Iron Oxide on Mars

If Mars has all that rust, where did the oxygen come from? We call Mars the “Red Planet” because it has iron oxide – LOTS of it. Where did it come from? Scientists believe both Earth and Mars got most of its surface iron oxides from meteor bombardment about 4 billion years ago. Why does Mars have so much more of it?

BBC has done interesting documentaries on stromatolites, large living bacterial beach “rock” formations we can still see and investigate in Australia. According to this theory, these cyanobacteria use a primitive photosynthesis to generate Earth’s earliest oxygen. This started oxidizing particulate meteorite iron dust suspended in the oceans, converting it to rust, which settled to the ocean bed and was sequestered there. When free iron particles were essentially used up, oxygen could then start accumulating in our atmosphere … paving the way for higher Earth life forms.

Mars seems once to have had copious water. Could it have also had cyanobacteria? Is that how Mars got all its iron oxide?

Well, according to another theory I found on starryskies.com, Martian oceans simply rusted all that meteoric iron away. Of course, if this is the full explanation, we don’t need the stromatolite theory at all to account for iron oxides on either planet.

I found a third theory on BioEd Online. It suggests the answer is not that simple. Researchers have been able to show that Earth’s powerful gravitational field generates enough pressure and heat to melt iron oxide, in effect smelting oxygen out of it, and allowing it to sink into the molten core. Theoretical calculations show smaller Mars could not have generated the required compressional pressures. This would account for Earth’s huge liquid iron core and the powerful dynamo generating our planet’s magnetic field, in turn protecting our atmosphere from the solar radiation that we expect blasted most of the unprotected Martian atmosphere away.

If all goes well, our new robotic explorer Curiosity will safely descend to the Martian surface at 1:31 a.m. Monday Aug. 6 EDT (0531 GMT) – about 10:30PM Sunday night, Pacific time. Facebook has a Curiosity page, and NASA/JPL will have a “live” feed on UStream’s Curiosity Cam. Curiosity will not broadcast photos until it finishes all its own internal checks. The first photos will be black and white, with color plates following on later transmissions.  Remember, there’s currently a 14 minute radio signal delay between Mars and Earth.

I plan to try to stay up to see if the mission is successful. As for our iron oxide questions, it often turns out in science there is not just one “right” contributory answer. It will be interesting to see what mysteries Curiosity can solve.

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Mars Hoax 2010

HOAX: Two moons 27th August 2010

The annual “Two Moons on Aug 27th” Mars e-mail is circulating again. Alas, the myth is another internet hoax, a best fit for the “liar liar pants on fire” category. Amateur astronomers already know this. This year, for the benefit of everybody else, we do our best to explain why.

A picture is worth a thousand words. See: http://www.astronomy.org.gg/hoax.htm

from astronomy.org.gg - click graphic for source article and image

The photo above is also true to my own experience, as I’ll narrate below.

Wikipedia on the “Mars Hoax” (emphasis mine):

Although nearly all of the claims made in the e-mail are true, the hoax stemmed from a misinterpretation of the third sentence of the second paragraph which states that “At a modest 75-power magnification Mars will look as large as the full moon to the naked eye”. The message was often quoted with a line break in the middle of this sentence, leading some readers to mistakenly believe that Mars would “look as large as a full moon to the naked eye” when, in reality, this only applies when a telescope with a 75-power magnification is used. This is the most likely source of misinterpretation.

We will never, EVER see a sight even remotely like the faked “two moons” e-mail image from Earth (or from anywhere else in the solar system). And 2010 is not even a particularly good year for telescopic viewing of Mars.

We already had Mars’ 2010 “closest approach” in January . Most non-astronomer citizens never would have noticed it. Phoenix and Bay area residents would probably be unable to see it with the naked eye unless it was an exceptionally clear night.

We actually have mathematical “closest approaches” every other year or so (Mars takes 687 Earth “days” to orbit the sun). Obviously, since both planets orbit the sun, there is always going to be some “closest” distance as the Earth swings round past Mars. That distance is not the same each year because the orbits if the two planets are not quite concentric, but elliptical — not quite perfect circles. Mars’ orbit is quite eccentric for a planet – about 9% longer on the long axis compared to the short dimension.

In 2003, we had the celebrated closest Mars approach “in 60,000 years”. Astronomers would have noticed Mars having an apparent diameter of almost twice its “farthest distance”. This difference doesn’t become readily apparent without a telescope of at least 6″ diameter.

The angular size of the Moon is about 1/2 degree (30 ARC MINUTES). By coincidence our Sun is of the same apparent diameter, which is why we can have perfect lunar eclipses. NASA confirms the angular size of Mars varies from a minimum of 3.4 ARC SECONDS to a maximum of 25.1 ARC SECONDS.

An arc second is 1/60 of an arc minute. Mars never stood a chance of looking close in size to the Moon!

From University of Wisconsin:

Even at its closest approaches Mars seldom appears larger than 26 arc seconds, or about 1/69 the apparent size of the moon.

Some sources compare this to the apparent size of a penny at 500 feet.

