|The ghost particle, so named because it resembles a thin wisp of smoke,
is believed by researchers at the University of Sheffield and University
of Buckingham to be proof of extraterrestrial life forms.|
(Photo : Sheffield University via Daily Express)
A group of astrobiologists at the Universities of Sheffield and Buckingham have released the image of the specter-looking particle to the Daily Express. The particle, which is 10 microns in width or approximately as thick as a single strand of human hair, resembles a wisp of smoke or a chiffon scarf, earning for it the nickname ghost particle.
"This is nothing short of a New Year's present from outer space," Wainwright says.
In a paper published in the Journal of Cosmology, Wainwright and his colleagues say the ghost particle is actually the cell wall (frustule) of a type of microscopic algae called diatom. In July last year, the researchers sent balloons 14 to 17 miles (22 to 27 kilometers) into the Earth's atmosphere to collect samples of particles in the stratosphere. The ghost particle, the researchers believe, may have been delivered by a comet.
"Most people will assume that these biological particles must have just drifted up to the stratosphere from Earth, but it is generally accepted that a particle of the size found cannot be lifted from Earth to heights of, for example, 27 kilometers," says Wainwright. "The only known exception is by a violent volcanic eruption, none of which occurred within three years of the sampling trip."
Skeptics, however, exist. Seth Shostak, astronomer at the Search for Extraterrestrial Intelligence in Mountain View, California, says the idea that life is distributed throughout the universe by being transported by objects such as comets, a notion called panspermia, is credible, at least over short distances, such as in solar systems. Shostak, however, says Wainwright's claims will have to stand up to scrutiny by the wider scientific community.
"In the past, most members of the astrobiology community have found it easier to ascribe these claims to terrestrial contamination than to extraterrestrial hitchhikers," Shostak says. "It remains to be seen whether that opinion will be changed by these new results."
However, Wainwright insists that the ghost particle, which is made up of carbon and oxygen, did not originate from the Earth. He says the particle appeared on the sampling stub in "absolutely pristine condition" with no traces of contamination by Earth particles, such as pollen, grass, or pollution particles. He also points to the impact craters the particles made on the sampling stub as further proof of their space origin.
Astrobiologist Chris McKay of the Ames Research Center of the National Aeronautics and Space Administration (NASA) is looking for more proof than that. Although he says it is likely the researchers discovered "curious stuff" in the atmosphere, he still subscribes to the Carl Sagan principle that "extraordinary claims require extraordinary proof."
One example of extraordinary proof McKay is looking for could be a biochemical indication that the ghost particle does not share biochemistry with life on Earth.
"If they were able to show that it was composed of all D amino acids (proteins in Earth life are made of L amino acids), that would be pretty convincing to me," McKay says.
Wainwright says he and his team are planning to conduct further studies on the ghost particle, such as finding the ratios of various isotopes, or the varieties of elements with different neutron numbers in the atomic nuclei. If the ratio of isotopes gives a certain number, the particle is from space; if it gives another, it is from Earth.
Last year, Russian scientists announced that they discovered traces of diatomic plankton on the surface and illuminators of the International Space Station (ISS). Although NASA dismissed the report, Russian ISS orbital mission chief Vladimir Solovyev said that it was the first time plankton was discovered in space. However, it isn't clear up to now how the particles have appeared on the ISS.