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134-527: NASA 's Mars Exploration Rover ( MER ) mission was a robotic space mission involving two Mars rovers , Spirit and Opportunity , exploring the planet Mars . It began in 2003 with the launch of the two rovers to explore the Martian surface and geology ; both landed on Mars at separate locations in January 2004. Both rovers far outlived their planned missions of 90 Martian solar days : MER-A Spirit

268-443: A biosphere based on autotrophic , chemotrophic and/or chemolithoautotrophic microorganisms , as well as ancient water, including fluvio-lacustrine environments ( plains related to ancient rivers or lakes) that may have been habitable . The search for evidence of habitability , taphonomy (related to fossils ), and organic carbon on the planet Mars was then switched to a primary NASA objective. In June 2018, Opportunity

402-412: A cross-section of a set of cross-beds. However, to get a true reading, the axis of the beds must be visible. It is also difficult to distinguish between the cross-beds of a dune and the cross-beds of an antidune . (Dunes dip downstream while antidunes dip upstream.) The direction of motion of the cross-beds can show ancient flow or wind directions (called paleocurrents). The foresets are deposited at

536-628: A decade of reliance on the Russians. In 2019, NASA announced the Artemis program , intending to return to the Moon and establish a permanent human presence. This was paired with the Artemis Accords with partner nations to establish rules of behavior and norms of space commercialization on the Moon. In 2023, NASA established the Moon to Mars Program office. The office is designed to oversee

670-452: A few tens of centimeters to a meter or more, but bed thickness down to 10 centimeters has been observed. Where the set height is less than 6 centimeters and the cross-stratification layers are only a few millimeters thick, the term cross-lamination is used, rather than cross-bedding. Cross-bed sets occur typically in granular sediments, especially sandstone , and indicate that sediments were deposited as ripples or dunes, which advanced due to

804-461: A fiber material, similar to Kevlar, that is sewn in a webbing pattern (like shoelace material) to make it stronger. The Zylon bridle provides space for airbag deployment, distance from the solid rocket motor exhaust stream, and increased stability. The bridle incorporates an electrical harness that allows the firing of the solid rockets from the backshell as well as provides data from the backshell inertial measurement unit (which measures rate and tilt of

938-469: A human in space, develop tracking and control systems, and identify other issues associated with human spaceflight. While much of NASA's attention turned to space, it did not put aside its aeronautics mission. Early aeronautics research attempted to build upon the X-1's supersonic flight to build an aircraft capable of hypersonic flight . The North American X-15 was a joint NASA–U.S. Air Force program, with

1072-583: A permanently manned space station and to do it within a decade. In 1985, NASA proposed the Space Station Freedom , which both the agency and President Reagan intended to be an international program. While this would add legitimacy to the program, there were concerns within NASA that the international component would dilute its authority within the project, having never been willing to work with domestic or international partners as true equals. There

1206-650: A possible source of antimatter at the center of the Milky Way and observing that the majority of gamma-ray bursts occur outside of the Milky Way galaxy. The Chandra X-ray Observatory was launched from the Columbia on STS-93 in 1999, observing black holes, quasars , supernova , and dark matter . It provided critical observations on the Sagittarius A* black hole at the center of the Milky Way galaxy and

1340-540: A space station since the agency was created. In 1973, following the end of the Apollo lunar missions, NASA launched its first space station, Skylab , on the final launch of the Saturn   V. Skylab reused a significant amount of Apollo and Saturn hardware, with a repurposed Saturn   V third stage serving as the primary module for the space station. Damage to Skylab during its launch required spacewalks to be performed by

1474-404: A team tightly folded the 48 suspension lines, three bridle lines, and the parachute. The parachute was loaded in a special structure that then applied a heavy weight to the parachute package several times. Before placing the parachute into the backshell, the parachute was heat set to sterilize it. After the parachute was deployed at an altitude of about 10 km (6.2 mi) above the surface,

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1608-415: A thicker, 13 mm ( 1 ⁄ 2  in), layer of the ablator. Instead of being painted, the backshell was covered with a very thin aluminized PET film blanket to protect it from the cold of deep space. The blanket vaporized during entry into the Martian atmosphere. The parachute helped slow the spacecraft during entry, descent, and landing. It is located in the backshell. The 2003 parachute design

1742-595: A variety of time scales can change water depth, and speed. Some rivers can be characterized by a predictable seasonably controlled hydrograph (reflecting snow melt or rainy season). Others are dominated by durational variations characteristic of alpine glaciers run-off or random storm events, which produce flashy discharge. Few rivers have a long term record of steady flow in the rock record. Bed forms are relatively dynamic sediment storage bodies with response times that are short relative to major changes in flow characteristics. Large scale bed forms are periodic and occur in

1876-435: A water or air current. Cross-beds are layers of sediment that are inclined relative to the base and top of the bed they are associated with. Cross-beds can tell modern geologists many things about ancient environments such as- depositional environment, the direction of sediment transport (paleocurrent) and even environmental conditions at the time of deposition. Typically, units in the rock record are referred to as beds, while

2010-474: A world other than Earth. After Opportunity's total odometry went over 35.744 km (22.210 mi), the rover surpassed the total distance driven by the Apollo 17 Lunar Roving Vehicle . And on July 28, 2014, Opportunity had driven further than any other vehicle on a world other than Earth. Opportunity covered over 40 km (25 mi), surpassing the total distance of 39 km (24 mi) driven by

2144-407: Is a protective shell that houses the rover, and together with the airbags, protects it from the forces of impact. The lander is a tetrahedron shape, whose sides open like petals. It is strong and light, and made of beams and sheets. The beams consist of layers of graphite fiber woven into a fabric that is lighter than aluminium and more rigid than steel. Titanium fittings are glued and fitted onto

2278-526: Is covered with a layer of phenolic honeycomb. This honeycomb is filled with an ablative material (also called an "ablator"), that dissipates heat generated by atmospheric friction. The ablator itself is a blend of cork wood, binder and many tiny silica glass spheres. It was invented for the heat shields flown on the Viking Mars lander missions. A similar technology was used in the first US crewed space missions Mercury , Gemini and Apollo . It

