Here’s a round-up of recent science headlines we didn’t want you to miss!

Ancient Rivers

Without a smart phone or GPS device, how did early humans find their way out of Africa? A study published last week in PLoS One determines that ancient rivers, now covered by the Sahara Desert, provided habitable routes to follow.

Simulating paleoclimates in the region, the researchers found evidence of three major river systems that likely existed in North Africa 130,000–100,000 years ago, but are now largely buried by dune systems in the desert. When flowing, these rivers likely provided fertile habitats for animals and vegetation, creating “green corridors” across the region.

“It’s exciting to think that 100,000 years ago there were three huge rivers forcing their way across 1000-km of the Sahara desert to the Mediterranean—and that our ancestors could have walked alongside them,” says lead author Tom Coulthard of the University of Hull, UK.

Cosmic Beginnings?

Did life on Earth hail from Mars, as one researcher proposed last month, or comet collisions? Apparently, in both cases, it all has to do with the chemistry. Carl Zimmer, one of our favorite science writers, has a recent New York Times article about the chemistry needed to produce DNA from RNA. And while it doesn’t look like early Earth had those compounds, Mars might have.

Then, earlier this week, a study published in Nature Geoscience finds that the collision of icy comets with planetary bodies could result in the formation of complex amino acids, the building blocks of proteins (and life).

The researchers suggest that this process provides another piece to the puzzle of how life was kick-started on Earth, after a period of time between 4.5 and 3.8 billion years ago when the planet was being bombarded by comets and meteorites.

The team made their discovery by recreating the impact of a comet by firing projectiles through a large high-speed gun. This gun, located at the University of Kent, uses compressed gas to propel projectiles at speeds of 7.15 kilometers per second into targets of ice mixtures, which have a similar composition to comets. The resulting impact created amino acids such as glycine and D- and L-alanine. Sounds like a fun method of discovery…

Speaking of fun collisions, if you want more of them, the Morrison Planetarium at the Academy is featuring Cosmic Collisions in its current show rotation. From the our website:

Creative and destructive, dynamic and dazzling, collisions are a key mechanism in the evolution of the Universe.

Missing Mars Methane

One chemical Mars seems to be missing? Methane. The gas was sought as a possible sign of microbial life currently living on the seemingly barren world. However, despite earlier reports that NASA’s Mars rover, Curiosity, discovered methane on the red planet, NASA reports today in Science that none has been found.

Curiosity’s earlier evidence of methane detection turned out to be within leftover air from Earth. And previous reports of localized methane concentrations up to 45 parts per billion on Mars were based on observations from Earth and from orbit around Mars.

“It would have been exciting to find methane, but we have high confidence in our measurements,” says the report’s lead author, Chris Webster. “We measured repeatedly from Martian spring to late summer, but with no detection of methane.”

But don’t give up on microbial Martians just yet… “This important result will help direct our efforts to examine the possibility of life on Mars,” says NASA’s Michael Meyer. “It reduces the probability of current methane-producing Martian microbes, but this addresses only one type of microbial metabolism. As we know, there are many types of terrestrial microbes that don’t generate methane.”

Looking for extraterrestrial life? Next month’s Brilliant!Science festival can deliver it to you. Visit this page for more information.

Image: the Tunable Laser Spectrometer on-board Curiosity: NASA/JPL-Caltech

The excitement in August of NASA’s Curiosity rover landing on the surface of Mars, inducing “seven minutes of terror,” is tricky to sustain four months into the mission. Instead of technologically savvy rocket engineering, now it’s all about the science—mostly chemistry, in fact. But last month, John Grotzinger, project scientist for the mission, generated a lot of interest by saying on NPR, “This data is gonna be one for the history books. It’s looking really good.”

But revealing those data had to wait until today, the first day of the annual American Geophysical Union (AGU) meeting here in San Francisco. And despite several reports that the news would be much ado about nothing, the press conference was held in a room almost ten times the size of the normal press conferences.

Of course, the biggest questions about Mars center around whether life exists on our nearest neighbor—or did it exist at some point in the past?

So, what did Curiosity find…?

