What you need to know:

Carbonates (like antacids that you dissolve in water) dissolve easily in water, and are deposited easily out of water. Sulfates (which are why Yellowstone’s fantastic mud-pots smell awful) are similar. Silica-rich deposits are more commonplace – so you need more detail to tell if they’re from water or not.

Up until now you’ve taken it for granted when you read in an article that a mineral discovered on Mars indicates the prehistoric existence of water. But how can a certain mineral in a rock tell you that there was once water? How can it tell you if that water was more recent or more ancient?

Carbonates

There are many carbonates, but calcium carbonate is probably the most familiar to you – and one of the most common carbonates. As you know from taking Tums or Alka-Seltzer – these dissolve easily in water. Many seashells are made of carbonates as well, and when those animals die, the shells are dissolved into the ocean and eventually that calcium carbonate is redeposited as limestone. Like that, all carbonates are usually formed in “hydro” and hydrothermal situations, and are also later dissolved by even a slightly acidic situation. Although this example only represents redeposition of carbonates – they are also deposited primarily (in the first place) by water as well. Finally, in order for carbonates to last a geologically long time they must be protected from water and other acids. Carbonates are either a good indication of water activity in the geologically recent past, or there hasn’t been any water near them in a long, long time.

Carbonates in ALH84001 (one of the meteorites from Mars)

Sulfates

Sulfate minerals are similar to carbonates in terms of their indication of water – they are also water-soluble, and occur in similar places to carbonates: embedded with limestones, etc. Sulfates tend to need more “thermal” in the term “hydrothermal” than carbonates – which is why you find a lot in volcanic regions like Yellowstone. That rotten-egg smell associated with hydrothermal areas on earth is due to the sulfur in sulfates. Sulfates are a great indicator for water activity paired with heat.

Spirit Unearths Sulfates on Mars

Silica

Almost every rock on Earth is silica-based. The presence of silicates in and of themselves is not an indication of water, current or prehistoric. More analysis or specificity is needed. After oxygen (yes, oxygen!) silica is the most common element in the Earth’s crust, as well as the crust of the Moon, and what we know of the surface of every other terrestrial planet.

Where’d I Get My Info?

Klein, Cornelius. The 22nd Edition of the Manual of Mineral Science.

~ A l i c e !

Here are my questions:

1. What is the possibility that intelligent life on other planets exists?

2. Have we found any signs of life on other planets?

3. What is the possibility that any life will be found on a moon such as Europa or Titan?

Again, I greatly appreciate your time, and thank you in advance for your response.

Many Thanks,

-Jacob

Jacob, ahh, these are the questions driving our exploration of the solar system.

1. What is the possibility that intelligent life on other planets exists?

This question is more of an opinion question at this point than a science question. There are just beginning to be scientists attempting to put a number to the possibility that there is life on other planets. I’d like to break this question down.

Life within our solar system (other than on Earth)

There is no evidence of intelligent life within our solar system. This does depend on your definition of intelligent, but one definition sometimes used by astronomers is that intelligent aliens would be able to form civilizations and use radio communication. We would have picked up those radio signals long ago had they been created within our solar system. It is entirely possible that there is life that is not creating radio signals – but we might have detected that life in other ways too:  noticing extra heat, carbon dioxide, oxygen, or methane in the atmospheres of other planets and moons within our solar system.

There is a scientist – Dr. Abel Méndez from Puerto Rico who is studying how likely it is that life could survive (the habitability of) on various planets and moons. He has actually ranked Enceladus, Saturn’s moon, as having more habitable area than Earth!!

Life outside our solar system

Since we have not yet found evidence of life outside our solar system, we have no way of knowing if it is there or not. If you like, you can use the Drake Equation to make your own guess, based on your own choices for the percentage of stars that you think might have planets, and the percentage of those that might be habitable.  If you talk to your math teacher about how to use this formula you can get your own best guess. If you’d rather though, scroll to the bottom of this page and choose the numbers you like best, and the webpage will calculate it for you.

