Earth Archives

August 30, 2013December 23, 2015 by Ken Kremer

Are We Martians? Chemist’s New Claim Sparks Debate

Are Earthlings really Martians ?
Did life arise on Mars first and then journey on rocks to our planet and populate Earth billions of years ago? Earth and Mars are compared in size as they look today. NASA’s upcoming MAVEN Mars orbiter is aimed at answering key questions related to the habitability of Mars, its ancient atmosphere and where did all the water go.
Story updated[/caption]

Are Earthlings really Martians?

That’s the controversial theory proposed today (Aug. 29) by respected American chemist Professor Steven Benner during a presentation at the annual Goldschmidt Conference of geochemists being held in Florence, Italy. It’s based on new evidence uncovered by his research team and is sure to spark heated debate on the origin of life question.

Benner said the new scientific evidence “supports the long-debated theory that life on Earth may have started on Mars,” in a statement. Universe Today contacted Benner for further details and enlightenment.

“We have chemistry that (at least at the level of hypothesis) makes RNA prebiotically,” Benner told Universe Today. “AND IF you think that life began with RNA, THEN you place life’s origins on Mars.” Benner said he has experimental data as well.

First- How did ancient Mars life, if it ever even existed, reach Earth?

On rocks violently flung up from the Red Planet’s surface during mammoth collisions with asteroids or comets that then traveled millions of miles (kilometers) across interplanetary space to Earth – melting, heating and exploding violently before the remnants crashed into the solid or liquid surface.

An asteroid impacts ancient Mars and send rocks hurtling to space - some reach Earth — An asteroid impacts ancient Mars and send rocks hurtling to space – some reach Earth. Did they transport Mars life to Earth? Or minerals that could catalyze the origin of life on Earth?

“The evidence seems to be building that we are actually all Martians; that life started on Mars and came to Earth on a rock,” says Benner, of The Westheimer Institute of Science and Technology in Florida. That theory is generally known as panspermia.

To date, about 120 Martian meteorites have been discovered on Earth.

And Benner explained that one needs to distinguish between habitability and the origin of life.

“The distinction is being made between habitability (where can life live) and origins (where might life have originated).”

NASA’s new Curiosity Mars rover was expressly dispatched to search for environmental conditions favorable to life and has already discovered a habitable zone on the Red Planet’s surface rocks barely half a year after touchdown inside Gale Crater.

Furthermore, NASA’s next Mars orbiter- named MAVEN – launches later this year and seeks to determine when Mars lost its atmosphere and water- key questions in the Origin of Life debate.

Curiosity accomplished Historic 1st drilling into Martian rock at John Klein outcrop on Feb 8, 2013 (Sol 182) and discovered a habitable zone, shown in this context mosaic view of the Yellowknife Bay basin taken on Jan. 26 (Sol 169). The robotic arm is pressing down on the surface at John Klein outcrop of veined hydrated minerals – dramatically back dropped with her ultimate destination; Mount Sharp. Credit: NASA/JPL-Caltech/Ken Kremer-kenkremer.com/Marco Di Lorenzo

Of course the proposed chemistry leading to life is exceedingly complex and life has never been created from non-life in the lab.

The key new points here are that Benner believes the origin of life involves “deserts” and oxidized forms of the elements Boron (B) and Molybdenum (Mo), namely “borate and molybdate,” Benner told me.

“Life originated some 4 billion years ago ± 0.5 billon,” Benner stated.

He says that there are two paradoxes which make it difficult for scientists to understand how life could have started on Earth – involving organic tars and water.

Life as we know it is based on organic molecules, the chemistry of carbon and its compounds.

But just discovering the presence of organic compounds is not the equivalent of finding life. Nor is it sufficient for the creation of life.

And simply mixing organic compounds aimlessly in the lab and heating them leads to globs of useless tars, as every organic chemist and lab student knows.

Benner dubs that the ‘tar paradox’.

Although Curiosity has not yet discovered organic molecules on Mars, she is now speeding towards a towering 3 mile (5 km) high Martian mountain known as Mount Sharp.

