Scientists develop new theory about how life forms on asteroids

 



 

Scientists have a working theory on how life may have come to Earth via an asteroid. But how did life get onto an asteroid in the first place? Several theories exist, but they're all a little bit different. Scientists at Rensselaer Polytechnic Institute, however, have come up with a new theory that could properly explain how organic material forms on an asteroid.

The theories most often taught in astrobiology revolve around the idea that the asteroids were once warm enough that they could sustain liquid water, which is necessary for organic molecules to form. The space where they originated in is cold, so how did they get heated up to the right temperature? One theory states that the asteroids were heated radioactively, similar to Earth’s interior. The other popular theory involves how plasma interacts with a magnetic field. However, both of these theories are based on the assumption that the asteroid belt between Jupiter and Mars was once warm enough to do do this. Unfortunately, these theories don’t work because the sun was much dimmer back then than originally thought, meaning that the area was even colder than it is now.

The Rensselaer scientists started by looking at the theory involving magnetic fields. That theory states that an asteroid creates an electric field when it moves through a magnetic field. This heats up the asteroid. This theory makes the assumption that a strong solar wind was present, but that has been disproved.

However, starting with this theory gave them something to work with. They used a new understanding of how the process works, and re-calculated the electric field. With that, they determined that something called multi-fluid magneto-hydrodynamics was also at work on the asteroids. This regards how plasma interacts when introduced to a magnetic field. Generally speaking, the plasma’s neutral particles rub up against other particles and create friction. This friction creates heat. This heat creates the correct temperature for organic molecules to form.

Although the scientists feel that this theory is a good one, they still believe there are more questions to be asked and answered regarding the origin of life on asteroids.

Did Venus give Earth the moon?

 

 



 

 

LONDON —The Earth's moon may be a present from Venus, which once had a moon and then lost it, a new theory suggests. Under the theory, Earth's gravity captured Venus' old moon, giving our planet its big natural satellite.

This idea contrasts to the thinking of the vast majority of moon researchers, who believe that the Earth's moon formed some 4.5 billion years ago when a planet-size body slammed into nascent Earth at high speed.

This giant impact hypothesis, however, has its own issues, as did all the alternative moon formation theories discussed this week at the Origin of the Moon conference at the Royal Society here. [The Moon: 10 Surprising Lunar Facts]

"I think part of the key to [understanding] the moon may be that Venus has no moon, and we certainly have to study it (Venus) more," said Dave Stevenson, professor of planetary science at the California Institute of Technology, who proposed the Venus idea at the conference. In an interview with SPACE.com after his presentation, Stevenson said that he himself favored the impact theory on moon formation, but unfortunately this theory did not yet answer all the questions.

How did Earth get its moon?
The "moon capture" theory assumes that Earth used its gravitational pull to attract a pre-formed space body into its orbit, thus making a satellite of this object. [How the Moon Formed: A Lunar Tour (Video)]

However, the geochemical composition of the moon and Earth likely trips up this theory. Analyses of the lunar rocks brought back by NASA's Apollo moon landing missions have shown that the satellite has an isotopic composition very similar to that of Earth.

Isotopes refer to varieties of chemical elements that have the same number of protons, but different numbers of neutrons. Two isotopes behave the same chemically.

And if both moon and Earth have very similar isotopes, it makes the capture theory difficult to maintain, said Alex Halliday, head of science at Oxford University. Such isotopic similarities suggest that "the material that makes up the moon did actually either come out of the Earth, or that the stuff that was in the disk that formed the moon got completely mixed up with the stuff in the Earth."

Nonetheless, some aspects of the idea that the moon may have come from Venus are intriguing, he said.

"The reason why it's interesting is that Earth and Venus are close to each other. They have similar mass, and people think they have probably formed in a similar way," he said. "So the question is, if Earth and Venus formed in similar ways, how come the Earth has a moon and Venus doesn't?"

Stevenson's idea would answer that question, Halliday said, "throwing a new twist into the whole capture theory."

There are many theories for what might have caused such a large moon for a planet as small as Earth. The most popular theory assumes an impact, where the debris of the collision — a mix of the material from Earth and the other body — gave birth to the moon. This body then stayed in orbit about the Earth, forever bound to its new home.

Another posits that the moon "fissioned" from the Earth's crust and mantle due to the centrifugal force of a rapidly spinning early Earth.

