Category: Space Exploration

An artist’s rendering of the Integrated Powerhead Demonstrator. Image credit: NASA. Click to enlarge.
When you think of future rocket technology, you probably think of ion propulsion, antimatter engines and other exotic concepts.

Not so fast! The final chapter in traditional liquid-fueled rockets has yet to be written. Research is underway into a new generation of liquid-fueled rocket designs that could double performance over today’s designs while also improving reliability.

Liquid-fueled rockets have been around for a long time: The first liquid-powered launch was performed in 1926 by Robert H. Goddard. That simple rocket produced roughly 20 pounds of thrust, enough to carry it about 40 feet into the air. Since then, designs have become sophisticated and powerful. The space shuttle’s three liquid-fueled onboard engines, for instance, can exert more than 1.5 million pounds of combined thrust en route to Earth orbit.

You might assume that, by now, every conceivable refinement in liquid-fueled rocket designs must have been made. You’d be wrong. It turns out there’s room for improvement.

Led by the US Air Force, a group consisting of NASA, the Department of Defense, and several industry partners are working on better engine designs. Their program is called Integrated High Payoff Rocket Propulsion Technologies, and they are looking at many possible improvements. One of the most promising so far is a new scheme for fuel flow:

The basic idea behind a liquid-fueled rocket is rather simple. A fuel and an oxidizer, both in liquid form, are fed into a combustion chamber and ignited. For example, the shuttle uses liquid hydrogen as its fuel and liquid oxygen as the oxidizer. The hot gases produced by the combustion escape rapidly through the cone-shaped nozzle, thus producing thrust.

The details, of course, are much more complicated. For one, both the liquid fuel and the oxidizer must be fed into the chamber very rapidly and under great pressure. The shuttle’s main engines would drain a swimming pool full of fuel in only 25 seconds!

This gushing torrent of fuel is driven by a turbopump. To power the turbopump, a small amount of fuel is “preburned”, thus generating hot gases that drive the turbopump, which in turn pumps the rest of the fuel into the main combustion chamber. A similar process is used to pump the oxidizer.

Today’s liquid-fueled rockets send only a small amount of fuel and oxidizer through the preburners. The bulk flows directly to the main combustion chamber, skipping the preburners entirely.

One of many innovations being tested by the Air Force and NASA is to send all of the fuel and oxidizer through their respective preburners. Only a small amount is consumed there–just enough to run the turbos; the rest flows through to the combustion chamber.

This “full-flow staged cycle” design has an important advantage: with more mass passing through the turbine that drives the turbopump, the turbopump is driven harder, thus reaching higher pressures. Higher pressures equal greater performance from the rocket.

Such a design has never been used in a liquid-fueled rocket in the U.S. before, according to Gary Genge at NASA’s Marshall Space Flight Center. Genge is the Deputy Project Manager for the Integrated Powerhead Demonstrator (IPD)–a test-engine for these concepts.

“These designs we’re exploring could boost performance in many ways,” says Genge. “We’re hoping for better fuel efficiency, higher thrust-to-weight ratio, improved reliability–all at a lower cost.”

“At this phase of the project, however, we’re just trying to get this alternate flow pattern working correctly,” he notes.

Already they’ve achieved one key goal: a cooler-running engine. “Turbopumps using traditional flow patterns can heat up to 1800 C,” says Genge. That’s a lot of thermal stress on the engine. The “full flow” turbopump is cooler, because with more mass running through it, lower temperatures can be used and still achieve good performance. “We’ve lowered the temperature by several hundred degrees,” he says.

IPD is meant only as a testbed for new ideas, notes Genge. The demonstrator itself will never fly to space. But if the project is successful, some of IPD’s improvements could find their way into the launch vehicles of the future.

Almost a hundred years and thousands of launches after Goddard, the best liquid-fueled rockets may be yet to come.

Original Source: NASA Science Article

Artist illustration of the new Crew Exploration Vehicle. Image credit: Northrop Grumman. Click to enlarge.
A Northrop Grumman-Boeing team has unveiled its plans to design and build NASA’s proposed Crew Exploration Vehicle, a successor to the space shuttle that will carry humans to the International Space Station by 2012 and back to the moon by 2018. Shown in these artist concepts, the new, modular space vehicle comprises a crew module reminiscent of the Apollo spacecraft, a service module and a launch-abort system.

A Northrop Grumman-Boeing team has unveiled its plans to design and build NASA’s proposed Crew Exploration Vehicle, a successor to the space shuttle that will carry humans to the International Space Station by 2012 and back to the moon by 2018. Shown in these artist concepts, the new, modular space vehicle comprises a crew module reminiscent of the Apollo spacecraft, a service module and a launch-abort system.

The CEV comprises a crew module that builds on NASA’s Apollo spacecraft, a service module and a launch-abort system. It is designed to be carried into space aboard a shuttle-derived launch vehicle — a rocket based on the solid rocket booster technology that powers the early phases of current shuttle flights.

The CEV will be produced both as a crewed space transportation system and as an uncrewed space vehicle capable of transporting cargo to and from the International Space Station. NASA expects to select a CEV prime contractor in the spring of 2006.

According to Doug Young, program manager for the Northrop Grumman-Boeing CEV team, the team’s design approach to the CEV and the overall mission architecture have been evolving over the past year.

