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The National Aeronautics and Space Administration is the U.S. government agency concerned with space exploration. It is not a military agency; it's a civilian agency (although some personnel, particularly astronauts, may be military officers on special assignment to the agency as a tour of duty). Much of the "military vs. civilian" confusion is likely due to the frequent misconception of NASA's responsibilities, as the agency is frequently portrayed as conducting activities--such as tracking objects in Earth orbit, or launching and controlling secret satellites, for example--that generally fall within the purview of military or intelligence communities (most often the United States Air Force).
Generally, a radio transmission addressed to "Houston" (especially from anyone in space) is a reference to NASA's Mission Control Center at Lyndon B. Johnson Space Center in the Texan city of the same name.
The Mercury Program The Russians had put Yuri Gagarin in space, so the US played catch-up. The goal of this program was simply putting Americans in orbit. After a test flight involving Ham the Chimp, Alan Shepard and John Glenn made their famous flights. All the Mercury capsules were named "Something 7" in reference to there being seven astronauts.
The Right Stuff is a movie about the Mercury astronauts, based on a nonfiction book by Tom Wolfe.
The Gemini Program Within three weeks after the first successful Mercury flight, in mid-1961, President Kennedy announced that the United states should commit to the goal of "landing a man on the Moon and returning him safely to the Earth" before the end of the 1960s. This, of course, meant that they needed a lot of practice. The Gemini Program focused on staying in space for long periods of time in two-person capsules, spacewalking, and rendezvous and docking in orbit.
Despite its crucial importance to the space race, Gemini is the forgotten middle child of the space program. Outside of non-fiction books, the most exposure it's gotten is half of an episode of the HBO Docu Drama Miniseries From the Earth To The Moon. There were some proposals to use Gemini as a quicker means of getting (fewer people) to the Moon, or using it as the basis for a larger orbital ship called Big Gemini - these tended to be suppressed by NASA after they had committed to Apollo.
The Apollo Program
NASA's most famous program. The Apollo spacecraft was a three-person vessel that had three main parts: the Command Module, a squat cone where the crew spent most of their time and which was the only bit that would survive re-entry; the Service Module, a big cylinder where all of the life-support equipment was kept, and the Lunar Module, the funny spidery thing that actually landed on the Moon. Missions to the Moon were propelled by the Saturn V, America's largest ever rocket, and the largest rocket ever successfully used (the Soviet N1 and Energia rockets were larger, but the N1 was a catastrophic failure and kept secret until 1990, and Energia was too expensive to be useful, especially after The Great Politics Mess-Up resulted in a near-bankrupt Russia). Notable missions include:
- Apollo 1: caught fire during a "dry run" for the launch, killing the three astronauts on board.
- Apollo 7: first successful manned flight of an Apollo spacecraft (Apollo missions 2 to 6 were unmanned)
- Apollo 8: a manned mission that went to the Moon and back, but did not land. Arguably the defining moment where the United States overtook the USSR in the Space Race. Also notable for the Christmas Eve broadcast, in which the astronauts read from Genesis during a scheduled television broadcast, and the famous Earthrise photograph.
- Apollo 11: first manned mission to land on the Moon. Neil Armstrong gets to say his famous lines. Gently parodied by The Dish, which loosely follows the tale of the radio observatory in Australia responsible for tracking the mission. NASA erased their recordings of the event.
- Apollo 13: the "successful failure". Several critical equipment failures meant that the craft could not land on the Moon, but due to the tenacity of both the astronauts in the craft and the controllers, astronauts, scientists and engineers on the ground, all three crew members made it back alive. Made into an excellent novel and movie.
- Jim Lovell, who went past the Moon twice on Apollo missions 8 and 13 but never got to land on it, deserves a special mention here.
- Apollo 15: the first of the J-missions. Changes to the launcher and its trajectory allowed a heavier payload, including a lunar rover, and total EVA time was about double that of Apollo 14. The Genesis Rock was discovered on this mission, which is probably one of the reasons NASA still considers it the most successful manned space mission ever, the infamous postage stamp incident notwithstanding.
- Apollo 17: the last mission to the Moon (Apollo missions 12, 14, 15, and 16 were successful manned landings and 18, 19 and 20 were cancelled). The only time where a civilian scientist (Harrison Schmitt) has been able to walk on the Moon.
Skylab and the Apollo Applications Program
From the beginning of the Apollo program, NASA had been looking into using spare Apollo hardware for a number of other scientific missions. This outgrowth of Apollo was called the Apollo Applications Program, which proposed a number of ambitious ideas. These included plans for a manned orbital observatory, a Venus flyby using the third stage of the Saturn V as a "wet workshop" and various lunar habitats. The only one of these ideas to reach fruition was Skylab, a space station built into an empty stage from a spare Saturn V. Skylab suffered severe damage during its launch in 1973, but the crews that followed it up managed to repair it, and it was inhabited for most of the next nine months. Early shuttle missions were planned to resuscitate the station, but it fell out of orbit before the shuttle could be launched.