A suite of Curiosity’s scientific instruments called SAM (Sample Analysis at Mars) has detected organic compounds in the soil… That’s the good news. However, those organic compounds have not yet been determined to come from Mars. Scientists must be very careful to ensure that these compounds are not the result of contamination from here on Earth. In addition, the researchers want to make sure that the chemicals truly originated on the Red Planet rather than from, say, cosmic dust.

Curiosity dug the soil from five different places at the Rocknest location—scooping just a few inches into the soil and sending it to different instruments within the rover. Curiosity’s team selected Rocknest as the first scooping site because it has fine sand particles suited for scrubbing interior surfaces of the arm’s sample-handling chambers. Sand was vibrated inside the chambers to remove residue from Earth. Funny to think that you can “clean” instruments with dirt.

Using mass spectroscopy, the SAM instruments discovered several chemicals in the soil, including water, carbon dioxide, oxygen, perchlorate, and sulfur dioxide. The carbon-based materials inspire the most caution in scientists. They want to make certain that these building blocks for life are indeed indigenous to the red planet.

So what next for Curiosity? It will drill at the Rocknest site and then move on to Mount Sharp, where more soil testing will potentially collect further clues about organic compounds on Mars.

Grotzinger reminded the packed press conference that, “Curiosity’s middle name is Patience.” And instead of seven minutes of terror, the true science mission is “three months of tension.” If not more… Stay tuned.

Image: NASA/JPL-Caltech/MSSS

The third Thursday of every month, give or take, Morrison Planetarium hosts “Universe Update” at the 6:30 planetarium shows during NightLife. We select our favorite astronomy stories from the past month, and give a brief run-down of current discoveries while taking audiences on a guided tour of the Universe.

We always start at Earth and work our way out to cosmological distances, and we’ll list the news stories in the same order—from closest to farthest from home.

Let’s start at Mars. Curiosity, the latest addition to our growing team of Martian rovers, landed on the Red Planet just a few months ago.  Previous landers sent back pictures and performed basic measurements, but Curiosity brought an entire geology and chemistry lab on a 225-million-kilometer expedition to Gale Crater, where the rover is using its instruments to search for evidence of Mars’s past.

In its “rocknest,” Curiosity found wind-swept dunes containing material similar to volcanic soil in Hawaii.  After vaporizing samples with its onboard laser, Curiosity’s CheMin instrument then used X-ray diffraction to search for clues to understanding the history of Mars’s atmosphere.  Evidence suggests that Mars once had a much thicker atmosphere, which disappeared a long time ago, leaving the thin layer we observe today.  As previous landers found layers of frozen water beneath Mars’s surface, Curiosity is taking the next step, equipped to hunt for methane, an organic molecule that’s a good indicator of life.  So far, Gale Crater seems devoid of this malodorous precursor, but Curiosity has two years and many kilometers of Martian soil to cover.

Our next stop is the giant asteroid Vesta: over 500 kilometers in diameter (the distance from San Francisco to Los Angeles), it’s the second-largest asteroid in our solar system.  The Dawn mission photographed it for over a year, looking at Vesta as a good example of what Earth may have looked like when it was just a wee baby protoplanet.  The big differences between light and dark in these photos puzzled scientists, since asteroid terrain isn’t usually so varied.  Space weathering should homogenize the surface, leaving a matte gray all over the surface.  But scientists now think that the dark material comes not from Vesta but from 300 smaller asteroid impacts over the last 3.5 billion years, each of which brought material such as the metallic dust, carbon, and hydrated minerals (minerals containing water) Dawn detected.  This mélange can account for the difference in light and dark areas, wrapping Vesta in powdered asteroid debris, one-to-two meters thick.

With a constant influx of data, astronomers are discovering new exoplanets faster than ever.  Re-examining old data can produce useful results, too, and astronomers have just announced that a planet somewhere between Earth- and Neptune-sized is orbiting HD 40307.  Despite only being three quarters as massive as our Sun, this star hosts six planets in total.  Most importantly, the new planet is orbiting right in that habitable sweet spot: not too cold and not too hot, this is a strong contender to have liquid water, that necessary ingredient for life on Earth (and very possibly elsewhere).

