Sunday, 21 October 2007

Integral's 5 year journey

Integral was launched on 17 October 2002. Since then, the satellite has helped scientists make great strides in understanding the gamma-ray universe - from the atoms that make up all matter, giant black holes, mysterious gamma-ray bursts to the densest objects in the universe.

Surveying the entire galaxy looking for the radioactive isotope aluminium 26 with Integral, scientists have been able to calculate that a supernova goes off in our galaxy, once every 50 years.

According to Integral, something is creating a lot of gamma rays at the centre of our galaxy - the suspect is positrons, the antimatter counterparts of electrons. Scientists have been baffled as to how vast numbers of such particles can be generated every second and how these sources would be distributed over the sky to match the gamma-ray map.

Within months of operation, Integral solved a thirty-year-old mystery by showing that the broadband gamma-ray emission observed towards the centre of the galaxy was produced by a hundred individual sources. A catalogue of close to 500 gamma-ray sources from all over the sky, most of them new, was then complied.

Scientists now know that a rare class of anomalous X-ray pulsars, or magnetars, generates magnetic fields a thousand million times stronger than the strongest steady magnetic field achievable in a laboratory on Earth. These sources show, unexpectedly, strong emission in the Integral energy range.

Integral revealed that a sub-class of X-ray binary stars, called super-giant fast X-ray transients, previously thought to be extremely rare, is actually common in our galaxy. The satellite has also discovered a completely new class of high-mass X-ray binaries, called highly absorbed X-ray binaries.

Integral has seen about 100 of the brightest supermassive black holes, the main producers of gamma radiation in our universe, in other galaxies. But while looking for them in nearby galaxies, surprisingly few have been found.

They are either too well-hidden or are only present in the younger galaxies which populate the more distant universe.

Galaxies throughout the universe are believed to be responsible for creating the diffuse background glow of gamma rays, observed over the entire sky. Integral used the Earth as a giant shield to disentangle this faint glow. Making the measurements possible was a technological and operational feat.

On 27 December 2004 Integral was hit by the strongest flux of gamma rays ever measured by any spacecraft and it even measured radiation that bounced off the Moon. The culprit was a magnetar, SGR 1806-20, located 50 000 light years away on the other side of our Milky Way. Thanks to this outburst, astronomers now think that some gamma-ray bursts might come from similar magnetars in other galaxies.

Integral has also been able to take images of gamma ray bursts, while the telescope was not pointed in the right direction. This was done using radiation that passed through the side of Integral’s imaging telescope and struck the detector.

Integral has indeed played a major role in modern gamma-ray astronomy. So much has happened in the span of five years but much more is still to come.

Source: Christoph Winkler, ESA Integral Project Scientist
The Genesis Probe - Clues to the Origins of the Solar System @ The Daily Galaxy

Tuesday, 16 October 2007

Future Space Ships

The risks from radiation in space, and the need to keep the crew safe on long flights, may influence the shape of future spaceships.

The major radiation sources are galactic cosmic rays, charged particles: from electrons up to the heavy metal elements and 'solar particle events', which throw out protons and helium nuclei.

Exposure from the hazards of severe space radiation in long-duration deep space missions is 'the show stopper'. Protection from the hazards of severe space radiation is of paramount importance to NASA's new vision to reach the Moon, Mars and beyond.

The electrons, protons & heavy-metal ions such as iron and uranium whiz through the void and can all cause cancers. But aluminium shielding capable of staving the radiation off on extended journeys would be prohibitively heavy, burning too much fuel.

The ideal form, according to Ram Tripathi, a spaceflight engineer at NASA, is a grapefruit spiked with cherries on sticks. Positively and negatively charged metal spheres be arranged on struts jutting out of the crew capsule, in carefully controlled directions, to give the crew a high degree of electrostatic radiation cover.

Tripathi calculates the "cherries" would need to be between 10 and 20 metres in diameter and would be stationed about 50 metres from the crew capsule – the "grapefruit". These spheres would protect the crew by deflecting charged particles away from the central habitat. Spheres give you more volume and less mass, and evenly distribute the deflecting charges over their surface.

The spheres would be made of lightweight hollow aluminium, the material shielding the crew capsule would incorporate carbon nanotubes – in a novel composite with aluminium. The nanotubes are light, and they can take a pounding from heavy incoming ions.

Or we could have spaceships with a more conventional shape like a submarine, the starship enterprise, the space shuttle or nerva, with a false skin filled with smaller spheres (or even tubes) having the same desired effect, deflecting radiation and adding volume, without overwhelmingly increasing the mass.