The Space Shuttle
Designed to be the opposite of the Saturn V, the Shuttle has been described as a "do anything vehicle, but not a go anywhere one": it is a versatile and (by the standards of space flight) economical vehicle, but it cannot get further than low Earth orbit. The Shuttle was originally proposed as part of a complete infrastructure of American Earth-orbit facilities, including the Space Station Freedom (see below); budgetary cutbacks meant that only one portion of the proposal could be funded, and the Shuttle was selected. Somewhat ironically, it is only in the final stages of its life-cycle that the advent of the International Space Station has allowed the Shuttle to be used in the capacity for which it was originally designed.
Strictly speaking, the big black-and-white thing that looks kind of like an airplane is called an "orbiter"; the space shuttle consists of an orbiter, a large external fuel tank (which is not recovered--a new one must be used every time), and two Solid Rocket Boosters. Six orbiters have been built in total:
- Enterprise (after that Enterprise, seriously!). Built primarily for testing purposes, Enterprise is not actually capable of spaceflight (as it is missing several minor things like heat shielding or engines), though there were originally plans to refit it for such.
- Now housed at the National Air and Space Museum's Udvar-Hazy Center. Go see it!
- Columbia (after the first American vessel to circumnavigate the world, and also the Apollo 11 Command Module). The first space shuttle launched (in 1981). Slightly different from later shuttles due to design changes. Columbia remained in service until 2003, when it broke up during atmospheric reentry.
- Challenger (after the ship used for the Challenger expedition). First launched in 1983. Sadly, Challenger is best known for its destruction in 1986 just over a minute after liftoff.
- Discovery (after quite a few different ships of exploration). First launched in 1984. Discovery was used to launch the Hubble Space Telescope, was the first American spacecraft to carry a Russian into space, and was the first shuttle to be launched after the destructions of both Columbia and Challenger.
- Also the Orbiter with the most flights and longest cumulative time in space.
- Atlantis (after an oceanographic research vessel). First launched in 1985. The final orbiter to be decommissioned, it took off on its final mission on July 8, 2011, about half an hour before noon Eastern Daylight Time.
- Endeavour (after James Cook's ship and also the Apollo 15 Command Module; Americans normally spell the word "endeavor"). First launched in 1992. Constructed as a replacement for Challenger.
The entire space shuttle fleet is scheduled to be decommissioned in 2011, in favor of a new system known as Orion that will, when using the Ares-class rockets, be able to go back to the Moon. A new system that is, at time of edit, cancelled. See "Project Constellation" for more details.
The International Space Station
An outgrowth of a design project known as Space Station Freedom, which was initiated under the Reagan administration (likely as a response to the Soviet - later Russian - Mir station). Following a series of budget cutbacks (and a trimmed-down redesign, jokingly known as "Space Station Fred"), the Freedom proposal was abandoned in favor of the ISS, a collaborative project between NASA, the Russian Space Agency, the Canadian Space Agency, the multinational European Space Agency, and the Japan Aerospace Exploration Agency. This orbital science research facility is commanded from mission control centers in Houston, U.S. (which typically has overall operational control); Moscow, Russia; Oberpfaffenhofen, Germany; and Tsukuba, Japan.
NASA's latest manned spaceflight project calls for the Shuttle to be retired some time around 2010 and replaced by the Orion spacecraft, a semi-reusable capsule similar to the Apollo spacecraft. New rockets are being developed, Ares I and V. The Orion spacecraft, together with the Altair lander, will be capable of manned lunar missions, near-Earth asteroid encounters, and potentially even interplanetary travel. The first test launch of the program, Ares I-X, took place on October 27, 2009.
In a development that has been controversial to say the least, the 2011 federal budget proposed by President Barack Obama on February 1, 2010 does not include any elements of Constellation, effectively canceling the program to develop the boosters and redefining the Orion capsule as a "Multi-Purpose Crew Module." In its place, the administration has proposed a stronger focus on education and research to develop "game-changing technologies" before continuing with a manned exploration agenda, with American access to the International Space Station delegated to an as-yet non-existent commercial spaceflight industry. This has garnered a mixture of both approval and criticism within NASA and within Congress (which has final authority over the budget) - some say that previous exploration goals were too ambitious for current technology, while others insist that if a clear-cut goal for exploration is defined, the required technology will be developed as it is needed (as it was during Apollo). Time will tell what the final outcome is.