Our view of the stars from Earth is strictly two-dimensional, and even with visualizations like the planetarium’s Digital Universe, we still rely on our Earth-bound view to determine distances to objects in space.  A new image (see above) from a 340-megapixel camera on a telescope in Hawaii has found a heretofore unidentified cluster of stars in the familiar Orion constellation.  The most studied part of our night sky, the Orion Nebula turns out to have many layers, and the stars we see in the middle are in fact older stars closer to us than we previously suspected.

Two twelve-billion-year-old supernovae live far, far from our starting point on Earth: because looking out into space also means looking back in time, the Universe has changed a lot since these stars exploded, so it’s hard to give you a distance in kilometers or even lightyears, but one of them holds the record as the most distant supernova yet observed.  Needless to say, these are very, very old explosions that came from even older, supermassive stars, the likes of which don’t exist in the nearby, more recent Universe.

As the Universe continues to accelerate outward, the light we can see here on Earth fades into the cosmos.  In a few billion years, information from these distant galaxies simply won’t make it to Earth anymore, and we’ll be living in a rather empty neighborhood.  The parallels with the economic downturn are a little alarming, and a press release from a group of European cosmologists hammers it home.  It turns out that stars in the Universe are only forming at 1/30 the rate they once were: a cosmic market crash that looks to continue till the end of time.  The Universe seemed to peak about 11 billion years ago… Let’s hope the same isn’t true for the American GDP!

Dan Brady is a planetarium presenter at the California Academy of Sciences. He earned his BS in Physics from UCLA and has taught science since 2008.

Image: CFHT/Coelum (J.-C. Cuillandre & G. Anselmi)

This is exciting as it gives us more evidence that the dry, red planet used to be wet with water. There is earlier evidence for the presence of water on Mars, but this evidence—images of rocks (like the one to the right) containing ancient streambed gravels—is the first of its kind. The sizes and shapes of stones in these images offer clues to the speed and distance of a long-ago stream’s flow.

“From the size of gravels it carried, we can interpret the water was moving about three feet per second, with a depth somewhere between ankle and hip deep,” says Curiosity science co-investigator William Dietrich of UC Berkeley. “Plenty of papers have been written about channels on Mars with many different hypotheses about the flows in them. This is the first time we’re actually seeing water-transported gravel on Mars. This is a transition from speculation about the size of streambed material to direct observation of it.”

“The shapes tell you they were transported and the sizes tell you they couldn’t be transported by wind. They were transported by water flow,” concurs Curiosity science co-investigator Rebecca Williams of the Planetary Science Institute.

The science team may use Curiosity to learn the elemental composition of the material, revealing more characteristics of the wet environment that formed these deposits.

The slope of Mount Sharp in Gale Crater remains the rover’s main destination. Clay and sulfate minerals detected there from orbit can be good preservers of carbon-based organic chemicals that are potential ingredients for life.

“A long-flowing stream can be a habitable environment,” says Mars Science Laboratory project scientist John Grotzinger of Caltech. “It is not our top choice as an environment for preservation of organics, though. We’re still going to Mount Sharp, but this is insurance that we have already found our first potentially habitable environment.”

Image: NASA/JPL-Caltech/MSSS

Benjamin Dean Lecture
Where will Curiosity Take Us?
Following the Mars Science Laboratory Rover as it Explores the Red Planet
Jennifer Blank, Bay Area Environmental Research Institute, NASA/Ames Research Center

Want more information on the Mars Curiosity mission? Follow these links…

Main Pages:
MSL/NASA page
http://www.nasa.gov/mission_pages/msl/index.html
Jet Propulsion Laboratory page
www.jpl.nasa.gov/msl
Mars Exploration Program
http://mars.jpl.nasa.gov/
http://mars.jpl.nasa.gov/msl

Twitter feeds:
Curiosity
https://twitter.com/MarsCuriosity
JPL
https://twitter.com/NASAJPL

Facebook page:
Curiosity
http://www.facebook.com/MarsCuriosity?ref=ts&fref=ts
NASA
https://www.facebook.com/NASA
JPL
https://www.facebook.com/NASAJPL?ref=ts&fref=ts

Latest headlines on Science Today:
http://www.calacademy.org/sciencetoday/?s=curiosity+mars

