Thursday, April 13, 2023

SpaceX - Starship Mission to Planet Mars

So-called "Mars" is the 4th planet from the Sun and the third largest and massive terrestrial object in the Solar System. Mars has a thin atmosphere and a crust primarily composed of elements similar to Earth's crust, as well as a core made of iron and nickel. Mars has surface features such as impact craters, valleys, dunes, and polar ice caps. Mars has two small, irregularly shaped moons, Phobos and Deimos.

Some of the most notable surface features on Mars include Olympus Mons, the largest volcano and highest-known mountain in the Solar System, and Valles Marineris, one of the largest canyons in the Solar System. The Borealis basin in the Northern Hemisphere covers approximately 40% of the planet and may be a large impact feature. Days and seasons on Mars are comparable to those of Earth, as the planets have a similar rotation period and tilt of the rotational axis relative to the ecliptic plane. Liquid water on the surface of Mars cannot exist due to low atmospheric pressure, which is less than 1% of the atmospheric pressure on Earth. Both of Mars's polar ice caps appear to be made largely of water. In the distant past, Mars was likely wetter, and thus possibly more suited for life. It is not known whether life has ever existed on Mars.

Although we usually think of water being liquid between zero and 100 degrees Celsius, this is only true for pure water at Earth's sea level atmospheric pressure (about 14.7 pounds per square inch or 1014 millibar).

The single combination of pressure and temperature at which liquid water, solid ice, and water vapor can coexist in a stable equilibrium occurs at exactly 273.1600 K (0.0100 °C; 32.0180 °F) and a partial vapor pressure of 611.657 pascals (6.11657 mbar; 0.00603659 atm).

At sufficiently low pressures there is no liquid phase, but the substance can exist as either gas or solid. For water, there is no liquid phase at pressures below 0.00600 atm. The phase change from solid to gas is called sublimation.

Can liquid water exist above 100 C? Yes. Temperature of water can not exceed 100 deg celsius only when pressure is 1 atm, as it starts boiling and vaporise. If pressure is increased, then the boiling point can also be increased and water can attain more than 100 degree celsius. This is why indeed pressure cookers cook faster.

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