Showing posts with label article. Show all posts
Showing posts with label article. Show all posts

Friday, July 31, 2009

Ares V

The Ares V is the cargo launching vehicle of the Constellation Program. It will replace the Space Shuttle when it is permanently phased out in 2010. At the beginning, the Ares V will launch the Earth Departure Stage and Altair lunar lander when NASA returns to the Moon, which is currently planned for 2019, but will also serve as the principle launcher for missions beyond the Earth-Moon system, including the program's ultimate goal, a manned mission to Mars after 2030. The unmanned Ares V will compliment the smaller, and man-rated Ares I rocket for the launching of the 3-4 person Orion spacecraft. Both rockets, deemed safer than the current Space Shuttle, will utilizing technologies developed for Project Apollo, the Shuttle, and the Delta IV EELV program.

The Ares V will be able to carry about 188 tonnes to Low Earth orbit, and 71 tonnes to the Moon. Upon completion the Ares V will be the most powerful rocket ever built, lifting more into orbit than even the American Saturn V, the failed Soviet N-1 for the cancelled Soviet Moonshot, and the successful Soviet/Russian Energia booster developed for the Buran Shuttle. The Ares V and the smaller Ares I are named after Ares, the Greek god of war, which is the equivalent to the Roman god Mars.

Thursday, July 30, 2009

Ares I

The Ares I is the crew launching vehicle which is presently being developed by NASA as part of Constellation Program. NASA is planning to use Ares I to launch Orion spacecraft, which is being designed by NASA for human spaceflight missions after the Space Shuttle is retired in 2010. Ares I was previously known as the Crew Launch Vehicle or CLV. Ares I will complement the larger, unmanned Ares V, which is the cargo launch vehicle for Constellation. NASA selected the Ares designs for their anticipated overall safety, reliability and cost-effectiveness. Ares I and V are named after the Greek deity Ares, who is identified with the Roman god Mars.

The Constellation Program includes two separate launching vehicles: the Ares I, for the crew; and the Ares V, for cargo. Having two separate launching vehicles will allow for more specialized designs for the different purposes the rockets will fulfill.

The Ares I rocket is specifically being designed to boost the Orion Crew spacecraft. Orion is intended as a crew capsule, similar in design to the Project Apollo capsule, to transport astronauts to the International Space Station, the Moon, and perhaps Mars. The first stage of the Ares I is a more powerful and reusable solid fuel rocket derived from the current Space Shuttle Solid Rocket Booster. This fifth segment will enable the Ares I to produce more thrust and burn longer. Other changes made to the solid rocket booster are the removal of the Space Shuttle External Tank attachment points and the replacement of the solid rocket booster nosecone with a new forward adapter that will interface with the liquid-fueled second stage. The adapter will be equipped with solid-fueled separation motors to facilitate the disconnection of the stages during ascent.

The upper stage is to be propelled by one J-2X rocket engine fueled by liquid hydrogen (LH2) and liquid oxygen (LOX). The J-2X is derived from the J-2 engine used on the Saturn IB and Saturn V rockets. On July 16, 2007, NASA awarded Rocketdyne a sole-source contract for the J-2X engines to be used for ground and flight tests. Although its J-2X engine is derived from an established design, the upper stage itself is wholly new. Originally based on the internal structure of the Shuttle's External Tank, the original design called for separate fuel and oxidizer tanks, separated by an "intertank" structure. Using a concept going back to the Apollo era, the "intertank" structure was dropped to decrease mass, and instead, a common bulkhead would be used between the tanks.

The upper stage of Ares I is to be built at the NASA Michoud Assembly Facility, the current location of the fabrication and construction of the Shuttle's External Tank, and the former construction site of the Saturn V's first stage, the S-IC.

Wednesday, July 29, 2009

Orion Spacecraft

Orion is a spacecraft design which is under development by NASA. Each Orion spacecraft will carry a crew of four to six astronauts. This new NASA spaceship will be launched by the Ares I, which is a launching booster also under development. Both Orion and Ares I are parts of NASA's Constellation Program, a space project to send human explorers to the Moon by 2020, and then onward to Mars and perhaps other destinations in the Solar System. On August 31, 2006, Lockheed Martin was granted the contract by NASA to design, develop, and build Orion.

Orion spacecraft will be launched from Launch Complex 39 at Kennedy Space Center, the same launch complex that currently launches the space shuttle. While shuttle operations continue from launch pad 39A, 39B is being readied for Ares launches. NASA will use Orion spacecraft for its human spaceflight missions after the last shuttle orbiter is retired in 2010. The first crewed Orion flight is anticipated in 2015. Subsequent flights will visit the International Space Station. If commercial orbital transportation services are unavailable, Orion will handle logistic flights to the Station. After that, Orion is to become a key component of human missions to the Moon and Mars.