Laser power stations, drawing energy from the local environment, might one day propel spacecraft throughout the solar system. NASA studies of advanced planetary missions have ranged from small robotic probes to multiple-spacecraft human exploration missions.

The completed International Space Station will have a mass of about 1,040,000 pounds. It will measure 356 feet across and 290 feet in length, with almost an acre of solar panels to provide electrical power to six laboratories.

The assembled space station will provide the first lab complex where gravity, a fundamental force on Earth, can be controlled for extended periods. This control of gravity opens up an unimaginable world where almost everything grows differently than on Earth. For example, purer protein crystals can be grown in space than on Earth. By analyzing crystals grown on the ISS, scientists may be able to develop medicines that target particular disease-causing proteins.

Such crystals for research into cancer, diabetes, emphysema and immune disorders grown on the space station have already shown promise. New drugs to fight influenza and post-surgery inflammation are already in clinical trials, and future research will benefit from the extended exposure to weightlessness available on the station.

Many of the changes in the human body that result from space flight mimic those seen on Earth as a result of aging. Understanding of the causes of these changes may lead to the development of countermeasures against bone loss, muscle atrophy, balance disorders and other symptoms common in an aging population.

The Johnson Space Centre, together with scientists and researchers at NASA's other field centers, is working on the technologies that will be required for further exploration of the universe in the next years. For example, a new rocket team at Marshall is developing revolutionary technologies that will make space transportation as safe, reliable and affordable as today's airline transportation.

Hospitals, business parks and solar electric power stations that beam clean, inexpensive energy back to Earth are likely to dot the "space-scape" 40 years from now. Space adventure tourism and travel, orbiting movie studios, and worldwide, two-hour express package delivery also appear just over the horizon.

By 2040, it's expected to cost only tens of dollars per pound to launch humans or cargo to space; today, it costs as much as $10,000 per pound. Bridging that gap requires intense research and technology development focused on accelerating breakthroughs that will serve as keys to open the space frontier for business and pleasure.

Space transportation technology breakthroughs will launch a new age of space exploration, just as the silicon chip revolutionized the computer industry and made desktop computers commonplace.
The New Space Race by Brian Appleyard @ The Sunday Times
The Johnson Space Centre Celebrates 40 Years of Human Space Flight

Tuesday, 9 October 2007

Nuclear Space Travel

Image Credit: Project Orion

Compared with the best chemical rockets, nuclear propulsion systems (NPS's) are more reliable and flexible for long-distance missions, and can achieve a desired space mission at a lower cost. The reason for these advantages in a nutshell is that NPS's can get "more miles per gallon" than a chemical rockets.

For any space mission, basic questions must be answered:

1 - What is the destination?
2 - What is the trip time?
3 - Do we want to return?
4 - the mass of the payload we want to send there & bring back?

In chemical rocket engines such as the Space Shuttle Main Engine (SSME), the chemical reaction between the hydrogen and oxygen releases heat which raises the combustion gases (steam and excess hydrogen gas) up to high temperatures (3000-4000 K). These hot gases are then accelerated through a thermodynamic nozzle, which converts thermal energy into kinetic energy, and hence provides thrust. The propellant and the heat source are one in the same.

Because there is a limited energy release in chemical reactions and because a thermodynamic nozzle is being used to accelerate the combustion gases that do not have the minimum possible molecular weight, there is a limit on the exhaust velocity that can be achieved.

The maximum specific impulse Isp that can be achieved with chemical engines is in the range of 400 to 500 s. So, for example, if we have an Isp of 450 s, and a mission delta-V of 10 km/s (typical for launching into low earth orbit (LEO)), then the mass ratio will be 9.63. The problem here is that most of the vehicle mass is propellant, and due to limitations of the strength of materials, it may be impossible to build such a vehicle, just to ascend into orbit.

Early rocket scientists got around this problem by building a rocket in stages, throwing away the structural mass of the lower stages once the propellant was consumed. This effectively allowed higher mass ratios to be achieved, and hence a space mission could be achieved with low-Isp engines. This is what all rockets do today, even the Space Shuttle. In spite of the relatively low Isp, chemical engines do have a relatively high thrust-to-weight ratio (T/W).

A high T/W (50-75) is necessary for a rocket vehicle to overcome the force of gravity on Earth and accelerate into space. The thrust of the rocket engines must compensate for the weight of the rocket engines, the propellant, the structural mass, and the payload. Although it is not always necessary, a high T/W engine will allow orbital and interplanetary space vehicles to accelerate quickly and reach there destinations in shorter time periods.