2. Have we found any signs of life on other planets?

Hmm. Not really. Scientists are looking for what they call “markers” of life or “markers of biogenic activity” (both phrases mean the same thing). For instance – if you see dog poop in the park, although the poop isn’t alive you can be pretty certain that there was a dog at that exact location not too long ago. Most of the markers scientists are looking for aren’t nearly as certain as that.

Methane

A while ago scientists studying Mars found new methane in the atmosphere. Methane is often produced when life forms digest food – it comes out of your body when you burp or fart. Bacteria make methane too, as do dogs, cows, and other animals. Unfortunately, the rock cycle can also make methane – especially when iron rusts. Mars is covered in rust – that’s why it is red. This discovery of methane could be either from geology or from biology, it is not necessarily a “marker of life.”

Magnetotactic Bacteria

Last week I wouldn’t have mentioned this, but there is a new scientific paper out this week. In 1996 scientists found what they thought were markers of life in a meteorite from Mars. This meteorite (ALH 84001) was discovered in Antarctica in the early 80s. There were two interesting things inside this meteorite: forms that might be fossilized bacteria, and strings of magnetite (a magnetic mineral). We can’t really tell about the shapes that might be fossilized bacteria, but the strings of magnetite are identical to magnetite strings created by certain bacteria (magnetotactic bacteria) here on Earth. This is a very new paper, so other scientists might have other ways to interpret the same information.

3. What is the possiblity that any life will be found on a moon such as Europa or Titan?

If you look at the work done by Dr. Abel Méndez it looks fairly likely that life might have begun on Europa or Enceladus. Titan is less likely, as is Mars. How likely is it that the life is still there or that we’ll find it? I don’t know. Scientists are constantly debating this one.

Useful Links

Dr. Abel Méndez on Planet Habitability

Methane on Mars

Magnetotactic Bacteria

Magnetotactic Bacteria from NASA

Advanced Links (My source material)

(These are source material, but I do not recommend them unless you want to spend hours piecing through the jargon)

Press release about Méndez’s work, with diagram

Méndez’s current abstract

Méndez’s previous article

~ A l i c e !

I read the papers. No, I mean the peer-reviewed scientific papers. The upshot is this. In 1984 we discovered a meteorite in Antarctica and proved it was from Mars. In 1996 a group of scientists released a paper claiming that there might be evidence for life in that meteorite, most famously in the form of  “fossils of bacteria” (I’ll get more technical on that later). It didn’t take long for other scientists to come up with a series of other possible sources for the markers that the first group were claiming as markers of life. Although the work continues, for the last 13 years it has been widely accepted by the public and by many scientists that the markers in the meteorite (ALH 84001) were not formed by bacteria, they were formed by “plain old  geology”. No life.

Well, last week that changed (as new science is wont to do). A group of scientists has been looking closer (literally, they’re using better electron microscopes than we had in 1996) at ALH 84001 for the last 13 years, and last month they published a paper claiming that the suggested geologic processes could not have made the formations found in the meteorite. In other words they disproved the disproof of their original hypothesis, which was that there was once life in this rock. Now, and this is very important to note, they do not claim to have found proof of life, or to have found indications of life. They simply claim that the possibility of a “biogenic origin” is once more back on the table. (Last update: 12/1/2009)

Magnetotactic Bacteria from NASA Johnson Space Center

Carbonates and Magnetotactic Bacteria

Explaining magnetotactic bacteria would overwhelm this AstroInfo, so I’ll save that for next time. Suffice it to say, there are bacteria that create very pure nano-scale (really-über-tiny) magnetite. When Kathie (K.L. Thomas-Keprta, primary author) and her team examined the magnetite in ALH84001 they found it identical to the magnetites created on Earth by magnetotactic bacteria. Most importantly – it was extremely pure. This magnetite was associate with carbonate grains in the meteorite, and carbonate is an indication of water. If the magnetite had formed from or with the carbonate it wouldn’t have been as pure as it is.

I look forward to reading any rebuttals put forward by scientists who do not see this as evidence of possible ancient bacteria on Mars.

Where’d I Get My Info?

