Why Send Humans to Mars? Looking Beyond Science

By Pabulo Henrique Rampelotto

In the last decade, the human exploration of Mars has been a topic of intense debate. Much of the focus of this debate lies on scientific reasons for sending, or not sending, humans to Mars. However, the more profound questions regarding why our natural and financial resources should be spent on such endeavor have not been addressed in a significant way. To be successful, the human exploration of Mars needs reasons beyond science to convince the public. People are far more interested in the short-term outcome of exploration than any nebulous long-term benefits. Finding the right balance of science and other factors is critical to convince taxpayers to part with $100 billion or more of their money over the next couple of decades to fund such endeavor. In the following, I briefly explain why the colonization of Mars will bring benefits for humans on Earth, looking beyond scientific reasons.

The engineering challenges necessary to accomplish the human exploration of Mars will stimulate the global industrial machine and the human mind to think innovatively and continue to operate on the edge of technological possibility. Numerous technological spin-offs will be generated during such a project, and it will require the reduction or elimination of boundaries to collaboration among the scientific community. Exploration will also foster the incredible ingenuity necessary to develop technologies required to accomplish something so vast in scope and complexity. The benefits from this endeavor are by nature unknown at this time, but evidence of the benefits from space ventures undertaken thus far point to drastic improvement to daily life and potential benefits to humanity as whole.

One example could come from the development of water recycling technologies designed to sustain a closed-loop life support system of several people for months or even years at a time (necessary if a human mission to Mars is attempted). This technology could then be applied to drought sufferers across the world or remote settlements that exist far from the safety net of mainstream society. The permanence of humans in a hostile environment like on Mars will require careful use of local resources. This necessity might stimulate the development of novel methods and technologies in energy extraction and usage that could benefit terrestrial exploitation and thus improve the management of and prolong the existence of resources on Earth.

The study of human physiology in the Martian environment will provide unique insights into whole-body physiology, and in areas as bone physiology, neurovestibular and cardiovascular function. These areas are important for understanding various terrestrial disease processes (e.g. osteoporosis, muscle atrophy, cardiac impairment, and balance and co-ordination defects). Moreover, medical studies in theMartian environment associated with researches in space medicine will providea stimulus for the development of innovative medical technology, much of which will be directly applicable to terrestrial medicine. In fact, several medical products already developed arespace spin-offs including surgically implantable heart pacemaker, implantable heart defibrillator, kidney dialysis machines, CATscans, radiation therapy for the treatment of cancer, among many others. Undoubtedly, all these space spin-offs significantly improved the human`s quality of life.

At the economical level, both the public and the private sector might be beneficiated with a manned mission to Mars, especially if they work in synergy. Recent studies indicate a large financial return to companies that have successfully commercialized NASA life sciences spin-off products. Thousands of spin-off products have resulted from the application of space-derived technology in fields as human resource development, environmental monitoring, natural resource management, public health, medicine and public safety, telecommunications, computers and information technology, industrial productivity and manufacturing technology and transportation. Besides, the space industry has already a significant contribution on the economy of some countries and with the advent of the human exploration of Mars, it will increase its impact on the economy of many nations. This will include positive impact on the economy of developing countries since it open new opportunities for investments.

To conclude, the human exploration oftthe red planet will significantly benefit all the humanity since it has the potential to improve human`s quality of life, provide economic returns to companies, stimulate the economy of many nations including developing countries and promote international collaboration.

Here is a series of ‘Analysis of Evidence of Life On Mars’…

Apollo 8: Christmas at The Moon

Christmas Eve, 1968. As one of the most turbulent, tragic years in American history drew to a close, millions around the world were watching and listening as the Apollo 8 astronauts — Frank Borman, Jim Lovell and Bill Anders– became the first humans to orbit another world. As their command module floatedabove the lunar surface, the astronauts beamed back images of the moon and Earth and took turns reading from the book of Genesis, closing with a wish for everyone “on the good Earth.” Borman recalled during 40th anniversary celebrations in 2008.

We were told that on Christmas Eve we would have the largest audience that had ever listened to a human voice.
The first ten verses of Genesis is the foundation of many of the world’s religions, not just the Christian religion. There are more people in other religions than the Christian religion around the world, and so this would be appropriate to that and so that’s how it came to pass.

The mission was also famous for the iconic “Earthrise” image, snapped by Anders, which would give humankind a new perspective on their home planet. Anders has said that despite all the training and preparation for an exploration of the moon, the astronauts ended up discovering Earth. The Apollo 8 astronauts got where they were that Christmas Eve because of a bold, improvisational call by NASA. With the clock ticking on President Kennedy’s challenge to land on the moon by decade’s end, delays with the lunar module were threatening to slow the Apollo program. So NASA decided to change mission plans and send the Apollo 8 crew all the way to the moon without a lunar module on the first manned flight of the massive Saturn V rocket.

