Local Lifestyle

Friday, Feb 01 2013 03:03 PM

NICK STROBEL: Landsat monitors land-use changes over last 40 years

By The Bakersfield Californian

About mid-month(on Feb. 11, if the weather permits), NASA will launch the eighth in the series of Landsat satellites called the "Landsat Data Continuity Mission" from Vandenberg Air Force Base. Since 1972, this series has provided an unparalleled record of how natural and human activity have transformed the land areas of our planet. Every 16 days, there's a Landsat satellite that passes overhead and acquires images of the land surface, including crops, fields and urban areas. Seeing the changes through the past 40 years has enabled us to better plan for the future, to make better decisions about how resource limitations will affect us in the future.

Forty years ago, the world's population was about half of what it is today but the amount of land area hasn't changed. In 1972, there was approximately 9.5 acres per person for food, fiber, production and anything else for which we depend on the land. By 2023, will be down to just 4.7 acres per person, so we will need to be more efficient in the use of the land. In order to figure that out, we need to use the lessons the Landsat series have given us through monitoring our land usage.

One instructive time-lapse video in the Landsat launch party kit (launchkit-ldcm.gsfc.nasa.gov/launch_party_kit/index.html) shows how Las Vegas and nearby Lake Mead have changed over the past 40 years. In the video, you see Las Vegas slowly growing with Lake Mead levels fluctuating up and down (more down than up) to the year 2000. In the following years up to 2010, Las Vegas really burst its boundaries and spread into surrounding areas. And, as Las Vegas spread, you can see the water levels in Lake Mead dramatically shrink.

Of course, Las Vegas is just one place among many where such things have been seen in the past 40 years. Another sequence between 1977 and 2010 shows the Aral Sea at the border of Kazakstan and Uzbekistan, which used to be the fourth-largest lake in the world, drained to three puddles as water was diverted for agriculture. The Landsat program has measured that agriculture accounts for 70 percent of global water usage and that there has been a 40 percent increase in irrigated agriculture since 1972. As we plan for changes in climate and pressures on water availability, questions like how much water is going to agriculture and whether there's going to be sufficient water are really critical.

One really cool thing about the Landsat program is that the archive of more than 3 million images (and growing!) is free to the public and use of the data from farmers, city planners, resource managers, agencies and governments around the world have really exploded since the archive was opened up in 2008. (Good thing too since all sorts of conflicts arise when people fail to understand why their once-dependable land resources shrink and dry up.)

The Landsat program is the only Earth-observing science satellite system that has a systematic acquisition strategy of the globe and the only one that distributes the data free of charge. That free and open policy has spurred the European Space Agency to adopt a free and open policy on the data collected by their Landsat-version Sentinel Satellites that will be launched over the next few years. To access the Landsat archive, go to landsat.usgs.gov or nasa.gov/landsat.

Eye on moon, planets

Last week the moon closely passed by Jupiter in our sky. Since this was the closest passage for the next 13 years and the sky was clear, I took some pictures, one of which I posted with my previous column in the Night Sky section of the William M. Thomas Planetarium's website (bakersfieldcollege.edu/planetarium). The planetarium's website also now has links to online purchasing of tickets for the upcoming shows. Tickets for March's "Dynamic Earth" and April's "Black Holes" shows will be available after the previous show's date (see the website for more details).

Tomorrow pre-dawn, the third quarter moon passes under the other giant planet of our solar system, Saturn, although the celestial bodies will be well-separated. They might just fit within the same field of your binoculars as shown in the main part of the attached chart.

The attached chart shows Venus very low in the south-southeast at 6:30 a.m. but the pre-dawn glow will probably be too much by the time it rises high enough to see. A very thin waning crescent moon will be to the upper right of Venus on the morning of Feb. 8. That thin moon will test your observation skills!

Jupiter continues to dominate the evening sky and is well up in the sky at sunset, but next week (Feb 12 to 20) you might be able to spot another bright planet if you face west. Mercury will make a brief appearance as it climbs up away and then plunges back down toward the sun in that span of time. Before then, on the evenings of Feb. 7 and 8, Mercury will pass by the dimmer orange-red Mars, a nice view through binoculars.

Curious about Curiosity

Perhaps by then we will have had news of Curiosity's first drilling into a martian rock. As I write this, the Curiosity rover team was still determining which particular rock on which it was going to use the rotary percussive drill for the first time on Mars (there were already plenty of tests on Earth). The drill grinds the rock into a fine powder and the powder is delivered to the ultra-sensitive Sample Analysis at Mars and the CheMin instruments onboard the rover.

The drill is at the end of a 7.5-foot arm in a turret of other instruments and tools that has a total mass of 73 pounds. The arm has to lift that massive turret with enough precision to deliver an aspirin tablet worth of powder into an opening the size of a thimble.

On Feb. 10, a very thin waxing crescent moon will be next to Mercury and Mars. Binoculars might be needed to pick them all out in the twilight glow. The inset graphic in the attached chart shows Mercury's motion in the early evening sky.

Observe light pollution

Later in the evening, see how many stars you can see in the Orion constellation and log your results at the GLOBE at Night's website (globeatnight.org). This winter's campaign will end on Feb. 9. Tonight, Orion will be due south at about 8:30 p.m.

GLOBE at Night invites everybody to measure the amount of light pollution in their area by comparing their view of a bright, famous constellation (such as Orion) with a standard set at different visibility levels. You'll need to know your latititude and longitude: Bakersfield is 35.4 degrees N latitude and 119 degrees W or use the webapp on the GLOBE at Night website to get your location very precisely.

Find Orion no earlier than 8 p.m. and match your view to one of the GLOBE at Night brightness charts and report your observation. You can also compare your observation with thousands of others around the world.

Want to see more of the stars at night and save energy? Shield your lights so that the light only goes down toward the ground. See darksky.org for how.

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