Press Release
Paper 1: Origins of magnetite nanocrystals in Martian meteorite ALH84001 (Peer-Reviewed)
Paper 2: Life on Mars: New Evidence from Martian Meteorites (Invited Paper)
Magnetotactic Bacteria

~ A l i c e !

by Guest Writer Sophie Arlow

Many people assume that astronomy is solely a human endeavor. After all, we have named constellations, created telescopes, and even landed on the Moon. However, humans are not the only species to use astronomy – from the Moon and stars to magnetic fields, animals also use information from the earth and skies.

The Mystery of Magnetite

What do salmon, dolphins, sea turtles, and whales have in common? These animals share much more than an underwater habitat – all are believed to use a mineral called magnetite to assist in navigation and migration. Magnetite is a special type of iron oxide which, as you might have guessed, is magnetic! Early humans used naturally-occurring deposits of magnetite, called lodestones, as primitive compasses.

Some specialized types of aquatic bacteria contain magnetite, which scientists hypothesize allows them to tell up from down. When exposed to a strong magnetic field, these bacteria all align perfectly, like miniature compass needles. On a larger scale, whales, dolphins, and salmon use magnetite to navigate deep below the water’s surface, where landmarks and visual cues like the sun and stars are not visible.

Expert Nautical Navigators

A serious contender for the title of most skilled animal navigator is the loggerhead sea turtle. Loggerhead hatchlings, only two inches long, emerge from their eggs, dig themselves out of the ground, and, with no help from their parents or other turtles, enter the ocean to begin their spectacular journey. Over a period of several years, loggerhead turtles travel more than 9,000 miles, spanning entire oceans before returning home to coastal regions in North America.

Loggerhead turtles travel over 9,000 miles in the Atlantic Ocean, guided by the Earth’s magnetic field. Credit: UNC Biology

How do hatchlings, never having seen the ocean before, maintain their headings across a vast expanse of often-featureless ocean? As hatchlings reach the water, they begin swimming directly into ocean waves until they are several miles from shore. At this point, hatchlings must use a new navigation method: orienting themselves using the Earth’s magnetic field. It also seems that they have a built-in magnetic map that guides them throughout their migration and allows them to return to the exact location where they hatched to lay their eggs.

How is this amazing feat possible? Scientists aren’t entirely sure. However, they do know that sea turtles’ brains contain tiny crystals of magnetite, which may allow them to sense the direction of the Earth’s magnetic field. This could enable them to find their way across thousands of miles of ocean and return to their birthplace decades later.

Moon Phases Trigger Coral Blooms

The Moon also influences various animals – including those in the sea! Coral reefs (made of huge colonies of coral – a tiny invertebrate animal closely related to a sea anemone) usually spawn once a year. For such a rare event, the coral polyps need to synchronize exactly when they release their gametes.

One trigger that helps them stay in synch is the phase of the Moon. One coral reef in the Caribbean spawns every year on the eighth day after the full Moon in August. That’s pretty specific. Other coral reefs are triggered by different Moon phases, but water temperature, currents, and tides also influence exactly when the coral bloom happens.

Sources

Magnetic Bacteria
The Innovations Report

Sea Turtle Navigation
PBS – NOVA
University of North Carolina Sea Turtle Research
National Geographic Today – Animal Migration

Coral Blooms
http://tinyurl.com/CoralBlooms

On the topic of aliens and UFOs, I agree with the giants of astronomy education (Carl Sagan, Neil DeGrasse Tyson, and Phil Plait to name a few). Somewhere out there is life. It may or may not be intelligent, but it probably exists. Have “they” visited us? The possibility is vanishingly small. In short: Space is huge, it would be amazing if the right combination of our 120+ known elements only came together to form life here on Earth and nowhere else.

I’m going out on a limb. I’m not trained in rhetoric, so I expect my discussion to have major loopholes. I invite readers knowledgeable about this topic and knowledgeable about rhetoric to comment, and help me close up those loopholes. I would also like to point out that I started writing this article on November 18th, 2008 (I’ve been struggling with it for a long time). Phil wrote his post of the same title on November 25th, 2008. Whether you believe me or not, I’m not copying him.

