New Data Find a Silver Lining of Cosmic Radiation

Artist's illustration of the Lunar Reconnaissance Orbiter. CRaTER is the instrument center-mounted at the bottom of LRO. Credit: Chris Meaney/NASA.


Cosmic radiation, it seems, may be a blessing and a curse. A team of scientists based at the University of New Hampshire have used data from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on NASA’s Lunar Reconnaissance Orbiter (LRO) to measure radiation on the Moon’s surface. They’ve found that while radiation is fatal, it can also cause the chemical changes that form the foundations of biological structures. 

CRaTER was designed to measure and characterize radiation on the Moon. It uses plastic and silicon detectors that mimic human flesh to give scientists an idea of how damaging the environment is to humans; the radiation in this case is from both galactic cosmic rays and solar energetic particles. Both these types of radiation pose a known threat to astronauts and robotic spacecraft alike.

An illustration showing the natural barrier Earth gives us against solar radiation. Credit: NASA.

NASA’s LRO has managed to gather remarkably good data. Its recent measurements were made during a quiet solar period. The lower power, pressure, fluctuations, and magnetic fluctuations of the solar wind means less interruptions. The galactic cosmic rays and solar energy particles have been able to interact more readily with detectors. Since the instruments orbit the Moon, there isn’t even an atmosphere present to shield the blow of these rays and particles.

This is a unique occurrence that has given scientists with sufficient data to validate their models of cosmic radiation. “Now we can… project GCR dose rates from the present period back through time when different interplanetary conditions prevailed,” says Nathan Schwadron, associate professor of physics at the UNH Space Science Center within the Institute for the Study of Earth, Oceans, and Space. These types of projections provide a clearer picture of the effects of cosmic rays on airless bodies throughout the Solar System’s history.

These new, more accurate models can also effectively predict radiation hazards spawned by cosmic rays and solar particles. Schwadron says that these “validated models will be able to answer the question of how hazardous the space environment is and could be during these high-energy radiation events.” Being able to anticipate high radiation events and environments will be necessary for any manned space exploration planned to go beyond low-Earth orbit.

A bootprint on the lunar regolith. Credit: NASA.

But CRaTER’s most recent finding revealed something else interesting: cosmic radiation has another important effect on the bodies it hits. While fatal to humans and damaging to robots, cosmic radiation irradiates water and ice to cause chemical alterations. The process releases oxygen atoms from water ice, which are then free to bind with carbon to form large molecules that are “prebiotic” organic molecules. The radiation process also causes the lunar soil, regolith, to darken over time. This is important in understanding the geologic history of the moon.

The data recorded on radiation environments support the current models of Earth-Moon-Mars interplanetary space. The full paper, titled “Lunar Radiation Environment and Space Weathering from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER),” was written by Schwadron and the director of EOS and lead scientist for the CRaTER instrument Harlan Spence and is published online in the American Geophysical Union’s Journal of Geophysical Research.

Source: University of New Hampshire

How NASA Will Improve its Telescopes’ Vision

The zodiacal light captures from Earth. Credit: ESO.


Most of us have experienced the frustration of pollution, fog, or clouds turning a night of stargazing into an exercise in frustration. Turns out, NASA has been dealing with the same problems since it started launching large telescopes. Even in orbit, telescopes can’t see too well through the dust that litters the inner Solar System. But a team of NASA scientists have come up with a way to lift astronomy out of this cosmic fog. 

Venus, Earth, and Mars all orbit within a dust cloud made by comets and occasional collisions between asteroids. This so-called zodiacal cloud is the Solar System’s most luminous feature after the Sun and can be up to a thousand times brighter than the objects astronomers are actually targeting. The light affects orbital observations the same way light from a full Moon affects ground based observations. The zodiacal cloud is so bright that it has interfered with every infrared, optical, and ultraviolet astronomical observation mission NASA has ever launched.

The components of the proposed EZE mission. Credit: NASA.