Another theory, called binary accretion, assumes that the moon was born at the same time and place as Earth.



 

 

Wandering moons
The biggest flaw of the fission, capture and binary accretion theories is that they cannot account for the high angular momentum of the Earth-moon system.

Scientists believe that initially the Earth was spinning so rapidly that a day lasted only five or six hours, and the moon was in a very low-altitude orbit. But gradually, tidal drag slowed the Earth's spin and pushed the moon's orbit up to its present level.

The capture theory will always face a challenge explaining the similar composition of the moon and Earth, Stevenson said. But if scientists analyze rocks from Venus and they turn out to be very similar to those on Earth, that would argue in favor of the capture theory. The giant impact idea also has trouble explaining why the Earth and the moon are so peculiarly similar.

Even though he himself favors the impact theory, Stevenson said he picked Venus for a larger purpose.

"We cannot understand the terrestrial planets unless we understand Venus, and at the moment, we don't know anything about Venus in terms of the isotopes" it has, he says. "And I also think that as a test of our understanding of the origin of the moon, we need to understand whether Venus ever had a moon."

If Venus indeed once had a moon and lost it, how might the planet have acquired a satellite in the first place?

Unlike what would have happened with Earth, the formation of any moon of Venus may have occurred much earlier, shortly after the formation of the solar system, Stevenson said.

Back then, there were still a lot of things whizzing around," he said.

So Venus possibly would have gotten its moon after an even earlier giant impact of some sort, and the planet may have lost its moon either by collision or by escape. This would mean an object passed close by the Venus system and caused the moon to depart from its orbit, says Stevenson.

But even aside from the Venus idea, the widely preferred giant impact theory still "is not satisfactory in all respects," Stevenson said.

Sean Solomon, the director of the Lamont-Doherty Earth Observatory of Columbia University, agrees. "We are still on the trail of the detailed scenario that would seem both likely and complete in its ability to account for all the geochemical and geophysical observations," he said.

Until scientists have figured out that scenario, even the escaped moon of Venus is a plausible theory, he said.

"Even with the giant impact idea, we don't know the origin of the impacting object. It could've been an early protoplanet. It could've been a moon of another object that was removed from the gravitational field of its original [planet]. It could've been a very large asteroid. All of those scenarios are still open."

 

ISRO: India's Mars Orbiter Mission to Launch on 28 October 2013

The Indian Space Research Organisation (ISRO) has announced that the country's most ambitious space project - Mars Orbiter Mission (MOM) - is scheduled for launch on 28 October.

Last week, ISRO scientists gave a detailed presentation about the Mars mission before a national committee of experts. After reviewing the status of MOM, the panel of experts, including former ISRO chairman UR Rao, space expert Roddam Narasimha and professors from Indian Institute of Science, gave approval to launch the mission on 28 October.

Earlier, ISRO officials allotted a launch window of 21 October to 14 November, but now the launch date has been fixed for 28 October though the final date of the launch window remains the same (19 November).

Black hole might have started the universe- says big bang alternative

An artistic impression of a black hole

We’re all familiar with the Big Bang theory, the one that states that the universe exploded out of a single, dense point. But there’s a major question tied up in the Big Bang that the known laws of physics can’t explain: what was the nothing that came before everything? Some cosmologists have taken this unknown start to the universe in a different direction and suggested a brand new model for our universe. Instead of a Big Bang, our universe was formed from debris ejected when a four-dimensional star collapsed into a black hole.

The Big Bang, which surfaced in the late 1920s in the work of physicist Georges LeMaître and received a big boost in the 1960s through measurements of the cosmic microwave background, does offer explanations to some of the phenomena we see in the cosmos. Namely the fact that space is expanding. But it leaves other questions unanswered. The Big Bang doesn’t explain why such a violent event could have yielded a universe so uniform in temperature. The most common explanation is that some unknown energy made the young universe expand faster than the speed of light, which would have allowed a small patch with a uniform temperature to stretch out and that’s the cosmos we live in and see.

But the main problem with the Big Bang model is that nothing can explain what happened the moment that single point went bang, which leaves explanations about a uniform temperature largely in the realm of speculation. As Niayesh Afshordi, an astrophysicist at the Perimeter Institute for Theoretical Physics in Waterloo, Canada, puts it, “For all physicists know, dragons could have come flying out of the singularity.”