Curiosity Spies Mount Sharp - her primary destination. Curiosity will ascend mysterious Mount Sharp and investigate the sedimentary layers searching for clues to the history and habitability of the Red Planet over billions of years. This mosaic was assembled from over 3 dozen Mastcam camera images taken on Sol 352 (Aug 2, 2013. Credit: NASA/JPL-Caltech/MSSS/ Marco Di Lorenzo/Ken Kremer — Curiosity Spies Mount Sharp – her primary destination
Curiosity will ascend mysterious Mount Sharp and investigate the sedimentary layers searching for clues to the history and habitability of the Red Planet over billions of years. This mosaic was assembled from over 3 dozen Mastcam camera images taken on Sol 352 (Aug 2, 2013. Credit: NASA/JPL-Caltech/MSSS/ Marco Di Lorenzo/Ken Kremer-kenkremer.com

Upon arrival sometime next spring or summer, scientists will target the state of the art robot to investigate the lower sedimentary layers of Mount Sharp in search of clues to habitability and preserved organics that could shed light on the origin of life question and the presence of borates and molybdates.

It’s clear that many different catalysts were required for the origin of life. How much and their identity is a big part of Benner’s research focus.

“Certain elements seem able to control the propensity of organic materials to turn into tar, particularly boron and molybdenum, so we believe that minerals containing both were fundamental to life first starting,” says Benner in a statement. “Analysis of a Martian meteorite recently showed that there was boron on Mars; we now believe that the oxidized form of molybdenum was there too.”

The second paradox relates to water. He says that there was too much water covering the early Earth’s surface, thereby causing a struggle for life to survive. Not exactly the conventional wisdom.

“Not only would this have prevented sufficient concentrations of boron forming – it’s currently only found in very dry places like Death Valley – but water is corrosive to RNA, which scientists believe was the first genetic molecule to appear. Although there was water on Mars, it covered much smaller areas than on early Earth.”

Parts of ancient Mars were covered by oceans, lakes and streams of liquid water in this artists concept, unlike the arid and bone dry Martian surface of today. Subsurface water ice is what remains of Martian water.

I asked Benner to add some context on the beneficial effects of deserts and oxidized boron and molybdenum.

“We have chemistry that (at least at the level of hypothesis) makes RNA prebiotically,” Benner explained to Universe Today.

“We require mineral species like borate (to capture organic species before they devolve to tar), molybdate (to arrange that material to give ribose), and deserts (to dry things out, to avoid the water problem).”

“Various geologists will not let us have these [borates and molybdates] on early Earth, but they will let us have them on Mars.”

“So IF you believe what the geologists are telling you about the structure of early Earth, AND you think that you need our chemistry to get RNA, AND IF you think that life began with RNA, THEN you place life’s origins on Mars,” Benner elaborated.

“The assembly of RNA building blocks is thermodynamically disfavored in water. We want a desert to get rid of the water intermittently.”

I asked Benner whether his lab has run experiments in support of his hypothesis and how much borate and molybdate are required.

“Yes, we have run many lab experiments. The borate is stoichiometric [meaning roughly equivalent to organics on a molar basis]; The molybdate is catalytic,” Benner responded.

“And borate has now been found in meteorites from Mars, that was reported about three months ago.

At his talk, Benner outlined some of the chemical reactions involved.

Although some scientists have invoked water, minerals and organics brought to ancient Earth by comets as a potential pathway to the origin of life, Benner thinks differently about the role of comets.

“Not comets, because comets do not have deserts, borate and molybdate,” Benner told Universe Today.

The solar panels on the MAVEN spacecraft are deployed as part of environmental testing procedures at Lockheed Martin Space Systems in Littleton, Colorado, before shipment to Florida 0on Aug. 2 and blastoff for Mars on Nov. 18, 213. Credit: Lockheed Martin — MAVEN is NASA’s next Mars orbiter and seeks to determine when Mars lost its atmosphere and water- key questions in the Origin of Life debate. MAVEN is slated to blastoff for Mars on Nov. 18, 2013. It is shown here with solar panels deployed as part of environmental testing procedures at Lockheed Martin Space Systems in Waterton, Colorado, before shipment to Florida in early August. Credit: Lockheed Martin

Benner has developed a logic tree outlining his proposal that life on Earth may have started on Mars.

