Study Shows Asteroids May Have Accelerated Life on Earth

A NASA-funded study indicates that an intense asteroid bombardment nearly 4 billion years ago may not have sterilized the early Earth as completely as previously thought. The asteroids, some the size of Kansas, possibly even provided a boost for early life.

The study focused on a particularly cataclysmic occurrence known as the Late Heavy Bombardment, or LHB. This event occurred approximately 3.9 billion years ago and lasted 20 to 200 million years. In a letter published in the May 21 issue of Nature magazine titled "Microbial Habitability of the Hadean Earth during the Late Heavy Bombardment," Oleg Abramov and Stephen Mojzsis, astrobiologists at the University of Colorado's Department of Geological Sciences, report on the results of a computer modeling project designed to study the heating of Earth by the bombardment.

Results from their project show that while the Late Heavy Bombardment might have generated enough heat to sterilize Earth's surface, microbial life in subsurface and underwater environments almost certainly would have survived.

"Exactly when life originated on Earth is a hotly debated topic," says Michael New, the astrobiology discipline scientist and manager of the Exobiology and Evolutionary Biology Program at NASA headquarters in Washington. "These findings are significant because they indicate that if life had begun before the LHB or some time prior to 4 billion years ago, it could have survived in limited refuges and then expanded to fill our world."

"Our new results point to the possibility life could have emerged about the same time that evidence for our planet's oceans first appears," says Mojzsis, principal investigator of the project.

A growing scientific consensus is that during our solar system's formation, planetary bodies were pummeled by debris throughout the Late Heavy Bombardment. A visual record of the event is preserved in the form of the scarred face of our moon. On Earth, all traces of the bombardment appear to have been erased by rock recycling forces like weathering, volcanoes or other conditions that cause the crust to move or change.

Surface habitats for microbial life on early Earth would have been destroyed repeatedly by the bombardment. However, at the same time, impacts could have created subsurface habitats for life, such as extensive networks of cracks or even hydrothermal vents. Any existing microbial life on Earth could have found refuge in these habitats. If life had not yet emerged on Earth by the time of the bombardment, these new subsurface environments could have been the place where terrestrial life emerged.

"Even under the most extreme conditions we imposed on our model, the bombardment could not have sterilized Earth completely," says Abramov, lead author of the paper. "Our results are in line with the scientific consensus that hyperthermophilic, or 'heat-loving,' microbes could have been the earliest life forms on Earth, or survivors from an even more ancient biosphere. The results also support the potential for the persistence of microbial biospheres on other planetary bodies whose surfaces were reworked by the bombardment, including Mars."

Watch more breaking news now on our video feed:



Bookmark http://universeeverything.blogspot.com/ and drop back in sometime.

Sensitive Laser Instrument Could Aid Search for Life on Mars

Minuscule traces of cells can be detected in a mineral likely present on Mars, a new study shows. The results, obtained using a technique developed at the U.S. Department of Energy's Idaho National Laboratory (INL), could help mission scientists choose Martian surface samples with the most promise for yielding signs of life.

INL's instrument blasts off tiny bits of mineral and looks for chemical signatures of molecules commonly found in cells. While other methods require extensive sample handling, this analysis relies on a "point-and-shoot" laser technique that preserves more of the rock and reduces contamination risk. In the current online issue of the peer-reviewed Geomicrobiology Journal, the researchers report they could detect biomolecules at concentrations as low as 3 parts per trillion.

High sensitivity is crucial for NASA's search for life on Mars, says INL scientist Jill Scott, whose team collaborated with researchers at the University of Montana-Missoula on the study.

"The worst-case scenario is a false negative," Scott says. "If you're just missing stuff, that would be devastating."

While other techniques also have achieved parts-per-trillion sensitivity, they often require scientists to first extract the organic cell remnants from the mineral. This type of preparation can use up large amounts of sample and potentially introduce contamination.

INL's method is based on a technique called laser desorption mass spectroscopy. By focusing a laser beam on a spot less than one-hundredth the width of a pencil point, the researchers can knock microscopic fragments off the mineral. Those fragments react with organic molecules to form detectable charged particles called ions. The team can then study the ion patterns for signatures that might be specific to biomolecules.