Space Launch System To replace the Ares boosters as the primary launch vehicle for the Orion/Multi-Purpose Crew Module, NASA is currently working on a new booster called the Space Launch System. Reusing as much Space Shuttle hardware as possible, including the solid rocket boosters and a five-engine configuration of the RS-25 main engines used by the Space Shuttle, the SLS continues the Ares concept with all flight-tested hardware.
Lots of these, given that robotic probes are much better at traveling far and wide to explore the solar system, not needing any life support, fuel to accelerate astronauts and their support systems to reasonable speeds, more fuel to accelerate that fuel, protection from cosmic rays, landing craft that can take off from other planets/moons, methods of surviving on said other worlds, and usually, no need for return journeys. Also, no lives to be lost, of course. Since mindless robot explorers are not as glamorous or exciting to watch as astronauts, the probe fleet is obviously not as well known as, say, Apollo, but some of them have leaked into the public consciousness nonetheless.
- Mars Missions:
- A few of the early Mariner missions targeted Mars. (Mariner missions 4, 6 and 7 flew by; Mariner 9 orbited.)
- Mariner 9 was especially important because it disproved the idea that Mars was little more than a big moon, which had been cultivated by the barren, cratered landscapes imaged by the previous missions.
- Viking landed two big stationary probes on Mars in the mid-1970s. Looked for life signs, found nothing. Also had two orbiters which mapped the planet in more detail than the previous Mariner 9 mission, provided data on Martian weather, and looked at near-Martian conditions.
- After Viking, there weren't anymore successful Mars missions until the mid-1990s with Mars Global Surveyor, an orbiter (usually called MGS), and Pathfinder a lander with a small rover called Sojourner. These reawakened interest in Mars exploration, leading to the large number of more recent probes: the European Mars Express and American 2001 Mars Odyssey orbiters, the 2003 Mars Exploration Rovers (Spirit and Opportunity), and 2005 Mars Reconnaissance Orbiter.
- The Mars Exploration Rovers, Spirit and Opportunity deserve a Moment of Awesome. Initially designed to last a minimum of 90 days and not expected to survive that long, as of April 2010, they were both still running. Although Spirit is stuck in some sandy soil and is now classified as a "stationary observational point" instead of a rover. Unfortunately in May 2011, Spirit stopped working completely, but Opportunity is still chugging along just fine.
- There are currently plans to launch quite a few more probes to Mars, including sample return missions and more and bigger rovers, such as the nuclear-decay powered Mars Science Laboratory or "Curiosity" rover set to launch in 2011.
- The cheap spider-bots they're currently building (not to be sent up for another decade, probably) can dance.
- After the rovers, the Phoenix lander program occurred during 2008. Due to landing near the polar locations, Phoenix was not expected to last very long as the harsh Martian winter would end up destroying or damaging much of its exterior. Nevertheless, as with Spirit and Opportunity, it provided volumes of data on the red planet. On November 2, 2008, Phoenix made it's final message back to Earth, a single word in binary: Triumph.
- Not all of the Mars missions were successful. Two of the unmanned Mars probes — the Mars Climate Orbiter, and the Mars Polar Lander — have gone down in infamy as two of NASA's biggest failures. The Climate Orbiter burned up in the Martian atmosphere because the output from one piece of Earth-based software was in pound-seconds and the program that used it as input expected Newton-seconds. The Polar Lander crashed on landing because onboard software detected a jolt while extending its landing gear, interpreted this jolt incorrectly as the landing pads touching the ground, and shut off the engines.
- A few of the early Mariner missions targeted Mars. (Mariner missions 4, 6 and 7 flew by; Mariner 9 orbited.)
- Venus Missions: This was more the Soviets' thing, but the US did have a few notable Venus missions.
- Mariner 2 was the first successful interplanetary mission done by any human probe; it flew by Venus in 1962 and established that it was really really hot (about 450 degrees Celsius)
- The next Venus missions launched by NASA were the Pioneer-Venus probes in the late 1970s. There were two probes, one designed to go through the atmosphere and look at its composition, and another designed to orbit, relay telemetry from the landers, and make radar maps of the surface. The probes successfully mapped a large part of Venus' surface and gathered data about the atmosphere.
- The most recent American Venus mission was the Magellan probe, designed to map the entire surface of Venus using radar. Very successfully generated a high-res 3D map of almost the entire Cytherean (the proper adjective relating to the veiled planet) surface. Notable for being made on the cheap out of spare parts from Voyager, Galileo, Ulysses, and Mariner 9.
- The Outer Solar System: The outer solar system probes are generally fly-bys, with a few orbiters and one lander to date. Five of them (The Pioneers, the Voyagers and New Horizons) have achieved escaped velocity for the solar system and are headed out into interstellar space, where they'll roam for millions of years unless picked up by a faster spacecraft at some far future date. None, however, are headed for any nearby star and at the speeds at which they are traveling, they'd take tens of thousands of years to cover the distances to the stars anyway. As solar power drops off as the distance from the Sun increases, these probes rely on nuclear decay to power themselves.