2412-403: Is determined by the axis of the trough. Paleocurrent direction is important in reconstructing past climate and drainage patterns: sand dunes preserve the prevalent wind directions, and current ripples show the direction rivers were moving. Cross-bedding is formed by the downstream migration of bedforms such as ripples or dunes in a flowing fluid. The fluid flow causes sand grains to saltate up

2546-591: Is fast enough and deep enough to develop large-scale bed forms fall into three natural groupings: rivers, tide-dominated coastal and marine settings. Cross-beds can tell geologists much about what an area was like in ancient times. The direction the beds are dipping indicates paleocurrent , the rough direction of sediment transport. The type and condition of sediments can tell geologists the type of environment (rounding, sorting, composition...). Studying modern analogs allows geologists to draw conclusions about ancient environments. Paleocurrent can be determined by seeing

2680-564: Is mostly composed of quartz grains is commonly found in beach environments, far from the source of the sediment. Poorly sorted and angular sediment that is composed of a diversity of minerals is more commonly found in rivers, near the source of the sediment. However, older sedimentary deposits are frequently eroded and re-mobilized. Thus, a river may well erode an older formation of well-rounded, well-sorted beach sands of nearly pure quartz. Flows are characterized by climate (snows, rain, and ice melting) and gradient. Discharge variations measured on

2814-677: The Big Bang . The James Webb Space Telescope , named after the NASA administrator who lead the Apollo program, is an infrared observatory launched in 2021. The James Webb Space Telescope is a direct successor to the Hubble Space Telescope, intended to observe the formation of the first galaxies. Other space telescopes include the Kepler space telescope , launched in 2009 to identify planets orbiting extrasolar stars that may be Terran and possibly harbor life. The first exoplanet that

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2948-797: The Environmental Science Services Administration on a series of weather satellites and the agency launched its experimental Applications Technology Satellites into geosynchronous orbit. NASA's first dedicated Earth observation satellite, Landsat , was launched in 1972. This led to NASA and the National Oceanic and Atmospheric Administration jointly developing the Geostationary Operational Environmental Satellite and discovering Ozone depletion . NASA had been pursuing spaceplane development since

3082-691: The Europa and observed that the moon may hold ice or liquid water. A joint NASA- European Space Agency - Italian Space Agency mission, Cassini–Huygens , was sent to Saturn 's moon Titan , which, along with Mars and Europa, are the only celestial bodies in the Solar System suspected of being capable of harboring life. Cassini discovered three new moons of Saturn and the Huygens probe entered Titan's atmosphere. The mission discovered evidence of liquid hydrocarbon lakes on Titan and subsurface water oceans on

3216-877: The International Space Station (ISS) along with the Commercial Crew Program , and oversees the development of the Orion spacecraft and the Space Launch System for the lunar Artemis program . NASA's science division is focused on better understanding Earth through the Earth Observing System ; advancing heliophysics through the efforts of the Science Mission Directorate 's Heliophysics Research Program; exploring bodies throughout

3350-784: The Johnson Space Center as the lead center for the design, development, and manufacturing of the Space Shuttle orbiter , while the Marshall Space Flight Center would lead the development of the launch system. NASA's series of lifting body aircraft, culminating in the joint NASA-U.S. Air Force Martin Marietta X-24 , directly informed the development of the Space Shuttle and future hypersonic flight aircraft. Official development of

3484-511: The Lunokhod 2 lunar rover , the previous record-holder. On March 23, 2015, Opportunity had driven the full 42.2 km (26.2 mi) distance of a marathon , with a finish time of roughly 11 years and 2 months. On January 24, 2014, NASA reported that then-current studies by the remaining rover, Opportunity , as well as by the newer Mars Science Laboratory rover Curiosity would now be searching for evidence of ancient life, including

3618-664: The Mars Global Surveyor orbiter and Mars Pathfinder , deploying the first Mars rover, Sojourner . During the early 2000s, the 2001 Mars Odyssey orbiter reached the planet and in 2004 the Sprit and Opportunity rovers landed on the Red Planet. This was followed in 2005 by the Mars Reconnaissance Orbiter and 2007 Phoenix Mars lander. The 2012 landing of Curiosity discovered that

3752-408: The Mars Global Surveyor . The next day, JPL received a beep from the rover, indicating that it was in fault mode. On January 23, the flight team succeeded in making the rover send. The fault was believed to have been caused by an error in the rover's flash memory subsystem. The rover did not perform any scientific activities for ten days, while engineers updated its software and ran tests. The problem

3886-555: The National Advisory Committee for Aeronautics (NACA) to give the U.S. space development effort a distinct civilian orientation, emphasizing peaceful applications in space science . It has since led most of America's space exploration programs, including Project Mercury , Project Gemini , the 1968–1972 Apollo Moon landing missions, the Skylab space station, and the Space Shuttle . Currently, NASA supports

4020-684: The National Advisory Committee for Aeronautics (NACA). Despite being the birthplace of aviation, by 1914 the United States recognized that it was far behind Europe in aviation capability. Determined to regain American leadership in aviation, the United States Congress created the Aviation Section of the U.S. Army Signal Corps in 1914 and established NACA in 1915 to foster aeronautical research and development. Over

4154-462: The Opportunity mission over, which also drew the 16-year long Mars Exploration Rover mission to a close. The Mars Exploration Rover was designed to be stowed atop a Delta II rocket . Each spacecraft consists of several components: Total mass is 1,063 kg (2,344 lb). The cruise stage is the component of the spacecraft that is used for travel from Earth to Mars. It is very similar to

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4288-614: The Orbiting Geophysical Observatory in the 1960s and 1970s to look down at Earth and observe its interactions with the Sun. The Uhuru satellite was the first dedicated x-ray telescope, mapping 85% of the sky and discovering a large number of black holes . Launched in the 1990s and early 2000s, the Great Observatories program are among NASA's most powerful telescopes. The Hubble Space Telescope

4422-658: The STS-1 mission, designed to serve as a flight test for the new spaceplane. NASA intended for the Space Shuttle to replace expendable launch systems like the Air Force's Atlas , Delta , and Titan and the European Space Agency 's Ariane . The Space Shuttle's Spacelab payload, developed by the European Space Agency, increased the scientific capabilities of shuttle missions over anything NASA