“We’ve been working closely with NASA to identify design options and technologies that would enable the nation to meet its space exploration goals of safety, affordability and reliability,” Young said. “Early on we concluded that this modular, capsule-based approach would establish an ideal foundation for a successful, sustainable human and robotic space exploration program. It’s also a system that can be designed and built today using proven technologies, which will help maintain the nation’s leadership role in human space flight.”

While similar in shape to the Apollo spacecraft that carried astronauts to the moon in the late ’60s and early ’70s, the new CEV is a quantum leap forward in terms of performance, reliability and on-orbit mission capability.

“The CEV we plan to build will benefit not so much from a single, technical breakthrough but rather from evolutionary improvements in structural technologies, electronics, avionics, thermal-management systems, software and integrated system- health-management systems over the past 40 years,” said Leonard Nicholson, the Northrop Grumman-Boeing team’s deputy program manager.

According to Nicholson, the CEV offers many fundamental improvements over Apollo. Among them:

– CEV’s crew module will have much more internal volume than the Apollo capsule, but will only be slightly heavier, due to the use of advanced structural materials and technologies that reduce the size, weight and power consumption of key subsystems.

– CEV’s crew module will carry up to six astronauts, while Apollo carried just three.

– CEV will carry more fuel for lunar return than Apollo, allowing it to change its orbit rather than relying on the moon and the Earth to be in the right relative positions.

– CEV will be able to operate as an autonomous spacecraft orbiting the moon for up to six months while its crew of four descends to the lunar surface in the lunar lander. Crew members and ground controllers will be able to communicate with the CEV and monitor its “vital signs” remotely. During the Apollo era, one astronaut stayed with the “mother ship” while the lunar lander carrying two astronauts descended to the moon.

– CEV will use two fault-tolerant subsystems and integrated system-health- management systems to allow it to detect, isolate and recover from subsystem failures. By comparison, Apollo generally had only single fault tolerance.

A unit of The Boeing Company, Boeing Integrated Defense Systems is one of the world’s largest space and defense businesses. Headquartered in St. Louis, Boeing Integrated Defense Systems is a $30.5 billion business. It provides network-centric system solutions to its global military, government and commercial customers. It is a leading provider of intelligence, surveillance and reconnaissance systems; the world’s largest military aircraft manufacturer; the world’s largest satellite manufacturer and a leading provider of space-based communications; the primary systems integrator for U.S. missile defense; NASA’s largest contractor; and a global leader in sustainment solutions and launch services.

Northrop Grumman Corporation is a global defense company headquartered in Los Angeles, Calif. It provides technologically advanced, innovative products, services and solutions in systems integration, defense electronics, information technology, advanced aircraft, shipbuilding and space technology. With more than 125,000 employees, and operations in all 50 states and 25 countries, the company serves U.S. and international military, government and commercial customers. Today, more than 20,000 of Northrop Grumman’s employees are devoted to space-related projects.

Original Source: Northrop Grumman News Release

Paul Campbell took this amazing picture of the Moon. Image credit: Paul Campbell. Click to enlarge.
ILEWG is a public forum sponsored by the world’s space agencies to support “international cooperation towards a world strategy for the exploration and utilization of the Moon – our natural satellite”. An example objective is the ready and free sharing of data to any and all parties. This allows for judicious review and most importantly avoids duplication. Also, by coordinating onboard experiments beforehand, agencies can avoid duplicating research and wasting scarce funding. Given the costs and risks associated with each expedition, together with the scarcity of public funds, avoiding duplication is a necessary goal.

Exploring the Moon never stopped after the Apollo program. However, researchers have had to fight for funding on an equal basis with every other government department. In consequence, the number of missions have been few and far between. Now, only one satellite, Smart-1, orbits the Moon. This will change. For returning to the Moon, setting up a base, and then continuing on to Mars, we will need to know more of the Moon to minimize the cost and maximize the benefit. The Holy Grail for lunar exploration is water ice. Finding sufficient, recoverable quantities would greatly facilitate a human presence (as in drinking water) and further exploration (as in rocket fuel production). Without water ice, we either use brute force to raise sufficient quantities out of Earth’s gravity well or invent new techniques. Both these represent signficantly greater challenges. Nevertheless, the researchers at ILEWG are well aware of their knowledge gaps and are actively preparing missions to fill these in.

Yet the ILEWG participants aren’t accepting the status quo with NASA being the only player in town. In addition to other national space agencies, there were many individuals and corporations who were promoting their own style of space exploration and utilization. Lunar telescopes, mines and tourist hotels were just some opportunities deemed potential. To facilitate these ventures, conference attendees were treated to lectures on property rights, the common heritage of humankind and investment financing. For instance, without any arbitration medium, imagine sitting at your new observatory on the moon only to feel blasting from a nearby mining operation! These additional conference contributors, and their ability to think outside the box, demonstrate the desire and ability of the big, independent players at ILEWG.