“To put it simply, it has never been night for space astronomers,” said Matthew Greenhouse, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, MD. Light from the cloud is greatest in the plane of Earth’s orbit, the same plane in which every space telescope operates.

So how is NASA planning to get away from the cloud? By tilting future telescopes’ orbits. This type of adjustment would let spacecraft spend a significant portion of each orbit above and below the thickest dust, giving it a clearer view of objects in space.

“Just by placing a space telescope on these inclined orbits, we can improve its sensitivity by a factor of two in the near-ultraviolet and by 13 times in the infrared,” Greenhouse explained. “That’s a breakthrough in science capability with absolutely no increase in the size of the telescope’s mirror.”

Greenhouse has teamed up with Scott Benson and the COllaborative Modeling and Parametric Assessment of Space Systems (COMPASS) study team, both at NASA’s Glenn Research Center in Cleveland, OH. They’re investigating missions to put a telescope in this type of angle plane — an extra-zodiacal orbit — using new developments in solar arrays, electric propulsion and lower-cost expendable launch vehicles.

They’ve developed a proof-of-concept mission called the Extra-Zodiacal Explorer (EZE), a 1,500-pound EX-class observatory. EZE would launch on a SpaceX Falcon 9 rocket. A powerful new solar-electric drive as its upper stage would direct the spacecraft on a gravity-assist manoeuver past Earth or Mars, a flyby that would redirect the mission into an orbit inclined by as much as 30 degrees to Earth’s.

A NEXT engine during a test fire. At the time the image was taken, in December 2009, the thruster had operated continuously for more than 25,000 hours; it has now run for more than 40,000 hours. Credit: NASA.

NASA’s Evolutionary Xenon Thruster (NEXT) engine is an improved type of ion drive. It operates by removing electrons from atoms of xenon gas and accelerating the charged ions through an electric field to create thrust. While these types of engine provide much less thrust at any given time than traditional chemical rockets, they are much more fuel efficient and can operate for years.

Two of these advanced engines, which get their power from onboard solar arrays, would be housed in the EZE upper stage. They would fire to send the spacecraft on the planetary flyby that would put it into an extra-zodiacal orbit. “We’ve run one NEXT thruster for over 40,000 hours in ground testing, more than twice the thruster operating lifetime needed to deliver the EZE spacecraft to its extra-zodiacal orbit,” Benson explained. “This is mature technology that will enable much more cost-effective space missions across both the astrophysics and planetary science disciplines.”

If this concept mission works, the team says, it will be the best performance from an observatory in the history of NASA’s Explorer program. It will also be a game changer. As Greenhouse explained, “it will make extra-zodiacal orbits available to any astronomer proposing to NASA’s Explorer program. This will enable unprecedented science capability for astrophysics Explorers.”

Source: NASA.

ALPHA Closes in on Antimatter

What matter and antimatter might look like annihilating one another. Credit: NASA/CXC/M. Weiss


We live in a universe made of matter. But at the moment of the Big Bang, matter and antimatter existed in equal amounts. That antimatter has all but disappeared suggests that nature, for some reason, has a strong preference for matter. Physicists want to know why matter has replaced its antimatter twin, and this week the ALPHA collaboration at CERN got a step closer to unraveling the mystery. 

ALPHA, an international collaborative experiment established in 2005, was designed to trap and measure antihydrogen particles with a specially designed experiment. It’s picking up where its antimatter-searching predecessor, ATHENA, left off. The focus is on antihydrogen because hydrogen is the most prevalent element in the universe and its structure is extremely well known to scientists.

Each hydrogen atom has one electron orbiting its nucleus. Firing light at the atoms excites the electron, causing it to jump into an orbit further away from the nucleus before it relaxes and returns to its resting orbit emitting light in the process. The frequency distribution of this emitted light is known; it has been precisely measured and, in our universe made of matter, is unique to hydrogen.

An illustration of hydrogen and antihydrogen. Credit: USAF

Basic physics dictates that hydrogen’s antimatter twin, antihydrogen, should be equally recognizable by having an identical spectrum. That is, if everything we know about particle physics is right. Capturing and measuring antihydrogen’s spectrum is the main goal of the ALPHA group.