4556-635: The STS-60 mission in 1994 and the Discovery rendezvoused, but did not dock with, the Russian Mir in the STS-63 mission. This was followed by Atlantis' STS-71 mission where it accomplished the initial intended mission for the Space Shuttle, docking with a space station and transferring supplies and personnel. The Shuttle- Mir program would continue until 1998, when a series of orbital accidents on

4690-541: The Solar System with advanced robotic spacecraft such as New Horizons and planetary rovers such as Perseverance ; and researching astrophysics topics, such as the Big Bang , through the James Webb Space Telescope , the four Great Observatories , and associated programs. The Launch Services Program oversees launch operations for its uncrewed launches . NASA traces its roots to

4824-535: The Space Race when the Soviet Union gave up its lunar ambitions. As the first human to step on the surface of the Moon, Neil Armstrong uttered the now famous words: That's one small step for man, one giant leap for mankind. NASA would conduct six total lunar landings as part of the Apollo program, with Apollo   17 concluding the program in 1972. Wernher von Braun had advocated for NASA to develop

4958-620: The Space Shuttle began in 1972, with Rockwell International contracted to design the orbiter and engines, Martin Marietta for the external fuel tank , and Morton Thiokol for the solid rocket boosters . NASA acquired six orbiters: the Enterprise , Columbia , Challenger , Discovery , Atlantis , and Endeavour The Space Shuttle program also allowed NASA to make major changes to its Astronaut Corps . While almost all previous astronauts were Air Force or Naval test pilots,

5092-405: The inner planets . Despite these successes, Congress was unwilling to fund further interplanetary missions and NASA Administrator James Webb suspended all future interplanetary probes to focus resources on the Apollo program. Following the conclusion of the Apollo program, NASA resumed launching interplanetary probes and expanded its space science program. The first planet tagged for exploration

5226-483: The "entry vehicle". Its main purpose was to protect the lander and the rover inside it from the intense heat of entry into the thin Martian atmosphere. It was based on the Mars Pathfinder and Mars Viking designs. The aeroshell was made of two main parts: a heat shield and a backshell. The heat shield was flat and brownish, and protected the lander and rover during entry into the Martian atmosphere and acted as

5360-420: The 1950s as a response to Soviet lunar exploration, however most missions ended in failure. The Lunar Orbiter program had greater success, mapping the surface in preparation for Apollo landings and measured Selenography , conducted meteoroid detection, and measured radiation levels. The Surveyor program conducted uncrewed lunar landings and takeoffs, as well as taking surface and regolith observations. Despite

5494-524: The 1960s, blending the administration's dual aeronautics and space missions. NASA viewed a spaceplane as part of a larger program, providing routine and economical logistical support to a space station in Earth orbit that would be used as a hub for lunar and Mars missions. A reusable launch vehicle would then have ended the need for expensive and expendable boosters like the Saturn V . In 1969, NASA designated

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5628-679: The 44 commercial companies that contracted with NASA to deploy their satellites to return to expendable launch vehicles. When the Space Shuttle returned to flight with the STS-26 mission, it had undergone significant modifications to improve its reliability and safety. Following the collapse of the Soviet Union, the Russian Federation and United States initiated the Shuttle- Mir program . The first Russian cosmonaut flew on

5762-520: The Army's Project Adam, served as the foundation for Project Mercury . NASA established the Space Task Group to manage the program, which would conduct crewed sub-orbital flights with the Army's Redstone rockets and orbital flights with the Air Force's Atlas launch vehicles. While NASA intended for its first astronauts to be civilians, President Eisenhower directed that they be selected from

5896-574: The Keplar space telescope confirmed was Kepler-22b , orbiting within the habitable zone of its star. NASA also launched a number of different satellites to study Earth, such as Television Infrared Observation Satellite (TIROS) in 1960, which was the first weather satellite. NASA and the United States Weather Bureau cooperated on future TIROS and the second generation Nimbus program of weather satellites. It also worked with

6030-542: The Mars Exploration Rover mission are the same type that Mars Pathfinder used in 1997. They had to be strong enough to cushion the spacecraft if it landed on rocks or rough terrain and allow it to bounce across Mars' surface at highway speeds (about 100 km/h) after landing. The airbags had to be inflated seconds before touchdown and deflated once safely on the ground. The airbags were made of Vectran , like those on Pathfinder. Vectran has almost twice

6164-472: The Mars Exploration Rover mission were to: The total cost of building, launching, landing and operating the rovers on the surface for the initial 90- sol primary mission was US$ 820 million. Each rover received five mission extensions, as they continued to function past their initially planned duration. The fifth mission extension was granted in October 2007, and ran to the end of 2009. The total cost of

6298-481: The Mars Pathfinder in design and is approximately 2.65 meters (8.7 feet) in diameter and 1.6 m (5.2 ft) tall, including the entry vehicle (see below). The primary structure is aluminium with an outer ring of ribs covered by the solar panels, which are about 2.65 m (8.7 ft) in diameter. Divided into five sections, the solar arrays can provide up to 600 watts of power near Earth and 300 W at Mars. Heaters and multi-layer insulation keep

6432-503: The Martian interior. The 2021 Perseverance rover carried the first extraplanetary aircraft, a helicopter named Ingenuity . NASA also launched missions to Mercury in 2004, with the MESSENGER probe demonstrating as the first use of a solar sail . NASA also launched probes to the outer Solar System starting in the 1960s. Pioneer 10 was the first probe to the outer planets, flying by Jupiter , while Pioneer 11 provided

6566-529: The Martian surface. A delegation of scientists showed pictures and data revealing a stratified pattern and cross bedding in the rocks of the outcrop inside a crater in Meridiani Planum , landing site of MER-B, Opportunity . This suggested that water once flowed in the region. The irregular distribution of chlorine and bromine also suggests that the place was once the shoreline of a salty sea, now evaporated. On April 8, 2004, NASA announced that it

6700-403: The Martian winter and might not wake up again for months. On May 22, 2011, NASA cease attempts to contact with Spirit , which had been stuck in a sand trap for two years. The last successful communication with the rover was on March 22, 2010. The final transmission to Spirit was on May 25, 2011. On May 16, 2013, NASA announced that Opportunity had driven further than any other NASA vehicle on

6834-483: The Moon and going to Mars. Embracing this approach, NASA's Commercial Crew Program started by contracting cargo delivery to the International Space Station and flew its first operational contracted mission on SpaceX Crew-1 . This marked the first time since the retirement of the Space Shuttle that NASA was able to launch its own astronauts on an American spacecraft from the United States, ending