The crew rocketed into orbit on December 21, and after circling the moon 10 times on Christmas Eve, it was time to come home. On Christmas morning, mission control waited anxiously for word that Apollo 8’s engine burn to leave lunar orbit had worked. They soon got confirmation when Lovell radioed, “Roger, please be informed there is a Santa Claus.”

The crew splashed down in the Pacific on December 27. A lunar landing was still months away, but for the first time ever, men from Earth had visited the moon and returned home safely.

[Image Details: Thirty-five years ago this Christmas, a turbulent world looked to the heavens for a unique view of our home planet. This photo of “Earthrise” over the lunar horizon was taken by the Apollo 8 crew in December 1968, showing Earth for the firsttime as it appears from deep space.

Astronauts Frank Borman, Jim Lovell and William Anders had become the first humans to leave Earth orbit, entering lunar orbit on Christmas Eve. In a historic live broadcast that night, the crew took turns reading from the Book of Genesis, closing with a holiday wish from Commander Borman: “We close with good night, good luck, a Merry Christmas, and God bless all of you — all of you on the good Earth.”]
Wishing happy holiday to all WeirdSciences Readers.
[Source: Nasa]
[Editor’s Note: The interruption in continuation of publishing article may be continued till 10 January.]

Fermi Telescope Finds Mysterious Giant Structure in Galaxy

It is really amazing to see it. Using data from NASA’s Fermi Gamma-ray Space Telescope, scientists have recently discovered a gigantic, mysterious structure in our galaxy. This feature looks like apair of bubbles extending above and below our galaxy’s center. Each lobe is 25,000 light-years tall and the whole structure may be only a few million years old.

[Image Details:From end to end, the newly discovered gamma-ray bubbles extend 50,000 light-years, or roughly half of the Milky Way’s diameter, as shown in this illustration. Hints of the bubbles’ edges were first observed in X-rays (blue) by ROSAT, a Germany-led mission operating in the 1990s. The gamma rays mapped by Fermi (magenta) extend much farther from the galaxy’s plane.Credit:NASA’s Goddard Space Flight Center]
NASA’s Fermi Gamma-ray Space Telescope has unveiled a previously unseen structure centered in the Milky Way. The feature spans 50,000 light-years and may be the remnant of an eruption from a supersized black hole at the center of our galaxy. Astronomer Doug Finkbeiner said:

What we see are two gamma-ray-emitting bubbles that extend 25,000 light-years north and south of the galactic center. We don’t fully understand the origin.

The structure spans more than half of the visible sky, from the constellation Virgo to the constellation Grus, and it may be millions of years old. Finkbeiner and his team discovered the bubbles by processing publicaly available data from Fermi’s Large Area Telescope (LAT). The LAT is the most sensitive and highest-resolution gamma-ray detector ever launched. Gamma rays are are the highest-energy form of light. Other astronomers studying gamma rays hadn’t detected the bubbles partly because of a fog of gamma rays that appears throughout the sky. The fog happens when particles moving near the speed of light interact with light and interstellar gas in the Milky Way. The LAT team constantly refines models to uncover new gamma-ray sources obscured by this so-called diffuse emission. By using various estimates of the fog, Finkbeiner and his colleagues were able to isolate it from the LAT data and unveil the giant bubbles. Scientists now are conducting more analyses to better understand how the never-before-seen structure was formed. The bubble emissions are much more energetic than the gamma-ray fog seen elsewhere in the Milky Way. The bubbles also appear to have well-defined edges. The structure’s shape and emissions suggest it was formed as a result of a large and relatively rapid energy release – the source of which remains a mystery. One possibility includes a particle jet from the supermassive black hole at the galactic center. In many other galaxies, astronomers see fast particle jets powered by matter falling toward a central black hole. While there is no evidence the Milky Way’s black hole has such a jet today, it may have in the past.

The bubbles also may have formed as a result of gas out flows from a burst of star formation, perhaps the one that produced many massive star clusters in the Milky Way’s center several million years ago. In other galaxies, we see that starbursts can drive enormous gas outflows. Whatever the energy source behind these huge bubbles may be, it is connected to many deep questions in astrophysics. Hints of the bubbles appear in earlier spacecraft data. X-ray observations from the German-led Roentgen Satellite suggested subtle evidence for bubble edges close to the galactic center, or in the same orientation as the Milky way. NASA’s Wilkinson Microwave Anisotropy Probe detected an excess of radio signals at the position of the gamma-ray bubbles. The Fermi LAT team also revealed Tuesday the instrument’s best picture of the gamma-ray sky, the result of two years of data collection. NASA scientist Julie McEnery said:

Fermi scans the entire sky every three hours, and as the mission continues and our exposure deepens, we see the extreme universe in progressively greater detail.