But an entirely different model might solve all these problems. With this question in mind, Afshordi and his colleagues turned to a 2000 study that states the three-dimensional universe is a membrane that floats through a ‘bulk universe’ made of four spatial dimensions.

No sign of life detected on martian surface

The Curiosity rover used a laser to sample freshly drilled rock dust on Mars. It has not found methane.

NASA's Curiosity rover has failed to find significant signs of methane in the Martian atmosphere, mission scientists reported on Thursday. The new rover information suggests that earlier reports of Martian methane—once seen as a possible sign of microbial life on the planet—may have been off target.
If the Curiosity finding holds up, it would raise questions about one of the most intriguing discoveries made about Mars in recent years: that periodic and large-scale plumes of organic methane are released from beneath the planet's surface.
"We consider this to be a quite definitive conclusion, and we're very confident with it," Chris Webster, manager of the Planetary Science Instrument Office at NASA's Jet Propulsion Laboratory in Pasadena, California, said of the new rover readings reported in the journal Science.
"It puts an upper limit on the background methane on Mars that is very constraining of any scenarios for its production on the planet."
The special interest in the gas comes from the fact that some 90 percent of the methane on Earth is the product of living microbes. Signs of methane plumes in the Martian atmosphere seen by Earth-based telescopes had earlier raised hopes of detecting similar microbial life hidden under the Martian surface.
Original Discovery Defended
The lead author of that 2009 methane plume discovery report, Michael Mumma of NASA's Goddard Space Flight Center in Greenbelt, Maryland, said that he stood by his finding that substantial and localized plumes of methane were released on Mars in 2003.
He suggests that the Martian atmosphere destroys methane much more quickly than Earth's does, and that within three years of the original measurements new observations showed that half of the methane was gone.
"These findings are actually consistent with our results," Mumma said of the findings from Curiosity. "We reported that the methane releases are likely to be sporadic and that the methane is quickly eliminated in the atmosphere.
"The good news here is that the rover instrument designed to detect methane is working, and we look forward to ongoing monitoring in the future."
Other American and European researchers have also detected elevated levels of methane in the atmosphere of Mars—for example, the European Space Agency's Mars Express orbiting spacecraft found methane in 2004—but none with the specificity reported by Mumma's team.
Curiosity Counters Methane Reports
Webster said that he took the previous reports of methane on Mars "at face value," since they too were published in peer-reviewed journals. But he said the Curiosity observations were clearly different.
While methane can be produced through geological processes, on Earth it is overwhelmingly a byproduct of microbes called methanogens. Best known as denizens of the guts of creatures ranging from humans to cattle to termites, these organisms produce the marsh gas found in wetlands and landfills. But they can also live deep underground.
Because of the harsh environment on Mars—high levels of surface radiation; low temperatures; and dry, acidic conditions—scientists have generally agreed that any microbes now alive on the planet would likely inhabit the deep underground.
Mumma's team did not point to biology as the source of the methane plumes they identified, but they did raise it as a possibility along with geological processes.
Surface Measurements Will Continue
The new paper makes the case that the methane levels Curiosity detected on the ground are so low that the likelihood of a biological source is vanishingly small.
"Methane is a very well understood gas that is quite stable," Webster said. "We know how long it lasts and how it is destroyed over decades."
While it is conceivable that something exists in the Martian atmosphere that destroys methane at a much faster pace than on Earth, "we have no evidence, no observations of what it might be," he said.
Webster said the rover's instruments have not detected any methane so far, but the possibility of error put the upper limit of methane at 1.7 parts per billion. That means that the Martian atmosphere could hold at most about 10,000 tons (nine million kilograms) of methane, notes the University of Michigan's Sushil Atreya, a co-author on the new study. On Earth, the atmosphere holds about six billion tons (5.44 trillion kilograms) of methane.
The methane-detecting device is on the rover's Sample Analysis at Mars (SAM) instrument panel and is called the tunable laser spectrometer. Webster said that efforts to detect methane will continue, but will likely be reduced if results continue to come back negative.
A European satellite is scheduled to arrive at Mars in 2016 with the specific goal of searching for gases such as methane. The ExoMars Trace Gas Orbiter was initially going to be a joint venture with NASA, but the agency pulled out for budgetary reasons.