ALPHA has taken the first modest measurements of antihydrogen. In the ALPHA apparatus, antihydrogen is trapped by an arrangement of magnets that affect the magnetic field of the atoms. Microwaves tuned to a specific frequency aimed on these antihydrogen atoms flips their magnetic orientation, liberating them. The freed antihydrogen meets hydrogen as it escapes and the two annihilate one another, leaving a well known pattern in particle detectors surrounding the apparatus.

The apparatus captured evidence of the electron jumping orbits in an antihydrogen atom after microwave radiation changed its internal state. The result further proves the validity of ALPHA’s approach, demonstrating that the apparatus has enough control and sensitivity to successfully carry out the experiment it was designed for. In the future, ALPHA will focus on improving the precision of its microwave measurements to uncover the antihydrogen spectrum using lasers.

The exciting results were hard to come by as antihydrogen does not exist in nature. It’s made in the ALPHA apparatus from antiprotons that are themselves made in the Antiproton Decelerator and positrons from a radioactive source. And it has to have a low enough energy level to stay trapped for measurements. But it’s working, and it just might give physicists the key they need to understand the mystery of the early universe.

Source: CERN

Our Early Universe: Inflation, or Something Totally Wacky?

A schematic look at the universe - where it came from and where it is now. Credit: NASA.


Astronomers generally accept the theory that our universe looks the way it does because of cosmic inflation — rapid expansion in the moments after its birth. This explains the expanse and apparent flat shape of the universe observed through instruments like NASA’s Wilkinson Microwave Anisotropy Probe. But inflation isn’t the only model that explains the early universe. There are others, and they get wacky. 

Three physicists from the University at Buffalo — Ghazal Geshnizjani, Will Kinney and Azadeh Moradinezhad Dizgah — set out to investigate other cosmic models. Their study titled “General Conditions for Scale-Invariant Perturbations in an Expanding Universe” appeared in November in the online Journal of Cosmology and Astroparticle Physics (not to be confused with the Journal of Cosmology) and contained some interesting results.

This picture of the infant universe from NASA's Wilkinson Microwave Anisotropy Probe (WMAP) reveals 13 billion+ year old temperature fluctuations that correspond to the seeds that grew to become the galaxies. Credit: NASA Goddard Space Flight Center.

They stuck with the basics — that the theory of gravity is correct and that the early universe did rapidly expand. With these two constraints, the team found that only three models explain the early universe and the distribution of matter we observe today. But these models require very strange physics.

According to their calculations, the early universe required an accelerated cosmic expansion (inflation), a speed of sound faster than the speed of light, or extremely high cosmic energy to end up with our current universe. The third model actually demands such high energy that scientists would need to invoke a theory of quantum gravity like string theory to explain the extra dimensions of space-time that would pop up.

The takeaway message? Inflation turns out to be the only way to explain the universe within the context of standard physics, said Kinney. He allows that someone might come up with exotic physics to explain or create other models, like a speed of sound faster than that of light, but suspects people are more comfortable working with models that fit within commonly accepted laws of particle physics.

The difficulty of explaining other models, said Kinney, “puts the idea of inflation on a much stronger footing, because the available alternatives have problems, or weirdnesses, with them.”

Cosmic inflation incorporates quantum field theory to explain the distribution of matter in the universe. Under normal circumstances, particles of matter and antimatter can pop into existence suddenly before colliding and annihilating each other instantly. These pairs flew apart so rapidly after the universe’s birth that they didn’t have a chance to recombine. The same theory applies to gravitons and antigravitons, which form gravity waves.

These particles of matter are the basis of all structure in the universe today. Tiny fluctuations cause matter to collapse and form stars, planets, and galaxies.

But the hunt for other viable models continues. Kinney for one isn’t finished exploring other theories, including those that rely on superluminal sound speeds. There may yet be some major changes to our understanding of the cosmos.