We all know from experience the Moon NEVER looks about the size of a penny at 500 feet. The Moon might look more like the size of a basketball at 100 feet. So how could Mars ever look like it was almost the same size? It can’t.

If that isn’t bad enough for backyard astronomers, more math (groan) conspires against us too. Remember that the area of a circle is proportional to the square of the radius. So, a planet of radius 1/2 will only display 1/4 the surface detail of a planet of radius 1, all other things being equal. A planet of radius 1/60 can, at best, display 1/3600 the surface detail of the larger one — not counting the distorting effects of the Earth’s atmosphere!

The 2003 Mars approach was a HUGE disappointment to Bob and me, and we (I) wasted a good deal of money trying to be ready to photograph this highly publicized event.

As actually viewed with the naked eye in 2003, it was hard to tell whether any kind of “disk” of Mars could be made out at all, or if Mars was just a really bright reddish point-source star like Aldebaran. With eye to our telescope eyepiece, we were barely able to see Mars’ polar icecap, but that was all. Bob and I tried to photograph Mars through the 8″ telescope with an expensive SLR camera body, without much success as we were inexperienced in photographing the night sky. Bob did the best job, holding up a “Brownie point and shoot” to the telescope eyepiece.

Our photo looked about like a penny at 500 feet. Copper-red, no surface detail visible at all. Unless you blow up the image (below), Mars looks like a little red dot in a huge black frame. This photo has been published here before. For a better color photo (looks like black-and-white), see also our Mars Elusive post (9-17-2003).

Mars 2003 - photo by Bob Sibley

The next “good” year for viewing Mars will be 2014, and it won’t get as good as 2003 again during our lifetimes.

Alex

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Mars Elusive

From urban Phoenix, this is probably as good as it’s going to get during the “apparition” or current period of closeness.

Viewers with a 3″ Tasco or AC Gilbert scope and a good viewing location will no doubt get a visually more satisfying image than this. However, the image to the left is a faithful reproduction of what we’re seeing through our 8″ LX-90 from the back yard in Phoenix.

This is the best of five images, focused as carefully as the LX-90 allows. We see an essentially featureless, blurry, yellow to sandy red ball. We see a hint of albedo that shows up as a false banding. Nothing so encouraging as a south polar ice cap, though it is late in the season and we’ve seen it earlier in the year.

The image on this page would probably be great if available visual detail were great. The blurriness and image size on this page is about what we were seeing with very careful focussing of the LX-90 with a 7.5mm Orion Lanthanum eyepiece. It was taken with a D100 digital camera at ISO 1000, 1/100 second. Coupler was a Meade variable-projection camera adapter. No camera lens or eyepiece is used in this setup. The raw JPG image was cropped and magnified to 200% (2x) in PhotoShop, but otherwise unprocessed.

In the SF Bay Area, strong winds had produced clearer than normal night skies (when it was not foggy). Due to our own schedules, our last hope for Mars this year is up north, whenever OPT is able to ship the new CG5-GT mount for our 10″ Big Bertha.

“We have a 4″ (or so) reflector, and I was able to convince myself that I could see a central spot and a white cap.  The mind does wondrous things.” — Dave N.”… and we had an 8″ reflector, and were therefore twice as convinced.” — Alex

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Mars Closest Approach

On August 27, 2003 Mars will be closer to Earth than at any time in the last 59,000 years — or any time in the next 25,000 years. Its apparent diameter will be four times what it is now (Feb 2003). We don’t want to have to wait around for the next time. Here’s the data for viewing this event on that date.

Photo on the left by Bob Sibley. This is our first, taken 8/2/2003 by the simple expedient of aiming a Kodak DCX3600 into a 12.5mm Orion Epic eyepiece. No detail? Fine; it’s still tons more than we had before. Bob reported being able to see the south polar icecap and the “canalii” in a moment of crisp viewing.

 

1. Here are the MICA
  ephemeris
for Mars June 15, 2003 to Feb 4, 2004
2. MARS August 27th, 2003 “Closest Apparition” –
  vic. Fomalhaut & Aquarius  positions based on location near Oakland, California
time azimith (degrees)  polar direction altitude (degrees)  above horizon comments
8PM 117° ESE  
9PM 128°   19°  
10PM 141°   27°  
11PM 156°   33° above Fomalhaut
12AM 172° South 36°  
1AM 190°   35°  
2AM 206°   32°  
3AM 221° SW 25°  
4AM 233°   16°  
5AM 244°    

posted February, 2004

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Mars approach, Phoenix, July 4, 2003

Learning curves, PhotoShop, flim-flammery and primrose paths

Photoshop illustration - Mars July 4, 2003Well, I must say we led ourselves down the proverbial primrose path on this Mars thing. We’re still new to amateur astronomy. With the closest approach of Mars coming August 27th, mentally we were preparing for a visitation that would loom over the heavens like Moon Over Miami.

Dash it all, old chaps. You can scotch any notion of us photographing Martian rilles and canyons. Are we soured? Nope. We had several factors going against us last night that add up to terrible viewing conditions. We still ended up awed.
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