Could a neutrino – an electrically neutral and nearly mass-free sibling to the electron – have triggered dark energy, the anti-gravity force discovered just over a decade ago?

That’s the latest idea from a team of theoretical physicists who suggest that dark energy was created from neutrino condensate in the split second after the universe’s birth 13.7 billion years ago.

The idea sprang from calculations showing that the density of dark energy is comparable to the value of neutrino mass, said lead researcher Jitesh Bhatt, with the Physical Research Laboratory in Ahmedabad, India.

Dark energy, an unknown force that is accelerating the expansion of the universe, is the leading cosmological mystery of modern-day science.

It was discovered in 1998 after astrophysicists noted that supernovae — the exploded remains of massive stars — showed an accelerated rate of expansion in the last 2 billion years or so when compared to older epochs.

Explanations for dark energy fall into two basic camps: those theories that add a new physical entity or those that change the laws of gravity, said Eric Linder with the University of California at Berkeley.

“If you search for ‘dark energy’ in just the titles (of research papers) in the past year, you will find 200 speculations on what dark energy is,” Linder wrote in an email to Discovery News. “There are a great many hypotheses for dark energy. Some ties to neutrinos have been considered for the last several years, but nothing substantial has yet come out of them.”

To account for the universe’s observed rate of acceleration, 75 percent of the mass and/or energy of the universe has to be comprised of a gravitationally repulsive force, or dark energy.

Scientists are developing several dark energy experiments, including the NASA/Department of Energy Joint Dark Energy Mission, in an attempt to refine dark energy measurements and reveal how it operates.

“It will take much more work before we can pin down the nature of dark energy,” Bhatt said. “Without knowing the nature of the dark energy, our knowledge of theoretical physics would remain incomplete.”

Bhatt’s research was published in last month’s issue of Physical Review D.

Indian researchers say they have found organic matter on the moon, a discovery that may be seconded by U.S. teams analyzing a plume of debris kicked up by the deliberate crash of a rocket body into a lunar crater.

Finding organic materials on the moon could help scientists understand the history of comet and meteorite impacts, as well as provide valuable resources for future lunar travelers or colonies.

Indian Space Research Organization scientists announced last week that a probe dispatched from the Chandrayaan-1 lunar orbiter detected chemical signatures of organic matter. The Moon Impact Probe, or MIP, separated from the Chandrayaan-1 orbiter on Nov. 14, 2008, and flew into Shackleton Crater, located on the moon’s south pole.

NASA followed with a similar mission in October that excavated a much larger debris plume from the crater Cabeus, also located on the moon’s south pole. Both teams reported finding water.

ISRO’s Surendra Pal said at a conference in Bangalore, India, last week that MIP also found organic compounds, though scientists were still working to confirm the results.

“It is an intriguing suggestion,” NASA’s chief lunar scientist Michael Wargo told Discovery News. “We are certainly very interested in learning more of their results.”

NASA scientists, meanwhile, are continuing to scrutinize data collected by the Lunar Crater Observation and Sensing Satellite, or LCROSS, and other probes which watched as a 2.5-ton empty rocket body smashed into the floor of Cabeus, kicking soil and ice past the crater’s rim and into sunlight for the first time in billions of years.

Organic compounds are composed of carbon in combination with other elements such as hydrogen, oxygen and nitrogen. Although they form the building blocks of life, they do not necessarily come from actual organisms.

Instead, they could have been created in outer space through chemical reactions and later delivered to the moon by comets or meteorites. One particular type of organic compound, polycyclic aromatic hydrocarbons, has been found in a wide variety of space environments.

NASA previously found molecules of carbon, hydrogen and nitrogen in lunar soil samples brought back to Earth during the Apollo missions of 1969 -1972, but the concentrations were extremely sparse. No complex compounds were found, although they likely were delivered to the moon by meteorites crashing into the lunar surface.

“Apparently, the harsh surface conditions destroy the more complex molecules exposed to space,” Paul Spudis, senior scientist with the Houston-based Lunar and Planetary Institute, wrote in an email to Discovery News.

The moon’s cold spots are different, he added.

“We’ve suspected that they might contain organic molecules for the same reason that water ice is there — they are protected by the extreme cold,” Spudis said.

Initial results from LCROSS show some organic material was present in the debris plume, though exactly what and how much has not yet been determined.

NASA is stepping up its space radiation studies with a round of experiments that for the first time in decades will use monkeys as subjects.

The point of the experiments is to understand how the harsh radioactive environment of space affects human bodies and behavior and what countermeasures can be developed to make long-duration spaceflight safe for travelers beyond Earth’s protective magnetic shield.

For the new study, 18 to 28 squirrel monkeys will be exposed to a low dose of the type of radiation that astronauts traveling to Mars can expect to encounter.

Scientists are particularly interested in studying how the radiation impacts the monkeys’ central nervous systems and behaviors over time.

“We realized there was a need for this kind of work,” Jack Bergman, a behavioral pharmacologist at Harvard Medical School’s McLean Hospital in Boston, told Discovery News.

“There’s a long-standing commitment on the part of NASA to deep space travel and with that commitment comes a need for knowing what kinds of adverse effects deep space travel might have, what are the risks to astronauts,” Bergman said. “That’s not been well assessed.”

NASA has zapped rats and mice to probe radiation’s impacts, but that provides only a small picture, Frank Cucinotta, head of the Space Radiation Health Project at the Johnson Space Center in Houston, told Discovery News.

“Obviously, the closer we get to man, the better,” added Eleanor Blakely, a biophysicist at Lawrence Berkeley National Laboratory who studies radiation-induced cataracts.

For Bergman’s study, squirrel monkeys trained on a variety of behavioral tasks will be tested to see how exposure to radiation impacts performance. The radiation exposures will take place at NASA’s Space Radiation Laboratory at the Department of Energy’s Brookhaven National Laboratory in New York.

“The beauty of this is that we can assess at different time points after exposure, so not only do we get a sense of rather immediate effects, but then we can look again at longer time points,” Bergman said. “That kind of information just hasn’t been available.”

The animals, which will not be killed, will remain at McLean Hospital, where they will be overseen by veterinarians and staff.

“McLean Hospital is responsible for the lifetime care of the primates,” NASA wrote in an email. “No further research is planned for them at this time.”

Before NASA first sent humans into space, it flew two chimpanzees, Ham and Enos, to test the Mercury capsules.

In all, 29 non-human primates have flown in space, including 12 on Soviet or Russian rockets and 17 on U.S. spacecraft, according to NASA’s chief veterinarian Joseph Bielitzki. Most of the missions were suborbital flights to test basic physiology and assess risks of launch and microgravity.