“It explains how you get to the conclusion that life originated on Mars. As you can see from the tree, you can escape that conclusion by diverging from the logic path.”

Finally, Benner is not one who blindly accepts controversial proposals himself.

He was an early skeptic of the claims concerning arsenic based life announced a few years back at a NASA sponsored press conference, and also of the claims of Mars life discovered in the famous Mars meteorite known as ALH 84001.

“I am afraid that what we thought were fossils in ALH 84001 are not.”

The debate on whether Earthlings are really Martians will continue as science research progresses and until definitive proof is discovered and accepted by a consensus of the science community of Earthlings – whatever our origin.

On Nov. 18, NASA will launch its next mission to Mars – the MAVEN orbiter. Its aimed at studying the upper Martian atmosphere for the first time.

“MAVENS’s goal is determining the composition of the ancient Martian atmosphere and when it was lost, where did all the water go and how and when was it lost,” said Bruce Jakosky to Universe Today at a MAVEN conference at the University of Colorado- Boulder. Jakosky, of CU-Boulder, is the MAVEN Principal Investigator.

MAVEN will shed light on the habitability of Mars billions of years ago and provide insight on the origin of life questions and chemistry raised by Benner and others.

Ken Kremer

…………….
Learn more about Mars, the Origin of Life, LADEE, Cygnus, Antares, MAVEN, Orion, Mars rovers and more at Ken’s upcoming presentations

Sep 5/6/16/17: “LADEE Lunar & Antares/Cygnus ISS Rocket Launches from Virginia”; Rodeway Inn, Chincoteague, VA, 8 PM

Oct 3: “Curiosity, MAVEN and the Search for Life on Mars – (3-D)”, STAR Astronomy Club, Brookdale Community College & Monmouth Museum, Lincroft, NJ, 8 PM

Oct 9: “LADEE Lunar & Antares/Cygnus ISS Rocket Launches from Virginia”; Princeton University, Amateur Astronomers Assoc of Princeton (AAAP), Princeton, NJ, 8 PM

August 29, 2013December 23, 2015 by Nancy Atkinson

Massive ‘Grand Canyon’ Found Hidden Beneath Greenland’s Ice

The NASA P-3B's shadow on sea ice off of southeast Greenland during an IceBridge survey on Apr. 9, 2013. Flying at a low altitude allows IceBridge researchers to gather detailed data. Credit: NASA / Jim Yungel

There’s a “Chuck Norris fact” that says Chuck once went skydiving but promised never to do it again, saying one Grand Canyon is enough. But Chuck must have taken another jump millions of years ago.

Data gathered by NASA’s Operation IceBridge, an aerial science observation mission, has uncovered a previously unknown massive canyon in Greenland, hidden under a kilometer of ice.

The canyon, found by airborne radar data, has the same characteristics of a winding river channel like the Grand Canyon in Arizona. It is at least 750 kilometers (460 miles) long, making it longer than the Grand Canyon. In some places, it is as deep as 800 meters (2,600 feet), on scale with parts of the Grand Canyon. This immense feature is thought to predate the ice sheet that has covered Greenland for the last few million years.

“One might assume that the landscape of the Earth has been fully explored and mapped,” said Jonathan Bamber, professor of physical geography at the University of Bristol in the United Kingdom, and lead author of the study. “Our research shows there’s still a lot left to discover.”

While additional airborne radar data was used, the majority of the data was collected by IceBridge flights over Greenland during flights from 2009 to 2013. IceBridge’s Multichannel Coherent Radar Depth Sounder can see through vast layers of ice to measure its thickness and the shape of bedrock below.

In their analysis of the radar data, Bamber and his team discovered a continuous bedrock canyon that extends from almost the center of the island and ends beneath the Petermann Glacier fjord in northern Greenland.

At certain frequencies, radio waves can travel through the ice and bounce off the bedrock underneath. The amount of time the radio waves took to bounce back helped researchers determine the depth of the canyon. The longer it took, the deeper the bedrock feature.

The researchers believe the canyon plays an important role in transporting sub-glacial meltwater from the interior of Greenland to the edge of the ice sheet into the ocean. Evidence suggests that before the presence of the ice sheet, as much as 4 million years ago, water flowed in the canyon from the interior to the coast and was a major river system.

