Dara Entekhabi, an MIT professor of civil and environmental engineering and of earth, atmospheric and planetary sciences, is the science team leader of NASA’s Soil Moisture Active Passive (SMAP) satellite, scheduled to be launched from Vandenberg Air Force Base in California on Jan. 29.

Artist’s rendering of the SMAP instrument. Credit: NASA

The satellite will provide measurements of the moisture in the top 2 inches of the soil, everywhere on Earth, over the course of its planned three-year mission, as well as specifying whether that water is liquid or frozen. Entekhabi discussed what he hopes this mission will be able to accomplish.

Q. How much of an improvement will SMAP represent over current ways of assessing soil moisture around the world? Why is it important to be able to do so?

A. Why we need soil moisture information, and what capability SMAP adds, can be explained by following a timeline of what we know about how the Earth system works, starting in the 1980s and 1990s. Read more

As we have been hearing, global water shortages are poised to exacerbate regional conflict and hobble economic growth. Yet the problem is growing worse, and is threatening to deal devastating blows to health, according to top water officials from the U.S. State Department and the U.S. Agency for International Development (USAID) who spoke before a House panel hearing today.

Ever-rising water demand, and climate change, are expected to boost water problems worldwide, especially in countries that are already experiencing shortages. Globally, the world is on track to meet the Millennium Development Goal of halving the number of people unable to reach or afford safe drinking water by 2015, but it still must make strides to improve global sanitation, says Aaron Salzberg, the State Department’s Special Coordinator for Water Resources. In addition to supply problems, unclean water causes more than four billion cases of diarrhea a year which lead to roughly 2.2 million deaths, and most are in children under the age of five. Read more

Water is everywhere on our planet. In the air, in our bodies, in our food and in our breath. Without it life as we know it would not be possible. Water is vital for the survival of all living things, yet as a molecule it has some pretty odd behaviour. Water molecules stick to each other, forming the ‘skin’ on ponds and droplets. The solid form floats on the liquid form. At room temperature water is a liquid, when most of the molecules closely related to it are gasses.

Why does water have so many strange and wonderful properties? What is it about this rather tiny and innocuous molecule that makes it so important for life?

To answer that you have to look at the actual structure of the molecule, exploring a world far, far smaller than microbiology usually goes. The properties of water are determined by the forces that hold it together.

A stylised diagram of a water molecule. All diagrams in this post (c) me.

The above diagram shows a water molecule, H2O. Two atoms of hydrogen attached to one molecule of oxgyen sharing electrons between them to form bonds. But the red lines that I’ve used to show the bonds hide a far more complicated story. This may be a bond, but it is not a very equal one because while oxgyen is a nice reasonably sized molecule, with eight electrons surrounding each atom, hydrogen is tiny. It only has one electron! Read more

The Earth is often compared to a majestic blue marble, especially by those privileged few who have gazed upon it from orbit. This is due to the prevalence of water on the planet’s surface. While water itself is not blue, water gives off blue light upon reflection.

For those of us confined to living on the surface, the fact that our world is mostly covered in water is a well known fact. But how much of our planet is made up of water, exactly? Like most facts pertaining to our world, the answer is a little more complicated than you might think, and takes into account a number of different qualifications. Read more

Freezing technology can be utilised in waste water treatment. When waste water freezes, it is purified through the formation of a cleaner layer of ice. The clean layer of ice can be removed from the rest of the waste water, and the remaining waste water is more concentrated.

The new energy-efficient method of purification is based on the natural freezing process of water: energy is required only for breaking the ice and transporting it from the waste water pool.

In practice, this method could be used by leaving waste water from mines to freeze in special pools under the open sky, after which the cleaner part could be removed by breaking the ice. After that the ice would be taken away using a machine designed for that purpose to another pool where the treated waste water would be recycled, or undergo further treatment using membrane filtration, for example, for the needs of various processes. Recycling water from the industrial process would reduce the amount of fresh water that is used. Read more