by Paul Gilster | Feb 18, 2005 | Astrobiology and SETI |
New Scientist continues the focus on possible Martian life with a story on Vittorio Formisano, a European Space Agency scientist who believes he has found formaldehyde on the Red Planet. His data come from the Planetary Fourier Spectrometer aboard Mars Express, and indicate a formaldehyde concentration of 130 parts per billion. Formisano, from the Institute of Physics and Interplanetary Science in Rome, will present these results next week at a conference in the Netherlands.
Formisano’s views are bound to be controversial; the scientist believes the formaldehyde is being produced by the oxidation of methane, and says that 2.5 million tons of methane would need to be generated each year to create this much of it. New Scientist writer Jenny Hogan quotes Formisano in A Whiff of Life on the Red Planet:
“I believe that until it is demonstrated that non-biological processes can produce this, possibly the only way to produce so much methane is life,” [Formisano] says. “My conclusion is there must be life in the soil of Mars.”
The presence of formaldehyde could explain why earlier studies found uneven distributions of methane on Mars, says Formisano. Because methane takes hundreds of years to break down by itself, the wind should even out the concentration of the gas around the planet. But if it is being oxidised in some regions, such as those that are rich in iron compounds, then you would find less methane in those areas.
At issue is the sensitivity of the Planetary Fourier Spectrometer instrument, and the larger question of whether the methane already detected on Mars really is biological in origin. Expect a protracted debate next week in the Netherlands. A key point: Martian geology in many ways remains unknown to us. Drawing conclusions on an issue this momentous from questionable measurements of formaldehyde is premature, a fact Formisano himself seems to acknowledge. As he told New Scientist: “The next step is to go there and look for it.”
by Paul Gilster | Feb 17, 2005 | Exoplanetary Science |
February’s issue of the journal Icarus will refine an increasingly intriguing theory of planetary formation. Richard Durisen, a professor of astronomy at Indiana University – Bloomington used computer models to demonstrate the motion of gas as it condenses around a parent star. “These are the disks of gas and dust that astronomers see around most young stars, from which planets form,” Durisen said. “They’re like a giant whirlpool swirling around the star in orbit. Our own solar system formed out of such a disk.”
What Durisen’s theory of gravitational imbalances adds to the picture is a model of how areas of stability within the planetary disks create places for denser gases to accumulate, allowing the formation of planets. That’s valuable information, because until now we haven’t understood how a gravitationally unstable disk could avoid violent interactions with other disks materials, thus destroying young planets before they could fully form.
Image: The rings near the center of this simulation may be protected areas where planets can start to form around a young star. Credit: Indiana University.
Durisen’s work challenges the rival ‘core accretion’ theory, which is that gas giant planets initially form, like terrestrial worlds, through solid objects colliding and growing over time. “Gas giant planets are more common than we could have guessed even 10 years ago,” Durisen said. “Nature is pretty good at making these planets.” But core accretion is challenged by the need for speed. We now know that gas disks dissipate quickly, over a few million years, so planetary formation has to be fast.
“In the core accretion theory, the formation of gas giant planets gets started by a process similar to the way planets such as Earth accumulate,” Durisen said. “Solid objects hit each other and stick together and grow in size. If a solid object grows to be about 10 times the mass of Earth, and there’s also gas around, it becomes massive enough to grab onto a lot of the gas by gravity. Once that happens, you get rapid growth of a gas giant planet.”
Observations of planets around other stars indicate that many of these gas giant extrasolar worlds could not have formed this way. They’re just too big, and because building them by core accretion could take up to 100 million years, sufficient gas resources would not remain available. That gives added credence to Durisen’s gravitational instability theory, and indicates that more than one mechanism may be at work in creating a complete solar system.
You can read more about Durisen’s work in Rings Around the Stars, an article by Hal Kibbey that explains gravitational instability theory. The upcoming article in Icarus is Durisen, Cai, Mejía et al. “A Hybrid Scenario for Gas Giant Planet Formation in Rings.”
by Paul Gilster | Feb 17, 2005 | Astrobiology and SETI |
In NASA Researchers Claim Evidence of Present Life on Mars, Space.com writer Brian Berger reports that two NASA scientists have evidence that life may exist on Mars. Which is true enough, though not in itself new, since uneven methane signatures in the Martian atmosphere (detected in 2004 by Mars Express) have already revealed the possibility of an underground biosphere.
What Carol Stoker and Larry Lemke of NASA’s Ames Research Center in Silicon Valley bring to the table are their findings in southwestern Spain, where the the acidic ecology of the Rio Tinto offers an environment somewhat similar to Mars. It’s telling that concentrations of the mineral salt jarosite have been identified both on Mars and in hot springs and bodies of water like the Rio Tinto. If life could exist in an underground microbial ecosystem under conditions not terribly dissimilar from Mars, it might also be found on Mars itself.