“It is quite remarkable that a channel the size of the Grand Canyon is discovered in the 21st century below the Greenland ice sheet,” said Studinger. “It shows how little we still know about the bedrock below large continental ice sheets.”

The IceBridge campaign will return to Greenland in March 2014 to continue collecting data on land and sea ice in the Arctic using a suite of instruments that includes ice-penetrating radar.

Bamber and his team had their findings published in the journal Science.

Source: NASA

August 21, 2013December 23, 2015 by Ken Kremer

Earthlings Wave at Saturn as Cassini Images Us

Earth Waves at Cassini on July 19, 2013- From more than 40 countries and 30 U.S. states, people around the world shared more than 1,400 images of themselves as part of the Wave at Saturn event organized by NASA's Cassini mission on July 19, 2013. The Cassini team created this image collage as a tribute to the people of Earth Credit: NASA/JPL-Caltech/People of Earth See link below to the absolutely gigantic full resolution version

Earth Waves at Saturn and Cassini on July 19, 2013
From more than 40 countries and 30 U.S. states, people around the world shared more than 1,400 images of themselves as part of the Wave at Saturn event organized by NASA’s Cassini mission on July 19, 2013. The Cassini team created this image collage as a tribute to the people of Earth
Credit: NASA/JPL-Caltech/People of Earth
See link below to the absolutely gigantic full resolution version [/caption]

On July 19, millions of Earthlings worldwide participated in NASA’s ‘Wave at Saturn’ campaign as the NASA Cassini Saturn orbiter turned about and imaged all of us.

Earthlings from 40 countries and 30 U.S. states heeded NASA’s call to photograph themselves while smiling and waving at Saturn and Cassini across 1 billion miles of interplanetary space and shared over 1400 images.

The results of all those images has now been assembled into a fabulous collage in the shape of our planet and released today (Aug. 21) by NASA and the Cassini team as a tribute to the People of Earth.

“Did you wave at Saturn and send us your photo? Then here’s looking at you!” NASA announced on the Cassini Facebook page.

This event was the first time that the citizens of Earth knew in advance that a distant interplanetary spacecraft was photographing portraits of our home planet and our Moon. NASA invited everyone to participate.

Photos flooded into NASA via Twitter, Facebook, Flickr, Instagram, Google+ and email.

Click here for the full resolution version. But be forewarned – it weighs in at over 26 MB and it’s far too big to post here.

The Day the Earth Smiled: Sneak Preview In this rare image taken on July 19, 2013, the wide-angle camera on NASA's Cassini spacecraft has captured Saturn's rings and our planet Earth and its moon in the same frame. Image Credit: NASA/JPL-Caltech/Space Science Institute — The Day the Earth Smiled: Sneak Preview
In this rare image taken on July 19, 2013, the wide-angle camera on NASA’s Cassini spacecraft has captured Saturn’s rings and our planet Earth and its moon in the same frame. Image Credit: NASA/JPL-Caltech/Space Science Institute

“Thanks to all of you, near and far, old and young, who joined the Cassini mission in marking the first time inhabitants of Earth had advance notice that our picture was being taken from interplanetary distances,” said Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory, Pasadena, Calif, in a statement.

“While Earth is too small in the images Cassini obtained to distinguish any individual human beings, the mission has put together this collage so that we can celebrate all your waving hands, uplifted paws, smiling faces and artwork.”

The Cassini imaging science team is still assembling the hundreds of images of Saturn and Earth snapped by the spacecraft as we were waving, to create individual color composites and a panoramic view of the ‘pale blue dot’ and the entire Saturnian system.

To capture all of Saturn and its wide swath of rings, Cassini’s wide angle camera snapped a mosaic of 33 footprints on July 19, 2013.

“At each footprint, images were taken in different spectral filters for a total of 323 images,” says Carolyn Porco, Cassini Imaging Team leader, Space Science Institute in Boulder, Colo.

Cassini took the pictures of Earth from a distance of about 898 million miles (1.44 billion kilometers) away from the home to every human being that has ever lived.

Here is our partial version of Cassini’s mosaic.