Finding a Place to Live:

When we talk about alien life, we talk about “life as we know it.” Life as we know it needs liquid water, which is between the temperatures of 0C and 100C. Our experience suggests that this occurs on planets and moons.

Have we found planets? Yup. We’ve got 322 (last I checked) planets orbiting other stars, and those were the ones that were EASY to detect. Those don’t tend to be in the right temperature zone, but if we’ve found 322 in just the last 5-10 years, imagine how many more there must be!

Creating Life:

You need some complex molecules to create even a single-celled organism. Carbon is great for this, because it can easily make form four bonds to other elements. Imagine Legos(TM). You can build anything you want out of Legos(TM), even if all you have is the quintessesntial 8-stud brick, because you can attach pieces together in other ways than just a straight line. When I was in school we also had Unifix Cubes. They were so frustrating, because all you could do was make a long chain. You couldn’t build robots or houses or anything. Carbon is the Lego of the Universe, Helium is the Unifix Cubes. There aren’t many other elements that can be the Lego of the Universe. Silicon is one, but Silicon is significantly less common in the Universe than Carbon. One of my astronomy professors argues strongly against the possibility of Silicon-based life, but I’d like to leave the door open on that one: the Universe is a strange place.

Something More:

We don’t know what it is, but there’s something else that you need to move from a gigantic mass of complex molecules to something “alive.” Is it protection from contamination? Is it the ability to take in and use energy? Scientists are working on this. (Here’s a much better article that reinforces the “moving energy around” idea as what got life going: Why Life Originated.The original link that caused me to say “protection from contamination” is here, though I don’t really like it much.)

So, the first two are easy. The third one we’re not sure about, but People Who Know think it’s a problem for us as humans to figure out, but not too difficult for Nature to stumble across. After all, Nature has a lot of space and a lot of materials, all combining in different ways all the time.

UFOs:

Once you’ve got life, you need to evolve into something intelligent. Then into something that can communicate – that took us millions of years. Then (if you want SETI to succeed) you’ve got to communicate across thousands, hundreds of thousands of lightyears, and stay alive long enough to get a response (this is hard). If you want our UFOs to be of real alien origin then you ALSO need to become spacefaring, travel across thousands, hundreds of thousands of lightyears, (stay alive for that entire journey – which is SUPER-HARD), and arrive at Earth. Hmm.

Earth has only been broadcasting signals into space for 50-100 years. If they’re further than 100 lightyears away, how would they decide to come here? Before we started broadcasting we were nobody. If they’re closer than that, and they can detect radio transmissions, why haven’t we heard their radios? Or, if you want to believe in UFOs, how did they get here so fast? It violates our understanding of Physics, and it doesn’t add up. They do this in Star Trek with fictitious (and awesome) inventions like subspace and warp drive. In Star Wars and Babylon 5 they use hyperspace. In Stargate they use a portal. Fiction. All of them.

When we invent warp drive (real and for true) I’ll eat my words and grant you the possibility that the UFOs really are aliens. Till then, I’m going to say it’s probably the Goodyear Blimp, a bollide, or even a pretty planet.

Who Do You Trust?

Why are you listening to me? I’m not an expert in aliens (who is?). I’ve only seen one UFO in my life (it later became an IFO: the Goodyear Blimp). So then, if I’m not the expert, what did I base this article on?

With the breadth and depth of knowledge now available to the human race, one person can no longer “know everything,” nor can one person understand everything. We are not Erastothsenes, Aristotle, or Plato. We have to trust other people to tell us things. Because of this, we have to choose where we get our information carefully, and everyone will choose different sources as trustworthy.

Me? I trust Carl Sagan and Phil Plait. I also tend to trust Neil DeGrasse Tyson, though I disagree with him on some points of quality education. I like to trust NPR, and I listen to everything Garrison Keillor has to say. I don’t trust Wikipedia to do anything other than jog my memory, point me towards a list of sources, or give me unimportant information (how old is Zac Efron?). I get my tech news from Boing Boing, and my local news and weather from specific blogs (I choose blogs for local information because they know they’re fast, up-to-the-minute, they know they’re biased and admit their bias, and the writers can change their minds and edit things anytime). For current astronomy questions I ask my college profs, re-read my texts, look at the data, and wade through the peer-reviewed papers (if I have time).