On January 14, 2004, President George W. Bush announced the Orion spacecraft, known then as the Crew Exploration Vehicle, as part of the Vision for Space Exploration. The proposal to create the Orion spacecraft was partly a reaction to the Space Shuttle Columbia accident, the subsequent findings and report by the Columbia Accident Investigation Board (CAIB), and the White House's review of the American space program. The Orion spacecraft effectively replaced the conceptual Orbital Space Plane (OSP), which itself was proposed after the failure of the Lockheed Martin X-33 program to produce a replacement for the space shuttle.

The Crew and Service Module stack of the Orion spacecraft is composed of two main parts: a conical Crew Module, and a cylindrical Service Module that holds the spacecraft's propulsion system and expendable supplies. Both are based substantially on the Apollo Command and Service Modules (Apollo CSM) flown between 1967 and 1975, but include advances derived from the space shuttle program. "Going with known technology and known solutions lowers the risk," according to Neil Woodward, director of the integration office in the Exploration Systems Mission Directorate.






Orion Spacecraft



Constellation Program

The Constellation Program is a human spaceflight program planned by NASA. The stated goals of the program are gaining significant experience in operating away from Earth's environment, developing technologies needed for opening the space frontier and conducting fundamental science. Constellation was developed through the Exploration Systems Architecture Study, which determined how NASA would pursue the goals laid out in the Vision for Space Exploration and the NASA Authorization Act of 2005.

As part of the Constellation program, NASA plans to develop spacecraft and booster vehicles to replace the Space Shuttle and send astronauts to the Moon and possibly to Mars as well. Currently, NASA is in the process of designing two boosters, the Ares I and Ares V. Ares I will have the sole function of launching mission crews into orbit. Ares V will be designed to launch other hardware for use on missions and will have a heavier lift capacity than the Ares I booster. In addition to these two boosters, NASA is designing a set of other spacecraft for use during Constellation. These will include the Orion crew capsule, the Earth Departure Stage and the Altair lunar lander. Concerned by price increases on the program, U.S. President Obama has ordered a review of the project that will report by August 2009.

A full-scale mockup of NASA's Orion crew module is being tested in water under simulated and real landing weather conditions. Beginning March 23, a Navy-built, 18,000-pound Orion mockup will be placed in a test pool at the Naval Surface Warfare Center's Carderock Division in West Bethesda, Md. Ocean testing will begin April 6 off the coast of NASA's Kennedy Space Center in Florida.

The goal of the operation, dubbed the Post-landing Orion Recovery Test, or PORT, is to determine what kind of motions the astronaut crew can expect after landing, as well as conditions outside for the recovery team. The experience will help NASA design landing recovery operations including equipment, ship and crew necessities.

The Carderock facility provides a controlled environment for crew recovery personnel to familiarize themselves with the Orion capsule before the team tests procedures in the uncontrolled waters of the Atlantic Ocean.

For the ocean testing, the team will use a space shuttle solid rocket booster recovery ship to take the mockup out to sea, going further into rougher conditions each day. A media opportunity to view testing visible from shore will be scheduled for April 7 at Kennedy.

During the Orion mockup's transportation from Maryland to Florida, it will make stops for public viewing. Designated opportunities are March 30 in front of the Smithsonian National Air and Space Museum in Washington and April 3 at the Kennedy Space Center Visitor's Complex in Florida.

NASA's Constellation Program, which includes the Orion crew vehicle and the Ares I rocket that will launch it, is America's next-generation human spaceflight system that will carry astronauts to the International Space Station, back to the moon and to destinations beyond.

The Constellation Program's Operations and Test Integration Office at NASA's Johnson Space Center in Houston is leading the PORT effort. Development of Orion and associated Constellation Program elements is a joint effort involving every NASA center and partners across the country. Results of these tests will influence Orion vehicle design at Johnson and recovery hardware designs under evaluation at Kennedy.


NASA`s Constellation Program

Tuesday, July 28, 2009

New Fuel Source

Nuclear waste could be the new fuel source. There is a tantalizing amount of energy in all that nuclear waste that was slated to sit in Yucca Mountain for eons. Now that it won't be sitting there, some think it should be used. All of the electricity used by a typical American in a year can be generated by just three inches of one of the 14-foot rods of uranium dioxide used to power nuclear reactors. Yet when that rod, which has the diameter of a Bic pen, is "spent" and set aside as nuclear waste, less than 10% of the energy in the rod has been turned into electricity.

"Waste is just too gross of a term for it," says Sherrell Greene, director of Nuclear Technology at Oak Ridge National Laboratory. "I'm trying to get to the 90% of the fuel in that rod."