[Source: NASA]

EPOXI Mission Reveals New Insight about Hartley 2

NASA’s EPOXI mission spacecraft successfully flew past comet Hartley 2 at 7 a.m. PDT (10 a.m. EDT) Thursday, Nov. 4. Scientists say initial images from the flyby provide new information about the comet’s volume and material spewing from its surface.”Early observations of the comet show that, for the first time, we may be able to connect activity to individual features on the nucleus,” said EPOXI Principal Investigator Michael A’Hearn.
We certainly have our hands full. The images are full of great cometary data, and that’s what we hoped for. EPOXI is an extended mission that uses the already in-flight Deep Impact spacecraft. Its encounter phase with Hartley 2 began at 1 p.m. PDT (4 p.m. EDT) on Nov. 3, when the spacecraft began to point its two imagers at the comet’s nucleus. Imaging of the nucleus began one hour later. The spacecraft has provided the most extensive observations of a comet in history. Scientists and engineers have successfully squeezed world-class science from a re-purposed spacecraft at a fraction of the cost to taxpayers of a new science project.

[Image details:This image montage shows comet Hartley 2 as NASA’s EPOXI mission approached and flew under the comet. The images progress in time clockwise, starting at the top left. Image credit: NASA/JPL-Caltech/UMD]

Images from the EPOXI mission reveal comet Hartley 2 to have 100 times less volume than comet Tempel 1, the first target of Deep Impact. More revelations about Hartley 2 are expected as analysis continues. Initial estimates indicate the spacecraft was about 700 kilometers (435 miles) from the comet at the closest-approach point. That’s almost the exact distance that was calculated by engineers in advance of the flyby. Tim Larson, EPOXI project manager at NASA’s Jet Propulsion Laboratory in Pasadena, said:

It is a testament to our team’s skill that we nailed the flyby distance to a comet that likes to move around the sky so much. While it’s great to see the images coming down, there is still work to be done. We have another three weeks of imaging during our outbound journey.

Various Aspects of Exotic Propulsion Systems

Travelling into the dark is too hazardous especially if you wish to contact extraterrestrial civilization–even at a high relativistic speed, it would take almost 21 years to reach to the nearest earth like planet, Gliese 581 g. Various mechanisms have been proposed to make it possible within our short life times however, none of them are either feasible to accomplish the mammoth task of interstellar travel. Almost all of them have already been reviewed on WeirdSciences[select category ‘quantum physics/astrophysics’].

One means to produce force is collisions. Conventional rocket propulsion is fundamentally based on the collisions between the propellant and the rocket. These collisions thrust the rocket in one direction and the propellant in the other.To entertain the analogy of collision forces for a space drive, consider the supposition that space contains a background of some form of isotropic medium that is constantly impinging on allsides of a vehicle. This medium could be a collection of randomly moving particles or electromagnetic waves, either of which possess momentum. If the collisions on the front of a vehicle could be lessened and/or the collisions on the back enhanced, a net propulsive force would result. We know that dark matter and negative energy are ubiquitous in this universe. Quantum fluctuations are more optimistic approach to get a picture of future propulsion technologies. For any of these concepts to work, there must be a real background medium in space. This medium must have a sufficiently large energy or mass density, must exist equally and isotropically across all space, and there must be a controllable means to alter the collisions with this medium to propel the vehicle. A high energy or mass density is required to provide sufficient radiation pressure or reaction momentum within a reasonable sail area. The requirement that the medium exist equally and isotropically across all space is to ensure that the propulsion device will work anywhere and in any direction in space. The requirement that there must be a controllable means to alter the collisions ensures that a controllable propulsive effect can be created.

Critical Issues

The critical issues for both the sail and field drives have been compiled into the problem statement offered below. Simply put, a space drive requires some controllable and sustainable means to create asymmetric forces on the vehicle without expelling a reaction mass, and some means to satisfy conservation laws in the process. Regardless of which concept is explored, the following criteria must be satisfied.

(1) A mechanism must exist to interact with a property of space, matter, or energy which satisfies these conditions:
(a) must be able to induce an unidirectional acceleration of the vehicle.
(b) must be controllable.
(c) must be sustainable as the vehicle moves.
(d) must be effective enough to propel the vehicle.
(e) must satisfy conservation of momentum.
(f) must satisfy conservation of energy.