Where Did I Get My Info?

Check out what Phil has said about SETI and about UFOs:

Neil DeGrasse Tyson gave a great speech about this to Congress.

How many aliens are there? Figure out your best guess with the Drake Equation.

I thought you all might be specifically interested in this month’s Science with a Twist (science for a 21 and over audience) here at Pacific Science Center. The topic of the fun, interactive evening is “Are We Alone?”

Science with a Twist presents “Are We Alone?”
Thursday, September 18
6:00 – 9:00 p.m.

Alien encounters – fact or fiction? Sip on eerie cocktails while exploring other galaxies in our planetarium, listen to accounts of extraterrestrial sightings and then decide for yourself if you are a believer! The evening begins with a paranormal happy hour featuring a presentation by Joe Hutchings, member of the Society for Sensible Explanations, entitled “Why Skeptics Can’t Win,” followed by “UFOs of the Northwest” presented by Charlette LeFevre and Philip Lipson, curators of Seattle’s Museum of the Mysteries. Decide if we are truly alone and then end the evening with a private space-themed Laser Show in the Seattle Laser Dome.

6 p.m. Happy Hour & Presentations
8 p.m. Laser show

Click →here to purchase tickets. Tickets include your first drink from the bar and snacks. $15 per person; $12 for Pacific Science Center members. 21+, ID Required.

Information at: http://www.pacsci.org/twist/

I’ll be there, doing some activities with you about exoplanets.

Just click it.

For this week’s AstroInfo I’m going to answer a set of questions posed by youth who are currently training to offer space-related interactive activities out among the Pacific Science Center’s exhibits. In several places I express my personal opinion – which you should note is NOT the same as fact.

When can the general population go into space without paying a lot of $?
Who knows, maybe 10 years? Maybe two years, maybe 50? There is a competition called the “X Prize” that’s trying to jumpstart space travel (and other sciences). Until a couple years ago, no new spaceships for carrying people had been invented since the Shuttle. The Ansari X-Prize (http://www.xprize.org/x-prizes/ansari-x-prize) offered $10 million dollars to anyone who could “launch a spacecraft capable of carrying three people to 100 kilometers above the earth’s surface, twice within two weeks.” Burt Rutan and company completed the task on October 4, 2004 – after spending more than $100 million creating SpaceShipOne (go to the Museum of Flight to see a mock-up of it). This should push the space-travel industry along a little faster.

How plausible is human colonization of Mars/Moon in the next 50 years?
My opinion: It’s not. I say that because you used the word “colonization” which I think will take a long time. Right now there’s a plan to send humans back to the Moon and eventually to Mars, but just to visit.
The program is called the Constellation Program and it has three components:

• Orion Crew Vehicle – like the current shuttle
• Ares Launch Vehicles – rocket to carry the Orion
• Altair Lunar Lander – landing people on the Moon

How do they come up with the ideas for finding stars or researching about stars?
What usually happens is that someone notices something strange about a star or something else, and they decide to find out what’s happening. A simple example is a variable star. Someone studying a variable star would notice that on different nights it appeared brighter or dimmer. Then they would want to find out why – is there something traveling in front of the star? Is the star flashing or pulsing? Is the star spinning, and is one part brighter than another? Any of these might affect brightness.

Is there intelligent life outside Earth?
Not that we’ve detected. My opinion: yes.

Does dark matter exist?
Most scientists believe so. Though the evidence is pretty overwhelming, I’m not quite ready to believe it. Redacted as of 6/4/08.

What elements are found in the gases on Uranus?

Edited as of 6/6/08: The atmosphere of Uranus has Hydrogen (mostly), Helium (a little), Methane (a trace), Water (a trace), Ammonia (a trace). The methane, water, and ammonia are all aerosol ices – suspended crystals of ice (not ice cubes or blocks of ice). A later AstroInfo will explain Uranus in more detail. I was embarrassed to realize at the Spring 2008 meeting of the American Astronomical Society that what I thought I knew was significantly wrong.