Soft landing (aeronautics)
A soft landing is any type of aircraft, rocket or spacecraft-lander landing that does not result in damage to/the destruction of the vehicle or anything on board. This can be achieved by parachute—often this is into water. Vertical rocket powered landing referred to as VTVL (vertical landing referred to as VTOL, is for aircraft landing in a "level" attitude, rather than rockets — first achieved by a Blue Origin New Shepard. Horizontal landing, most aircraft and some spacecraft, such as the Space Shuttle, land this way. Being caught, as attempted with Genesis and followed by some other form of landing. Soft landing can be contrasted with the term hard landing
Spirit known as MER-A or MER-2, is a robotic rover on Mars, active from 2004 to 2010. It was one of two rovers of NASA's Mars Exploration Rover Mission, it landed on Mars at 04:35 Ground UTC on January 4, 2004, three weeks before its twin, which landed on the other side of the planet. Its name was chosen through a NASA-sponsored student essay competition; the rover became stuck in a "sand trap" in late 2009 at an angle that hampered recharging of its batteries. The rover completed its planned 90-sol mission. Aided by cleaning events that resulted in more energy from its solar panels, Spirit went on to function over twenty times longer than NASA planners expected. Spirit logged 7.73 km of driving instead of the planned 600 m, allowing more extensive geological analysis of Martian rocks and planetary surface features. Initial scientific results from the first phase of the mission were published in a special issue of the journal Science. On May 1, 2009, Spirit became stuck in soft soil; this was not the first of the mission's "embedding events" and for the following eight months NASA analyzed the situation, running Earth-based theoretical and practical simulations, programming the rover to make extrication drives in an attempt to free itself.
These efforts continued until January 26, 2010 when NASA officials announced that the rover was irrecoverably obstructed by its location in soft soil, though it continued to perform scientific research from its current location. The rover continued in a stationary science platform role until communication with Spirit stopped on March 22, 2010. JPL continued to attempt to regain contact until May 24, 2011, when NASA announced that efforts to communicate with the unresponsive rover had ended, calling the mission complete. A formal farewell took place at NASA headquarters shortly thereafter; the Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for NASA's Office of Space Science, Washington. The primary surface mission for Spirit was planned to last at least 90 sols; the mission lasted about 2,208 sols. On August 11, 2007, Spirit obtained the second longest operational duration on the surface of Mars for a lander or rover at 1282 Sols, one sol longer than the Viking 2 lander.
Viking 2 was powered by a nuclear cell. Until Opportunity overtook it on May 19, 2010, the Mars probe with longest operational period was Viking 1 that lasted for 2245 Sols on the surface of Mars. On March 22, 2010, Spirit sent its last communication, thus falling just over a month short of surpassing Viking 1's operational record. An archive of weekly updates on the rover's status can be found at the Spirit Update Archive. Spirit's total odometry as of March 22, 2010 is 7,730.50 meters. The scientific objectives of the Mars Exploration Rover mission were to: Search for and characterize a variety of rocks and soils that hold clues to past water activity. In particular, samples sought will include those that have minerals deposited by water-related processes such as precipitation, sedimentary cementation or hydrothermal activity. Determine the distribution and composition of minerals and soils surrounding the landing sites. Determine what geologic processes have shaped the local terrain and influenced the chemistry.
Such processes could include water or wind erosion, hydrothermal mechanisms and cratering. Perform calibration and validation of surface observations made by Mars Reconnaissance Orbiter instruments; this will help determine the accuracy and effectiveness of various instruments that survey Martian geology from orbit. Search for iron-containing minerals and quantify relative amounts of specific mineral types that contain water or were formed in water, such as iron-bearing carbonates. Characterize the mineralogy and textures of rocks and soils and determine the processes that created them. Search for geological clues to the environmental conditions that existed when liquid water was present. Assess whether those environments were conducive to life. NASA sought evidence of life on Mars, beginning with the question of whether the Martian environment was suitable for life. Life forms known to science require water, so the history of water on Mars is a critical piece of knowledge. Although the Mars Exploration Rovers did not have the ability to detect life directly, they offered important information on the habitability of the environment during the planet's history.