(2.1) If properties of matter or energy are used for the propulsive effect, this matter or energy…
(a) must have properties that enable conservation of momentum in the propulsive process.
(b) must exist in a form that can be controllably collected, carried, and positioned on the vehicle, or be controllably created on the vehicle.
(c) must exist in sufficiently high quantities to create a sufficient propulsive effect.

(2.2) If properties of space are used for the propulsive effect, these properties…
(a) must provide an equivalent reaction mass to conserve momentum.
(b) must be tangible; must be able to be detected and interacted with.
(c) must exist across all space and in all directions.
(d) must have a sufficiently high equivalent mass density within the span of the vehicle to be used as a propulsive reaction mass.
(e) must have characteristics that enable the propulsive effect to be sustained once the vehicle is in motion.
(3) The physics proposed for the propulsive mechanism and for the properties of space, matter, or energy used for the propulsive effect must be completely consistent with empirical observations.

Now it depend on us what kind of propulsion technology might be dispensable according to future needs.
[Ref: Challenge to Create the Space Drive by Millis M.]

Spirit Finds Evidence of Subsurface Water

The ground where NASA’s Mars Exploration Rover Spirit became stuck last year holds evidence that water, perhaps as snow melt, trickled into the subsurface fairly recently and on a continuing basis.Stratified soil layers with different compositions close to the surface led the rover science team to propose that thin films of water may have entered the ground from frost or snow. The seepage could have happened during cyclical climate changes in periods when Mars tilted farther on its axis. The water may have moved down into the sand, carrying soluble minerals deeper than less soluble ones. Spin-axis tilt varies over timescales of hundreds of thousands of years.

The relatively insoluble minerals near the surface include what is thought to be hematite, silica and gypsum. Ferric sulfates, which are more soluble, appear to have been dissolved and carried down by water. None of these minerals are exposed at the surface, which is covered by wind-blown sand and dust. The lack of exposures at the surface indicates the preferential dissolution of ferric sulfates must be a relatively recent and ongoing process since wind has been systematically stripping soil and altering landscapes in the region Spirit has been examining.

Analysis of these findings appears in a report in the Journal of Geophysical Research published by Arvidson and 36 co-authors about Spirit’s operations from late 2007 until just before the rover stopped communicating in March.The twin Mars rovers finished their three-month prime missions in April 2004, then kept exploring in bonus missions. One of Spirit’s six wheels quit working in 2006.In April 2009, Spirit’s left wheels broke through a crust at a site called “Troy” and churned into soft sand. A second wheel stopped working seven months later. Spirit could not obtain a position slanting its solar panels toward the sun for the winter, as it had for previous winters. Engineers anticipated it would enter a low-power, silent hibernation mode, and the rover stopped communicating March 22. Spring begins next month at Spirit’s site, and NASA is using the Deep Space Network and the Mars Odyssey orbiter to listen if the rover reawakens.

Researchers took advantage of Spirit’s months at Troy last year to examine in great detail soil layers the wheels had exposed, and also neighboring surfaces. Spirit made 13 inches of progress in its last 10 backward drives before energy levels fell too low for further driving in February. Those drives exposed a new area of soil for possible examination if Spirit does awaken and its robotic arm is still usable. With insufficient solar energy during the winter, Spirit goes into a deep-sleep hibernation mode where all rover systems are turned off, including the radio and survival heaters. All available solar array energy goes into charging the batteries and keeping the mission clock running. The rover is expected to have experienced temperatures colder than it has ever before, and it may not survive. If Spirit does get back to work, the top priority is a multi-month study that can be done without driving the rover. The study would measure the rotation of Mars through the Doppler signature of the stationary rover’s radio signal with enough precision to gain new information about the planet’s core. The rover Opportunity has been making steady progress toward a large crater, Endeavour, which is now approximately 8 kilometers (5 miles) away.

Spirit, Opportunity, and other NASA Mars missions have found evidence of wet Martian environments billions of years ago that were possibly favorable for life. The Phoenix Mars Lander in 2008 and observations by orbiters since 2002 have identified buried layers of water ice at high and middle latitudes and frozen water in polar ice caps. These newest Spirit findings contribute to an accumulating set of clues that Mars may still have small amounts of liquid water at some periods during ongoing climate cycles.