However, even though great thinkers and doers were present, this doesn’t guarantee a lunar ‘gold rush’ happening any time soon. After all, if there were quick riches to be made, we would have had colonies already turning the lunar regolith into Swiss cheese. Instead, we’ve had to rely on public funds, i.e. taxpayer’s dollars. And unless some unforeseen magic appears, we will need a huge amount of this money to build a suitable infrastructure to reliably establish a human presence on the Moon’s surface. This showcases one omission from ILEWG. Very little attention was given to promoting lunar and space activities to the general public. Given the incessant demand for public funds that comes from every quarter, there needs to be solid and continual vindication for lunar base allocations. Alongside the great thinkers and doers, we need exuberant public relations experts to sell this endeavour.

Without the public’s interest, we will neither establish lunar colonies nor ever move off of Earth. The preponderance of technical data and investigations at the ILEWG conference demonstrate that we have the technical ability. But where is the justification? There is precious little economic justification. The monetary cost and consumption of Earth’s natural resources for people to live and work on the Moon is far greater than the equivalent cost of doing business on Earth. Further, the Moon has no unique qualities, after all, the Moon’s surface is very similar to the Earth’s. So, though service and resource providers may facilitate lunar colonies, they will not economically create such a colony.

But I am a believer. We need to step off of Earth and give ourselves a future that encompasses more than this one planet. We know our planet’s environment changes drastically. We know large asteroids regularly pummel the Earth’s surface. We know our Sun’s radiation fluctuates and the Sun itself will undergo a final tumultuous collapse. Restricting our children to the confines of the Earth’s surface is an artificial limiter that prevents our species from being the best it can be. We can do better. So get involved, talk to people, remind them that space is still a new harsh environment onto which we have barely stepped. Make them believe in a future more challenging and rewarding than simply lying on the ground at night wondering what the shiny dots above might be.

Whether, homesteaders, governments or organizations are the instigators, the Moon is our stepping stone off the Earth. The organization ILEWG is helping coordinate research and exploration amongst nations to quicken the building of our society off world. The gravity well that is Earth will remain for as long as the Earth so let’s acknowledge this, not as a barrier, but as a test to our civilization. Let’s work together and pass this test and decide our future, or we will stay moribund on Earth waiting for the future to decide our fate.

Written by Mark Mortimer

Astronaut on the Moon surface. Image credit: NASA Click to enlarge
A breakthrough by a team of British, US and French scientists will help protect astronauts, spacecraft and satellites from radiation hazards experienced in space.

Reporting in the journal Nature this week, the team describe how their study of rare and unusual space storms provided a unique opportunity to test conflicting theories about the behaviour of high energy particles in the Van Allen radiation belts* – a volatile region 12000 miles (19,000 km) above the Earth.

Lead author, Dr Richard Horne of the British Antarctic Survey (BAS) says

?Solar storms can increase radiation in the Van Allen belts to levels that pose a threat to spacecraft. As modern society relies increasingly on satellites for business, communications, and security, it is important to understand the environment that spacecraft operate in so that we can help protect our space investment.

?For a long time scientists have been trying to explain why the number of charged particles inside the belts vary so much. Our major breakthrough came when we observed two rare space storms that occurred almost back-to-back in October and November 2003. During the storms part of the Van Allen radiation belt was drained of electrons and then reformed much closer to the Earth in a region usually thought to be relatively safe for satellites.

? When the radiation belts reformed they did not increase according to a long-held theory of particle acceleration. Instead, by using scientific instruments in Antarctica and on the CLUSTER mission satellites, we showed that very low frequency radio waves caused the particle acceleration and intensified the belts.

?This new information will help spacecraft operators and space weather forecasters who must predict when satellites and missions are most at risk from radiation events allowing them to take measures to protect instruments and systems from damage, and astronauts from risks to their health.?

Original Source: BAS News Release

Artist’s concept of humans set off to Mars. Image credit: NASA Click to enlarge
After reading this article, you might never look at trash bags the same way again.

We all use plastic trash bags; they’re so common that we hardly give them a second thought. So who would have guessed that a lowly trash bag might hold the key to sending humans to Mars?

Most household trash bags are made of a polymer called polyethylene. Variants of that molecule turn out to be excellent at shielding the most dangerous forms of space radiation. Scientists have long known this. The trouble has been trying to build a spaceship out of the flimsy stuff.

But now NASA scientists have invented a groundbreaking, polyethylene-based material called RXF1 that’s even stronger and lighter than aluminum. “This new material is a first in the sense that it combines superior structural properties with superior shielding properties,” says Nasser Barghouty, Project Scientist for NASA’s Space Radiation Shielding Project at the Marshall Space Flight Center.

To Mars in a plastic spaceship? As daft as it may sound, it could be the safest way to go.

Less is more

Protecting astronauts from deep-space radiation is a major unsolved problem. Consider a manned mission to Mars: The round-trip could last as long as 30 months, and would require leaving the protective bubble of Earth’s magnetic field. Some scientists believe that materials such as aluminum, which provide adequate shielding in Earth orbit or for short trips to the Moon, would be inadequate for the trip to Mars.

Barghouty is one of the skeptics: “Going to Mars now with an aluminum spaceship is undoable,” he believes.

Plastic is an appealing alternative: Compared to aluminum, polyethylene is 50% better at shielding solar flares and 15% better for cosmic rays.