It's a difficult thing to do, but these days there's much more incentive to try. This spring the Obama administration effectively ended the long-tortured idea of storing the nation's spent nuclear fuel deep under Yucca Mountain in south-central Nevada. At the same time, the nation seems to be inching toward adding new nuclear reactors, creating more waste that we don't know what to do with. (When Yucca Mountain was conceived, it was assumed that the nuclear reactors in the United States would be shut down as they aged and not replaced.)

There is already a method used by countries like France and Japan to reprocess spent nuclear fuel. It has a long list of nasty problems associated with it, however. It's very expensive--the cost of uranium would have to jump by a factor of six to match the price of reprocessed fuel. Though reprocessing nuclear fuel shrinks the amount of waste, it doesn't eliminate it. And, worst of all, it results in the creation of plutonium, which could be used to make nuclear weapons.

For all of these reasons, the U.S., which invented the process as part of its nuclear weapons program in the 1940s and 1950s then pushed it as a recycling method up until the early 1970s, never built a reprocessing plant and has strongly discouraged other nations from doing so.

But the politics of reprocessing have been heating up. Pro-nuclear energy Sens. John McCain, R-Ariz., and Lamar Alexander, R-Tenn., pushed Energy Secretary Steven Chu on the issue in the spring. McCain and others suggest one big reason new nuclear reactors are not being built is the uncertainty around where the spent fuel is going to go.

In June, the House Science and Technology Committee held a hearing asking experts for suggestions about how reprocessing should be approached. Mark Peters, of Argonne National Laboratory, said that because the U.S. never invested in a big, current-generation reprocessing plant, the country has the opportunity to instead design and build a safer system.

The hope is that researchers can develop a method that extracts the usable portion of the spent fuel without isolating the plutonium. Left behind would be very poisonous nuclear waste, but waste that would degrade in tens of years instead of tens of thousands of years, making the need for very long-term storage less acute.

(When nuclear waste includes extremely radioactive elements, it is said to be "self-protecting"--the gamma rays that it emits would cook a person so fast that it's all but impossible to do something nefarious with it. Plutonium on its own, while very dangerous if inhaled, emits comparatively weak alpha radiation, which can be easily shielded.)

At Oak Ridge, Greene's team last year demonstrated a method by which it removed the uranium and the plutonium together. The team processed just 45 pounds of material, and Greene admits that they are far from proving it can be done on an industrial scale. "But it is now an established fact that we know a new set of processes to produce a new fuel without having to produce plutonium," he says. "It may very well be that it doesn't end up being the best method, but if there is one set of processes to do it, there are others. I'm confident we can find a way to do this."

Argonne National Laboratory has developed a method called pyroprocessing that uses molten salt to separate the materials instead of a water-based approach, like the methods used abroad and at Oak Ridge. Some so-called Generation IV nuclear reactors being researched eliminate the need for reprocessing or include pyroprocessing. And some suggest using nuclear fission to help transform nuclear waste into fuel. (See "Reinventing Nuclear Power.")

Many, though, are adamantly opposed to reprocessing. They argue that though some methods, new and old, do reduce the volume of waste, they actually complicate waste disposal by creating different types of radioactive waste. They also remain extraordinarily expensive. And while methods like the one being explored at Oak Ridge do protect the plutonium slightly, it's not nearly enough to eliminate the threat of proliferation.

"It's an oxymoron to talk about proliferation-resistant reprocessing," says Frank von Hippel, a physicist and professor of public and international affairs at Princeton University's Woodrow Wilson School. "Nobody has a good idea at the moment."

Another critic: John Holdren, Obama's science adviser, who argued against nuclear reprocessing in a 2003 paper.

In the meantime, nuclear waste in the U.S. is being stored at nuclear plants. The spent rods are cooled in pools of water for at least a year and then transferred to thick casks of steel and concrete.

No one seems to think this method is ideal, but both proponents and opponents of reprocessing agree that the method is acceptable for the next few decades. Which may give us time to either come up with better reactors or better reprocessing technologies.

"The vision in this country is that as long as we have nukes, we have an assumption that there will always be nuclear waste so we should learn to deal with it," says Oak Ridge's Greene. "Well, maybe there are other nuclear fuel cycles and reactors and processes that can minimize creation of problem."

(Source: www.forbes.com )

Sunday, August 31, 2008

A Natural Phenomenon

A natural phenomenon is an observable fact or event that occurs naturally, without human intervention, in the earth's environment, or in outer space, following the laws of physics or chemistry. Some natural phenomena are harmless, but there are those that could be extremely dangerous for humans and animals as they greatly affect man's environment. Wind, rain, tornadoes, lightning, volcanic eruptions, earthquakes, etc. are natural phenomena.

Phenomenon (singular), phenomena (plural).