Spirit are six-wheeled, solar-powered robots standing 1.5 meters high, 2.3 meters wide and 1.6 meters long and weighing 180 kilograms. Six wheels on a rocker-bogie system enable mobility over rough terrain; each wheel has its own motor. The vehicle is steered at front and rear and is designed to operate safely at tilts of up to 30 degrees. Maximum speed is 5 centimeters per second. Both Spirit and Opportunity have pieces of the fallen World Trade Center's metal on them that were "turned into shields to protect cables on the drilling mechanisms". Solar arrays generate about 140 watts for up to four hours per Martian day while rechargeable lithium ion batteries store energy for use at night. Spirit's onboard computer uses a 20 MHz RAD6000 CPU with 128 MB of DRAM, 3 MB o
Messenger was a NASA robotic spacecraft that orbited the planet Mercury between 2011 and 2015. The probe was launched aboard a Delta II rocket in August 2004 to study Mercury's chemical composition and magnetic field; the instruments carried by MESSENGER were used on a complex series of flybys – the spacecraft flew by Earth once, Venus twice, Mercury itself three times, allowing it to decelerate relative to Mercury using minimal fuel. During its first flyby of Mercury in January 2008, MESSENGER became the second mission after Mariner 10's 1975 flyby to reach Mercury. MESSENGER entered orbit around Mercury on March 2011, becoming the first spacecraft to do so, it completed its primary mission in 2012. Following two mission extensions, the MESSENGER spacecraft used the last of its maneuvering propellant and deorbited as planned, impacting the surface of Mercury on April 30, 2015. MESSENGER's formal data collection mission began on April 4, 2011; the primary mission was completed on March 2012, having collected close to 100,000 images.
MESSENGER achieved 100% mapping of Mercury on March 6, 2013, completed its first year-long extended mission on March 17, 2013. MESSENGER's second extended mission lasted for over two years, but as its low orbit degraded, it required reboosts to avoid impact, it conducted its final reboost burns on October 24, 2014, January 21, 2015, before crashing into Mercury on April 30, 2015. During its stay in Mercury orbit, MESSENGER's instruments yielded significant data, including a characterization of Mercury's magnetic field and the discovery of water ice at the planet's north pole, which had long been suspected on the basis of Earth-based radar data. In 1973, Mariner 10 was launched by NASA to make multiple flyby encounters of Mercury. Mariner 10 provided the first detailed data of Mercury, mapping 40–45% of the surface. Mariner 10's final flyby of Mercury occurred on March 16, 1975. No subsequent close-range observations of the planet would take place for more than 30 years. In 1998, a study detailed a proposed mission to send an orbiting spacecraft to Mercury, as the planet was at that point the least-explored of the inner planets.
In the years following the Mariner 10 mission, subsequent mission proposals to revisit Mercury had appeared too costly, requiring large quantities of propellant and a heavy lift launch vehicle. Moreover, inserting a spacecraft into orbit around Mercury is difficult, because a probe approaching on a direct path from Earth would be accelerated by the Sun's gravity and pass Mercury far too to orbit it. However, using a trajectory designed by Chen-wan Yen in 1985, the study showed it was possible to seek a Discovery-class mission by using multiple, consecutive gravity assist,'swingby' maneuvers around Venus and Mercury, in combination with minor propulsive trajectory corrections, to slow the spacecraft and thereby minimize propellant needs; the MESSENGER mission was designed to study the characteristics and environment of Mercury from orbit. The scientific objectives of the mission were: to characterize the chemical composition of Mercury's surface. To study the planet's geologic history. To elucidate the nature of the global magnetic field.
To determine the size and state of the core. To determine the volatile inventory at the poles. to study the nature of Mercury's exosphere. The MESSENGER spacecraft was designed and built at the Johns Hopkins University Applied Physics Laboratory. Science operations were managed by Sean Solomon as principal investigator, mission operations were conducted at JHU/APL; the MESSENGER bus measured 1.85 meters tall, 1.42 m wide, 1.27 m deep. The bus was constructed with four graphite fiber / cyanate ester composite panels that supported the propellant tanks, the large velocity adjust thruster, attitude monitors and correction thrusters, the antennas, the instrument pallet, a large ceramic-cloth sunshade, measuring 2.5 m tall and 2 m wide, for passive thermal control. At launch, the spacecraft weighed 1,100 kilograms with its full load of propellant. MESSENGER's total mission cost, including the cost of the spacecraft's construction, was estimated at under US$450 million. Main propulsion was provided by 317 sec.
Isp bipropellant large velocity assist thruster. The model used was the LEROS 1b, developed and manufactured at AMPAC‐ISP's Westcott works, in the United Kingdom; the spacecraft was designed to carry 607.8 kilograms of propellant and helium pressurizer for the LVA. Four 22 N monopropellant thrusters provided spacecraft steering during main thruster burns, twelve 4.4 N monopropellant thrusters were used for attitude control. For precision attitude control, a reaction wheel attitude control system was included. Information for attitude control was provided by star trackers, an inertial measurement unit and six sun sensors; the probe included two small deep space transponders for communications with the Deep Space Network and three kinds of antennas: a high gain phased array whose main beam could be electronically steered in one plane, a medium-gain "fan-beam" antenna and a low gain horn with a broad pattern. The high gain antenna was used as transmit-only at 8.4 GHz, the medium-gain and low gain antennas transmit at 8.4 GHz and receive at 7.2 GHz, all three antennas operate with right-hand circularly polarized radiation.
