![]() The capabilities of such chambers are limited by size, power requirements, and remote control from Earth. Often, the data from multiple instruments and camera images must be put together to actually determine what’s on or even just below the surface.Īdditionally, landers and rovers can collect samples from the surface of the planet to be placed in an analysis chamber that can determine the chemical composition and types of minerals in the sample, such as clay minerals that likely formed in a liquid water environment. These signals can be further interpreted to detect atomic elements such as hydrogen (H), which is one component of water. The relative intensity of reflection of different wavelengths is together called a spectrum, which is measured to narrow down the possible range of materials on the surface of an extraterrestrial body.Īdditional instruments can be designed to detect other wavelengths of light or elementary particles like neutrons emanating from the surface of an extraterrestrial body. The latter includes ultraviolet (shorter wavelengths than visible that can give you a sunburn) and infrared (longer wavelengths than visible that can be used to heat food in your microwave). Different materials, including water, absorb and reflect different wavelengths of light – both visible light that humans see as different colors, and light that we cannot see with our eyes. In addition to camera images, scientists also indirectly understand what material is on a planet by measuring the reflectance of light off the surface. These include landers, rovers, and various varieties of telescopes. There are many different ways that we search for water on extraterrestrial bodies, such as planets, moons, and asteroids. Spacecraft that can land and even drive on the planet’s surface (called rovers), allow humans to “move” around a planet to look at the size and shape of rocks ranging from larger boulders to tiny pebbles. Placing a camera closer to a planet via an orbiting spacecraft allows scientists to collect much higher resolution images of the surface. Optical telescopes can also give some indication of mountains and valleys on other planets, but the large distance from Earth makes it very difficult to determine the size and structure of smaller geological features, like those that may have been formed with the help of flowing water. As such, optical telescopes alone cannot confirm the presence of water. However, when it’s cold enough, even carbon dioxide (a gas at room temperature on Earth) forms a reflective solid. Brighter regions, especially near the north or south pole of a planet or moon could indicate reflections of frozen water (think of how shiny ice can be when you walk down the street in winter). ![]() Optical telescopes that collect visible light and provide visual images of distant bodies only give us some indication of the brightness and large-scale shapes and structures of large regions. While on Earth we can see water and handle it with our bare hands, detecting water or finding evidence of past water from far away is much more difficult. ![]() But how exactly do we find water in such far off places without going there ourselves? How do we find water in the solar system? Water away from Earth would be necessary for drinking, breathing, and producing fuel to operate spacecraft or spacebase systems. Additionally, if humans are to ever have a long-term presence on an extraterrestrial body, there will need to be native sources of water at those locations. Essential to the formation of all known life, evidence of stable liquid water elsewhere could indicate an environment beyond Earth that could sustain the formation of extraterrestrial life. Water has been a major driver of exploration of the solar system. Could such a stream have contained extraterrestrial life long ago? The size and shape of these stones indicates that they were likely formed by a river stream on the surface of Mars some time in the ancient past. There, you find a slab of rocks made of pieces of gravel smooshed together. On the way, you take images with a high-resolution camera. You begin traveling across the Gale crater toward Mount Sharp, 18,000 feet higher than the floor of the crater. You’ve just arrived on Mars after an eight-month journey from Earth. Picture yourself as the Curiosity Rover, which landed on Mars in 2012.
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