Nuclear propulsion systems have the ability to overcome the Isp limitations of chemical rockets because the source of energy and the propellant are independent of each other. The energy comes from a critical nuclear reactor in which neutrons split fissile isotopes, such as 92-U-235 (Uranium) or 94-Pu-239 (Plutonium), and release energetic fission products, gamma rays, and enough extra neutrons to keep the reactor operating.

The energy density of nuclear fuel is enormous. The heat energy released from the reactor can then be used to heat up a low-molecular weight propellant (such as hydrogen) and then accelerate it through a thermodynamic nozzle in same way that chemical rockets do. This is how nuclear thermal rockets (NTR's) work.

Solid-core NTR's (See Figure 2) have a solid reactor core with cooling channels through which the propellant is heated up to high temperatures (2500-3000 K). Although solid NTR's don't operate at temperatures as high as some chemical engines (due to material limitations), they can use pure hydrogen propellant which allows higher Isp's to be achieved (up to 1000 s).

In gas-core NTR's, the nuclear fuel is in gaseous form and is inter-mixed with the hydrogen propellant. Gas core nuclear rockets (GCNR) can operate at much higher temperatures (5000 - 20000 K), and thus achieve much higher Isp's (up to 6000 s).

Of course, there is a problem in that some radioactive fission products will end up in the exhaust, but other concepts such as the nuclear light bulb (NLB) can contain the uranium plasma within a fused silica vessel that easily transfers heat to a surrounding blanket of propellant. At such high temperatures, whether an open-cycle GCNR, or a closed-cycle NLB, the propellants will dissociate and become partially ionized.

In this situation, a standard thermodynamic nozzle must be replaced by a magnetic nozzle which uses magnetic fields to insulate the solid wall from the partially-ionized gaseous exhaust.

NTR's give a significant performance improvement over chemical engines, and are desirable for interplanetary missions. It may also be possible that solid core NTR's could be used in a future launch vehicle to supplement or replace chemical engines altogether4. Advances in metallurgy and material science would be required to improve the durability and T/W ratio of NTR's for launch vehicle applications.

An alternative approach to NTR's is to use the heat from nuclear reactor to generate electrical power through a converter, and then use the electrical power to operate various types of electrical thrusters (ion, hall-type, or magneto-plasma-dynamic (MPD)) that operate on a wide variety of propellants (hydrogen, hydrazine, ammonia, argon, xenon, fullerenes) This is how nuclear-electric propulsion (NEP) systems work.

To convert the reactor heat into electricity, thermoelectric or thermionic devices could be used, but these have low efficiencies and low power to weight ratios. The alternative is to use a thermodynamic cycle with either a liquid metal (sodium, potassium), or a gaseous (helium) working fluid. These thermodynamic cycles can achieve higher efficiencies and power to weight ratios.

No matter what type of power converter is used, a heat rejection system is needed, meaning that simple radiators, heat pipes, or liquid-droplet radiators would be required to get rid of the waste heat. Unlike ground-based reactors, space reactors cannot dump the waste heat into a lake or into the air with cooling towers.

The electricity from the space nuclear reactor can be used to operate a variety of thrusters. Ion thrusters use electric fields to accelerate ions to high velocities. In principle, the only limit on the Isp that can be achieved with ion thrusters is the operating voltage and the power supply. Hall thrusters use a combination of magnetic fields to ionize the propellant gas and create a net axial electric field which accelerates ions in the thrust direction. MPD thrusters use either steady-state or pulsed electromagnetic fields to accelerate plasma (a mixture of ions and electrons) in the thrust direction. To get a high thrust density, ion thrusters typically use xenon, while Hall thrusters and MPD thrusters can operate quite well with argon or hydrogen.

Compared with NTR's, NEP systems can achieve much higher Isp's. Their main problem is that they have a low power to weight ratio, a low thrust density, and hence a very low T/W ratio. This is due to the mass of the reactor, the heat rejection system, and the low-pressure operating regime of electrical thrusters.

This makes NEP systems unfeasible for launch vehicle applications and mission scenarios where high accelerations are required; however, they can operate successfully in low-gravity environments such as LEO and interplanetary space.

In contrast to a chemical rocket or an NTR which may operate only for several minutes to less than an hour at a time, an NEP system might operate continuously for days, weeks, perhaps even months, as the space vehicle slowly accelerates to meet its mission delta-V. An NEP system is well suited for unmanned cargo missions between the Earth, Moon and other planets.

For manned missions to the outer planets, there would be a close competition between gas-core NTR's and high-thrust NEP systems.

The performance gain of nuclear propulsion systems over chemical propulsion systems is overwhelming. Nuclear systems can achieve space missions at a significantly lower cost due to the reduction in propellant requirements.