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6968-659: The Naval Research Laboratory's Project Vanguard, the Army's Jet Propulsion Laboratory (JPL), and the Army Ballistic Missile Agency under Wernher von Braun . This left NASA firmly as the United States' civil space lead and the Air Force as the military space lead. Plans for human spaceflight began in the U.S. Armed Forces prior to NASA's creation. The Air Force's Man in Space Soonest project formed in 1956, coupled with

7102-730: The Pilotless Aircraft Research Division. The Soviet Union's launch of Sputnik 1 ushered in the Space Age and kicked off the Space Race . Despite NACA's early rocketry program, the responsibility for launching the first American satellite fell to the Naval Research Laboratory 's Project Vanguard , whose operational issues ensured the Army Ballistic Missile Agency would launch Explorer 1 , America's first satellite, on February 1, 1958. The Eisenhower Administration decided to split

7236-557: The Russians be included. In 1993, the Clinton Administration announced that the Space Station Freedom would become the International Space Station in an agreement with the Russian Federation. This allowed the Russians to maintain their space program through an infusion of American currency to maintain their status as one of the two premier space programs. While the United States built and launched

7370-507: The Russians to fly to the International Space Station for four days, despite the opposition of NASA to the idea. Advocates of this new commercial approach for NASA included former astronaut Buzz Aldrin , who remarked that it would return NASA to its roots as a research and development agency, with commercial entities actually operating the space systems. Having corporations take over orbital operations would also allow NASA to focus all its efforts on deep space exploration and returning humans to

7504-422: The Solar System. Mars has long been a planet of intense fascination for NASA, being suspected of potentially having harbored life. Mariner 5 was the first NASA spacecraft to flyby Mars, followed by Mariner 6 and Mariner 7 . Mariner 9 was the first orbital mission to Mars. Launched in 1975, Viking program consisted of two landings on Mars in 1976. Follow-on missions would not be launched until 1996, with

7638-633: The Space Shuttle Columbia disaster in 2003, NASA was forced to rely on Russian Soyuz launches for its astronauts and the 2011 retirement of the Space Shuttle accelerated the station's completion. In the 1980s, right after the first flight of the Space Shuttle, NASA started a joint program with the Department of Defense to develop the Rockwell X-30 National Aerospace Plane. NASA realized that

7772-418: The Space Shuttle allowed NASA to begin recruiting more non-military scientific and technical experts. A prime example is Sally Ride , who became the first American woman to fly in space on STS-7 . This new astronaut selection process also allowed NASA to accept exchange astronauts from U.S. allies and partners for the first time. The first Space Shuttle flight occurred in 1981, when the Columbia launched on

7906-514: The Space Shuttle and expand space exploration beyond low Earth orbit. Constellation was intended to use a significant amount of former Space Shuttle equipment and return astronauts to the Moon. This program was canceled by the Obama Administration . Former astronauts Neil Armstrong , Gene Cernan , and Jim Lovell sent a letter to President Barack Obama to warn him that if the United States did not get new human spaceflight ability,

8040-554: The Space Shuttle began flying, selling it as an orbital laboratory, repair station, and a jumping off point for lunar and Mars missions. NASA found a strong advocate in President Ronald Reagan , who declared in a 1984 speech: America has always been greatest when we dared to be great. We can reach for greatness again. We can follow our dreams to distant stars, living and working in space for peaceful, economic, and scientific gain. Tonight I am directing NASA to develop

8174-686: The Space Shuttle, while a massive technological accomplishment, would not be able to live up to all its promises. Designed to be a single-stage-to-orbit spaceplane, the X-30 had both civil and military applications. With the end of the Cold War , the X-30 was canceled in 1992 before reaching flight status. Following the Space Shuttle Columbia disaster in 2003, President Bush started the Constellation program to smoothly replace

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8308-483: The Space Shuttle. Due to technical challenges, the spacecraft was cancelled in 2001. Despite this, it was the first time a commercial space company directly expended a significant amount of its resources into spacecraft development. The advent of space tourism also forced NASA to challenge its assumption that only governments would have people in space. The first space tourist was Dennis Tito , an American investment manager and former aerospace engineer who contracted with

8442-507: The Space Station Freedom was controversial, with much of the debate centering on cost. Several redesigns to reduce cost were conducted in the early 1990s, stripping away much of its functions. Despite calls for Congress to terminate the program, it continued, in large part because by 1992 it had created 75,000 jobs across 39 states. By 1993, President Bill Clinton attempted to significantly reduce NASA's budget and directed costs be significantly reduced, aerospace industry jobs were not lost, and

8576-602: The U.S. risked become a second or third-rate space power. As early as the Reagan Administration, there had been calls for NASA to expand private sector involvement in space exploration rather than do it all in-house. In the 1990s, NASA and Lockheed Martin entered into an agreement to develop the Lockheed Martin X-33 demonstrator of the VentureStar spaceplane, which was intended to replace

8710-491: The United States' military and civil spaceflight programs, which were organized together under the Defense Department 's Advanced Research Projects Agency . NASA was established on July 29, 1958, with the signing of the National Aeronautics and Space Act and it began operations on October 1, 1958. As the US's premier aeronautics agency, NACA formed the core of NASA's new structure by reassigning 8,000 employees and three major research laboratories. NASA also proceeded to absorb

8844-412: The angle of repose (~34 degrees from the horizontal), so geologists are able to measure dip direction of the cross-bedded sediments and calculate the paleoflow direction. However, most cross-beds are not tabular, they are troughs . Since troughs can give a 180 degree variation of the dip of foresets, false paleocurrents can be taken by blindly measuring foresets. In this case, true paleocurrent direction

8978-452: The beams to allow it to be bolted together. The rover was held inside the lander by bolts and special nuts that were released after landing with small explosives. NASA The National Aeronautics and Space Administration ( NASA / ˈ n æ s ə / ) is an independent agency of the U.S. federal government responsible for the civil space program , aeronautics research, and space research. Established in 1958 , it succeeded

9112-423: The bedform (ripple or dune). These foresets are individually differentiable because of small-scale separation between layers of material of different sizes and densities. Cross-bedding can also be recognized by truncations in sets of ripple foresets, where previously-existing stream deposits are eroded by a later flood, and new bedforms are deposited in the scoured area. Cross-bedding can be subdivided according to