But proceed with caution. Stoker and Lemke won’t have their paper out until May; it is currently undergoing peer review at Nature. And the next Mars rover won’t fly until 2009. We’re building an interesting case but it’s still circumstantial and will be until we have better instrumentation on the scene.
by Paul Gilster | Feb 16, 2005 | Deep Sky Astronomy & Telescopes |
Construction of the world’s largest scientific instrument is proceeding in the frigid wastes of Antarctica. The initial deployment of what will become the IceCube neutrino telescope involved drilling a 1.5-mile deep hole into Antarctic ice, then installing 60 optical detectors in it that will detect the elusive particles. But that’s just the beginning: IceCube demands 70 such holes and 4200 of the volley-ball sized optical detectors. The final telescope will take up a cubic kilometer of ice and capture particles from the edge of the visible universe.
What makes neutrinos so interesting is their ability to travel vast distances without deflection or absorption; they seem to pass ghost-like through ordinary matter, and are unaffected by magnetic fields. “Neutrinos travel like bullets through a rainstorm,” Francis Halzen, a University of Wisconsin-Madison professor of physics and the principal investigator for the project explains. “Immense instruments are required to find neutrinos in sufficient numbers to trace their origin.”
And because neutrinos are associated with huge, violent events like galactic collisions and the formation of quasars, they may be able to tell us a great deal about the earliest days of the universe.
A University of Wisconsin article explains how IceCube works:
The optical modules that make up the detector act like light bulbs in reverse. They are able to sense the fleeting flash of light created when neutrinos passing through the Earth from the Northern Hemisphere occasionally collide with other atoms. The subatomic wreck creates another particle called a muon. The muon leaves a trail of blue light in its wake that allows scientists to trace its direction, back to a point of origin, potentially identifying the cosmic accelerators – black holes or crashing galaxies, for example – that produce the high-energy neutrinos.
Image: A total of 4,200 digital optical modules or DOMs, designed to sample high-energy neutrino particles from deep space, are being deployed in 70 deep holes in the Antarctic ice by an international team of scientists, engineers and technicians. Funded primarily by the National Science Foundation, IceCube is being built by an international consortium of universities and scientific laboratories. Photo: courtesy Daan Hubert
Centauri Dreams‘ take: Tracking neutrinos to their source offers insights into the early universe unavailable through other forms of astronomy — even cosmic rays are deflected in their path to us by intervening matter and magnetic fields. But what a challenge: the hot-water drill system for IceCube by itself took 30 separate C-130 flights from McMurdo Station to the South Pole. With ten more holes and their associated detectors planned for next year, IceCube will one day emerge as a major player in our understanding of cosmology.
by Paul Gilster | Feb 15, 2005 | Outer Solar System
What Cassini heard from Huygens as it descended to Titan’s surface is now available as an audio file from the European Space Agency, but it may be easier to download it from Ralph Lorenz’ home page. Lorenz is an assistant research scientist at the University of Arizona’s Lunar and Planetary Laboratory and a co-investigator on Huygens’ Surface Science Package; he created the sound file based on Cassini data. The file compresses four hours of real-time audio into about a minute.
What the listener hears is a tone whose frequency depends on the strength of the Huygens signal as received by Cassini. The probe’s antenna emitted radio energy unevenly, “…like the petals of a flower rather than the smooth shape of a fruit,” as Lorenz puts it. As the probe’s orientation changed durings its long descent, its spin rate slowed, causing rapid changes in the tone. “You can hear how the motion becomes slower and steadier later in the descent,” Lorenz said. A UA press release on Lorenz’ work can be found here.
Meanwhile, the 2005 AAAS meeting opens February 17 in Washington, DC. The American Association for the Advancement of Science is the world’s largest scientific society, with 262 affiliated societies serving over ten million people, more than 10,000 of whom are expected at the Washington meeting. Among them will be Steven W. Squyres, who will present the latest from the Mars rovers, and mission scientists from JPL who will offer further updates on Cassini. The meeting opens just a few days after today’s Titan flyby (Cassini’s fourth), with an Enceladus encounter on the horizon for the 17th. The latter should be interesting; Enceladus reflects more than 90 percent of arriving sunlight, and is the most reflective body in the Solar System.
Image: This Cassini image of Saturn’s moon Enceladus shows a region containing bizarre, wrinkled terrain. Enceladus is covered with bright water ice. The part of its surface visible here appears to be largely free of craters — indicating that it is geologically young.
The first close imaging of this moon will be done by Cassini in February 2005 and should reveal many surprises. Enceladus has a diameter of 499 kilometers (310 miles). Credit: NASA/JPL/Space Science Institute.
You may remember that Enceladus was at one point to be the destination for Project Orion, back in the halcyon days when the mammoth nuclear rocket looked like it might become a reality. Orion was designed for huge payloads; Freeman Dyson even pondered Project Deluge, a plan for bringing water from Enceladus (where it is plentiful) to Mars via the Orion craft. For more on this, see George Dyson’s wonderful Project Orion: The True Story of the Atomic Spaceship (New York: Henry Holt, 2002). Anyone with an interest in interstellar issues should have Dyson’s book on their shelves.