The advantage of plastic-like materials is that they produce far less “secondary radiation” than heavier materials like aluminum or lead. Secondary radiation comes from the shielding material itself. When particles of space radiation smash into atoms within the shield, they trigger tiny nuclear reactions. Those reactions produce a shower of nuclear byproducts — neutrons and other particles — that enter the spacecraft. It’s a bit like trying to protect yourself from a flying bowling ball by erecting a wall of pins. You avoid the ball but get pelted by pins. “Secondaries” can be worse for astronauts’ health than the original space radiation!

Ironically, heavier elements like lead, which people often assume to be the best radiation shielding, produce much more secondary radiation than lighter elements like carbon and hydrogen. That’s why polyethylene makes good shielding: it is composed entirely of lightweight carbon and hydrogen atoms, which minimizes secondaries.

These lighter elements can’t completely stop space radiation. But they can fragment the incoming radiation particles, greatly reducing the harmful effects. Imagine hiding behind a chain-link fence to protect yourself in a snowball fight: You’ll still get some snow on you as tiny bits of snowball burst through the fence, but you won’t feel the sting of a direct hit from a hard-packed whopper. Polyethylene is like that chain link fence.

“That’s what we can do. Fragmenting — without producing a lot of secondary radiation — is actually where the battle is won or lost,” Barghouty says.

Made to order

Despite their shielding power, ordinary trash bags obviously won’t do for building a spaceship. So Barghouty and his colleagues have been trying to beef-up polyethylene for aerospace work.

That’s how Shielding Project researcher Raj Kaul, working together with Barghouty, came to invent RXF1. RXF1 is remarkably strong and light: it has 3 times the tensile strength of aluminum, yet is 2.6 times lighter — impressive even by aerospace standards.

“Since it is a ballistic shield, it also deflects micrometeorites,” says Kaul, who had previously worked with similar materials in developing helicopter armor. “Since it’s a fabric, it can be draped around molds and shaped into specific spacecraft components.” And because it’s derived from polyethylene, it’s an excellent radiation shield as well.

The specifics of how RXF1 is made are secret because a patent on the material is pending.

Strength is only one of the traits that the walls of a spaceship must have, Barghouty notes. Flammability and temperature tolerance are also important: It doesn’t matter how strong a spaceship’s walls are if they melt in direct sunlight or catch fire easily. Pure polyethylene is very flammable. More work is needed to customize RXF1 even further to make it flame and temperature resistant as well, Barghouty says.

The Bottom Line

The big question, of course, is the bottom line: Can RXF1 carry humans safely to Mars? At this point, no one knows for sure.

Some “galactic cosmic rays are so energetic that no reasonable amount of shielding can stop them,” cautions Frank Cucinotta, NASA’s Chief Radiation Health Officer. “All materials have this problem, including polyethylene.”

Cucinotta and colleagues have done computer simulations to compare the cancer risk of going to Mars in an aluminum ship vs. a polyethylene ship. Surprisingly, “there was no significant difference,” he says. This conclusion depends on a biological model which estimates how human tissue is affected by space radiation–and therein lies the rub. After decades of spaceflight, scientists still don’t fully understand how the human body reacts to cosmic rays. If their model is correct, however, there could be little practical benefit to the extra shielding polyethylene provides. This is a matter of ongoing research.

Because of the many uncertainties, dose limits for astronauts on a Mars mission have not been set, notes Barghouty. But assuming that those dose limits are similar to limits set for Shuttle and Space Station flights, he believes RXF1 could hypothetically provide adequate shielding for a 30 month mission to Mars.

Today, to the dump. Tomorrow, to the stars? Polyethylene might take you farther than you ever imagined.

Original Source: NASA News Release

ISS photographed by STS crewmember. Image credit: NASA Click to enlarge
After saying goodbye to the Space Shuttle Discovery’s crew on Saturday, International Space Station (ISS) Commander Sergei Krikalev and NASA Science Officer John Phillips spent much of the week preparing for a spacewalk scheduled for next week.

The six-hour spacewalk begins at 2:55 p.m. EDT, Thursday. Live coverage on NASA TV starts at 1:30 p.m. EDT.

On the spacewalk, the crew will change out a Russian biological experiment, retrieve some radiation sensors, remove a Japanese materials science experiment, photograph a Russian materials experiment, install a TV camera and relocate a grapple fixture.

At 1:44 a.m. EDT, Tuesday, Krikalev’s time spent in space will surpass any other human. Cosmonaut Sergei Avdeyev set the previous record with 748 days in orbit. Krikalev is a veteran of two long-duration flights to the Soviet Union’s Space Station Mir; two flights on the Shuttle; and two flights to the ISS. Krikalev was aboard Mir when the Soviet Union disintegrated; was the first Russian to fly on the Shuttle in 1994; was a member of the Shuttle crew that began assembly of the ISS in 1998; and a member of the first crew to live on board the Station in 2000.

Krikalev and Phillips had an off-duty day on Sunday. On Monday they unpacked and prepared spacewalk tools and the Pirs docking compartment. They will use the Pirs for the spacewalk. During the week, they checked the Russian Orlan spacesuits they will wear and talked with spacewalk experts in the Russian Mission Control Center and in Houston.

On Thursday, the Russian Vozdukh carbon dioxide removal system shut down. The system is one of multiple systems used to scrub the Station cabin air. Flight controllers in Houston activated a U.S. Carbon Dioxide Removal Assembly to perform that function while the Vozdukh is not operating. Russian specialists are analyzing the problem.