9246-534: The bounding surfaces are curved, and hence limited in horizontal extent. Tabular (planar) cross-beds consist of cross-bedded units that are large in horizontal extent relative to set thickness and that have essentially planar bounding surfaces. The foreset laminae of tabular cross-beds are curved so as to become tangential to the basal surface. Tabular cross-bedding is formed mainly by migration of large-scale, straight-crested ripples and dunes. It forms during lower-flow regimes. Individual beds range in thickness from

9380-476: The channel (scaled to depth). Their presence and morphologic variability have been related to flow strength expressed as mean velocity or shear stress . In a fluvial environment, the water in a stream loses energy and its ability transport sediment. The sediment "falls" out of the water and is deposited along a point bar. Over time the river may dry up or avulse and the point bar may be preserved as cross-bedding. Tide dominated environments include: In general,

9514-467: The constituent layers that make up the bed are referred to as laminae, when they are less than 1 cm thick and strata when they are greater than 1 cm in thickness. Cross-beds are angled relative to either the base or the top of the surrounding beds. As opposed to angled beds, cross-beds are deposited at an angle rather than deposited horizontally and deformed later on. Trough cross-beds have lower surfaces which are curved or scoop shaped and truncate

9648-428: The depositional environment and the size of the bedform. Cross-bedding can form in any environment in which a fluid flows over a bed with mobile material. It is most common in stream deposits (consisting of sand and gravel), tidal areas, and in aeolian dunes. Cross-bedded sediments are recognized in the field by the many layers of " foresets ", which are the series of layers that form on the downstream or lee side of

9782-467: The electronics "warm". A freon system removes heat from the flight computer and communications hardware inside the rover so they do not overheat. Cruise avionics systems allow the flight computer to interface with other electronics, such as the Sun sensors , star scanner and heaters. The star scanner (without a backup system) and Sun sensor allowed the spacecraft to know its orientation in space by analyzing

9916-574: The end of the 1960s and installed James E. Webb as NASA administrator to achieve this goal. On May   25, 1961, President Kennedy openly declared this goal in his "Urgent National Needs" speech to the United States Congress, declaring: I believe this Nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to Earth. No single space project in this period will be more impressive to mankind, or more important for

10050-591: The estuary are flood dominated and other parts are ebb dominated. The temporal and spatial variability of flow and sediment transport, coupled with regular fluctuating water levels creates a variety of bed form morphology. Large scale bed forms occur on shallow, terrigenous or carbonate clastic continental shelves and epicontinental platforms which are affected by strong geostrophic currents , occasional storm surges and/or tide currents. In an aeolian environment, cross-beds often exhibit inverse grading due to their deposition by grain flows . Winds blow sediment along

10184-507: The first aerobrake for the spacecraft. The backshell was large, cone-shaped and painted white. It carried the parachute and several components used in later stages of entry, descent, and landing, including: Built by Lockheed Martin Space in Denver, Colorado, the aeroshell is made of an aluminium honeycomb structure sandwiched between graphite-epoxy face sheets. The outside of the aeroshell

10318-420: The first close up view of the planet. Both probes became the first objects to leave the Solar System. The Voyager program launched in 1977, conducting flybys of Jupiter and Saturn , Neptune , and Uranus on a trajectory to leave the Solar System. The Galileo spacecraft, deployed from the Space Shuttle flight STS-34 , was the first spacecraft to orbit Jupiter, discovering evidence of subsurface oceans on

10452-515: The first crew to make it habitable and operational. Skylab hosted nine missions and was decommissioned in 1974 and deorbited in 1979, two years prior to the first launch of the Space Shuttle and any possibility of boosting its orbit. In 1975, the Apollo–Soyuz mission was the first ever international spaceflight and a major diplomatic accomplishment between the Cold War rivals, which also marked

10586-736: The first four mission extensions was $ 104 million, and the fifth mission extension cost at least $ 20 million. The mission was managed by the Jet Propulsion Laboratory (JPL), which designed, built, and operated the rovers. In recognition of the vast amount of scientific information amassed by both rovers, two asteroids have been named in their honor: 37452 Spirit and 39382 Opportunity . The MER-A ( Spirit ) and MER-B ( Opportunity ) were launched on June 10, 2003 and July 7, 2003, respectively. Though both probes launched on Boeing Delta II 7925-9.5 rockets from Cape Canaveral Space Launch Complex 17 (CCAFS SLC-17), MER-B

10720-402: The first humans to see the Earth as a globe in space, the first to witness an Earthrise , and the first to see and manually photograph the far side of the Moon. The first lunar landing was conducted by Apollo   11. Commanded by Neil Armstrong with astronauts Buzz Aldrin and Michael Collins , Apollo   11 was one of the most significant missions in NASA's history, marking the end of

10854-440: The first spacecraft to traverse ten kilometers (6.2 miles) on the surface of Mars. In July 2007, during the fourth mission extension, Martian dust storms blocked sunlight to the rovers and threatened the ability of the craft to gather energy through their solar panels , causing engineers to fear that one or both of them might be permanently disabled. However, the dust storms lifted, allowing them to resume operations. Opportunity

10988-417: The geometry of the sets and cross-strata into subcategories. The most commonly described types are tabular cross-bedding and trough cross-bedding. Tabular cross-bedding, or planar bedding consists of cross-bedded units that are extensive horizontally relative to the set thickness and that have essentially planar bounding surfaces. Trough cross-bedding, on the other hand, consists of cross-bedded units in which

11122-462: The greater the tidal range the greater the maximum flow strength. Cross-stratification in tidal-dominated areas can lead to the formation of Herringbone cross-stratification . Although the flow direction reverses regularly, the flow patterns of flood on ebb currents commonly do not coincide. Consequently, the water and transport sediment may follow a roundabout route in and out of the estuary. This leads to spatially varied systems where some parts of

11256-400: The heatshield was released using 6 separation nuts and push-off springs. The lander then separated from the backshell and "rappelled" down a metal tape on a centrifugal braking system built into one of the lander petals. The slow descent down the metal tape placed the lander in position at the end of another bridle (tether), made of a nearly 20 m (66 ft) long braided Zylon . Zylon is