Human Mission to Mars: Brief Review on Infection Risks

Liquid water has almost certainly been a feature on Mars in its earlier history, and the presence of extinct or present life on Mars cannot be excluded. However, based on our current understanding of host-pathogen relationships and evolutionary processes, we may conclude that the chance of a human mission to Mars to encounter pathogenic microorganisms is small, albeit not zero. A set of safety measures to prevent, diagnose and eventually treat infections with Martian microorganisms should be considered. If the history of space exploration can be used as a lesson, the highest risk for such a mission will be catastrophic vehicle failure. However, visiting an alien planet will also come with a certain degree of biological risks, in terms of infection or contamination of either the astronauts, the technical crew on the ground, or even Earth ecosystems upon return of the mission.

The important question is here, before delving much into the topic, is whether life on mars is possible. Mars mapping by Mariner 9and by Viking 1 and 2 revealed channels resembling riverbeds,and information collected by the Mars Global Surveyor (MGS) strengthened the case for early surface water on Mars. Even more striking, data from Mars Exploration Rovers discovered round pebbles scattered on the surface of Meridiani Planum, suggesting that this region has once been submerged.

Studies on the Martian meteorite ALH84001 that reported the discovery of carbonate granules resembling microfossils, have been hailed as the first probable direct evidence of life outside Earth. Within the same meteorite, magnetite crystals with properties compatible with biogenic terrestrial magnetite have also been found. However, these reports remain controversial, as non-biological processes have also been proposed to explain the features found in ALH84001 meteorite, yet all such evidences boost the possibility of probable micro-life forms. The detection of methane and formaldehyde in Mars’s atmosphere could be another indication that microbes exist on Mars. Although the presence of methane could be a mere sign of geographical processes, it is well known that most of the methane in Earth’s atmosphere is produced by microbes. Thus, a straightforward aspect for martian life is that it would more likely be microscopic. Viruses are obligate intracellular organisms, needing a host to replicate and transmit genetic information, which make them additionally vulnerable to extreme environments.

How likely is that a Martian bacteria would be pathogenic for humans, or disruptive for an Earth ecosystem? The chance of a Martian microbe, adapted to extremely slow, cold and anaerobic conditions having the ability to attach to cells of a terrestrial host and invade its cells or tissues, and hence produce infection, in full competition with terrestrial microbes, is very small. Less likely is even transmission to a second ‘vulnerable’ host.

However, a pathogenic potential of Martian microbes cannot be excluded either. Even if they were not capable of directly invading the host and causing infection, Martian microbes could still have pathogenic potential by secreting toxins that could indirectly harm the astronauts (e.g. through wounds, contaminated food). Examples of powerful microbial toxins secreted by terrestrial microbes abound. Still, one has to recognize that the majority of such toxins of terrestrial bacteria are proteins, which in turn are recognized by specific cellular receptors, again requiring a history of previous interaction between the pathogenic agent and the host. Would such putative toxins of Martian microbes also be proteins, would they have similar biochemistry, would they even be made of the same aminoacids? Although it is possible that horizontal gene transfer may play an important role in injecting genes and genetic exchanges.

A different aspect of the biohazard potential of Martian microbes is the capacity of such microorganisms to disrupt Earth ecosystems, should contaminated material from a Mars mission reach the environment upon return. This risk is most likely also small, as environmental conditions such as temperature, humidity, chemistry, atmospheric pressure,and nutrients fundamentally differ between Earth and and Mars. From an evolutionary point of view, it is highly unlikely that a Martian microbe that in Earth terms would be characterized as an extremophile would be able to compete successfully with terrestrial microbes which are optimaly adapted to environment through millions of years evolution. Despite the low probability of pathogenic microorganisms as indicated above, it cannot be excluded that Mars harbors microscopic life, and the possibility that astronauts would come in contact with it necessitate precautionary measures to insure safety of the crew and Earth habitats upon return of the mission.
[Ref: Infection Risk of a Human Mission to Mars by Mihai G. Netea]

NASA Simulated the Power of Sun to Test Hardware Intended for Space

In the hostile environment of space, satellites could get burned by the ultra-hot sun in front of them and chilled by the frigid cold conditions of space behind them.Researchers at NASA’s Marshall Space Flight Centre are using their Solar Thermal Test Facility to simulate some of the harshest conditions space has to offer to learn what these extreme temperatures can do to flight hardware close to the sun. They’re currently testing Strofio, a unique NASA instrument that will fly aboard an upcoming European Space Agency mission, in this facility to test the thermal balance before the instrument is on its way to Mercury. The facility looks like it belongs in a galaxy far, far away. A two-story tall curved mirror — actually is made of 144 separate mirror segments, each hexagonally shaped and about 18 inches in diameter — forms the backbone of the facility. About 50 yards away, sitting in a field, lies another mirror tilted at a slight angle. This secondary mirror reflects the sun towards the primary mirror, which captures the energy and then focuses inside a small vacuum chamber mounted in front of the mirror’s focal point.