Information about crew activities on board the Station, future launch dates, previous status reports and sighting ISS opportunities is available on the Web at: http://www.nasa.gov/station

For information about NASA and other agency programs on the Web, visit: http://www.nasa.gov/home/index.html

Original Source: NASA News Release

Artist’s concept of possible exploration programs. Image credit: NASA Click to enlarge
Have you ever walked across a wool carpet in leather-soled shoes on a dry winter day, and then reached out toward a doorknob? ZAP! A stinging spark leaps between your fingers and the metal knob.

That’s static discharge–lightning writ small.

Static discharge is merely annoying to anyone on Earth living where winters have exceptionally low humidity. But to astronauts on the Moon or on Mars, static discharge could be real trouble.

“On Mars, we think the soil is so dry and insulating that if an astronaut were out walking, once he or she returned to the habitat and reached out to open the airlock, a little lightning bolt might zap critical electronics,” explains Geoffrey A. Landis, a physicist with the Photovoltaics and Space Environmental Effects Branch at NASA Glenn Research Center in Cleveland, Ohio.

This phenomenon is called triboelectric charging.

The prefix “tribo” (pronounced TRY-bo) means “rubbing.” When certain pairs of unlike materials, such as wool and hard shoe-sole leather, rub together, one material gives up some of its electrons to the other material. The separation of charge can create a strong electric field.

Here on Earth, the air around us and the clothes we wear usually have enough humidity to be decent electrical conductors, so any charges separated by walking or rubbing have a ready path to ground. Electrons bleed off into the ground instead of accumulating on your body.

But when air and materials are extraordinarily dry, such as on a dry winter’s day, they are excellent insulators, so there is no ready pathway to ground. Your body can accumulate negative charges, possibly up to an amazing 20 thousand volts. If you touch a conductor, such as a metal doorknob, then–ZAP!–all the accumulated electrons discharge at once.

On the Moon and on Mars, conditions are ideal for triboelectric charging. The soil is drier than desert sand on Earth. That makes it an excellent electrical insulator. Moreover, the soil and most materials used in spacesuits and spacecraft (e.g., aluminized mylar, neoprene-coated nylon, Dacron, urethane-coated nylon, tricot, and stainless steel) are completely unlike each other. When astronauts walk or rovers roll across the ground, their boots or wheels gather electrons as they rub through the gravel and dust. Because the soil is insulating, providing no path to ground, a space suit or rover can build up tremendous triboelectric charge, whose magnitude is yet unknown. And when the astronaut or vehicle gets back to base and touches metal–ZAP! The lights in the base may go out, or worse.

Landis and colleagues at NASA Glenn first noticed this problem in the late 1990s before Mars Pathfinder was launched. “When we ran a prototype wheel of the Sojourner rover over simulated Martian dust in a simulated Martian atmosphere, we found it charged up to hundreds of volts,” he recalls.

That discovery so concerned the scientists that they modified Pathfinder’s rover design, adding needles half an inch long, made of ultrathin (0.0001-inch diameter) tungsten wire sharpened to a point, at the base of antennas. The needles would allow any electric charge that built up on the rover to bleed off into the thin Martian atmosphere, “like a miniature lightning rod operating in reverse,” explains Carlos Calle, lead scientist at NASA’s Electrostatics and Surface Physics Laboratory at Kennedy Space Center, Florida. Similar protective needles were also installed on the Spirit and Opportunity rovers.

On the Moon, “Apollo astronauts never reported being zapped by electrostatic discharges,” notes Calle. “However, future lunar missions using large excavation equipment to move lots of dry dirt and dust could produce electrostatic fields. Because there’s no atmosphere on the Moon, the fields could grow quite strong. Eventually, discharges could occur in vacuum.”

“On Mars,” he continues, “discharges can happen at no more than a few hundred volts. It’s likely that these will take the form of coronal glows rather than lightning bolts. As such, they may not be life threatening for the astronauts, but they could be harmful to electronic equipment.”

So what’s the solution to this problem?

Here on Earth, it’s simple: we minimize static discharge by grounding electrical systems. Grounding them means literally connecting them to Earth–pounding copper rods deep into the ground. Ground rods work well in most places on Earth because several feet deep the soil is damp, and is thus a good conductor. The Earth itself provides a “sea of electrons,” which neutralizes everything connected to it, explains Calle.

There’s no moisture, though, in the soil of the Moon or Mars. Even the ice believed to permeate Martian soil wouldn’t help, as “frozen water is not a terribly good conductor,” says Landis. So ground rods would be ineffective in establishing a neutral “common ground” for a lunar or Martian colony.

On Mars, the best ground might be, ironically, the air. A tiny radioactive source “such as that used in smoke detectors,” could be attached to each spacesuit and to the habitat, suggests Landis. Low-energy alpha particles would fly off into the rarefied atmosphere, hitting molecules and ionizing them (removing electrons). Thus, the atmosphere right around the habitat or astronaut would become conductive, neutralizing any excess charge.

Achieving a common ground on the Moon would be trickier, where there’s not even a rarefied atmosphere to help bleed off the charge. Instead, a common ground might be provided by burying a huge sheet of foil or mesh of fine wires, possibly made of aluminum (which is highly conductive and could be extracted from lunar soil), underneath the entire work area. Then all the habitat’s walls and apparatus would be electrically connected to the aluminum.