11390-433: The hypersonic test aircraft becoming the first non-dedicated spacecraft to cross from the atmosphere to outer space. The X-15 also served as a testbed for Apollo program technologies, as well as ramjet and scramjet propulsion. Escalations in the Cold War between the United States and Soviet Union prompted President John F. Kennedy to charge NASA with landing an American on the Moon and returning him safely to Earth by

11524-425: The inner ring, and a cruise medium-gain antenna in the outer ring. The low-gain antenna was used close to Earth. It is omni-directional, so the transmission power that reached Earth fell faster with increasing distance. As the craft moved closer to Mars, the Sun and Earth moved closer in the sky as viewed from the craft, so less energy reached Earth. The spacecraft then switched to the medium-gain antenna, which directed

11658-451: The last flight of the Apollo capsule. Flown in 1975, a U.S. Apollo spacecraft docked with a Soviet Soyuz capsule. During the 1960s, NASA started its space science and interplanetary probe program. The Mariner program was its flagship program, launching probes to Venus , Mars , and Mercury in the 1960s. The Jet Propulsion Laboratory was the lead NASA center for robotic interplanetary exploration, making significant discoveries about

11792-484: The long-range exploration of space; and none will be so difficult or expensive to accomplish. Kennedy gave his " We choose to go to the Moon " speech the next year, on September   12, 1962 at Rice University , where he addressed the nation hoping to reinforce public support for the Apollo program. Despite attacks on the goal of landing astronauts on the Moon from the former president Dwight Eisenhower and 1964 presidential candidate Barry Goldwater , President Kennedy

11926-423: The lower slopes. Drivers directed Spirit to a smaller sloped feature, dubbed "Low Ridge Haven", where it spent the long Martian winter, waiting for spring and increased solar power levels suitable for driving. That September, Opportunity reached the rim of Victoria crater, and Spaceflight Now reported that NASA had extended mission for the two rovers through September 2007. On February 6, 2007, Opportunity became

12060-434: The majority of the International Space Station, Russia, Canada, Japan, and the European Space Agency all contributed components. Despite NASA's insistence that costs would be kept at a budget of $ 17.4, they kept rising and NASA had to transfer funds from other programs to keep the International Space Station solvent. Ultimately, the total cost of the station was $ 150 billion, with the United States paying for two-thirds.Following

12194-556: The military. The Mercury 7 astronauts included three Air Force pilots, three Navy aviators, and one Marine Corps pilot. On May 5, 1961, Alan Shepard became the first American to enter space, performing a suborbital spaceflight in the Freedom 7 . This flight occurred less than a month after the Soviet Yuri Gagarin became the first human in space, executing a full orbital spaceflight. NASA's first orbital spaceflight

12328-634: The moon of Enceladus , which could harbor life. Finally launched in 2006, the New Horizons mission was the first spacecraft to visit Pluto and the Kuiper Belt . Beyond interplanetary probes, NASA has launched many space telescopes . Launched in the 1960s, the Orbiting Astronomical Observatory were NASA's first orbital telescopes, providing ultraviolet, gamma-ray, x-ray, and infrared observations. NASA launched

12462-476: The next forty years, NACA would conduct aeronautical research in support of the U.S. Air Force , U.S. Army , U.S. Navy , and the civil aviation sector. After the end of World War II , NACA became interested in the possibilities of guided missiles and supersonic aircraft, developing and testing the Bell X-1 in a joint program with the U.S. Air Force . NACA's interest in space grew out of its rocketry program at

12596-427: The paleocurrent. The sediment that goes on to form cross-stratification is generally sorted before and during deposition on the "lee" side of the dune, allowing cross-strata to be recognized in rocks and sediment deposits. The angle and direction of cross-beds are generally fairly consistent. Individual cross-beds can range in thickness from just a few tens of centimeters, up to hundreds of feet or more depending upon

12730-447: The plains in order to characterize Meridiani Planum's vast diversity of rocks—some of which may have been blasted out of craters such as Victoria. The rover had been exploring Victoria Crater since September 11, 2007. As of January 2009, the two rovers had collectively sent back 250,000 images and traveled over 21 kilometers (13 mi). After driving about 3.2 kilometers (2.0 mi) since it left Victoria crater, Opportunity first saw

12864-529: The position of the Sun and other stars in relation to itself. Sometimes the craft could be slightly off course; this was expected, given the 500-million-kilometer (320 million mile) journey. Thus navigators planned up to six trajectory correction maneuvers, along with health checks. To ensure the spacecraft arrived at Mars in the right place for its landing, two light-weight, aluminium-lined tanks carried about 31 kg (about 68 lb) of hydrazine propellant . Along with cruise guidance and control systems,

12998-436: The propellant allowed navigators to keep the spacecraft on course. Burns and pulse firings of the propellant allowed three types of maneuvers: The spacecraft used a high-frequency X band radio wavelength to communicate, which allowed for less power and smaller antennas than many older craft, which used S band . Navigators sent commands through two antennas on the cruise stage: a cruise low-gain antenna mounted inside

13132-570: The radiation levels on Mars were equal to those on the International Space Station , greatly increasing the possibility of Human exploration, and observed the key chemical ingredients for life to occur. In 2013, the Mars Atmosphere and Volatile Evolution ( MAVEN ) mission observed the Martian upper atmosphere and space environment and in 2018, the Interior exploration using Seismic Investigations Geodesy, and Heat Transport ( InSight ) studied

13266-429: The rim of Endeavour crater on March 7, 2009. It passed the 16 km (9.9 mi) mark along the way on sol 1897. Meanwhile, at Gusev crater, Spirit was dug in deep into the Martian sand, much as Opportunity was at Purgatory Dune in 2005. On January 26, 2010, after six years on Mars, NASA announced that Spirit would be used as a stationary research platform, after several months of unsuccessful attempts to free

13400-418: The rover from soft sand. NASA announced on March 24, 2010, that Opportunity , which had an estimated remaining drive distance of 12 km (7.5 mi) to Endeavour Crater, had traveled over 20 km (12.4 mi) since the start of its mission. Each rover was designed with a mission driving distance goal of just 600 meters. In March 2010 it was announced that Spirit may have gone into hibernation for

