The Jet Propulsion Laboratory is a NASA center specializing in the robotic exploration of the solar solar system and worlds beyond.
In today's universe, it seems unimaginable that a planetary spacecraft would leave the comfort of its terrestrial perch without some kind of imaging system on board. But in the early 1960s, as NASA's Jet Propulsion Laboratory was reveling in the success of its first planetary mission to Venus and setting its sights on Mars -- a destination whose challenges would unfurl themselves much more readily than they had with Venus -- for some scientists, the question of camera or none was still just that, a question.
Bud Schurmeier, project manager for NASA's Ranger missions, a few years ago recalled, "There were a lot of scientists who said, 'Pictures, that's not science. That's just public information.' Over the years, that attitude has changed so markedly, and so much information has been obtained just from the photographs."
The recent passing of former JPL Director and career-long planetary imaging advocate Bruce C. Murray, 81, is a reminder of how different our understanding of the planets -- and our appreciation of them -- would be without space-based cameras.
This truth was evident as early as 1965, when NASA's Mariner 4, carrying an imaging system designed by a young Murray and his colleagues, arrived at Mars. It marked the world's first encounter with the Red Planet, a remarkable achievement in itself. But for an anxious press, public and mission team, the Holy Grail lay in catching that first glimpse of Mars up-close.
It was a waiting game that was too much for some. For everyone, in fact:
What resulted became known as "The first image of Mars." And in many ways it symbolizes -- more than any of the actual 22 photographs captured by Mariner 4 -- how significant this opportunity to truly "see" Mars had been.
Now, nearly 50 years after Mariner 4's arrival at Mars, imaging systems are an integral piece of our quest to understand the planets and the universe beyond, playing key roles in scientific investigations, spacecraft navigation and public support for missions. It's because of that first image that we can now look at that red dot in the night sky and picture what has become our new reality of Mars:
Today, JPL Earth scientist Hui Su joins thousands of other bloggers in more than 130 countries around the world for the Blog Action Day '09 Climate Change.
Blog Action Day is an annual event that unites the world's bloggers in posting about the same issue on the same day, with the aim of sparking discussion around an issue of global importance. The theme of this year's event, climate change, affects us all and will be the topic of international climate negotiations taking place in Copenhagen, Denmark, this December.
As a world leader in studying Earth's climate, NASA researchers play a vital role in shaping our understanding of global change. In today's post, Su discusses the critical role clouds play in climate, and why learning more about them is a key to predicting how our climate will change in the future. For more information on Blog Action Day, visit: http://www.blogactionday.org .
Clouds are among the most fascinating natural phenomena and have inspired countless works of literature and art. Their ever-changing forms make them a great challenge to atmospheric scientists working to predict how our climate will change in the future in response to increasing greenhouse gases such as carbon dioxide.
Clouds occur at many different heights in our atmosphere and take many different forms. There are three main types of clouds: stratus, cumulus and cirrus. Stratus clouds are low clouds, usually within 2 kilometers (7,000 feet) above the surface. They look like a gray blanket, extending thousands of kilometers across the sky. Cumulus clouds look like puffy cotton balls and extend vertically for large distances. The third type is wispy and feathery-looking cirrus. Cirrus clouds are usually high in the sky, about 7 kilometers (23,000 feet) above the surface. These three types of clouds have different impacts on Earth's climate due to their unique abilities to reflect sunlight and trap heat radiated from Earth's surface.
Stratus clouds can effectively block sunlight from reaching the surface; therefore, they act as an umbrella that cools Earth. Cirrus clouds are relatively transparent to sunlight but can trap terrestrial radiation, JUST AS carbon dioxide does, so they have a net warming effect on Earth. Cumulus clouds can block sunlight and also trap terrestrial radiation. Their net effect varies greatly depending on their actual heights and thicknesses.
Climate scientists have long struggled to quantify how different types of clouds change when global warming occurs. For example, an increase in stratus clouds may cool Earth's surface, compensating for global warming; while an increase in cirrus clouds may further warm Earth's surface, exacerbating global warming. Up to now, scientists have not been able to come to a consensus as to whether stratus, cumulus or cirrus clouds will increase or decrease as global temperatures increase.
A key advancement in cloud studies in recent years has been the availability of global satellite observations of clouds, especially the measurements of clouds at different heights provided by NASA satellites like CloudSat, managed by NASA's Jet Propulsion Laboratory (JPL). These observations are allowing scientists to better simulate clouds in climate models, which are the primary tools climate scientists use to predict future climate change. Up till now, the dynamic nature of clouds has made them very difficult to simulate in current climate models. But by applying space data, we at JPL are working closely with modelers to improve cloud simulations and thereby improve predictions of future climate change.
To learn more about JPL's research in this field and the CloudSat mission, visit: http://cloudsat.atmos.colostate.edu/home .
Planets, stars, buildings, cars, you and I, we are all made of the same basic stuff - atoms, the building blocks of matter. The late Carl Sagan famously said "we are star stuff," as the heavy elements in our bodies were all forged in supernovas, the explosions of dying stars. In a real scientific sense, we are one with everything we see in the night sky.
We have since learned that everything we see is awash in another kind of matter, a "dark" matter, made of particles yet to be discovered. Dark matter is all around us, but we cannot see it. Some estimate that a billion dark matter particles whiz through your body every second, but you cannot feel them. We now believe that the universe contains five times more dark matter than ordinary matter. While we all may be made of star stuff, we find that the universe is mostly made of something very different.
Why do we believe that dark matter exists? How can we study something that we cannot see or even feel? And how can we unravel the universe's greatest mystery - what is this dark matter?
The idea of dark matter was born at Caltech in 1933. (Just three years later, JPL would be born there as the "rocket boys" began their first launch experiments.) In observations of a nearby cluster of galaxies named the Coma cluster, Fritz Zwicky calculated that the collective mass of the galaxies was not nearly enough to hold them together in their orbits. He postulated that some other form of matter was present but undetected to account for this "missing mass." Later, in the 1970's and '80's, Vera Rubin similarly found that the arms of spiral galaxies should fly off their cores as they are orbiting much too quickly.
Today dark matter is a widely accepted theory, which explains many of our observations. My colleagues and I at JPL are among those working to reveal and map out dark matter structures. Dark matter is invisible. But astronomers can "see" it in a way and you can too, if you know what to look for! For instance, if you have a wineglass on a table and you look through the glass, the images behind it are distorted. So too when we look through a dense clump of dark matter, we see distorted and even multiple images of galaxies more distant. Matter bends space according to Einstein's Theory of General Relativity, and light follows these bends to produce the distorted images. By studying these "lensed" images, we can reconstruct the shape of the lens, or in our case, the amount and distribution of dark matter in our gravitational lens.
Our observations of dark matter in outer space force particle physicists to revise their theories to explain what we see. Hopefully through their efforts, physicists will soon produce dark matter in the lab, catch and identify a small fraction of that which passes through us, and ultimately explain the relationship between dark matter and "star stuff."