When humanity gains the will to explore and develop space more ambitiously, nuclear propulsion will be an attractive choice.

Source: Nuclear Propulsion from Astro Digital. - Quasar9
Innovative Nuclear Space Power and Propulsion Institute University of Florida

Tuesday, 25 September 2007

Fluid theory confirmed

The Foton M-3. Credit ESA

The Foton M-3 capsule carries a 400 kg European experiment payload with experiments in a range of scientific disciplines - including fluid physics, biology, crystal growth, radiation exposure and exobiology.

The capsule spends 12 days orbiting the Earth, exposing the experiments to microgravity and, in the case of a handful of experiments also exposing them to the harsh environment of open space, before re-entering the atmosphere and landing in the border zone between Russia and Kazakhstan.

All liquids experience minute fluctuations in temperature or concentration as a result of the different velocities of individual molecules. These fluctuations are usually so small that they are extremely difficult to observe.

In the 1990s, scientists discovered that these tiny fluctuations in fluids and gases can increase in size, and even be made visible to the naked eye, if a strong gradient is introduced. One way to achieve this is to increase the temperature at the bottom of a thin liquid layer, though not quite enough to cause convection. Alternatively, by heating the fluid from above, convection is suppressed, making it possible to achieve more accurate measurements.

It was suggested that the fluctuations would become much more noticeable in a weightless environment. Now, thanks to the Foton mission, the opportunity to test this prediction has come about, and the results completely support the earlier forecast.

To the delight of the science team, the images visually support the theoretical predictions by showing a very large increase in the size of the fluctuations. Data analysis has also shown that the amplitude of the fluctuations in temperature and concentration greatly increased.

It may be that the results will influence other types of microgravity research, such as the growth of crystals. This research may even lead to some new technological spin-offs.

Read more: Fluid Theory confirmed by Foton

Thursday, 30 August 2007

Hayabusa limps home

A third ion engine is now running on Japan's problem-plagued Hayabusa spacecraft. Having another working engine increases the chances that the spacecraft will be able to limp back to Earth.

If the craft does return as planned in 2010, researchers will finally find out whether it collected the first-ever samples from an asteroid during its two landings on the tiny space rock Itokawa.

watch an animated video of the mission

In late 2005, the spacecraft lost all the fuel for its chemical thrusters because of a leak, so mission managers have been trying to get Hayabusa home using its ion engines instead.
These engines ionise xenon gas and then use electric fields to accelerate the ions, providing a steady – though weak – thrust. They were meant to be used only for the outward journey to the asteroid.

Two of the four ion engines were tested in mid 2006 and found to be in working order, and Hayabusa began its return journey in April 2007. But these engines are in danger of failing – one of them has been firing for a total of 13,500 hours, close to its design lifetime of 14,000 hours.

Now, spacecraft operators have coaxed a third engine back to life. The engine started firing ions on 28 July after several days had been spent warming up the engine's power supply, a statement on the Japan Aerospace Exploration Agency (JAXA) website said.

This third engine has only been fired for 7,000 hours, leaving it with more expected lifetime than either of the others. The fourth engine is being reserved as a spare in case the others fail.

Hayabusa was meant to collect samples from Itokawa by firing pellets into the surface of the 535-metre-long rock and scooping up the resulting debris. But data from two landings in November 2005 suggest that the pellets never fired because the craft's onboard computer sent conflicting signals to its collection instruments.

Still, mission officials hope to bring the spacecraft back to Earth in case some asteroid dust slipped into its collection chamber by chance. If it completes the trip, it is expected to drop a capsule in the Australian outback in June 2010.
Mini-Mag Orion: A Near-Term Starship? from Centauri Dreams

Thursday, 23 August 2007


The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) system encompasses three linked magnetic cells. The "Plasma Source" cell involves the main injection of neutral gas (typically hydrogen, or other light gases) to be turned into plasma and the ionization subsystem. The "RF Booster" cell acts as an amplifier to further energize the plasma to the desired temperature using electromagnetic waves. The "Magnetic Nozzle" cell converts the energy of the plasma into directed motion and ultimately useful thrust.

Coupled with nuclear power this new type of rocket technology could dramatically shorten human transit times between planets (less than 3 months to Mars) and propel robotic cargo missions with a very large payload mass fraction. Trip times and payload mass are major limitations of conventional and nuclear thermal rockets because of their inherently low specific impulse (less than 1000 seconds). Plasma rockets such as VASIMR enable a very high specific impulse (greater than 10,000 seconds.) For these missions VASIMR will operate with hydrogen or deuterium propellant, both are abundant throughout the known universe.