Typically, this method would require the organic molecules to be embedded in a synthetic matrix that encourages ion formation. But the INL team simply relies on the rock to act as the matrix, eliminating the need for sample preparation.

"We thought, what can the rock do for you?" Scott says. "You don't want to damage the sample more than you have to. You'd like to just shoot it directly."

With funding from NASA's Astrobiology program, the researchers have done previous studies showing that minerals like halite and jarosite yield distinct ion patterns when organic molecules are present. This time, they tried thenardite, a compound thought to be part of the Martian surface. Because thenardite is left behind when lakes dry up, its presence could signify the past existence of water -- and hence life.

The team tested thenardite samples taken from the evaporated Searles Lake bed in California. They also created artificial thenardite samples that contained traces of stearic acid, which is left behind by dead cells, and glycine, the simplest amino acid used by organisms on Earth. In all cases, the researchers found a distinct ion pattern that did not appear for thenardite alone, suggesting they had detected a signature for the biomolecules.

The team also measured the sensitivity of its instrument for the first time. By testing more and more dilute artificial samples, they found they could detect the stearic acid signature at levels as low as 3 parts per trillion. In fact, the signatures became even more distinct as concentration dropped, presumably because more ion-producing matrix surrounded each biomolecule.

While the instrument is too big to send into space, it could potentially be used for analysis if NASA brings Martian samples back to Earth.

Watch more breaking news now on our video feed:



Bookmark http://universeeverything.blogspot.com/ and drop back in sometime.

NASA GeneSat Shows Small Satellites Can Deliver Big Science

A very small NASA satellite has proven that scientists can quickly design and launch a new class of inexpensive spacecraft -- and conduct significant science. The 11-pound GeneSat-1, carrying bacteria inside a miniature laboratory, was launched on Dec. 16, 2006. It was a secondary payload on an Air Force four-stage Minotaur 1 rocket that delivered the Air Force TacSat 2 satellite to orbit.

GeneSat-1 began to transmit data on its first pass over the mission's California ground station. Scientists still receive data from the satellite regularly.

"GeneSat proves that big science can be done using small satellites," says GeneSat project manager John Hines, an engineer and scientist at NASA Ames Research Center, Moffett Field, Calif. "GeneSat's success points out how NASA can spend less money and time to learn new things in space."

According to Hines, GeneSat-1 is NASA's first fully automated, self-contained biological spaceflight experiment on a satellite of its size. "Based on this success, we expect that in the near future, this class of small satellite will see increasing acceptance and usage by the science community," Hines notes.

These small satellites will help scientists understand the hazards and risks associated with human space travel, Hines believes.

The cost to develop the GeneSat satellite class, launch the first spacecraft and operate it was a fraction of what it normally costs to conduct a mission in space, according to scientists.

Subsequent GeneSat-class missions will cost much less, Hines predicts. Researchers say that knowledge gained from GeneSat-1 will help scientists understand how spaceflight affects the human body. GeneSat-1's onboard micro-laboratory includes sensors and optical systems that can detect proteins that are the products of specific genetic activity.

Biological data returned so far have exceeded the project’s pre-launch success criteria, according to GeneSat-1 lead biologist Macarena Parra. "Throughout the experiment, the temperature remained constant and all systems functioned properly to record our required data," Parra says.
Researchers will further analyze GeneSat-1's on-board systems during the remaining life of the satellite, according to Bruce Yost, the GeneSat-1 mission manager.“We plan to conduct a number of engineering tests and evaluations to increase our confidence in the GeneSat platform," Yost says. "In the next few weeks, we will hand over the GeneSat-1 spacecraft to Santa Clara University, Santa Clara, Calif., for use as a training tool for future aerospace engineers.”

GeneSat-1 will reenter the Earth’s atmosphere and burn up before the end of the year. "Our partnership with the Santa Clara University mission operations team has surpassed all of our expectations with their level of performance and professionalism," Hines says. "This is the first NASA mission to be operated by a student-based team; they worked around the clock and over a holiday break to complete our primary mission. It was a remarkable success," Hines adds.


Bookmark http://universeeverything.blogspot.com/ and drop back in sometime.

Enter your Email





Preview Powered by FeedBlitz