NASA

NASA Headquarters, in Washington, provides overall guidance and direction to the agency, under the leadership of Administrator Michael Griffin. Ten field centers and a variety of installations conduct the day-to-day work, in laboratories, on air fields, in wind tunnels and in control rooms.

NASA's mission is to pioneer the future in space exploration, scientific discovery and aeronautics research. Since its founding on October 1, 1958, NASA has pushed the boundaries of human exploration. We've put footprints on the moon and tire tracks on Mars. We've given the world breathtaking images of our home planet, our solar system and the galaxies beyond. We invented the first re-usable spacecraft and, with our international partners, established a permanent human presence in space. Along the way, we've pioneered new technologies that have improved people's lives. Now, we're blazing a new trail into the cosmos. Before the end of the next decade, NASA astronauts will again explore the surface of the moon, traveling in a new spaceship that builds on the best of Apollo and shuttle technology. And this time, we're going to stay, building outposts and paving the way for eventual journeys to Mars and beyond. To do that, thousands of people have been working around the world -- and off of it -- for almost 50 years, trying to answer some basic questions. What's out there in space? How do we get there? What will we find? What can we learn there, or learn just by trying to get there, that will make life better here on Earth?

A
Little History

President Dwight D. Eisenhower established the National Aeronautics and Space Administration in 1958, partially in response to the Soviet Union's launch of the first artificial satellite the previous year. NASA grew out of the National Advisory Committee on Aeronautics (NACA), which had been researching flight technology for more than 40 years.
President John F. Kennedy focused NASA and the nation on sending astronauts to the moon by the end of the 1960s. Through the Mercury and Gemini projects, NASA developed the technology and skills it needed for the journey. On July 20, 1969, Neil Armstrong and Buzz Aldrin became the first of 12 men to walk on the moon, meeting Kennedy's challenge. Meanwhile, NASA was continuing the aeronautics research pioneered by NACA. It also conducted purely scientific research and worked on developing applications for space technology, combining both pursuits in developing the first weather and communications satellites.

After Apollo, NASA focused on creating a reusable ship to provide regular access to space: the space shuttle. First launched in 1981, the space shuttle has had 120 successful flights. In 2000, the
United States and Russia established permanent human presence in space aboard the International Space Station, a multinational project representing the work of 16 nations. NASA also has continued its scientific research. In 1997, Mars Pathfinder became the first in a fleet of spacecraft that will explore Mars in the next decade, as we try to determine if life ever existed there. The Terra and Aqua satellites are flagships of a different fleet, this one in Earth orbit, designed to help us understand how our home world is changing. NASA's aeronautics teams are focused on improved aircraft travel that is safer and cleaner. Throughout its history, NASA has conducted or funded research that has led to numerous improvements to life here on Earth.

NASA Today

NASA conducts its work in four principle organizations, called mission directorates:

* Aeronautics: pioneers and proves new flight technologies that improve our ability to explore and which have practical applications on Earth

* Exploration Systems: creates new capabilities and spacecraft for affordable, sustainable human and robotic exploration.

* Science: explores the Earth, moon, Mars and beyond; charts the best route of discovery; and reaps the benefits of Earth and space exploration for society.

* Space Operations: provides critical enabling technologies for much of the rest of NASA through the space shuttle, the International Space Station and flight support.

In the early 21st century, NASA's reach spans the universe. Spirit and Opportunity, the Mars Exploration Rovers, are still studying Mars after more than three years. Cassini is in orbit around Saturn. The Hubble Space Telescope continues to explore the deepest reaches of the cosmos

Closer to home, the latest crew of the International Space Station is extending the permanent human presence in space. Earth Science satellites are sending back unprecedented data on Earth's oceans, climate and other features. NASA's aeronautics team is working with other government organizations, universities, and industry to fundamentally improve the air transportation experience and retain our nation's leadership in global aviation.

The Future

In the next 20 years, NASA will be laying the groundwork for sending humans not only beyond Earth's orbit, but further into to space than they've ever been. The next key steps are:

* Complete the International Space Station and retire the Space Shuttle by 2010

* Begin robotic missions to the moon by 2008 and return people there by 2020

* Continue robotic exploration of Mars and the Solar System

* Develop a crew exploration vehicle and other technologies required to send people beyond low Earth orbit

Though nearly 50 years old, NASA is only beginning the most exciting part of its existence.