The VASIMR has two additional important features that distinguish it from other plasma propulsion systems:
1. Ability to vary the exhaust characteristics (thrust and specific impulse) in order to optimally match mission requirements. This results in the lowest trip time with the highest payload for a given fuel load.
2. VASIMR is driven by electromagnetic (RF) waves and has no physical material electrodes in contact with the hot plasma. This results in greater reliability and longer life and enables a much higher power density than competing designs.

4-th State of Matter
The first step to understanding how a plasma rocket operates is learning about plasma. A plasma state can be achieved when a substance in its gaseous state is heated to very high temperatures - tens of thousands to millions of degrees. At this temperatures, electrons are stripped, or lost, from the neutral atoms.

In the overheated gas, electrons, which hold a negative charge, and ionized atoms, which hold a positive charge, mixed together making an electrically neutral "soup" of charged particles that is a plasma. This is a very common occurrence in nature. In fact, 99 percent of the visible universe is in some form of a plasma state, including lightning, very hot flames, nebulas, the Sun and other stars. The plasmas at the extreme temperatures required of a plasma rocket cannot be contained by any known material. Fortunately, plasmas can be controlled by a magnetic field.

Monday, 20 August 2007

Hinode & Solar Mysteries

Hinode (Sunrise in Japanese) was launched to study magnetic fields on the Sun and their role in powering the solar atmosphere and driving solar eruptions. With its Extreme Ultraviolet Imaging Spectrometer (EIS), effectively a solar speed camera, it is now possible to pinpoint the source of eruptions during solar flares and to find new clues about the heating processes of the corona.

The speed camera is a spectrometer, an instrument that splits the light coming from solar plasma, a tenuous and highly variable gas, into its distinct colours (or spectral lines), providing detailed information about the plasma. The velocity of the gases in a solar feature is measured by the Doppler effect - the same effect that is used by police radars to detect speeding motorists.

Read more Hinode helps unravel long-standing solar mysteries
Princeton scientists confirm long-held theory about source of sunshine
Voyager Interstellar Mission Proceeds from Centauri Dreams

Friday, 17 August 2007

Moving to the Sun's Rythm

Scientists from the Ulysses mission have proven that sounds generated deep inside the Sun cause the Earth to shake and vibrate in sympathy. They found that Earth’s magnetic field, atmosphere and terrestrial systems, all take part in this cosmic sing-along.

The HISCALE experiment on board Ulysses, a joint mission between ESA and NASA, present evidence that proves that Earth moves to the rhythm of the Sun. They show that distinct, isolated tones, predicted to be generated by pressure and gravity waves in the Sun, manage to reach Earth and are detectable in our environment.

Just as seismologists on Earth use sound waves to probe the interior of our world, solar scientists would like to use g-modes to probe the core of the Sun, if only they could detect them. G-modes have been undetectable optically.

The team examined a wide range of data sets covering natural phenomena and technological systems in fields as diverse as telecommunications and seismology and continued to find new evidence of discrete tones with characteristics of solar oscillations in what was previously considered background “noise”. This added to the puzzle posed by the Ulysses findings.

David Thomson from the Ulysses team believes that the key to the problem is magnetism. He suggests that the g-mode vibrations are picked up by the magnetic field at the Sun’s surface. Part of this magnetic field is then carried away from Sun into interplanetary space by solar wind, where it can be detected by space probes like Ulysses.

The magnetic field of the solar wind in turn interacts with the Earth’s magnetic field and causes it to vibrate in sympathy, retaining the characteristic g-mode signals. The motions of the geomagnetic field then couple into the solid Earth to produce small, but easily detectable, responses as Earth, with many of its technological systems, moves to the rhythm of the Sun.

Ulysses is a joint ESA/NASA mission studying the interplanetary medium and solar wind in the inner heliosphere, beyond the Sun's equator, for the first time.

Read more Moving to the Rythm of the Sun from ESA
How Solar Neutrinos make the Sun's heart beat @ Scientific Blogging
Voyager Interstellar Mission Proceeds from Centauri Dreams

Sunday, 5 August 2007

Nasa's Phoenix Mission to Mars

The aeroshell which contains the phoenix lander is visible in this close-up view of the spacecraft entering the martian atmosphere.

NASA's Phoenix Mars Mission blasted off Saturday, aiming for a May 25, 2008, arrival at the Red Planet and a close-up examination of the surface of the northern polar region.

Perched atop a Delta II rocket, the spacecraft left Cape Canaveral Air Force Base at 5:26 a.m. Eastern Time into the predawn sky above Florida's Atlantic coast.