The giant wall of mirrors works by capturing the light from the sun and redirecting that energy to whatever happens to be sitting in the vacuum chamber. That superheats the instrument, allowing scientists to know how their hardware will behave as it nears the sun. Of course they can’t use all 144 mirror segments at once — that would beam 5000 watts worth of energy onto whatever happens to be inside the vacuum chamber. For the Strofio tests, engineers will only need to partially uncover about 26 mirror segments. They’ll reach temperatures hot enough to test their instrument, but not so high that they melt away their hard work. But that’s only half the equation. Thanks to the Southwest Research Institute, the NASA facility has installed a liquid nitrogen shroud on the inside of the vacuum chamber that will flow super-cold liquid nitrogen. That will allow engineers to chill the vacuum chamber to the freezing cold temperatures, just like those in deep space.In the front, the mirrors expose the instrument to the hotness of the sun. In the back, the nitrogen exposes it to the coldness of a vacuum. Together they accurately mimic the conditions of space, allowing scientists to test how their instrument will perform on its actual mission.

These tests prove vital for equipment like Stofio that are destined to travel close to the sun. Strofio will fly in polar orbit around Mercury where it will determine the chemical composition of Mercury’s surface using a technique called mass spectroscopy, providing a powerful new data to study the planet’s geological history. It will launch with the ESA’s Mercury Planetary Orbiter mission in 2014. When Strofio reaches its orbit around mercury, the sun will expose it to temperatures over 120 degrees Celsius or 248 Fahrenheit. That’s a stretch even for the relatively resilient NASA computers which historically only operate at around 24 degrees Celsius or 75 Fahrenheit. Engineers will have to continuously test Strofio to handle the tough Mercury conditions. For now, the Solar Thermal Test Facility’s team continues to test Strofio in preparation for its upcoming mission. Hopefully, they’ll continue to have the opportunity to bring the conditions of deep space to the Earth.

[Source: NASA]

Railgun: As Future Space Vehicle

While exotic propulsion technologies viz. traversable wormholes, kroniskov tubes,macroscopic casimir effects etc are quite pessimistic, railguns may still be paramount for future commercialization of space. As NASA studies possibilities for the next launcher to the stars, a team of engineers from Kennedy Space Center and several other field centers are looking for a system that turns a host of existing cutting-edge technologies into the next giant leap spaceward. An early proposal has emerged that calls for a wedge-shaped aircraft with scramjets to be launched horizontally on an electrified track or gas-powered sled. The aircraft would fly up to Mach 10, using the scramjets and wings to lift it to the upper reaches of the atmosphere where a small payload canister or capsule similar to a rocket’s second stage would fire off the back of the aircraft and into orbit. The aircraft would come back and land on a runway by the launch site. Engineers also contend the system, with its advanced technologies, will benefit the nation’s high-tech industry by perfecting technologies that would make more efficient commuter rail systems, better batteries for cars and trucks, andnumerous other spinoffs. It might read as the latest in a series of science fiction articles, but NASA’s Stan Starr, branch chief of the Applied Physics Laboratory at Kennedy, points out that nothing in the design calls for brand-new technology to be developed. However, the system counts on a number of existing technologies to be pushed forward. He said:

All of these are technology components that have already been developed or studied. We’re just proposing to mature these technologies to a useful level, well past the level they’ve already been taken.


[Image Details: Different technologies to push a spacecraft down a long rail have been tested in several settings, including this Magnetic Levitation (MagLev) System evaluated at NASA’s Marshall Space Flight Center. Engineers have a number of options to choose from as their designs progress. Photo credit: NASA]
For example, electric tracks catapult rollercoaster riders daily at theme parks. But those tracks call for speeds of a relatively modest 60 mph — enough to thrill riders, but not nearly fast enough to launch something into space. The launcher would need to reach at least 10 times that speed over the course of two miles in Starr’s proposal. The good news is that NASA and universities already have done significant research in the field, including small-scale tracks at NASA’s Marshall Space Flight Center in Huntsville, Ala., and at Kennedy. The Navy also has designed a similar catapult system for its aircraft carriers.As far as the aircraft that would launch on the rail, there already are real-world tests for designers to draw on. The X-43A,or Hyper-X program, and X-51 have shown that scramjets will work and can achieve remarkable speeds.
The Advanced Space Launch System is not meant to replace the space shuttle or other program in the near future, but could be adapted to carry astronauts after unmanned missions rack up successes. The studies and development program could also be used as a basis for a commercial launch program if a company decides to take advantage of the basic research NASA performs along the way. Starr said NASA’s fundamental research has long spurred aerospace industry advancement, a trend that the advanced space launch system could continue. For now, the team proposed a 10-year plan that would start with launching a drone like those the Air Force uses. More advanced models would follow until they are ready to build one that can launch a small satellite into orbit. A rail launcher study using gas propulsion already is under way, but the team is applying for funding under several areas, including NASA’s push for technology innovation, but the engineers know it may not cometo pass. The effort is worth it, however, since there is a chance at revolutionizing launches.
Remarks: The idea of railguns goes as back as science fiction itself. Railguns are excellent for short trips like say for near orbit programmes to space stations but if you are thinking to make them applicable at very large scale, it would probably not be possible economically since it would need very large electric power supply. However I find it very useful expecially in space transportation. A while back I received an email from a reader in which he proposed another equally as good idea which I’ll describe in detail in upcoming articles. Well why to choose railguns while we have ion drives?