One of each of these antennas was mounted on the front of the probe facing the Sun, one of each wa
Venera 7 was a Soviet spacecraft, part of the Venera series of probes to Venus. When it landed on the Venusian surface, it became the first spacecraft to land on another planet and first to transmit data from there back to Earth; the lander was designed to be able to survive pressure of up to 180 bars and temperatures of 580 °C. This was greater than what was expected to be encountered but significant uncertainties as to the surface temperatures and pressure of Venus resulted in the designers opting for a large margin of error; the degree of hardening added mass to the probe which limited the amount of mass available for scientific instruments both on the probe itself and the interplanetary bus. The probe was launched from Earth on 17 August 1970, at 05:38 UTC, it consisted of an interplanetary bus based on a lander. During the flight to Venus two in-course corrections were made using the bus's on-board KDU-414 engine. Venera 7 entered the atmosphere of Venus on 15 December 1970; the lander remained attached to the interplanetary bus during the initial stages of atmospheric entry to allow the bus to cool the lander to −8 °C for as long as possible.
The lander was ejected. The parachute opened at a height of 60 km and atmospheric testing began with results showing the atmosphere to be 97% carbon dioxide; the parachute appeared resulting in a descent more rapid than planned. As a result, the lander struck the surface of Venus at about 16.5 m/s at 05:37:10 UTC. The landing coordinates are 5°S 351°E; the probe appeared to go silent on impact but recording tapes kept rolling. A few weeks upon a review of the tapes by the radio astronomer Oleg Rzhiga another 23 minutes of weak signals were found on them; the spacecraft had landed on Venus and bounced onto its side, leaving the medium gain antenna not aimed for strong signal transmission to Earth. The probe transmitted information to Earth for 53 minutes, which included 20 minutes from the surface, it was found that the temperature at the surface of Venus was 475 °C ± 20 °C Using the temperature and models of the atmosphere a pressure of 9 Megapascal ± 1.5 MPa was calculated. From the spacecraft's rapid halt it was possible to conclude that the craft had hit a solid surface with low levels of dust.
The probe provided information about the surface of Venus, which could not be seen through a thick veil of atmosphere. The spacecraft definitively confirmed that humans cannot survive on the surface of Venus, excluded the possibility that there is any liquid water on Venus. List of missions to Venus Timeline of artificial satellites and space probes Venera 7 NASA NSSDC Master Catalog Data Plumbing the Atmosphere of Venus
Venera 8 was a probe in the Soviet Venera program for the exploration of Venus and was the first robotic space probe to conduct a successful landing on the surface of Venus. Venera 8 was lander, its instrumentation included temperature and light sensors as well as an altimeter, gamma ray spectrometer, gas analyzer, radio transmitters. The spacecraft took 117 days to reach Venus with one mid-course correction on 6 April 1972, separating from the bus and entering the atmosphere on 22 July 1972 at 08:37 UT. A refrigeration system attached to the bus was used to pre-chill the descent capsule's interior prior to atmospheric entry in order to prolong its life on the surface. Descent speed was reduced from 41,696 km/h to about 900 km/h by aerobraking; the 2.5 meter diameter parachute opened at an altitude of 60 km. Venera 8 transmitted data during the descent. A sharp decrease in illumination was noted at 35 to 30 km altitude and wind speeds of less than 1 m/s were measured below 10 km. Venera 8 landed at 09:32 UT in what is now called Vasilisa Region, within 150 km radius of 10.70°S 335.25°E / -10.70.
The lander mass was 495 kg. The lander continued to send back data for 50 minutes, 11 seconds after landing before failing due to the harsh surface conditions; the probe confirmed the earlier data on the high Venus surface temperature and pressure returned by Venera 7, measured the light level as being suitable for surface photography, finding it to be similar to the amount of light on Earth on an overcast day with 1 km visibility. Venera 8's photometer measurements showed for the first time that the Venusian clouds end at a high altitude, the atmosphere was clear from there down to the surface; the on-board gamma ray spectrometer measured the uranium/thorium/potassium ratio of the surface rock, indicating it was similar to granite. Temperature and pressure sensors - ITD Accelerometer - DOU-1M Photometers - IOV-72 Ammonia analyser - IAV-72 Gamma ray spectrometer - GS-4 Radar altimeter Radio Doppler experiment List of missions to Venus Timeline of artificial satellites and space probes Plumbing the Atmosphere of Venus Venera 8 NASA NSSDC Master Catalog Data