13534-466: The rovers for another six months. Opportunity was to leave Endurance crater, visit its discarded heat shield, and proceed to Victoria crater . Spirit was to attempt to climb to the top of the Columbia Hills . With the two rovers still functioning well, NASA later announced another 18-month extension of the mission to September 2006. Opportunity was to visit the "Etched Terrain" and Spirit

13668-516: The rovers to have spent five years exploring the Martian surface, pending their continued survival. On August 26, 2008, Opportunity began its three-day climb out of Victoria crater amidst concerns that power spikes, similar to those seen on Spirit before the failure of its right-front wheel, might prevent it from ever being able to leave the crater if a wheel failed. Project scientist Bruce Banerdt also said, "We've done everything we entered Victoria Crater to do and more." Opportunity will return to

13802-424: The same amount of transmission power into a tighter beam toward Earth. During flight, the spacecraft was spin-stabilized with a spin rate of two revolutions per minute (rpm). Periodic updates kept antennas pointed toward Earth and solar panels toward the Sun. The aeroshell maintained a protective covering for the lander during the seven-month voyage to Mars. Together with the lander and the rover, it constituted

13936-507: The satellites were repaired and relaunched. Despite ushering in a new era of spaceflight, where NASA was contracting launch services to commercial companies, the Space Shuttle was criticized for not being as reusable and cost-effective as advertised. In 1986, Challenger disaster on the STS-51L mission resulted in the loss of the spacecraft and all seven astronauts on launch, grounding the entire space shuttle fleet for 36 months and forced

14070-676: The separation of dark and regular matter during galactic collisions. Finally, the Spitzer Space Telescope is an infrared telescope launched in 2003 from a Delta II rocket. It is in a trailing orbit around the Sun, following the Earth and discovered the existence of brown dwarf stars . Other telescopes, such as the Cosmic Background Explorer and the Wilkinson Microwave Anisotropy Probe , provided evidence to support

14204-508: The setback caused by the Apollo   1 fire, which killed three astronauts, the program proceeded. Apollo   8 was the first crewed spacecraft to leave low Earth orbit and the first human spaceflight to reach the Moon . The crew orbited the Moon ten times on December   24 and   25, 1968, and then traveled safely back to Earth . The three Apollo   8 astronauts— Frank Borman , James Lovell , and William Anders —were

14338-592: The space agency where he would serve as the director of the Apollo program. Development of the Saturn   V rocket was led by Wernher von Braun and his team at the Marshall Space Flight Center , derived from the Army Ballistic Missile Agency's original Saturn   I . The Apollo spacecraft was designed and built by North American Aviation , while the Apollo Lunar Module was designed and built by Grumman . To develop

14472-549: The space shuttle be retired. In 2006, the Space Shuttle returned to flight, conducting several mission to service the Hubble Space Telescope , but was retired following the STS-135 resupply mission to the International Space Station in 2011. NASA never gave up on the idea of a space station after Skylab's reentry in 1979. The agency began lobbying politicians to support building a larger space station as soon as

14606-481: The space station spelled an end to the program. In 2003, a second space shuttle was destroyed when the Columbia was destroyed upon reentry during the STS-107 mission, resulting in the loss of the spacecraft and all seven astronauts. This accident marked the beginning of the retiring of the Space Shuttle program, with President George W. Bush directing that upon the completion of the International Space Station,

14740-406: The spacecraft) to the flight computer in the rover. Because the atmospheric density of Mars is less than 1% of Earth's, the parachute alone could not slow down the Mars Exploration Rover enough to ensure a safe, low landing speed. The spacecraft descent was assisted by rockets that brought the spacecraft to a dead stop 10–15 m (33–49 ft) above the Martian surface. A radar altimeter unit

14874-466: The spaceflight skills and equipment required for a lunar mission, NASA initiated Project Gemini . Using a modified Air Force Titan   II launch vehicle, the Gemini capsule could hold two astronauts for flights of over two weeks. Gemini pioneered the use of fuel cells instead of batteries, and conducted the first American spacewalks and rendezvous operations . The Ranger Program was started in

15008-412: The stoss (upstream) side of the bedform and collect at the peak until the angle of repose is reached. At this point, the crest of granular material has grown too large and will be overcome by the force of the moving water, falling down the lee(downstream) side of the dune. Repeated avalanches will eventually form the sedimentary structure known as cross-bedding, with the structure dipping in the direction of

15142-455: The strength of other synthetic materials, such as Kevlar, and performs better in cold temperatures. Six 100 denier (10 mg/m) layers of Vectran protected one or two inner bladders of Vectran in 200 denier (20 mg/m). Using 100 denier (10 mg/m) leaves more fabric in the outer layers where it is needed, because there are more threads in the weave. Each rover used four airbags with six lobes each, all of which were connected. Connection

15276-501: The underlying beds. The foreset beds are also curved and merge tangentially with the lower surface. They are associated with sand dune migration. The shape of the grains and the sorting and composition of sediment can provide additional information on the history of cross-beds. Roundness of the grains, limited variation in grain size, and high quartz contents are generally attributed to longer histories of weathering and sediment transport. For example: well-rounded, and well-sorted sand that

15410-508: The various projects, mission architectures and associated timelines relevant to lunar and Mars exploration and science. Cross bedding Cross-bedding forms during deposition on the inclined surfaces of bedforms such as ripples and dunes ; it indicates that the depositional environment contained a flowing medium (typically water or wind). Examples of these bedforms are ripples, dunes, anti-dunes, sand waves , hummocks , bars , and delta slopes. Environments in which water movement

15544-461: Was Venus , sharing many similar characteristics to Earth. First visited by American Mariner 2 spacecraft, Venus was observed to be a hot and inhospitable planet. Follow-on missions included the Pioneer Venus project in the 1970s and Magellan , which performed radar mapping of Venus' surface in the 1980s and 1990s. Future missions were flybys of Venus, on their way to other destinations in

15678-507: Was June 25, 2003. NASA's Launch Services Program managed the launch of both spacecraft. The probes landed in January 2004 in widely separated equatorial locations on Mars. On January 21, 2004, the Deep Space Network lost contact with Spirit , for reasons originally thought to be related to a flare shower over Australia . The rover transmitted a message with no data, but later that day missed another communications session with