Source: The University of Buffalo

NEOShield: a Preemptive Strike Against Asteroids

What an asteroid hitting the Earth might look like. Image credit: NASA/Don Davis.


Scientists aren’t entirely sure when the last major asteroid hit the Earth, but it’s certain to happen again. Alan Harris, asteroid researcher at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR), is hoping to head the next one off. Last month, Harris established an international collaboration of 13 researchers to investigate methods of shielding the Earth from near Earth objects (NEOs). The project is, appropriately, called NEOShield.

Asteroids approaching the planet typically travel between 5 and 30 kilometres (about 5 to 19 miles) per second. As that speed, a moderate sized body can have major consequences. The Barringer Crater in Arizona, often referred to as Meteor Crater, is a 1,200 metre crater (about 3,950 feet or 0.7 miles) that scientists hypothesize was caused by a 50 metre (164 feet) meteor.

The bad news is that there are thousands of known NEOs just like the one that made Meteor Crater, leading experts to posit that a dangerous collision could occur as often as every two hundred years.

Meteor Crater near Winslow, Arizona. Image credit: NASA.

The good news is that it’s possible to stop an asteroid hitting the Earth. You just have to be in the right place at the right time to give the object the right push in another direction.

Scientists are focusing on possible methods of redirecting threatening asteroids so they miss the Earth. “In order to modify their orbit and prevent a collision with Earth, a force must be exerted on them,” explains Alan Harris. “And at the precise time, as well.” One way to do this is to have a spacecraft impact a threatening asteroid, imparting enough force to change its orbit. “In my opinion, this is a very practical method,” said Harris. But there are still questions to answer, like how to guide the spacecraft to a moving target at the right angle for the right impact and how to minimize the effects of fuel movement on the spacecraft’s path.

Another way is to use the spacecraft’s gravitational pull to nudge the asteroid into a different orbit. If the object is far enough away, a tiny tug could have a big effect. But so far, “this method only exists on paper,” said Harris, “but it could work.”

An asteroid, docile in space but deadly to Earth. Image credit: NASA/JPL

Another third, less appealing prospect, is to use explosive power to break up an Earth-bound asteroid. But this could be disastrous, creating a shower of debris instead of one solid piece. As such, Harris considers this method a last resort. “If a very large, dangerous object with a diameter of one kilometre [0.6 miles] or more is discovered,” explains Harris, changing its orbit won’t be a option. “The greatest force we would be able to use to divert the asteroid from its path would be a nuclear explosion. This technique is regarded as a very controversial.”

Over the next three years, during which the European Union will support the project with four million Euros and international partners will contribute an additional 1.8 million Euros, the NEOShield project will research these defence methods. The scientists will focus on data from asteroid observations and lab experiments to generate computer simulations, ultimately determining how best to protect the Earth from future devastating impacts.

Source: DLR News Portal

NASA’s Going Green

he launch of the Phoenix spacecraft on a Delta II rocket in 2007. NASA is looking for alternatives to hydrazine monopropellant, used en route by Phoenix's navigational thrusters Image credit: NASA/Sandra Joseph and John Kechele


NASA announced yesterday that it’s looking for new technology proposals using environmentally friendly fuels to launch payload. The space agency is hoping to move away from hydrazine, the fuel that currently launches anything that travels beyond the atmosphere from commercial satellites to private spaceflight and exploration probes. 

As a rocket propellant, hydrazine is great. It’s incredibly efficient, can be stored for long periods of time, has excellent handling characteristics, is stable up to 250 degrees Celsius (482 Fahrenheit) under normal conditions, and decomposes cleanly.

It also happens to be extremely toxic.

Shifting away from hydrazine would be a shift away from known environmental hazards and pollutants. There would be fewer operational hazards for those dealing with fueled rockets before launch. The change could also simplify the complexity of the rockets’ systems and, possibly, increase overall propellant performance.