Partial context mosaic of the Earth and Saturn taken by NASA’s Cassini orbiter on July 19, 2013. This mosaic was assembled from five wide angle camera raw images. Credit: NASA/JPL-Caltech/Ken Kremer/Marco Di Lorenzo — Partial context mosaic of the Earth and Saturn taken by NASA’s Cassini orbiter on July 19, 2013. This mosaic was assembled from five Cassini wide angle camera raw images and offers a sneak peek of the complete panorama. Earth at lower right. Credit: NASA/JPL-Caltech/Ken Kremer/Marco Di Lorenzo

Cassini was launched from Florida in 1997.

It achieved orbit at Saturn in 2004 and has transmitted breathtaking images and science that revolutionized our understanding of the Saturnian system.

The mission is scheduled to continue until 2017 when it will commit a suicide death dive into the humongous gas giant.

Coincidentally, the first humans (Neil Armstrong and Buzz Aldrin) set foot on the Moon 44 years ago nearly to the day of Cassini’s Earth-Moon portrait on July 20, 1969 aboard Apollo 11.

And likewise on July 19, 2013, billionaire space enthusiast Jeff Bezos announced that his dive teams had recovered components of an Apollo 11 first stage F-1 rocket engine from the Saturn V moon rocket that propelled the first humans to the Moon.

Ken Kremer

JPL Waves at Saturn As NASA's Cassini spacecraft turned its imaging cameras to Earth, scientists, engineers and visitors at NASA's Jet Propulsion Laboratory, Pasadena, Calif., gathered to wave at our robotic photographer in the Saturn system on July 19, 2013. Credit: NASA/JPL-Caltech — JPL Waves at Saturn As NASA’s Cassini spacecraft turned its imaging cameras to Earth, scientists, engineers and visitors at NASA’s Jet Propulsion Laboratory, Pasadena, Calif., gathered to wave at our robotic photographer in the Saturn system on July 19, 2013. Credit: NASA/JPL-Caltech

August 20, 2013December 23, 2015 by Jason Major

Earth’s Highest Clouds Shine at the “Top of the Orbit”

Polar mesospheric clouds shine over a midnight sunrise above Alaska on August 4, 2013 (NASA)

Looking for a new desktop background? This might do nicely: a photo of noctilucent “night-shining” clouds seen above a midnight Sun over Alaska, taken from the ISS as it passed over the Aleutian Islands just after midnight local time on Sunday, August 4.

When this photo was taken Space Station was at the “top of the orbit” — 51.6 ºN, the northernmost latitude that it reaches during its travels around the planet.

According to the NASA Earth Observatory site, “some astronauts say these wispy, iridescent clouds are the most beautiful phenomena they see from orbit.” So just what are they? Read on…

Found about 83 km (51 miles) up, noctilucent clouds (also called polar mesospheric clouds, or PMCs) are the highest cloud formations in Earth’s atmosphere. They form when there is just enough water vapor present to freeze into ice crystals. The icy clouds are illuminated by the Sun when it’s just below the horizon, after darkness has fallen or just before sunrise, giving them their eponymous property.

NLCs seen in the southern hemisphere in Jan. 2010 (NASA)

Noctilucent clouds have also been associated with rocket launches, space shuttle re-entries, and meteoroids, due to the added injection of water vapor and upper-atmospheric disturbances associated with each. Also, for some reason this year the clouds appeared a week early.

Some data suggest that these clouds are becoming brighter and appearing at lower latitudes, perhaps as an effect of global warming putting more greenhouse gases like methane into the atmosphere.

“When methane makes its way into the upper atmosphere, it is oxidized by a complex series of reactions to form water vapor,” said James Russell, the principal investigator of NASA’s Aeronomy of Ice in the Mesosphere (AIM) project and a professor at Hampton University. “This extra water vapor is then available to grow ice crystals for NLCs.”

A comparison of noctilucent cloud formation from 2012 and 2013 has been compiled using data from the AIM spacecraft. You can see the sequence here.

And for an incredible motion sequence of noctilucent clouds — taken from down on the ground — check out the time-lapse video below by Maciej Winiarczyk, coincidentally made at around the same time as the ISS photo above:

(The video was featured as the Astronomy Picture of the Day (APOD) for August 19, 2013.)