Blogs:
Martian diaries
http://mars.jpl.nasa.gov/blogs/
JPL Blog
http://blogs.jpl.nasa.gov/
NASA blogs
http://blogs.nasa.gov/cm/newui/blog/mainblogs.jsp

Apps and Downloads:
Spacecraft 3D
iTunes: https://itunes.apple.com/us/app/spacecraft-3d/id541089908?mt=8
Mars Images
iTunes: https://itunes.apple.com/us/app/mars-images/id492852224?mt=8
Googleplay: https://play.google.com/store/apps/details?id=com.powellware.marsimages&hl=en
NASA Be a Martian
iTunes: https://itunes.apple.com/us/app/nasa-be-a-martian/id543704769?mt=8
Android: https://play.google.com/store/apps/details?id=gov.nasa.jpl.beam
Windows: http://www.windowsphone.com/en-us/store/app/nasa-be-a-martian/00eb41c4-97e3-df11-a844-00237de2db9e
Mars Map
Android: https://play.google.com/store/apps/details?id=com.atlogis.marsmap&hl=en
Mars Globe
iTunes: https://itunes.apple.com/us/app/mars-globe/id324185998?mt=8
Curiosity: The Mars Mission (game)
Android: https://play.google.com/store/apps/details?id=com.reflectivelayer.curiosity&hl=en
WorldWide Telescope Mars
PC: http://www.worldwidetelescope.org/ExperienceIt/ExperienceIt.aspx?Page=DownloadWWT

For more NASA apps see: http://www.nasa.gov/connect/apps.html

Music:
Curiosity’s “Wake Up” songs
https://itunes.apple.com/us/playlist/mars-curiosity-mix/id569312397

The latest Mars rover, Curiosity, will soon begin its adventure on the Red Planet! Curiosity will land in Gale Crater this August 5th.

With less than a month before Curiosity’s landing, Dr. David Blake gave a Benjamin Dean Lecture at the California Academy of Sciences on July 9th, 2012. A senior staff scientist in the Exobiology Branch at NASA Ames Research Center, Dr. Blake designed one of Curiosity’s science instruments, CheMin (Chemistry and Mineralogy).

CheMin will use X-ray diffraction to measure the mineral structure in samples of Mars dust: an X-ray beam shot through a dust sample will scatter in a distinctive pattern that depends on the arrangement of atoms and molecules present in the sample. CheMin also measures the energy of individual X-ray photons to determine what elements make up the sample.

Other important instruments onboard Curiosity will photograph the rover’s surroundings, drill into rock samples, look for traces of organic compounds, and conduct a variety of experiments that earned Curiosity its original name, “Mars Science Laboratory.”

The 900-kilogram roving laboratory requires a landing sequence different from previous, smaller rovers’ landings. Smaller rovers descended to the Martian surface protected by giant airbags, bouncing to a stop before deflating the airbags and beginning operations. Curiosity needs to complete an elaborate series of steps nicknamed the “Seven Minutes of Terror,” so called because NASA engineers have no way to control what happens during the seven minutes it takes the spacecraft to traverse the thickness of the Martian atmosphere. Dr. Blake showed the audience an interesting clip of the simulated landing process…

After its eight-month journey from Earth, the capsule is racing toward Mars. The Aeroshell, on the outside, includes a heat shield that protects the craft during its initial entry into the Martian atmosphere. At a designated point in its descent, the Aeroshell deploys a parachute. The heat shield drops away, and the Sky Crane carrying the rover then separates and executes a controlled descent under its own power before deploying a cable to lower the rover down to a carefully selected landing site. Flight engineers have refined Curiosity’s landing site during the eight-month voyage, pinpointing a relatively small area inside Gale Crater.

For the first few months that Curiosity is surveying Mars, Dr. Blake will live on “Mars time.” The days on Mars are about 40 minutes longer than our 24-hour Earth day, and scientists and engineers will adjust to the longer day, working on the same schedule as the rover. But all this extra time definitely adds up: Dr. Blake compares it to shifting a time zone a day for the duration of the switch, and when he practiced living on Mars time for a week, he didn’t relish the experience.

Keep up to date with Curiosity’s progress here!

Alyssa Keimach is an astronomy and astrophysics student at the University of Michigan and volunteers for the Morrison Planetarium.

Image credit: NASA/JPL-Caltech