The ALICE powered rocket before launch. Image credit: Dr. Steven F. Son, Purdue University

The benefits don’t stop there. Advantages on every level trickle down. “High performance green propulsion has the potential to significantly change how we travel in space,” said Michael Gazarik, director of NASA’s Space Technology Program at the agency’s headquarters in Washington. “By reducing the hazards of handling fuel, we can reduce ground processing time and lower costs for rocket launches, allowing a greater community of researchers and technologists access to the high frontier.”

Developing green propellants won’t be quick or easy. It will be a major challenge for NASA, particularly from a cost, schedule, and risk perspective. The agency has established the Technology Demonstration Missions Program at the Marshall Spaceflight Centre in Huntsville, Alabama to oversee the green fuel program. It will act as a bridge between laboratory confirmation of a technology and its use on a mission.

This isn’t the first time NASA has tried to develop green fuel. In 2009, the space agency and the US Air Force successfully launched a 9-foot rocket 1,300 vertical feet using a mixture of aluminum powder and water ice. The mixture, called ALICE, has been studied since the 1960s as an alternative propellant. The reaction between substances produces a large amount of energy during combustion and green exhaust products.

Environmental impact aside, fuels like ALICE could be manufactured on the Moon or Mars, negating the cost of sending propellants along as cargo on long-duration missions. This would be when designing long-term missions.

The winning aircraft - Pipistrel-USA, Taurus G4 - during its flight as part of the miles per gallon flight. (NASA/Bill Ingalls)

Aviation, too has been an outlet for NASA’s green fuel initiatives in the past. 2011’s CAFE Green Flight Challenge, sponsored by Google, had competitors in general aviation design aircraft capable of flying 200 miles in less than two hours and use less than one gallon of fuel per passenger. The first place winner of $1.35 million was the team of State College, Pennsylvania used an electric aircraft that achieved twice the fuel efficiency required by the competition — they flew 200 miles on the equivalent of a half-gallon of fuel per passenger.

With this shift to green fuels, NASA hopes to partner with American companies to usher in a new environmentally friendly era of open access to space. The agency is planing to make multiple contract awards for green technologies with no single away exceeding $50 million.

Source: NASA


Russia Sets Its Sights on the Moon for 2020

The Moon. Image credit: NASA.


Looks like Republican Presidential hopeful Newt Gingrich might have some competition if he wants to be the first to build a base on the Moon. Last week, the Russian Space Agency Roscosmos announced plans to put a man on the Moon by the end of the decade with a lunar base as its next step.  

After canceling its lunar Zond program in early 1970s, the former Soviet Union took aim elsewhere in space. In 1998, Russia jumped back in the Moon game with Luna Glob, a series of robotic missions to the Moon that could come together to make a lunar orbiting space station or a base on the surface.

USSR's Zond 3 spacecraft. Image credit: NASA.

Now, Russia’s sights are set on a manned mission. “Man should return to the Moon,” head of Roscosmos Vladimir Popovkin told the Ekho Moskvy radio station. “And not just like in 1969, to leave a mark. We can do important work there.” He lists solar observation among the science goals.

More recently, another opportunity has arisen for Russia to pursue a lunar program. In 2008, NASA proposed the creation of an International Lunar Network, a set of interconnected manned bases scattered over the surface of the Moon. Popovkin said recently that Russia may coordinate with the European Space Agency and join the ILN.

Russia’s lunar announcement comes on the heels of a bad year for Roscosmos. The agency lost five missions in 2011, including the Phobos-Grunt mission that never reached its target Martian Moon. After months in Earth orbit it fell through the atmosphere earlier this year. This most recent loss might be the spark behind the new push for exploration. “Perhaps, we need a more specific, realistic Moon program, and do any Mars research as a part of a bigger international program,” Anatoliy Davydov, the deputy head of Roscosmos, said in the aftermath of the Phobos-Grunt failure.

Illustration of a Luna Glob landing module. Image credit: RussianSpaceWeb.

But the loss of Phobos-Grunt could anticipate trouble on the Luna Glob missions and any later attempts to reach the Moon. Luna Glob is technologically similar to the failed Mars mission, which means it shares the same vulnerabilities. There will have to be some major changes before Russia can move forward towards the Moon. “The design decisions used on Phobos-Grunt need to be reconsidered and significantly adjusted. Unfortunately, the same ones are used on the lunar missions. This is likely to push back the dates of any future launches, particularly of the Luna Glob modules” said Lev Zelenkin, who is closely involved with both projects.