SPACE CRAFT

A spacecraft is a craft or machine designed for spaceflight. On a spaceflight, a spacecraft enters space then returns to the Earth. For an orbital spaceflight, a spacecraft enters a closed orbit around the planetary body. Spacecraft used for human spaceflights carry people on board as crew or passengers. Spacecraft used for robotic space missions operate either autonomously or electromagnetically. Robotic spacecraft that leave the vicinity of the planetary body are space probes. Robotic spacecraft that remain in orbit around the planetary body are artificial satellites. Starships, which are built for interstellar travel, are so far a theoretical concept only. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and space tourism. Spacecraft and space travel are common themes in works of spacecraft subsystems A spacecraft system comprises various subsystems, dependent upon mission profile. Spacecraft subsystems may include: attitude determination and control (variously called AD AC, ADC or SACS), guidance, navigation and control (ENC or GEN&C), communications (CORMS), command and data handling (CH or C&DH), power (ESP), thermal control (TICS), propulsion, structures, and payload. Spacecraft intended for human spaceflight must also include a life support system for the crew. This can include many different types of Oxygen Systems, such as the one seen in the movie Apollo 13 that exploded and almost cost the crew their lives.

Spacecraft could do with an attitude control subsystem to be correctly oriented in space and respond to external torques and forces properly. The attitude control subsystem consists of sensors and actuators, together with controlling algorithms. The attitude control subsystem permits proper pointing meant for the science objective, sun pointing for supremacy to the cosmological arrays furthermore earth-pointing for communications. Guidance refers to the calculation of the commands (usually done by the CH subsystem) needed to steer the spacecraft where it is desired to be. Navigation means determining a spacecraft's orbital elements or position. Control means adjusting the path of the spacecraft to get together mission requirements. On some missions, ENC and Attitude Control are combined interested in individual subsystem of the spacecraft.

The CH subsystem receives commands from the communications subsystem, performs validation and decoding of the commands, and distributes the commands to the appropriate spacecraft subsystems and components. The CH also receives housekeeping data and science data from the other spacecraft subsystems and components, and packages the data for storage on a solid state recorder or transmission to the ground passing through the communications subsystem. Other functions of the CH include maintaining the spacecraft clock in addition to state-of-health monitoring.

Spacecraft need an electrical power generation and distribution subsystem for powering the various spacecraft subsystems. For spacecraft near the Sun, solar panels are frequently used to generate electrical power. Spacecraft designed to operate in more distant locations, for example Jupiter, might employ a Radioisotope Thermoelectric Generator (RT) to generate electrical power. Electrical power is sent through power conditioning equipment before it passes through a power distribution unit over an electrical bus to other spacecraft components. Batteries are typically connected to the bus via a battery charge regulator, and the batteries are used to provide electrical power during periods when primary power is not available, for example when a Low Earth Orbit (LEO) spacecraft is eclipsed by the Earth.

Thermal control

Spacecraft must be engineered to withstand transit through the Earth's atmosphere and the space environment. They must operate in a vacuum with temperatures potentially ranging across hundreds of degrees Celsius as well as (if subject to reentry) in the presence of plasmas. Material requirements are such that either high melting temperature, low density materials such as be and C-C or (possibly due to the lower thickness requirements despite its high density) W or ablative C-C composites are used. Depending on mission profile, spacecraft may also need to operate on the surface of another planetary body. The thermal control subsystem can be passive, dependent on the selection of materials with specific radiative properties. Active thermal control makes use of electrical heaters and certain actuators such as louvers to control temperature ranges of equipments within specific ranges. Science fiction.

STARSHIP

Is a theoretical spacecraft designed for traveling between the stars, as opposed to a vehicle designed for orbital spaceflight or interplanetary travel. The term is mostly found in science fiction, as humanity has not yet constructed such vehicles (while the Voyager and Pioneer probes have traveled into local interstellar space, they are not generally considered starships, mainly because they are both empowered and unmanned). However, exploratory engineering has been undertaken on several preliminary designs and feasibility studies for starships that could be built with modern technology or technology thought to be available in the near future. For examples of such studies, see Project Daedal us, Project Orion, and Project Long shot.

A common literary device is to posit a faster-than-light propulsion system (such as warp drive) or travel through hyperspace, although some starships may be outfitted for centuries-long journeys of slower-than-light travel. Other designs posit a way to boost the ship to near-light speed, allowing relatively "quick" travel (i.e. decades, not centuries) to nearer stars. This results in a general categorization of the kinds of starships: Sleeper ships, which put their passengers into stasis during a long trip. Eneration ships, where the destination will be reached by descendants of the original passengers. Relativistic ships, taking advantage of time dilation at close-to-light-speeds, so long trips will seem much shorter (but still take the same amount of time for outside observers). Faster-than-light ships, which can move between places very quickly (transcending current understanding of physics or using interdimensional 'shortcuts'). Fiction that discusses slower-than-light starships is relatively rare, since the time scales are so long. Instead of describing the interaction with the outside world, those fictions tend to focus on setting the whole story within the world of the (often very large) starship during its long travels. Sometimes the starship is a world, in perception or reality.