Phoenix Mars Mission @ Arizona Education
NASA Phoenix Mission, going to the artic planes of Mars
NASA's Endeavour Launch from Quasar9
NASA's Space Shuttle Cargo from Space COM
What Makes Mars Magnetic? from Science Daily & ESF

Sunday, 29 July 2007

NASA Fusion Jet

The journey time from Earth orbit to Mars could be slashed from six months to less than six weeks if NASA's idea for a nuclear fusion-powered engine takes off.

The space-flight engine is being developed by a team led by Bill Emrich, an engineer at NASA's Marshall Space Flight Center in Huntsville, Alabama. He predicts his fusion drive would be able to generate 300 times the thrust of any chemical rocket engine and use only a fraction of its fuel mass.

That means interplanetary missions would no longer need to wait for a "shortest journey" launch window. You can launch when you want.

The principle is to sustain an on-board fusion reaction and fire some of the energy created out the back of the spacecraft, generating thrust. Of course, harnessing fusion is no easy task. Scientists have struggled to contain the super-hot plasmas of charged ions needed for fusion reactions.

Bare nuclei
To achieve fusion, scientists heat the hydrogen isotopes deuterium and tritium to at least 100 million kelvin. This strips electrons from the isotopes, creating a plasma of bare nuclei. If this plasma is hot and dense enough, the two types of nuclei fuse, giving off neutrons and huge amounts of energy.

However, the plasma can only be contained by strong magnetic fields, and creating containment fields that do not leak has proved very difficult. What is more, no one has managed to generate a stable fusion reaction that passes the "break-even" point, where the reaction is generating more energy than it takes to sustain it.

Fortunately for Emrich, the reaction would not need to go far beyond the break-even point to generate thrust. And containment is less of a headache because you actually want some of the plasma to escape, he says. "That's where the thrust comes from."

The problem is 100 million kelvin is not hot enough to generate thrust. At that temperature, the fusion reaction only generates neutrons, which are uncharged and therefore cannot be steered and fired through a magnetic jet nozzle. To produce thrust, you need charged particles.

Bold solution
Emrich is proposing a bold solution. He wants to use microwaves to heat the plasma to 600 million kelvin, triggering a different kind of fusion reaction that generates not neutrons but charged alpha particles - helium nuclei. These can then be fired from a magnetic nozzle to push the craft along.

Emrich has tested the idea with a scaled-down version using an argon plasma. He found that he could get around many of the containment problems by using a long, cylindrical magnetic field with powerful magnets at each end (see graphic).

In a fusion drive, the fields at the end could easily be controlled to release the highly energetic alpha particles and propel the craft.

If fusion researchers can ever achieve stable, break-even fusion, Emrich believes a full-scale fusion drive - perhaps 100 metres long - could be ready and waiting within two decades.

Nuclear fusion could power NASA spacecraft

Sunday, 24 June 2007

Superconducting Turbojet

An all-electric aircraft could soon appear over the horizon thanks to high-flying scientific research published today in the Institute of Physics' journal, Superconductor Science and Technology. The new type of aircraft, currently on the drawing board, could be far more efficient than conventional aircraft, produce less greenhouse emissions, and be quieter.

Air travel is on the increase, but it comes at a price in terms of the emissions driving climate change. Aircraft currently account for about 5% of UK emissions with a single long-haul flight the equivalent of a ton of carbon dioxide per passenger. With such worrying figures making the headlines, alternatives to combustion-based propulsion systems could be the key.

Superconducting motors could be one such alternative, according to scientists in America. Philippe Masson and Cesar Luongo from Florida State University, who have collaborated with Gerald Brown at NASA and Danielle Soban at Georgia Institute of Technology, explain that because superconductors lose no energy through electrical resistance, they could be very efficient components for a new type of aircraft propulsion.

The researchers explain that to build an electric aircraft will require propulsion motors that are high power, lightweight and compact. Current technology cannot meet these demands because an electric motor using conventional magnets can weigh up to five times as much as conventional jet engine and not be as fuel efficient.

In contrast, a superconducting motor would be very lightweight and far more efficient electrically, generating three times the torque of a conventional electric motor for the same energy input and weight. In addition, an electric aircraft would be far quieter than a conventional jet as there are no internal combustion processes involved. It is the combustion of fossil fuels to drive a conventional aircraft that makes them so noisy.

However, superconducting magnets not only have to be cold, but require a unique energy supply. Masson and his colleagues believe they could solve both problems by using chilly liquid hydrogen to run an electric fuel cell. Liquid hydrogen is cold enough to make the superconducting magnets work but also has four times as much energy weight for weight than aviation fuel.