Another variable in a Russian lunar program is NASA’s possible withdrawal from the ESA-based ExoMars mission. If NASA does pull out, the ESA hopes Roscosmos will step in. Not having NASA’s power and experience on Mars will certainly change the mission, as well Russia’s involvement. The country’s track record on Mars isn’t stellar, and a decision to tempt that galactic ghoul again with another mission to the red planet would likely supercede any Russian missions to the Moon.

Vladimir Popovkin, head of Roscosmos. Image credit: Space Daily.

If Russia does turn its attention to manned lunar missions and eventually a lunar base, anyone will be eligible to go. Roscosmos is looking for volunteer cosmonauts through an X-Factor style search it hopes will rekindle public interest in Russian spaceflight. If you have a scientific or medical degree, are fluent in English, and wear shoes no bigger than a UK size 11, you could be the first cosmonaut to leave a boot print on the lunar surface.

Source: RT

Looks Like We’re Still Looking for Earthly Life Forms on Other Planets

GFAJ-1, the bacterium found in California's Lake Mono. Image credit: Science/AAAS


In late 2010, NASA set the Internet buzzing when it called a press conference to discuss an astrobiological finding that would impact the search for extraterrestrial life. Many speculated that some primitive life had been found on Mars or one of Saturn’s moons. But the evidence was found on Earth; a strain of bacteria in California’s Lake Mono that had arsenic in its genetic structure. The discovery implied that life could thrive without the elements NASA typically looks for, mainly carbon and phosphorous. But now, a new study challenges the existence of arsenic-based life forms. 

The 2010 paper announcing arsenic based life, “Arsenic-eating microbe may redefine chemistry of life,” was written by a team of scientists led by Felisa Wolfe-Simon. The paper appeared in Science and refuted the long-held assumption that all living things need phosphorus to function, as well as other elements including carbon, hydrogen, and oxygen.

Lake Mono, as seen from Space. Image credit: NASA

The phosphate ion plays several essential roles in cells: it maintains the structure of DNA and RNA, it combines with lipids to make cell membranes, and it transports energy within the cell through the molecule adenosine triphosphate (ATP). Finding a bacteria that uses normally poisonous arsenic in the place of phosphate shook up the guidelines that have structured NASA’s search for life on other worlds.

But microbiologist Rosie Redfield didn’t agree with Wolfe-Simon’s article and published her concerns as technical comments in subsequent issues of Science. Then, she put Wolfe-Simon’s results to the test. She led a team of scientists at the University of British Columbia in Vancouver and tracked her progress online in the name of open science.

Redfield followed Wolfe-Simon’s procedure. She grew GFAJ-1 bacteria, the same strain found in Lake Mono, in a solution of arsenic with a very small amount of phosphorus. She then purified DNA from the cells and sent the material to Princeton University in New Jersey. There, graduate student Marshall Louis Reaves separated the DNA into fractions of varying densities using caesium chloride centrifugation. Caesium chloride, a salt, creates a density gradient when mixed with water and put in a centrifuge. Any DNA in the mixture will settle throughout the gradient depending on its structure. Reaves studied the resulting DNA gradient using a mass spectrometer to identify the different elements at each density. He found no trace of arsenic in the DNA.

Redfield’s results aren’t by themselves conclusive; one experiment isn’t enough to definitively disprove Wolfe-Simon’s arsenic-life paper. Some biochemists are eager to continue the research and want to figure out the lowest possible level of arsenic that Redfield’s method could detect as a way of determining exactly where arsenic from the GFAJ-1 DNA ends up on a caesium chloride gradient.

Dr. Redfield. Image credit: M. Dee/Nature

Wolfe-Simon is also not taking Redfield’s results as conclusive; she is still looking for arsenic in the bacterium. “We are looking for arsenate in the metabolites, as well as the assembled RNA and DNA, and expect others may be doing the same. With all this added effort from the community, we shall certainly know much more by next year.”