Faster-than-light

Travel at velocities greater than the speed of light is impossible according to the known laws of physics, although apparent FTL is not excluded by general relativity. Science fiction has, however, provided many examples Such starships are typically large, multi-passenger vehicles (compared to star fighters). They range. in size from small personal yachts and courier ships, up to vast bulk containers (used for intersystem shipping) and enormous warships Starships are usually depicted as operating under laws and guidelines similar to real-world seagoing vessels. The primary reason for this concept (beyond artistic license) is that deep space is an even more hazardous environment than the open sea, and so extreme caution would have to be taken in all starship operations. A side effect of this is that space going fleets, especially space militaries, are usually described as being organized similar to modern Earth navies.

A starship may be fitted with a wide variety of engines, weapons, equipment, and internal compartments. Small freighters used for smuggling are typically fast, modified to avoid detection, are often heavily armed, and may have secret holds for hiding contraband cargo. Large container ships usually have little in the way of or weaponry, but have huge, powerful engines necessary for moving vast quantities of cargo through (or between) star systems. Passenger vessels, are often described as being similar to modern ocean liners, containing luxurious passenger cabins, gambling halls, showrooms, restaurants, and lounges. Warships contain crew quarters, extensive weaponry and shielding, massive engines, sophisticated sensor and communications arrays, and usually a detachment of non-naval Marine-like soldiers trained in assaulting and capturing enemy spacecraft, targets on planetary surfaces, or both.

Exceptions

Exceedingly large space going craft (for example the Death Star of the Star Wars universe) are typically not referred to as 'starships' (but see 'slower-than-light ships' above). Terms like may be considered to be more accurate. Space stations and other structures intended to orbit a celestial body or serve as a point of contact/maintenance/docking station for other ships are not usually called starships, even if they can move under their own power.

WHAT IS SPACE?

Space is a boundless, three-dimensional extent in which objects and events occur and have relative position and direction. Physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of the boundless four-dimensional field known as space-time. In mathematics spaces with different numbers of dimensions and with different underlying structures can be examined. The concept of space is measured to be of fundamental importance to an understanding of the universe although disagreement continues between philosopher over whether it is itself an entity, a relationship between entities, or part of a conceptual structure.

Many of the philosophical questions arose in the 17th century, during the early development of classical mechanics. In Isaac Newton's view, space was unconditional - in the sense that it existed permanently and independently of whether there were any matter in the space. Other natural philosophers, notably Gottfried Leibniz, thought instead that space was a collection of relationships between objects, given by their distance and direction from one another. In the 18th century, Immanuel Kant described space and time as elements of a systematic framework which humans use to structure their experience. In the 19th and 20th centuries mathematicians began to examine non-Euclidean geometries, in which space can be said to be curved, rather than flat. According to Albert Einstein's theory of general relativity, space around gravitational fields deviates from Euclidean space. Experimental tests of general relativity have established that non-Euclidean space provides a better model for explaining the existing laws of mechanics and optics.

Outer space comprises the relatively unfilled regions of the universe outside the atmospheres of celestial bodies. Outer space is used to distinguish it from airspace and terrestrial locations. There is no apparent boundary between Earth's atmosphere and space as the density of the atmosphere gradually decreases as the altitude increases. Nevertheless, the Federation Aéronautique International has established the Kerman line at an altitude of 100 kilometers (62 mi)) as a working classification for the boundary between aeronautics and astronautics. This is used because above an altitude of roughly 100 kilometers (62 mi), as Theodore von Kerman calculated, a vehicle would have to travel faster than orbital velocity in order to derive sufficient aerodynamic lift from the environment to support itself. The United States designates people who travel above an altitude of 50 miles (80 km)) as astronauts. During re-entry, roughly 120 kilometers (75 mi) marks the boundary where atmospheric drag becomes noticeable, depending on the ballistic coefficient of the vehicle.

Contrary to popular sympathetic, outer space is not completely empty (i.e. a perfect vacuum,) but contains a low density of particles, principally hydrogen plasma, as well as electromagnetic radiation. Supposedly, it also contains dark matter and dark energy.

The term outer space was first recorded by H. G. Wells in his novel First Men in the Moon in 1901. The shorter term space is actually older, first used to mean the region beyond Earth's sky in John Milton's Paradise Lost in 1667.