A fuel cell produces no polluting emissions, just warm water as the hydrogen combines with oxygen. This, say the researchers would mean zero carbon emissions from the aircraft as it flies. "The idea is to reduce the emissions from the aircraft and airports," explains team leader Masson, "The energy needed to produce the liquid hydrogen could come from a remote powerplant". Such a powerplant might be solar or wind powered.

"We could potentially build a superconducting motor and generator smaller than a gas turbine, which would make possible electric propulsion," says Masson. Electrical propulsion would not only decrease emissions but also reduce to a minimum the needs for maintenance as all hydraulic systems would be eliminated, he adds. The team has designed such systems with high fidelity models and optimization tools.

Masson adds that the team is now looking for an industrial partner to build a prototype of the superconducting "turbofan". "The technology is there," he says, "it is a matter of finding a source of funding."

Original Source: Institute of Physics, News

Monday, 21 May 2007

Magnetic Sails Deployed

Some day fleets of interplanetary craft powered by the solar wind may cross the Solar System, using huge magnetic fields as their ’sails.’
Image: Artist’s impression of a mini-magnetosphere deployed around a spacecraft. Credit: Robert Winglee/University of Washington.

The concept is increasingly well understood, and researchers like Robert Winglee (University of Washington) have been extending it to include beamed propulsion methods as well.

Winglee’s concept is called MagBeam, useful if your goal is to move deeper still into nearby space. But for all this to happen, we’ll need to learn much more about the solar wind itself and how we might ride it.

Plasma or ionized gas is trapped on the magnetic field lines generated onboard, and this plasma inflates the magnetic field much like hot air inflates a balloon. The mini-magnetosphere is then blown by the plasma wind from the Sun called the solar wind which has a speed of between about 350 to 800 km/s.

Enter NASA’s Solar Wind Experiment, flying aboard the Wind spacecraft launched in 1994, and designed to study such things as the stream of electrically charged particles constantly produced by the Sun.

The Solar Wind Experiment can measure the speed, density and temperature of those particles. And it turns out to be particularly well placed for such work, according to John Steinberg from Los Alamos National Laboratory: “We study the solar wind for practical reasons; the character of the solar wind blowing by Earth at any time determines conditions in the near-Earth space environmen.

It turned out that the Wind Solar Wind Experiment data were ideal for this particular study because of continuous data coverage that the spacecraft provided during the previous solar activity cycle minimum in 1996, through the recent solar max in 2001, and into the solar activity declining phase afterward.”

A key part of the analysis is to understand how the solar wind is accelerated to speeds between 600,000 and one million miles per hour. And it turns out that helium is implicated in the result. Most of the material in the solar corona is hydrogen, but as the hydrogen escapes the corona, it drags some heavier helium along with it, in the process slowing down.

But the huge events called coronal mass ejections show five to ten times the amount of helium normally found in the solar wind. Evidently helium building up in the solar atmosphere is suddenly expelled during these events. When the solar wind is at lower speeds, it is made up primarily of hydrogen, with little helium observed. Thus we have a lower speed limit established by the retardant effects of helium, with the coronal mass ejections showing what happens periodically to the helium that remains.

Helium: Speed Brake for the Solar Wind? from Centauri Dreams

Thursday, 19 April 2007

Starship: Plasma Shields

Shields For Starships: A Reality?

To protect the occupants from the potentially lethal radiation in space from the Sun, a superconducting ring on board the space craft could produce a magnetic field, or mini-magnetosphere, similar to the Earth's, which would create a 'deflector or plasma shield'.
(Credit: Image courtesy of Royal Astronomical Society)

Cosmic rays and radiation from the Sun itself can cause acute radiation sickness in astronauts and even death. Between 1968 and 1973, the Apollo astronauts going to the moon were only in space for about 10 days at a time and were simply lucky not to have been in space during a major eruption on the sun that would have flooded their spacecraft with deadly radiation. In retrospect Neil Armstrong’s ‘one small step for Man’ would have looked very different if it had.

On the International Space Station there is a special thick-walled room to which the astronauts have had to retreat during times of increased solar radiation. However on longer missions the astronauts cannot live within shielded rooms, since such shielding would add significantly to the mass of the spacecraft, making them much more expensive and difficult to launch. It is also now known that the ‘drip-drip’ of even lower levels of radiation can be as dangerous as acute bursts from the sun.

On the surface of the Earth we are protected from radiation by the thick layers of the atmosphere. And the terrestrial magnetic field extends far into space, acting as a natural ‘force field’ to further protect our planet and deflecting the worst of the energetic particles from the Sun by creating a ‘plasma barrier’.