Research is still preliminary. So ideas differ amongst the physicists who are seeking, well, some common ground.

Original Source: NASA News Release

Artist’s conception of a bio-nanorobot. Image credit: NASA. Click to enlarge
When it comes to taking the next “giant leap” in space exploration, NASA is thinking small — really small.

In laboratories around the country, NASA is supporting the burgeoning science of nanotechnology. The basic idea is to learn to deal with matter at the atomic scale — to be able to control individual atoms and molecules well enough to design molecule-size machines, advanced electronics and “smart” materials.

If visionaries are right, nanotechnology could lead to robots you can hold on your fingertip, self-healing spacesuits, space elevators and other fantastic devices. Some of these things may take 20+ years to fully develop; others are taking shape in the laboratory today.

Simply making things smaller has its advantages. Imagine, for example, if the Mars rovers Spirit and Opportunity could have been made as small as a beetle, and could scurry over rocks and gravel as a beetle can, sampling minerals and searching for clues to the history of water on Mars. Hundreds or thousands of these diminutive robots could have been sent in the same capsules that carried the two desk-size rovers, enabling scientists to explore much more of the planet’s surface — and increasing the odds of stumbling across a fossilized Martian bacterium!

But nanotech is about more than just shrinking things. When scientists can deliberately order and structure matter at the molecular level, amazing new properties sometimes emerge.

An excellent example is that darling of the nanotech world, the carbon nanotube. Carbon occurs naturally as graphite — the soft, black material often used in pencil leads — and as diamond. The only difference between the two is the arrangement of the carbon atoms. When scientists arrange the same carbon atoms into a “chicken wire” pattern and roll them up into miniscule tubes only 10 atoms across, the resulting “nanotubes” acquire some rather extraordinary traits. Nanotubes:

– have 100 times the tensile strength of steel, but only 1/6 the weight;
– are 40 times stronger than graphite fibers;
– conduct electricity better than copper;
– can be either conductors or semiconductors (like computer chips), depending on the arrangement of atoms;
– and are excellent conductors of heat.

Much of current nanotechnology research worldwide focuses on these nanotubes. Scientists have proposed using them for a wide range of applications: in the high-strength, low-weight cable needed for a space elevator; as molecular wires for nano-scale electronics; embedded in microprocessors to help siphon off heat; and as tiny rods and gears in nano-scale machines, just to name a few.

Nanotubes figure prominently in research being done at the NASA Ames Center for Nanotechnology (CNT). The center was established in 1997 and now employs about 50 full-time researchers.

“[We] try to focus on technologies that could yield useable products within a few years to a decade,” says CNT director Meyya Meyyappan. “For example, we’re looking at how nano-materials could be used for advanced life support, DNA sequencers, ultra-powerful computers, and tiny sensors for chemicals or even sensors for cancer.”

A chemical sensor they developed using nanotubes is scheduled to fly a demonstration mission into space aboard a Navy rocket next year. This tiny sensor can detect as little as a few parts per billion of specific chemicals–like toxic gases–making it useful for both space exploration and homeland defense. CNT has also developed a way to use nanotubes to cool the microprocessors in personal computers, a major challenge as CPUs get more and more powerful. This cooling technology has been licensed to a Santa Clara, California, start-up called Nanoconduction, and Intel has even expressed interest, Meyyappan says.

If these near-term uses of nanotechnology seem impressive, the long-term possibilities are truly mind-boggling.

The NASA Institute for Advanced Concepts (NIAC), an independent, NASA-funded organization located in Atlanta, Georgia, was created to promote forward-looking research on radical space technologies that will take 10 to 40 years to come to fruition.

For example, one recent NIAC grant funded a feasibility study of nanoscale manufacturing–in other words, using vast numbers of microscopic molecular machines to produce any desired object by assembling it atom by atom!

That NIAC grant was awarded to Chris Phoenix of the Center for Responsible Nanotechnology.

In his 112 page report, Phoenix explains that such a “nanofactory” could produce, say, spacecraft parts with atomic precision, meaning that every atom within the object is placed exactly where it belongs. The resulting part would be extremely strong, and its shape could be within a single atom’s width of the ideal design. Ultra-smooth surfaces would need no polishing or lubrication, and would suffer virtually no “wear and tear” over time. Such high precision and reliability of spacecraft parts are paramount when the lives of astronauts are at stake.

Although Phoenix sketched out some design ideas for a desktop nanofactory in his report, he acknowledges that — short of a big-budget “Nanhatten Project,” as he calls it — a working nanofactory is at least a decade away, and possibly much longer.

Taking a cue from biology, Constantinos Mavroidis, director of the Computational Bionanorobotics Laboratory at Northeastern University in Boston, is exploring an alternative approach to nanotech:

Rather than starting from scratch, the concepts in Mavroidis’s NIAC-funded study employ pre-existing, functional molecular “machines” that can be found in all living cells: DNA molecules, proteins, enzymes, etc.

