December 22, 2007
3:07 p.m. EST
NASA, Dept. of Big Rocks
Coco Beach, FL 32931
Dear Wayfaring Strangers:
I couldn’t resist throwing in this little note to you all regarding a news item I saw in Yahoo! News:
Asteroid May Hit Mars in Next Month
by Alicia Chang, AP Science Writer
(http://news.yahoo.com/s/ap/20071221/ap_on_sc/mars_asteroid;_ylt=AnDeaMWgPpCzLXhBFJ7DiK4PLBIF)
Here’s an excerpt:
Mars could be in for an asteroid hit. A newly discovered hunk of space rock has a 1 in 75 chance of slamming into the Red Planet on Jan. 30, scientists said Thursday. “These odds are extremely unusual. We frequently work with really long odds when we track … threatening asteroids,” said Steve Chesley, an astronomer with the Near Earth Object Program at NASA’s Jet Propulsion Laboratory.
Please click on the above link to read the entire article. I’m only going to bring up a couple of points of interest to me (and thus, I hope to you).
First, in the fourth paragraph, Chang writes that the scientists who are tracking said asteroid “initially put the odds of impact at 1 in 350 but increased the chances this week.” What?! Did they get more information that led them to draw a different conclusion? Or was this a case of circumstances changing (like the trajectory of the asteroid) so that the chances of a hit itself increased? In other words, what changed: the objective situation or the scientists’ perception of the objective situation?
Now, I am the first to recognize that philosophical questions like this are well outside the scope of a news article. Chang did an excellent job of reporting the science in terms we laypersons can easily understand. But I do have to wonder… what’s really going on in those NASA labs? Those white-coated men and women of science are people like you and me: that is to say, with prejudices, loves and dislikes, motives, and personal challenges. Exactly how do these people handle the intrusion of their personal lives into their work? This isn’t exactly a major worry of mine at present, but suppose an asteroid really was coming awfully close to Earth. I would hope that the folk interpreting the data were very, very sober that day, wouldn’t you?
I am in no way casting aspersions upon the fine academics and engineers at NASA. This question is purely hypothetical and intended only to get my readers to question their own assumptions about how the business of science is actually done here in really, real reality. Would you be willing, for instance, to be the first test subject to use an anti-gravity vehicle (flying car)? How about the first volunteer to try out a jet propelled backpack? Would you like to be the first person to use a transporter a la Star Trek?
The second interesting question I have about Chang’s article stems from her third paragraph:
“ The asteroid…is similar in size to an object that hit remote central Siberia in 1908, unleashing energy equivalent to a 15-megaton nuclear bomb and wiping out 60 million trees.”
I’m going to gloss over the obvious questions like: 1) where did she get the figures of “60 million” and “15-megaton,” and 2) is it pronounced “new-clear” or “nyoo-clear,” and move right on to a deeper question having to do with the public’s perception of science journalism.
Did you notice that the above quote assumes that there was indeed an asteroid that hit Siberia in 1908? That something exploded in the air above Tunguska on June 30, 1908 at around 7 a.m. is supported by many eyewitnesses’ testimonies. For a collection of these eyewitness accounts with some amazing artist’s renderings of the event check out the site entitled “1908 Siberia Explosion: Reconstructing an Asteroid Impact from Eyewitness Accounts” by William K. Hartmann of the Planetary Science Institute based in Tuscon, Arizona.
[http://www.psi.edu/projects/siberia/siberia.html]
Hartmann writes about the reindeer herders who were camped roughly 30 kilometers (or approximately18.64 miles):
“One older man at about this distance was reportedly blown about forty feet into a tree, causing a compound fracture of his arm, and he soon died. Hundreds of the herders’ reindeer, in the general area around ground zero, were killed. Many campsites and storage huts scattered in the area were destroyed.”
You can also find out more about the Institute itself at its website:
[http://www.psi.edu/]
If you click on “About the Institute” on the left hand column of the home page you’ll find the following excerpt describing their collective mission:
“The Planetary Science Institute is a nonprofit science research institute focusing on the exploration of the solar system. Our scientists are distributed in 13 states, the United Kingdom, Italy, Russia, Switzerland and Japan. We are headquartered in Tucson, Arizona, where PSI was founded in 1972. We are involved in numerous NASA missions, the study of Mars, asteroids, comets, interplanetary dust, impact physics, the origin of the solar system, planet formation about other stars, dynamics, impact physics, and the rise of life.”