[Source: NASA]

Ion Thruster Could be The Only Hope For Interstellar Travel

Ion thrusters, the propulsion of choice for science fiction writers have become the propulsion of choice for scientists and engineers at NASA. The ion propulsion system’s efficient use of fuel and electrical power enable modern spacecraft to travel farther, faster and cheaper than any other propulsion technology currently available. Chemical rockets have demonstrated fuel efficiencies up to 35 percent, but ion thrusters have demonstrated fuel efficiencies over 90 percent. Currently, ion thrusters are used to keep communication satellites in the proper position relative to Earth and for the main propulsion on deep space probes. Several thrusters can be used on a spacecraft, but they are often used just one at a time. Spacecraft powered by these thrusters can reach speeds up to 90,000 meters per second (over 200,000 mph). In comparison, the Space Shuttles can reach speeds around 18,000 mph.

The trade-off for the high top speeds of ion thrusters is low thrust (or low acceleration). Current ion thrusters can provide only 0.5 newtons (or 0.1 pounds) of thrust, which is equivalent to the force you would feel by holding 10 U.S. quarters in your hand. These thrusters must be used in a vacuum to operate at the available power levels, and they cannot be used to put spacecraft in space because large amounts of thrust are needed to escape Earth’s gravity and atmosphere.

[Image Details:Artist’s concept of Deep Space 1 probe with its ion thruster operating at full power. Credit: NASA ]

To compensate for low thrust, an ion thruster must be operated for a long time for the spacecraft to reach its top speed. Acceleration continues throughout the flight, however, so tiny, constant amounts of thrust over a long time add up to much shorter travel times and much less fuel used if the destination is far away. Deep Space 1 used less than 159 pounds of fuel in over 16,000 hours of thrusting. Since much less fuel must be carried into space, smaller, lower-cost launch vehicles can be used.

Propulsion

Sir Isaac Newton’s third Law states that every action has an equal and opposite reaction. This is like air escaping from the end of a balloon and propelling it forward. Conventional chemical rockets burn a fuel with an oxidizer to make a gas propellant. Large amounts of the gas push out at relatively low speeds to propel the spacecraft.
Modern ion thrusters use inert gases for propellant, so there is no risk of the explosions associated with chemical propulsion. The majority of thrusters use xenon, which is chemically inert, colorless, odorless, and tasteless. Other inert gases, such as krypton and argon, also can be used. Only relatively small amounts of ions are ejected, but they are traveling at very high speeds. For the Deep Space 1 probe, ions were shot out at 146,000 kilometers per hour (more than 88,000 mph).

Making Ions and Plasma

Ion thrusters eject ions instead of combustion gases to create thrust: the force applied to the spacecraft that makes it move forward. An ion is simply an atom or molecule that has an electrical charge because it has lost (positive ion) or gained (negative ion) an electron. With ion propulsion, the ions have lost electrons, so they are positively charged. A gas is considered to be ionized when some or all the atoms or molecules contained in it are converted into ions.

Plasma is an electrically neutral gas in which all positive and negative charges–from neutral atoms, negatively charged electrons and positively charged ions–add up to zero. Plasma exists everywhere in nature (for example, lightning and fluorescent light bulbs), and it is designated as the fourth state of matter (the others are solid, liquid and gas). It has some of the properties of a gas but is affected by electric and magnetic fields and is a good conductor of electricity. Plasma is the building block for all types of electric propulsion, where electric and/or magnetic fields are used to accelerate the electrically charged ions and electrons to provide thrust. In ion thrusters, plasma is made up of positive ions and an equal amount of electrons.

NASA’s conventional method of producing ions is called electron bombardment. The propellant is injected into the ionization chamber from the downstream end of the thruster and flows toward the upstream end. This injection method is preferred because it increases the time that the propellant remains in the chamber.

