 February 1966 at 18:45:30 UT. The spacecraft was developed in the design bureau known as OKB-1, under Chief Designer Sergei Korolev; the first 11 Luna missions were unsuccessful for a variety of reasons. At that time the project was transferred to Lavochkin design bureau since OKB-1 was busy with a manned expedition to the Moon. Luna 9 was the twelfth attempt at a soft-landing by the Soviet Union. All operations prior to landing occurred without fault, the 58-centimetre spheroid ALS capsule landed on the Moon at 18:45:30 UT on 3 February 1966 west of the craters Reiner and Marius in the Ocean of Storms. Five minutes after touchdown, Luna 9 began transmitting data to Earth, but it was seven hours before the probe began sending the first of nine images of the surface of the Moon. 250 seconds after landing in the Oceanus Procellarum, four petals which covered the top half of the spacecraft opened outward for increased stability.
The television camera system began a photographic survey of the lunar environment. Seven radio sessions with a total of 8 hours and 5 minutes were transmitted, as well as three series of TV pictures. After assembly the photographs gave a panoramic view of the immediate lunar surface, comprising views of nearby rocks and of the horizon, 1.4 kilometres away. The pictures from Luna 9 were not released by the Soviet authorities, but scientists at Jodrell Bank Observatory in England, monitoring the craft, noticed that the signal format used was identical to the internationally agreed Radiofax system used by newspapers for transmitting pictures; the Daily Express rushed a suitable receiver to the Observatory and the pictures from Luna 9 were decoded and published worldwide. The BBC speculated that the spacecraft's designers deliberately fitted the probe with equipment conforming to the standard, to enable reception of the pictures by Jodrell Bank; the radiation detector, the only scientific instrument on board, measured a dosage of 30 millirads per day.
The mission determined that a spacecraft would not sink into the lunar dust. Last contact with the spacecraft was at 22:55 UTC on 6 February 1966. Zarya - Luna 9 chronology Animation of mission Luna 9 panoramas