Redfield, however, isn’t planning any follow-up experiments to support her initial findings. “What we can say is that there is no arsenic in the DNA at all,” she said. “We’ve done our part. This is a clean demonstration, and I see no point in spending any more time on this.”

It’s unlikely that scientists will conclusively prove or disprove the existence arsenic-based life anytime soon. For the time being, NASA will likely confine its search for extraterrestrial life to phosphorus-dependent forms we know exist.


NASA’s New Eyes in the Sky

An artist's concept of NuSTAR in space. Image credit: NASA/JPL-Caltech/Orbital


On March 14, NASA will launch the Nuclear Spectroscopic Telescope Array or NuSTAR. This is the first time a telescope will focus on high energy X-rays, effectively opening up the sky for more sensitive study. The telescope will target black holes, supernova explosions, and will study the most extreme active galaxies. NuSTAR’s use of high-energy X-rays have an added bonus: it will be able to capture and compose the most detailed images ever taken in this end of the electromagnetic spectrum. 

NuSTAR’s eyes are two Wolter-I optic units; once in orbit each will ‘look’ at the same patch of sky. The Wolter-I mirror works by reflecting an X-ray twice, once off of an upper mirror shaped like a parabola and again off a lower mirror shaped like a hyperbola. The mirrors are nearly parallel to the direction of the incoming X-ray, reflecting most of the X-ray instead of absorbing it, but the slight angle allows for a very small collection area per surface. To get a full picture, mirrors of varying size are nested together.

Technicians work on NuSTAR this month at the Orbital Science Corporation in Dulles, Virginia. Image credit: NASA/JPL-Caltech/Orbital

Each of NuSTAR’s eyes, each unit, are made of 133 concentric shells of mirrors shaped from flexible glass like that found in laptop computer screens. This is an improvement over past missions like Chandra and XMM-Newton that both used high density materials such as Platinum, Iridium and Gold as mirror coatings. These materials achieve great reflectivity for low energy X-rays but can’t capture high energy X-rays.

Like human eyes, NuSTAR’s optical units are co-aligned to give the telescope a wider field of view and enable the capture of more sensitive images. These images will be made into detailed composites by scientists on the ground.

Also like human eyes, NuSTAR’s optical units need to be distanced from one another since X-ray telescopes require long focal lengths. In other words, the optics must be separated by several meters from the detectors. NuSTAR does this with a 33 foot (10 metre) long mast or boom between units.

Previous X-ray missions have accommodated these long focal lengths by launching fully deployed observatories on large rockets. NuSTAR won’t. It has a unique deployable mast that will extend once the payload is in orbit. This allows for a launch on the small Pegasus rocket. Undeployed, the telescope measures just 2 metres in length and one metre in diameter.

During its two-year primary mission, NuSTAR will map the celestial sky focussing on black holes, supernova remnants, and particle jets traveling near the speed of light. It will also look at the Sun. Observations of microflares could explain the temperature of the Sun’s corona. It will also search the Sun for evidence of a hypothesized dark matter particle to test a theory about dark matter.

NuSTAR's mast. Image credit: NASA/JPL-Caltech/Orbital

“NuSTAR will provide an unprecedented capability to discover and study some of the most exotic objects in the universe, from the corpses of exploded stars in the Milky Way to supermassive black holes residing in the hearts of distant galaxies,” said Lou Kaluzienski, NuSTAR program scientist at NASA Headquarters in Washington.

The telescope shipped from the Orbital Sciences Corporation in Dulles, Virginia to Vandenberg Air Force Base in California on January 27. There, it will be mated to its Pegasus launch vehicle on February 17. It will launch from underneath the L-1011 “Stargazer” aircraft on March 14 after taking off near the equator from Kwajalein Atoll in the Pacific.