Shaped by evolution over millions of years, these biological molecules are already very adept at manipulating matter at the molecular scale — which is why a plant can combine air, water, and dirt and produce a juicy red strawberry, and a person’s body can convert last night’s potato dinner into today’s new red blood cells. The rearranging of atoms that makes these feats possible is performed by hundreds of specialized enzymes and proteins, and DNA stores the code for making them.

Making use of these “pre-made” molecular machines — or using them as starting points for new designs — is a popular approach to nanotechnology called “bio-nanotech.”

“Why reinvent the wheel?” Mavroidis says. “Nature has given us all this great, highly refined nanotechnology inside of living things, so why not use it — and try to learn something from it?”

The specific uses of bio-nanotech that Mavroidis proposes in his study are very futuristic. One idea involves draping a kind of “spider’s web” of hair-thin tubes packed with bio-nanotech sensors across dozens of miles of terrain, as a way to map the environment of some alien planet in great detail. Another concept he proposes is a “second skin” for astronauts to wear under their spacesuits that would use bio-nanotech to sense and respond to radiation penetrating the suit, and to quickly seal over any cuts or punctures.

Futuristic? Certainly. Possible? Maybe. Mavroidis admits that such technologies are probably decades away, and that technology so far in the future will probably be very different from what we imagine now. Still, he says he believes it’s important to start thinking now about what nanotechnology might make possible many years down the road.

Considering that life itself is, in a sense, the ultimate example of nanotech, the possibilities are exciting indeed.

Original Source: NASA News Release

A magnified view of muscle fibres. Image credit: UM. Click to enlarge.
Experiments for NASA space missions have shown that small amounts of edible meat can be created in a lab. But the technology that could grow chicken nuggets without the chicken, on a large scale, may not be just a science fiction fantasy.

In a paper in the June 29 issue of Tissue Engineering, a team of scientists, including University of Maryland doctoral student Jason Matheny, propose two new techniques of tissue engineering that may one day lead to affordable production of in vitro – lab grown — meat for human consumption. It is the first peer-reviewed discussion of the prospects for industrial production of cultured meat.

“There would be a lot of benefits from cultured meat,” says Matheny, who studies agricultural economics and public health. “For one thing, you could control the nutrients. For example, most meats are high in the fatty acid Omega 6, which can cause high cholesterol and other health problems. With in vitro meat, you could replace that with Omega 3, which is a healthy fat.

“Cultured meat could also reduce the pollution that results from raising livestock, and you wouldn’t need the drugs that are used on animals raised for meat.”

Prime Without the Rib
The idea of culturing meat is to create an edible product that tastes like cuts of beef, poultry, pork, lamb or fish and has the nutrients and texture of meat.

Scientists know that a single muscle cell from a cow or chicken can be isolated and divided into thousands of new muscle cells. Experiments with fish tissue have created small amounts of in vitro meat in NASA experiments researching potential food products for long-term space travel, where storage is a problem.

“But that was a single experiment and was geared toward a special situation – space travel,” says Matheny. “We need a different approach for large scale production.”

Matheny’s team developed ideas for two techniques that have potential for large scale meat production. One is to grow the cells in large flat sheets on thin membranes. The sheets of meat would be grown and stretched, then removed from the membranes and stacked on top of one another to increase thickness.

The other method would be to grow the muscle cells on small three-dimensional beads that stretch with small changes in temperature. The mature cells could then be harvested and turned into a processed meat, like nuggets or hamburgers.

Treadmill Meat
To grow meat on a large scale, cells from several different kinds of tissue, including muscle and fat, would be needed to give the meat the texture to appeal to the human palate.

“The challenge is getting the texture right,” says Matheny. “We have to figure out how to ‘exercise’ the muscle cells. For the right texture, you have to stretch the tissue, like a live animal would.”

Where’s the Beef?
And, the authors agree, it might take work to convince consumers to eat cultured muscle meat, a product not yet associated with being produced artificially.

“On the other hand, cultured meat could appeal to people concerned about food safety, the environment, and animal welfare, and people who want to tailor food to their individual tastes,” says Matheny. The paper even suggests that meat makers may one day sit next to bread makers on the kitchen counter.

“The benefits could be enormous,” Matheny says. “The demand for meat is increasing world wide — China ‘s meat demand is doubling every ten years. Poultry consumption in India has doubled in the last five years.

“With a single cell, you could theoretically produce the world’s annual meat supply. And you could do it in a way that’s better for the environment and human health. In the long term, this is a very feasible idea.”

Matheny saw so many advantages in the idea that he joined several other scientists in starting a nonprofit, New Harvest, to advance the technology. One of these scientists, Henk Haagsman, Professor of Meat Science at Utrecht University, received a grant from the Dutch government to produce cultured meat, as part of a national initiative to reduce the environmental impact of food production.

Other authors of the paper are Pieter Edelman of Wageningen University , Netherlands ; Douglas McFarland, South Dakota State University ; and Vladimir Mironov, Medical University of South Carolina.

Original Source: UM News Release

Computer illustration of a potential antimatter drive. Image credit: Positronics Research LLC. Click to enlarge.
We all played the game as children – “leapfrog” involved one child squatting on all fours while a second placed their hands on the first’s shoulders. Braced against the pull of gravity, the standing child bends at the legs deeply then thrusts up and over the top of the first. The result? The second child now squats and the another froglike leap follows in turn. Not the most efficient way to get to the swing set – but a lot of fun in the right company!

