Water on Mars Revisited

From Giovanni Schiaparelli to Robert Heinlein the notion of water-filled "canals" on the surface of Mars was a popular one in science and science fiction during some of the late 19th and early 20th century. By the time I discovered science (fiction), the hypothesis of straight canals with flowing water on Mars had long since been dispelled. By the time I began to study Mars, Mariner and Viking had already sent back images from the Martian surface that meant I didn't have to imagine it. I could just look up the images. As I looked at Martian landscapes apparently devoid of any visible water, the notion of streams with flowing water on Mars appeared quaint and naive. 

Now, Curiosity has sent back images from Gale Crater that contain evidence of ancient, quick-flowing water on Mars. NASA's newest rover on the Red Planet found a tilted block of rock that is part of an ancient streambed, along with gravelly rocks whose shape and size indicate they were formed by having been tumbled in water, for a long time. The gravel is too heavy to have been shaped by wind. This is the first time that water-transported gravel has been found on Mars.

Evidence of an ancient streambed on Mars (left), compared to a similar formation on Earth

The size and shape of the gravel also provides clues about flow rate and duration: The water was between ankle- and hip-deep and flowed at a rate of 3 feet (1 meter) per second. That is a pretty brisk-moving stream. When water did flow on Mars in this location, it flowed for a very long time, a very long time ago.

We are certain to find additional clues as Curiosity continues its journey towards the Glenelg area of Mt. Sharp on Mars. In the meantime, I am left with a whole new, awesome dimension of Martian geological history. While Gale Crater was picked as the rover's landing site partly because orbital data indicated the presence of an alluvial flow, I have to ask: If Curiosity practically landed in an ancient Martian streambed, how common was water on Mars back when Gale Crater sported at least one knee-deep, briskly moving stream of water? Was it common or rare? Did the flowing water environment support any life? What happened to the planet between then and now? How did it change from an environment supporting liquid water to what it is today? Where did all that water go? 

We may not have reliable answers to these questions for a while but the fact that we can now ask them and look for clues in data directly from the Martian surface is a spectacular achievement of planetary science. 

Go Curiosity!

For my coverage of Curiosity's landing on Mars from Planetfest 2012, click here and here

For my coverage of the NASA/JPL tweetup featuring Curiosity in June 2011, click here

Welcome to Los Angeles, Endeavour!

Space Shuttle Endeavour arrived safely and to a huge welcome at Los Angeles International Airport on Friday, September 21, 2012.

Since it's easy to get caught up in the excitement of seeing a space shuttle soar overhead on top of a modified 747 (aka SCA = shuttle carrier aircraft) let's take a look at a rare photograph first. Below is Endeavour in her full splendor docked to the completed International Space Station during her last mission to space. Italian Astronaut Paulo Nespoli snapped this picture on May 23, 2011 from a Soyuz capsule. While there are a number of photos showing parts of shuttles photographed from inside the ISS, this is the only picture showing all of Endeavour docked to the completed ISS. This picture shows her doing what she was made for: Spaceflight. Building and servicing the International Space Station. An amazing machine that gave us the ability to construct a human outpost in orbit. Endeavour may be ready for retirement now and I can't wait to visit her at her new home at the California Science Center. I'm sure she will be breathtaking. 

But to me she was never more magnificent than doing what she did best - In Space.

Photo credit: Paulo Nespoli / NASA

Around 9 a.m. on Sept. 21, I started making my way to LAX a few miles away. I took the bus and train to avoid the predicted traffic chaos and shortage of parking at the location I had in mind: The East Side of Aviation Blvd, at the end of LAX's south runway. If you know the area, this stretch of road is located north of the Proud Bird restaurant. The runway starts on the other side of the street. It's a great spot for watching incoming planes fly low before touchdown. 

I arrived at the location at 10:30 a.m, as planned, for a shuttle landing time of 11 a.m., just as I learned that landing time had been postponed to 12:45 p.m. Aviation Blvd. is not one of those quaint, picturesque L.A. streets. It's a major four-lane airport access road and the ambiance is razor wire fence-industrial. The "sidewalk" is a narrow strip of gravel.  (Note: If you ever find yourself stranded on a narrow strip of gravel for a long wait, do so with a Southwest flight attendant who has a carry-on. They have everything you need in that bag for hot, dusty, historic space events!)

When I arrived, the crowd was still relatively thin. I settled in for a 2+ hour wait. Twitter dropped in and out of being accessible during that time so my #spottheshuttle tweets from the location are a bit... spotty. 

As I have found to be the case at all space events, nothing is easier than striking up a conversation with strangers. I met two flight attendants from Southwest Air, one who had come from Minneapolis, the other Las Vegas. I met an engineer who had worked on Endeavour's SSMEs. A mother who had brought her kid to see the shuttle; they had been waiting since 6 a.m. Two film students with professional equipment who planned to get footage of the landing and use it in their film project this semester, and many more. As a bonus, I got a ferocious sunburn despite SPF50. No matter.

By noon, the crowd had grown considerably and was now clustered along Aviation Blvd. in both directions as far as anyone could see. The cops amused us trying to contain everybody on the gravel strip, keeping them out of the bike path and street. This was a doomed effort. The bike path was ours. During the shuttle's final landing approach, the cops caved in, stopped traffic and let us take the street. That is when the long, dusty, brutally hot wait paid off. This is what we saw - no zoom, no filters, a glorious moment:

Photo credit: Tanya Ehret

The aircraft in the upper right is an F-19 fighter aircraft, one of two that accompany the shuttle carrier aircraft (SCA), a converted 747, flying space shuttles across the country. While the shuttle program was active, NASA maintained two SCAs to return shuttles from California. Shuttle landings were diverted to land at Edwards Air Force Base in California on a number of occasions.

Video credit: Tanya Ehret

 

The landing approach was Endeavour's third pass above us. We first glimpsed the plane carrying Endeavour as a speck in the northwest, from the direction of Santa Barbara, heading inland over Santa Monica, beginning its flyby of L.A. landmarks, including Griffith Observatory and Jet Propulsion Laboratory. The SCA then headed south, where it flew over Disneyland, Boeing and the U.S.S. Iowa. It then returned to LAX and gave us two approaches: The first one much higher than the above pic; even though it looked like it might land. At the last moment, the 747 pulled up and completed one last long loop to the southeast toward its final landing approach.    Welcome to Los Angeles, Endeavour! We are proud to have you. I will see you again during the parade to the CA Science Center on October 12. Below is a collection of some of my favorite photos.  


 

Endeavour began her journey to Southern California with flyovers of Sacramento and San Francisco 

Endeavour over Candlestick Park in San Francisco.

The two photos above were taken by a photographer for the L.A. Times from a skyscraper rooftop in nearby downtown Los Angeles

 A sight that was never before seen over downtown Los Angeles - 

and never will be again

 Endeavour soars over NASA's Jet Propulsion Laboratory in Pasadena 

 Touchdown at LAX

 You don't see this every day: Angelenos stop and get out of their cars along a busy airport access road to get a better look at History in the Making. 

By Saturday afternoon, Endeavour had been de-mated from the SCA. This marks the first time Endevour was seen nose-to-nose with a NASA shuttle carrier aircraft