- Pioneers 10 and 11 gave us our first close-up looks at Jupiter and Saturn. Since their trajectories will take them into interstellar space, both Pioneers carry a plaque containing some information about Earth, just in case. They were followed by...
- Voyagers 1 and 2, some of the most famous spacecraft of all time, launched in 1977, the farthest and fastest machines ever built by humanity to date. They explored Jupiter and Saturn in greater detail than the Pioneers, using gravitational slingshots to propel them from planet to planet on their tour of the outer solar system. Voyager 1's mission ended at Saturn, but Voyager 2 went on to study Uranus and Neptune (on a extended journey that took the entire decade of the 1980s). Like the Pioneers, they are headed out of the solar system, so they carry golden phonograph records designed by Carl Sagan carrying the sounds of Earth, including music and greetings in dozens of human languages and one whale language, with them out into the great void. In 1991, at Sagan's request, NASA had Voyager 1 turned its cameras back on the solar system to take a family portrait of the planets, including the iconic Pale Blue Dot, an image of its home world the Earth from almost 4 billion miles out. In 1999, Voyager 1 became the most distant object ever created by the human race, a lead it is currently continually increasing. As of 2011, the Voyagers are still sending back data, taking readings of the solar wind as it drops away behind them.
- Galileo, a dedicated Jupiter mission. Named for the famous Italian who got in trouble when he trained a telescope on Jupiter for the first time. Launched in 1989 and arrived at Jupiter in 1995 and successfully carried out an extensive survey of Jupiter and its moons despite it's main antenna not opening properly. Dropped a probe into Jupiter's atmosphere, found evidence for a liquid ocean underneath Europa and observed a lot of volcanoes on Io. Crashed into the upper atmosphere of Jupiter in 2003.
- Since 2004, the Cassini orbiter has been studying Saturn and its moons and rings. It deployed the European-built Huygens miniprobe, which landed on the surface of the mysterious moon Titan.
- The New Horizons probe, launched in 2006, will be the first to study dwarf planet Pluto and its moons, and potentially other nearby Kuiper Belt objects. The fifth spacecraft on a trajectory to leave the solar system, Horizons derives its velocity from a more powerful launch rocket and one gravitational assist from Jupiter.
- The Dawn mission, a probe propelled by ion engines, on a mission to dwarf planet Ceres and asteroid Vesta. The ion engines have lower thrust than normal rockets but are very efficient and can fire continuously for long durations to achieve an overall greater velocity. Dawn is a hybrid of a fly-by craft and an orbiter, as its ion engines permit to enter orbit, then exit and head to a different location.
- The Stardust-NExT mission, a comet-chasing probe that flew through the tail of comet Wild 2 and brought back samples to Earth before being sent on another mission to revisit and reanalyze comet Tempel 1, which had been hit by a kinetic slug several years earlier by another probe, Deep Impact.
- Solar Missions: Yes, NASA looks at The Sun, too.
- Ulysses: A joint project with the European Space Agency, intended to look at the Sun from all latitudes--Earth-based observation can't observe the solar poles all that well. Launched aboard Discovery in 1990 because the planned launch aboard Challenger in May 1986 was nixed by the loss of Challenger that January. The process needed to get into a polar orbit around the Sun was long and complicated--it involved flying by Jupiter so the probe could play with the giant planet's gravity--which is how it got its name (indeed, the original idea was to call it Odysseus until the Europeans insisted on the Latin term to reference Ulysses' appearance in the Inferno). Even after that, Ulysses' orbit was very wide--it never got closer to the Sun than the Earth does, and at its most distant it went to 5 AU (i.e. 5 times the distance from the Earth to the Sun).
The first "A" in NASA stands for Aeronautics, after all. Although NASA's manned space missions get most of the attention, and NASA's unmanned space missions get most of the attention not already garnered by the manned missions, NASA also engages in and/or encourages research into improving flight within Earth's atmosphere.
It was NASA's predecessor, NACA (National Advisory Committee for Aeronautics), for example, who contracted the development of the Bell X-1 rocket plane to purposely break the sound barrier. NASA also led the way with research into the Scramjet for the (now cancelled) National Aerospace Plane, and is looking into laminar airflow to allow supersonic aircraft to cruise more efficiently.
- This mission was originally going to be called "Apollo 3", because there had been two unmanned Apollo missions prior. The astronauts, however, unofficially claimed the "Apollo 1" name for their mission. After the fire, NASA officially granted them the "Apollo 1" name, bumping the two unmanned missions to 2 and 3.
- It was originally to be named Constitution in honor of the frigate launched in 1797