Leapfrogging however is not the same as ‘bootstrapping’. While bootstrapping, a single player bends and grabs the leather loops on the outside of both boots. The player then makes a tremendous exertion upward with the arms. Leapfrogging works – bootstrapping doesn’t, it just can’t be done without hopping – an entirely different thing altogether.

The NASA Institute for Advanced Concepts (NIAC) believes in leapfrogging – no not on the playground but in aerospace. From the institutes own website: “NIAC encourages proposers to think decades into the future in pursuit of concepts that will “leapfrog” the evolution of current aerospace systems.” NIAC is looking for a few good ideas and is willing to support them with six-month-long seed grants to test feasibility before serious research and development funds – available from NASA and elsewhere – are allocated. Hopefully such seeds are allowed to germinate and future investment grows them to maturity.

NIAC wants to separate out leapfrogging from bootstrapping, however. One works and the other makes no sense whatsoever. According to NIAC, the positron drive could lead to a giant leap forward in the way we travel throughout the solar system and beyond. There’s probably no bootstrapping about it.

Consider the positron – mirror twin of the electron – like human twins, a very rare thing. Unlike human twins, a positron is unlikely to survive the birth process. Why? Because positrons and their siblings – electrons – find each other irresistible and quickly annihilate in a burst of soft gamma rays. But that burst, under controlled circumstances, can be converted into any form of ‘work’ you might want to do.

Need light? Mix a positron and an electron then irradiate a gas to incandescence. Need electricity? Mix another pair and irradiate a metal strip. Need thrust? Shoot those gamma rays into a propellant, heat it to outlandishly high temperatures and push the propellant out the back of the rocket. Or, shoot those gamma rays into tungsten plates in a stream of air, heat that air and jettison it out the back of an aircraft.

Imagine having a supply of positrons – what could you do with them? According to Gerald A. Smith, Principle Investigator for Positronics Research, LLC of Sante Fe, New Mexico you could go just about anywhere, “the energy density of antimatter is ten orders of magnitude greater than chemical and three orders of magnitude greater than nuclear fission or fusion energy.”

And what does this mean in terms of propulsion? “Less weight, far, far, far less weight.”

Using chemically based propulsion systems, 55 percent of the weight associated with the Huygens-Cassini probe sent to explore Saturn was found in the probe’s fuel and oxidizer tanks. Meanwhile to hurl the probes 5650 kg of weight beyond the Earth required a launch vehicle weighing some 180 times that of fully-fueled Cassini-Huygens itself (1,032,350 kgs).

Using Dr. Smith’s numbers alone – and only considering the maneuvering thrust required for Cassini-Huygens using positron-electron annihilation, the 3100 kgs of chemical propellant burdening the original 1997 probe could be reduced to a mere 310 micrograms of electrons and positrons – less matter than that found in a single atomized drop of morning mist. And with this reduction in mass the total launch weight from Canaveral to Saturn could easily be reduced by a factor of two.

But positron-electron annihilation is like having plenty of air but absolutely no gasoline ? your car won?t get far on oxygen alone. Electrons are everywhere, while positrons are not naturally available on Earth. In fact where they do occur – near black hole event horizons or for short periods of time after high energy particles enter the Earth’s atmosphere – they soon find one of those ubiquitous electrons and go photonic. For this reason you have to make your own.

Enter the particle accelerator
Companies such as Positronics Research, headed up by Dr. Smith, are working on technologies inherent in the use of particle accelerators – like the Stanford Linear Accelerator (SLAC) located in Menlo Park, California. Particle accelerators create positrons using electron-positron pair-production techniques. This is done by smashing a relativistically accelerated electron beam into a dense tungsten target. The electron beam is then converted into high energy photons which move through the tungsten and turn into matched sets of electrons and positrons. The problem before Dr. Smith and others creating positrons is easier than trapping, storing, transporting, and using them effectively.

Meanwhile during pair-production, all you’ve really done is packed a whole lot of earth-bound energy into extremely small amounts of highly volatile – but extremely light-weight – fuel. That process itself is extremely inefficient and introduces major technical challenges related to accumulating enough anti-particles to power a spacecraft capable of journeying into the Great Beyond at velocities making large space probe – and human spacetravel – possible. How is all this likely to play out?

According to Dr. Smith, “for many years physicists have squeezed positrons out of the tungsten targets by colliding the positrons with matter, slowing them down by a thousand or so to use in high resolution microscopes. This process is horribly inefficient; only one millionth of the positrons survive. For space travel we need to increase the slowing down efficiency by at least a factor of one thousand. After four years of hard work with electromagnetic traps in our labs, we are preparing to capture and cool five trillion positrons per second in the next few years. Our long-range goals are five quad-trillion positrons per second. At this rate we could fuel up for our first positron-fueled flight into space in a matter of hours.”

While it is true that a positron-annihilation engine also requires propellent (typically in the form of compressed hydrogen gas), the amount of propellant itself is reduced to almost 10 percent of that required by a conventional rocket – since no oxidizer is needed to react with the fuel. Meanwhile, future craft may actually be able to scoop propellant up from the solar wind and interstellar medium. This should also lead to a significant reduction in the launch weight of such spacecraft.

Written by Jeff Barbour