Quite an impressive institutional resume, I’d say. These are the people who have done the scientific detective work to back up their hypotheses with facts. As a writer and layperson (meaning I have just enough knowledge about science to be dangerous), I would consider information from PSI to be reliable and would have confidence in using these scientists as a source in writing an article about, say, the odds of an asteroid hitting the Earth.
While the theory of an asteroid explosion (more accurately called a “meteroid airburst”) for the Tunguska event is now widely accepted, the material composition of the body which exploded in mid-air remains controversial. The Wikipedia entry entitled “Tunguska event” relates this historical contoversy in section 3.3 entitled “Asteroid or comet?”
“In 1930, the British astronomer F.J. Whipple suggested that the Tunguska body was a small comet. A cometary meteorite, being composed primarily of ice and dust, could have been completely vaporized by the impact with the Earth’s atmosphere, leaving no obvious traces. The comet hypothesis was further supported by the glowing skies (or “skyglows” or “bright nights”) observed across Europe for several evenings after the impact, possibly explained by dust and ice that had been dispersed from the comet’s tail across the upper atmosphere. The cometary hypothesis gained a general acceptance amongst Soviet Tunguska investigators by the 1960s.”
By the end of the twentieth century, however, further research gave more credence to the asteroid theory rather than the comet. The author[s] of the Wikipedia entry conclude section 3.3 with the following paragraph:
“During the 1990s, Italian researchers extracted resin from the core of the trees in the area of impact to examine trapped particles that were present during the 1908 event. They found high levels of material commonly found in rocky asteroids and rarely found in comets.”
The note immediately following this paragraph reads “citation needed,” which means that an editor for Wikipedia felt that the statement was (to quote the Wikipedia help file) “dubious or sufficiently controversial as to demand ‘citation.’”
For the purposes of this weblog, I don’t have to rely on a “dubious” lack of citation. Hartmann cites other research that supports a “non-comet” conclusion:
“In 1993 researchers Chris Chyba, Paul Thomas, and Kevin Zahnle studied the Siberian explosion and concluded it was… a stone meteorite that exploded in the atmosphere. This conclusion was supported when Russian researchers found tiny stoney particles embedded in the trees at the collision site, matching the composition of common stone meteorites.”
And this brings us back to the original question I had regarding AP science writer Alicia Chang’s article about the possible asteroid striking Mars. In order to give her readers an idea of the size of asteroid 2007 WD5 which was discovered in November, she compares it to the “object that hit remote central Siberia in 1908.”
Chang’s article is clear, concise and, considering the time and column-length constraints familiar to every journalist, accurate to a fault. I am not criticizing Chang’s writing at all. I simply want to point out that popular science writing is quite different from technical writing, for example; and the writing that eventually makes its way into Discover magazine or Scientific American is different in both process and result from the articles that eventually get published in The New England Journal of Medicine or the Journal of Glacial Geology and Geomorphology.
Writers whose job it is to pare down highly technical information from peer-reviewed science or medical periodicals into a form that a moderately sophisticated layperson can understand know exactly what goes into (and gets left out of) the average science column inch. The average reader of Yahoo! News, on the other hand, may not be aware of this literary alchemy and thus take for fact that an asteroid did indeed hit Tunguska that fateful summer in 1908. It simply isn’t possible for someone on a tight deadline to cite every source or check every fact with enough credible sources to guarantee some absolute standard of truth.
And this is the reason that Chang’s article speculating that an asteroid might hit Mars next month really got my attention. That is, after I got over the the giddy feeling from reading the headline: a sensation similar to the one when your next door neighbor’s house gets struck by the tornado and yours is spared, only in this case on a cosmic scale. After the excitement died down in my cynical soul, I asked myself the question I often ask after reading an article about science in a popular magazine: oh, yeah? Who says?
Sincerely,
David R. Farthing
P.S. Many thanks to the authors of the following websites where I did
research for this article:
National Aeronautics and Space Administration
http://www.nasa.gov
United States Postal Service Zip Code Lookup
http://zip4.usps.com/zip4/welcome.jsp
I Dream of Jeannie Online
http://www.idreamofjeannie.com/