Source: NASA Earth Observatory

August 19, 2013December 23, 2015 by Nancy Atkinson

Stunning Aerial Tour of the Arctic

Horseshoe-shaped lateral moraines at the margin of the Penny Ice Cap on Baffin Island, Nunavut, Canada. Lateral moraines are accumulations of debris along the sides of a glacier formed by material falling from the valley wall. Credit: NASA / Michael Studinger

Enjoy this tour of the Arctic and Greenland, courtesy of the pilots of IceBridge, a six-year NASA mission to survey the ice at both of Earth’s poles. These views come from NASA’s P-3B aircraft, and the video is a selection of some of the best footage from the forward and nadir cameras mounted to the aircraft taken during IceBridge’s spring deployment over Greenland and the Arctic Ocean.

This airborne mission is collecting radar, laser altimetry, and other data on the changing ice sheets, glaciers, and sea ice of the Arctic and Antarctic. It is the largest airborne survey of Earth’s polar ice ever flown, and it will provide an unprecedented three-dimensional view of Arctic and Antarctic ice sheets, ice shelves and sea ice. These flights will provide a yearly, multi-instrument look at the behavior of the rapidly changing features of the Greenland and Antarctic ice.

Data collected during IceBridge will help scientists bridge the gap in polar observations between NASA’s Ice, Cloud and Land Elevation Satellite (ICESat) — in orbit since 2003 — and ICESat-2, planned for late 2015. ICESat stopped collecting science data in 2009, making IceBridge critical for ensuring a continuous series of observations.

Find out more about the mission and see more images and videos at the Operation IceBridge website.

August 16, 2013December 30, 2015 by Jason Major

Why the North Pole Is Really a South Pole (and Vice Versa)

If you go out hiking this weekend and somehow find yourself hopelessly lost in the wilderness, but suddenly remember you have a compass with you, you can use it to find north because the needle always points towards the Earth’s geographic north pole, which never changes… right?

Wrong, wrong, and wrong. And this video from MinutePhysics explains why.

(But still bring a compass with you. They do come in handy.)

See more videos from MinutePhysics here.

August 7, 2013December 23, 2015 by Nancy Atkinson

Astronauts Wax Poetic About Seeing Earth from Space

An aurora seen from the International Space Station on September 26, 2011. Credit: NASA.

Astronauts have tried to explain the view of Earth from space, with many saying that there just aren’t the words to describe how beautiful it is. In the latest episode of the “Science Garage,” recent ISS astronauts Tom Marshburn and Chris Hadfield might do the best job so far of relating not only the “incredible and unwrapping perspective of looking at the Earth,” but how it changed their perspective of humanity. Hadfield compares coming into the cupola of the International Space Station as being like “entering the Sistine Chapel.”

Watch below:

August 7, 2013December 23, 2015 by Nancy Atkinson

Watch Sprite Lightning Flash at 10,000 frames Per Second

Elusive sprite lightning captured from an airplane above Boulder, Colorado as part of a sprite observing campaign. Credit and copyright: Jason Ahrns.

Mysterious red sprite lightning is intriguing: sprites occur only at high altitudes above thunderstorms, only last for a thousandth of a second and emit light in the red portion of the visible spectrum. Therefore, studying sprites has been notoriously difficult for atmospheric scientists. Astrophotographer Jason Ahrns has had the chance to be part of a sprite observing campaign, and with a special airplane from the National Center for Atmospheric Research’s Research Aircraft Facility in Boulder, Colorado, has been on flights to try and observe red sprite lightning from the air.

Jason had some success on a recent flight, and was able to capture a sprite (above) on high speed film. Below you can see a movie of it at 10,000 frames per second:

Pretty amazing!

Scientists say that while sprites have likely occurred on Earth for millions of years, they were first discovered and documented only by accident in 1989 when a researcher studying stars was calibrating a camera pointed at the distant atmosphere where sprites occur.

Sprites usually appear as several clusters of red tendrils above a lighting flash followed by a breakup into smaller streaks. The brightest region of a sprite is typically seen at altitudes of 65-75 km (40-45 miles), but often as high as 90 km (55 miles) into the atmosphere.