Now scientists at the Rutherford Appleton Laboratory in Oxfordshire plan to mimic nature. They will build a miniature magnetosphere in a laboratory to see if a deflector shield can be used to protect humans living on space craft and in bases on the Moon or Mars.

In order to work, an artificial mini-magnetosphere on a space craft will need to utilise many cutting edge technologies, such as superconductors and the magnetic confinement techniques used in nuclear fusion.

Thus science is following science fiction once again. The writers of Star Trek realised that any space craft containing humans would need protection from the hazardous effects of cosmic radiation. They envisioned a ‘deflector shield’ spreading out from the Starship Enterprise that the radiation would bounce off. These experiments will help to establish whether this idea could one day become a practical real.
Astronomers Map Out Planetary Danger Zone
Astronomers Make Detailed Image Of Giant Stellar Nursery
Hubble Space Telescope Reveals The Aftermath Of 'Star Wars'

Sunday, 15 April 2007

Where is The Proton?

Scientists Discover Footprints Of Shared Protons

This week in Science, Yale researchers present "roadmaps" showing that shared protons, a common loose link between two biological molecules, simply vibrate between the molecules as a local oscillator, rather than intimately entangling with the molecular vibrations of the attached molecules.

The paper reports clear "roadmaps" for the widely varying, characteristic vibrational frequencies that occur when an excess proton binds together simple nitrogen and oxygen containing molecules.

Rather than studying the proton-trapped pairs of molecules in crystals or in solution at room temperature, as has been common in the past, Johnson's team made their measurements of proton interactions with 18 simple molecules by isolating them in the gas-phase and cooling them to about 50 Kelvin by taking advantage of recent advances in argon nanomatrix spectroscopy.

"Historically it has been very difficult to isolate the signature of an excess proton in a complex environment like a cell membrane, and say with confidence 'Aha, I have one,'" said Johnson. "The proton is in constant motion in a warm, disordered medium, which causes its natural vibrational frequency to spread out over a huge spectral range. As a result, its 'signature' is often thought to comprise the continuous 'junk' background in the vibrational spectra of protonated samples."

"When we cool the isolated systems, the protons sing out their sharp vibrational frequencies, and therefore provide clear signatures that are characteristic of each kind of interaction," said Johnson.

Two oxygen atoms on different molecules are connected by their mutual attraction to an extra proton, shown as a fuzzy ball between them. The presence of such intermolecular binding can now be identified by monitoring the precise vibrational frequency of the bridging proton. (Credit: Image courtesy of Yale University)

The research shows that the extra proton is associated with a specific pair of atoms on the two tethered molecules, participating in partial chemical bonds to both. "In biological systems, any time you have molecules with a nitrogen or oxygen, and add in an extra proton, the proton forms a bond with one of the extra electron pairs that are available," according Johnson. "It crashes the party and changes the character of the molecule."

Extending Johnson's analogy, if another molecule containing nitrogen or oxygen comes by, the proton crashes that party, too. Because the proton is not deciding between one molecule and the other, it is creating a bond between them - crashing both parties at the same time. "A proton is a great handshaker that works the room until it gets to where it is needed," he said.

This motif is the generic intermediate involved in passing a proton through a biological membrane. Each paired interaction forms a locally stable intermediate. In a sense, the oxygen atoms in water molecules chaperone protons between oxygen and nitrogen atoms on organic structures. For example, the primary events in trans-membrane proton pumps require passing protons through many relay steps across the cell membrane.

In earlier studies, Johnson looked only at water molecules trapping protons. This study expands the work to biologically relevant molecules that contain oxygen and nitrogen atoms. In it the researchers were able to look at how stiff the proton trap is between two molecules, and how this stiffness depends on the properties of the molecules to which the protons are attached.

"The strength with which the proton is grabbed by a nitrogen - or oxygen- containing molecule is highly affected by the environment," said Johnson. "So, we systematically changed that environment over a huge range and followed how the localization of the proton changed. We found that the way the proton is localized depends very much on the chemical properties of the atoms you are trapping it with."
Mew NMR Methods by Kurt W Zilm
LUMO Analogy among three fluorides
Argon Nanomatrix Spectroscopy by Mark A Johnson

Friday, 30 March 2007

Possible Worlds

Possible Worlds by ThinkingThing

When looking at the inmensity of Space we are left in no doubt of its vastness. When we look at earth we see on its surface the rivers and roads, the highways and railways, the ringroads and tunnels that link us across the world. The airports and skyways that exist on the surface of this globe.

This is only the beginning of The New Age.
A New Dawn is upon us, where the distances and dimensions we travel through grow and expand beyond the horizon.