In such ion thrusters, electrons are generated by a hollow cathode, called the discharge cathode, located at the center of the thruster on the upstream end. The electrons flow out of the discharge cathode and are attracted (like hot socks pulled out of a dryer on a cold day) to the discharge chamber walls, which are charged highly positive by the thruster’s power supply.

Diagram showing discharge hollow cathode, anode, hollow cathode neutralizer, magnetic field, etc.

[Image Details: Ion thruster operation: Step 1–Electrons (shown as small, pale green spheres) are emitted by the discharge hollow cathode, traverse the discharge chamber, and are collected by the anode walls. Step 2–Propellant (shown in green) is injected from the plenum and travels toward the discharge cathode. Step 3–Electrons impact the propellant atoms to create ions (shown in blue). Step 4–Ions are pulled out of the discharge chamber by the ion optics. Step 5–Electrons are injected into the beam for neutralization. Credit: NASA]

When a high-energy electron (negative charge) from the discharge cathode hits, or bombards, a propellant atom (neutral charge), a second electron is released, yielding two negative electrons and one positively charged ion. High-strength magnets are placed along the discharge chamber walls so that as electrons approach the walls, they are redirected into the discharge chamber by the magnetic fields. Maximizing the length of time that electrons and propellant atoms remain in the discharge chamber, increases the chances that the atoms will be ionized.

NASA also is researching electron cyclotron resonance to create ions. This method uses high-frequency radiation (usually microwaves) coupled with a high magnetic field to add energy to the electrons in the propellant atoms. This causes the electrons to break free of the propellant atoms and create plasma. Ions can then be extracted from this plasma.

In a gridded ion thruster, ions are accelerated by electrostatic forces. The electric fields used for this acceleration are generated by two electrodes, called ion optics or grids, at the downstream end of the thruster. The greater the voltage difference between the two grids, the faster the positive ions move toward the negative charge. Each grid has thousands of coaxial apertures (or tiny holes). The two grids are spaced close together (but not touching), and the apertures are exactly aligned with each other. Each set of apertures (opposite holes) acts like a lens to electrically focus ions through the optics.

NASA’s ion thrusters use a two-electrode system, where the upstream electrode (called the screen grid) is charged highly positive, and the downstream electrode (called the accelerator grid) is charged highly negative. Since the ions are generated in a region that is highly positive and the accelerator grid’s potential is negative, the ions are attracted toward the accelerator grid and are focused out of the discharge chamber through the apertures, creating thousands of ion jets. The stream of all the ion jets together is called the ion beam. The thrust is the force that exists between the upstream ions and the accelerator grid. The exhaust velocity of the ions in the beam is based on the voltage applied to the optics. Whereas a chemical rocket’s top speed is limited by the heat-producing capability of the rocket nozzle, the ion thruster’s top speed is limited by the voltage that is applied to the ion optics, which is theoretically unlimited.

Because the ion thruster ejects a large amount of positive ions, an equal amount of negative charge must be ejected to keep the total charge of the exhaust beam neutral. Otherwise, the spacecraft itself would attract the ions. A second hollow cathode called the neutralizer is located on the downstream perimeter of the thruster and pushes out the needed electrons.

Electric Propulsion System

The ion propulsion system consists of five main parts: the power source, the power processing unit, the propellant management system, the control computer, and the ion thruster. The power source can be any source of electrical power, but solar or nuclear are usually used. A solar electric propulsion system (like that on Deep Space 1) uses sunlight and solar cells to generate power. A nuclear electric propulsion system (like that planned for the Jupiter Icy Moons Orbiter) uses a nuclear heat source coupled to an electric generator.

Photograph: HiPEP ion thruster being tested at 20 kilowatts.
[Image Details: HiPEP ion thruster being tested at 20 kilowatts in Glenn’s Vacuum Facility 6. For comparison, a household microwave operates at about 1 kilowatt. Credit: NASA]

The power processing unit converts the electrical power generated by the power source into the power required for each component of the ion thruster. It generates the voltages required by the ion optics and discharge chamber and the high currents required for the hollow cathodes. The propellant management system controls the propellant flow from the propellant tank to the thruster and hollow cathodes. It has been developed to the point that it no longer requires moving parts. The control computer controls and monitors system performance. The ion thruster then processes the propellant and power to propel the spacecraft. The first ion thrusters did not last very long, but the ion thruster on Deep Space 1 exceeded expectations and was used more than 16,000 hours during a period of over 2 years. The ion thrusters being developed now are being designed to operate for 7 to 10 years.

[Via: NASA]

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