Some of the latest research shows that only a specific type of lightning is the trigger that initiates sprites aloft.

You can read more (and see more images) about Jason’s experiences with sprites at his website.

August 5, 2013December 30, 2015 by Elizabeth Howell

This Is What Leaving Earth Behind Really Looks Like

Prepare yourself for some goosebumps. The Mercury spacecraft MESSENGER took this series of images of Earth eight years ago today as it swung by the planet (again) en route to its final destination.

Few humans have seen the Earth as an entire orb. Only a handful of missions, all in the Apollo era, have ventured beyond low Earth orbit. The people who traveled furthest were Jim Lovell, Fred Haise and Jack Swigert during Apollo 13, when their spacecraft (which had been crippled by an explosion) looped around the moon on the way home.

MESSENGER is happily traveling around Mercury these days and recently recorded a cool series of images showing the planet as a colorful, spinning sphere. The spacecraft — the first to do an extended stay around that planet — has shown scientists a lot of things, including the discovery of water ice and organics.

Thanks to Astronomy Picture of the Day for reminding us of this video.

July 29, 2013December 23, 2015 by Jason Major

30 Years of City Growth Seen From Space

China's now-industrialized Pearl River Delta, seen in October 1973 (top) and January 2003 (bottom)

Since the launch of its first satellite in 1972, the eight NASA/USGS Landsat satellites have made the longest continuous observations of Earth’s surface, providing invaluable data for research in agriculture, geology, forestry, regional planning, education, mapping, global change research, as well as important emergency response and disaster relief information. In addition, having such a long span of data allows us to easily see the expansion of human development in many areas — unprecedented before-and-after views of city growth seen from space.

These images, taken over the course of the Landsat program, illustrate the visible impact of over three decades of human development:

Chandler, Arizona imaged in 1985 (top) and 2011 (bottom.) As its economy shifted from agriculture to manufacturing and electronics, Chandler's population multiplied 8 times to over 236,000. — Chandler, Arizona imaged in 1985 (top) and 2011 (bottom.) As its economy shifted from agriculture to manufacturing and electronics, Chandler’s population multiplied 8 times to over 236,000.

The explosion of Istanbul's population from 2 to 3 million people is evident in these Landsat images, comparing 1975 to 2011. Vegetation appears red in the imaging wavelengths used here. — The explosion of Istanbul’s population from 2 to 13 million people is evident in these Landsat images, comparing 1975 to 2011. Vegetation appears red in the imaging wavelengths used here.

A few years ago one of the fastest-growing cities in the US, Las Vegas is seen here in images taken in 1984 (top) and 2011 (bottom.) The sprawling development -- as well as the decrease in water level of Lake Mead -- is evident. — A few years ago one of the fastest-growing cities in the US, Las Vegas is seen here in images taken in 1984 (top) and 2011 (bottom.) The sprawling development — as well as the decrease in water level of Lake Mead — is evident.

Some of the most dramatic -- and rapid -- changes have occurred in Dubai, whose artificial offshore islands suddenly appear between images taken in 2000 (top) and 2010 (bottom.) Once barely visible against the desert landscape, Dubai is now an international center of business, tourism, and oil production. — Some of the most dramatic — and rapid — changes have occurred in Dubai, whose palm- and continent-shaped artificial islands suddenly appear between images taken in 2000 (top) and 2010 (bottom.) Once barely visible against the desert landscape, Dubai is now an international center of business, tourism, and oil production.

See more of these images on NASA Goddard Space Flight Center’s Flickr album here.

The Landsat Program is a series of Earth-observing satellite missions jointly managed by NASA and the U.S. Geological Survey. In 1972, the launch of ERTS-1 (Earth Resources Technology Satellite, later renamed Landsat 1) started the era of a series of satellites that have since continuously acquired space-based land remote sensing data.

The latest satellite in the Landsat series, the Landsat Data Continuity Mission (LDCM) — now named Landsat 8 — was launched on February 11, 2013. Landsat 8 data is now available free to the public online here.

Read more on the USGS Landsat mission page here.

Image credits: USGS/NASA