15812-683: Was able to previously accomplish. NASA launched its first commercial satellites on the STS-5 mission and in 1984, the STS-41-C mission conducted the world's first on-orbit satellite servicing mission when the Challenger captured and repaired the malfunctioning Solar Maximum Mission satellite. It also had the capability to return malfunctioning satellite to Earth, like it did with the Palapa B2 and Westar 6 satellites. Once returned to Earth,

15946-424: Was able to protect NASA's growing budget, of which 50% went directly to human spaceflight and it was later estimated that, at its height, 5% of Americans worked on some aspect of the Apollo program. Mirroring the Department of Defense's program management concept using redundant systems in building the first intercontinental ballistic missiles, NASA requested the Air Force assign Major General Samuel C. Phillips to

16080-469: Was active until March 22, 2010, while MER-B Opportunity was active until June 10, 2018. The mission's scientific objective was to search for and characterize a wide range of rocks and soils that hold clues to past water activity on Mars . The mission is part of NASA 's Mars Exploration Program , which includes three previous successful landers: the two Viking program landers in 1976 and Mars Pathfinder probe in 1997. The scientific objectives of

16214-472: Was also a concern with sharing sensitive space technologies with the Europeans, which had the potential to dilute America's technical lead. Ultimately, an international agreement to develop the Space Station Freedom program would be signed with thirteen countries in 1985, including the European Space Agency member states, Canada , and Japan . Despite its status as the first international space program,

16348-488: Was caught in a global-scale dust storm and the rover's solar panels were not able to generate enough power, with the last contact on June 10, 2018. NASA resumed sending commands after the dust storm subsided but the rover remained silent, possibly due to a catastrophic failure or a layer of dust covering its solar panels. A press conference was held on February 13, 2019, announcing that after numerous attempts to contact Opportunity , with no response since June 2018, NASA declared

16482-601: Was conducted by John Glenn on February 20, 1962, in the Friendship 7 , making three full orbits before reentering. Glenn had to fly parts of his final two orbits manually due to an autopilot malfunction. The sixth and final Mercury mission was flown by Gordon Cooper in May 1963, performing 22 orbits over 34 hours in the Faith 7 . The Mercury Program was wildly recognized as a resounding success, achieving its objectives to orbit

16616-413: Was corrected by reformatting Spirit 's flash memory and using a software patch to avoid memory overload; Opportunity was also upgraded with the patch as a precaution. Spirit returned to full scientific operations by February 5. Both rovers' missions were initially just 90- sol -long. On March 23, 2004, a news conference was held announcing "major discoveries" of evidence of past liquid water on

16750-564: Was designed and constructed in South Windsor, Connecticut by Pioneer Aerospace , who also designed the parachute for the Stardust mission. The parachute is made of two durable, lightweight fabrics: polyester and nylon . A triple bridle made of Kevlar connects the parachute to the backshell. The amount of space available on the spacecraft for the parachute was so small that the parachute had to be pressure-packed. Before launch,

16884-399: Was extending the mission life of the rovers from three to eight months. It immediately provided additional funding of US$ 15 million through September, and $ 2.8 million per month for continuing operations. Later that month, Opportunity arrived at Endurance crater , taking about five days to drive the 200 meters. NASA announced on September 22 that it was extending the mission life of

17018-427: Was important, since it helped abate some of the landing forces by keeping the bag system flexible and responsive to ground pressure. The airbags were not attached directly to the rover, but were held to it by ropes crisscrossing the bag structure. The ropes gave the bags shape, making inflation easier. While in flight, the bags were stowed along with three gas generators that are used for inflation. The spacecraft lander

17152-497: Was launched in 1990 on STS-31 from the Discovery and could view galaxies 15 billion light years away. A major defect in the telescope's mirror could have crippled the program, had NASA not used computer enhancement to compensate for the imperfection and launched five Space Shuttle servicing flights to replace the damaged components. The Compton Gamma Ray Observatory was launched from the Atlantis on STS-37 in 1991, discovering

17286-408: Was on the heavy version of that launch vehicle, needing the extra energy for Trans-Mars injection . The launch vehicles were integrated onto pads right next to each other, with MER-A on CCAFS SLC-17A and MER-B on CCAFS SLC-17B. The dual pads allowed for working the 15- and 21-day planetary launch periods close together; the last possible launch day for MER-A was June 19, 2003 and the first day for MER-B

17420-548: Was part of a long-term Mars parachute technology development effort and is based on the designs and experience of the Viking and Pathfinder missions. The parachute for this mission is 40% larger than Pathfinder's because the largest load for the Mars Exploration Rover is 80 to 85 kilonewtons (kN) or 80 to 85 kN (18,000 to 19,000 lbf) when the parachute fully inflates. By comparison, Pathfinder's inflation loads were approximately 35 kN (about 8,000 lbf). The parachute

17554-540: Was poised to enter Victoria Crater from its perch on the rim of Duck Bay on June 28, 2007, but due to extensive dust storms, it was delayed until the dust had cleared and power returned to safe levels. Two months later, Spirit and Opportunity resumed driving after hunkering down during raging dust storms that limited solar power to a level that nearly caused the permanent failure of both rovers. On October 1, 2007, both Spirit and Opportunity entered their fifth mission extension that extended operations into 2009, allowing

17688-416: Was specially formulated to react chemically with the Martian atmosphere during entry and carry heat away, leaving a hot wake of gas behind the vehicle. The vehicle slowed from 19,000 to 1,600 km/h (5,300 to 440 m/s) in about a minute, producing about 60 m/s (6 g ) of acceleration on the lander and rover. The backshell and heat shield are made of the same materials, but the heat shield has

17822-433: Was to climb a rocky slope toward the top of Husband Hill . On August 21, 2005, Spirit reached the summit of Husband Hill after 581 sols and a journey of 4.81 kilometers (2.99 mi). Spirit's front right wheel ceased working on March 13, 2006, while the rover was moving itself to McCool Hill . Its drivers attempted to drag the dead wheel behind Spirit , but this only worked until reaching an impassable sandy area on

17956-530: Was used to determine the distance to the Martian surface. The radar's antenna was mounted at one of the lower corners of the lander tetrahedron. When the radar measurement showed the lander was the correct distance above the surface, the Zylon bridle was cut, releasing the lander from the parachute and backshell so that it was free and clear for landing. The radar data also enabled the timing sequence on airbag inflation and backshell RAD rocket firing. Airbags used in

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