Mars Mission Critics Misunderstand Chemistry
Some critics of NASA's new Mars mission think NASA scientists are dummies since they should be looking for helium-based life, or perhaps vanadium-based life. These critics are missing something, as are creationist critics who live in an alternative universe in which evolution is pseudoscience.
Mars Mission Critics Misunderstand Chemistry
I’m finally back from a series of vacations and ready to pick up regular blogging again. And there’s going to be plenty of good material coming up the rest of the summer. Sunday night/Monday morning NASA’s latest Mars mission will attempt to land. Today’s Inquirer featured this front page story about the science behind the mission. Here’s an excerpt:
The rover, called Curiosity, is huge compared to its predecessors, the toy-size Sojourner and the golf-cart-size Spirit and Opportunity. It carries a host of instruments, including devices that measure radiation, detect carbon, and use lasers to vaporize and analyze minerals.
At the landing site, Gale Crater, orbiting spacecraft have previously revealed layers of sediments possibly laid down by a lake. Inside the crater is Mount Sharp, which promises exposed layers of Martian geologic history.
Scientists chose the site in hopes it could address a profound mystery of the Martian climate. Geologic features suggest water flowed there in the distant past, but nobody knows where the water went or why the climate froze up.
"There was a big event in the history of Mars where it goes from being a warm planet, wet planet, that possibly could have been amenable to life, to one that's harsh and extreme," said John Grotzinger, chief scientist for the overall mission, officially known as the Mars Science Laboratory. Solving that mystery might help scientists better understand and model the climate on Earth.
Water is one substance common to all life on Earth, said Grotzinger, a Philadelphia native and now a professor at the California Institute of Technology. On Earth, he said, life exists just about everywhere that has a source of water, energy, and carbon. One of Curiosity's missions is to determine whether Mars ever had those three components of habitability.
Some of the critics in the comments section say they can’t believe the scientists can be so stupid as to focus on carbon based life as opposed to, say, xenon-based life. Those people not only slept through high-school chemistry, they missed the column last week which featured Andy Knoll of Harvard.
NASA defines life as any self-replicating system that can undergo Darwinian evolution. It's a broad enough denfinition that it allows life without carbon, but there are reasons that carbon is well-suited to the task.
Carbon has a tendency to form chains and rings with other carbon atoms. Carbon is good at forming the backbones of long, complex molecules. Silicon has some similar chemical properties but it can’t make up the same variety of compounds. And xenon – I don’t think so.
Knoll said he reminds his students that other planets have the same periodic table of elements and same rules of chemistry that we do here on Earth. If something is chemically impossible here, it’s chemically impossible on Mars too.
If we define life too loosely, then any rock can be declared a living organism, and the quest becomes uninteresting. Scientists have to have some standards. Read more here.
Re: John Grotzinger, chief scientist for the overall mission.
In Time magazine's cover story, "Evolution's Big Bang" by J. Madeleine Nash (December 4, 1995) it was reported that John Grotzinger and his team used zircon dating to recalibrate the geological clock, "chopping the Cambrian period to about half its former length", and "announced that the interval of major evolutionary innovation did not span the entire 30 million years, but rather was concentrated in the first third". Nash reported this "explosion of biological diversity" occurred "within the span of no more than 10 million years" (p.40).
Stephen Jay Gould reduced this figure even further, and wrote: "...an elegant study, published in 1993, clearly restricts this period of phyletic flowering to a mere five million years." (Scientific American, October 1994, p. 89).
However, if the Cambrian explosion is now deemed to have occurred within a time frame of no more than 10 million years [Gould was convinced it was "a mere five million years"] then how does Grotzinger (or any other evolutionist for that matter) know with certainty how long the Cambrian period was, or that the Cambrian explosion happened "almost exactly 543 million years ago"? It all depends on the assumptions built into the dating methods used.
For example, all radiometric dating methods assume a) that no decay product was present initially or that initial quantities can be accurately estimated b) that the decay system was closed through the years and c) that the decay rate was constant over time.
One question that needs to be asked is: What conditions could invalidate these assumptions?
As Sam Bowring (one member of Grotzinger's team) commented in the Time article: "And what I like to ask my biologist friends is, How fast can evolution get before they start feeling uncomfortable?"
I would add: Is it at four million, three million, two million, one million years?
— dab- dab
Not only are you an ignorant idiot, you're also an unoriginal plagiarizer. I cut and pasted your comment in Google and this exact same argument (word for word) was on about 5 other different creationist sites over the last 14 years! Are you a robot? It's amazing how dumb you guys look trying to "outsmart" scientist who are exponentially smarter than you.— Aquanerd09 - http://www.icr.org/zircon-helium/— dab
- Actually, the modern estimate for the duration of the "explosion" is a minimum of 35 million years. That includes only the first three stages of the Cambrian. As bilaterians have now been recorded well back into the Ediacaran, perhaps 75 million years is the more relevant time frame.— anaxyrus
In pursuit of her stories, writer Faye Flam has weathered storms in Greenland, gotten frost nip at the South Pole, and floated weightless aboard NASA’s zero-g plane. She has a degree in geophysics from the California Institute of Technology and started her writing career with the Economist. She later took on the particle physics and cosmology beat at Science Magazine before coming to the Inquirer in 1995. Her previous science column, “Carnal Knowledge,” ran from 2005 to 2008. Her new column and blog, Planet of the Apes, explores the topic of evolution and runs here and in the Inquirer’s health section each Monday. Email Faye at fflam@phillynews.com.
Reach Planet of the at fflam@phillynews.com.