Source: NASA

A Pegasus rocket launches from underneath a L-1011 "Stargazer" aircraft, just like NuSTAR will do in March. Image credit: NASA/JPL-Caltech/Orbital

Remembering NASA’s Lost Astronauts

Credit: NASA.


Today is NASA’s Day of Remembrance, a occasion to recall the seventeen astronauts who have died in pursuit of space exploration. The anniversaries of each accident — Apollo 1, Challenger, and Columbia — fall eerily close together, and give us recourse to stop and think about the cost of traveling beyond our planet.

The Apollo 1 crew. From the left: Ed White, Gus Grissom, and Roger Chaffee. Credit: NASA

On January 27, 1967, the Apollo 1 crew was killed when a fire broke out in the command module during a routine prelaunch test. Engineers outside the spacecraft were unable to open the hatch and the crew died of asphyxiation.

Commander Gus Grissom was one of NASA’s first astronauts, a veteran of the Mercury and Gemini programs. Senior pilot Ed White was a Gemini veteran already in the history books as the first American to complete extra-vehicular activity, more commonly known as a spacewalk. The mission’s pilot was Roger Chaffee, a rookie whose first flight would be Apollo 1.

The Challenger crew. From the left: Ellison Onizuka, Michael Smith, Christa McAuliffe, Dick Scobee, Gregory Jarvis, Judith Resnick, and Ronald McNair. Credit: NASA

On January 28, 1986, the NASA’s Shuttle program experienced its first major setback. Just 73 seconds after the launch of STS-51, one of the external booster rockets failed. A faulty o-ring didn’t make a tight seal over one of the joints and a jet of hot flame escaped. This breached the external fuel tank, allowing the liquid hydrogen and liquid oxygen it contained to come into contact. The fuel ignited and the tank exploded. The force ripped the Challenger orbiter apart, killing the crew of seven.

Commander Dick Scobee, Mission Specialists Ronald McNair, Ellison Onizuka, and Judith Resnick, as well as Pilot Michael Smith were veteran astronauts. Payload specialist Gregory Jarvis was making his first flight into space, as was Christa McAuliffe. McAuliffe, the most recognizable member of the crew, was part of NASA’s Teacher in Space program. Her participation on the flight symbolized the accessibility of space and was an inspiration to children. Millions of students across the nation had followed her story and saw the disaster unfold on live television.

On February 1, 2003, the orbiter Columbia disintegrated during reentry; NASA lost contact with the crew just 16 minutes before its planned landing. A piece of foam had fallen from one of the external solid rocket boosters during launch, tearing a hole in the orbiter’s wing. With its structural integrity compromised, the forces of reentry became too great, and the spacecraft fell apart. None of the crew survived.

The Columbia crew. From the left: Mission Specialist David Brown, Commander Rick Husband, Mission Specialists Laurel Clark, Kalpana Chawla and Michael Anderson, Pilot William McCool and Payload Specialist Ilan Ramon. Credit: NASA.

Commander Rick husband was a veteran astronaut, as were Mission Specialists Kalpana “K.C.” Chawla and Michael Anderson. The rest of the crew made their first spaceflight on the STS-107 mission: Pilot Willie McCool, Payload Specialist Ilan Ramon and Mission Specialists Laurel Salton Clark and David Brown.

The very thin silver lining, and what we should bear in mind as we mourn fallen astronauts, is that NASA has learned from these experiences. The sacrifices these men and women have made has made spaceflight safer. Risk is a inescapable part of human space exploration, but that doesn’t make it not worthwhile.

Grissom poses with his Mercury Capsule Liberty Bell 7. Credit: NASA.

Gus Grissom serendipitously wrote his memoirs during the Gemini program, and address the risk inherent in spaceflight in his closing paragraph. I can think of no better words, and so I’ll let Grissom set the tone we ought to take when remembering those lost in pursuit of space exploration: “There will be risks, as there are in any experimental program, and sooner or later, inevitably, we’re going to run head-on into the law of averages and lose somebody. I hope this never happens… but if it does, I hope the American people won’t feel it’s too high a price to pay for our space program.”

Source: NASA