1.5 astronomical units

one astronomical unit

Mars has a very eccentric orbit; that is, it deviates from a perfect circle more than any other planet’s orbit At its farthest distance (aphelion), Mars is 154 million miles (249 million km) from the sun. At its closest (perihelion), Mars is 128 million miles (206 million km) distant.

Because Mars is farther from the Sun than Earth, the Sun appears only about two-thirds the size we see when we watch sunsets here on Earth.

For a start there are very few cloudy nights on Mars. We know it does have some clouds because they have been photographed by every orbiter, rover and lander that has ever been there, and occasionally Mars dust storms brew up that can cover the whole sky for months.

The sky of Mars near the Sun appears blue, while the sky far away from the Sun appears red. The disk of the Sun appears mostly white, with a slight bluish tinge. This has nothing to do with clouds or ice, but by the Martian dust that permeates throughout the planet’s atmosphere.

The sky is not blue as on Earth because Martian air is extremely thin, and the dust particles in the air are large relative to the wavelength of visible light.

The dust in the atmosphere absorbs blue light, giving the sky its red color, but it also scatters some of the blue light into the area just around the Sun because of its size. The blue color only becomes apparent near sunrise and sunset, when the light has to pass through the largest amount of dust.

The students found that dandelions would flourish on Mars and have significant benefits: they grow quickly, every part of the plant is edible, and they have high nutritional value. Other thriving plants include microgreens, lettuce, arugula, spinach, peas, garlic, kale and onions.

The atmosphere of Mars is CO2, but it is only about 1/100 the density of Earth’s atmosphere… it is effectively a Vacuum. Even if the Cacti could somehow find liquid water (they can’t), the vacuum would cause that water to boil out of them immediately.

In The Martian, potatoes are successfully harvested after 48 sols (a Martian solar day – 24 hours 39 minutes long), but the success of the venture does not last: Watney’s potato-growing is put to an abrupt end as the front of his habitat blows off, exposing his entire crop to the Martian air.

NASA study: Life from Earth could survive on Mars, at least for a while. Researchers from NASA and the German Aerospace Center (DLR) sent certain microbes into Earth’s stratosphere, where conditions are strikingly similar to those at the surface of Mars.

Scientists have found that some Earth microbes could survive on Mars temporarily after testing several types of bacteria and fungi for their survival skills by launching them into Earth’s stratosphere on the MARSBOx (Microbes in Atmosphere for Radiation, and Biological Outcomes experiment) space balloon, since the …

But most of the water, a new study concludes, went down, sucked into the red planet’s rocks. And there it remains, trapped within minerals and salts. Indeed, as much as 99 percent of the water that once flowed on Mars could still be there, the researchers estimated in a paper published this week in the journal Science.

Ice and hydrated minerals on Mars are sources of water. Carbon dioxide can get converted into oxygen. In comparison, there is no food naturally available on Mars, and there is no easy way to create it from any raw materials on the Red Planet using, say, a simple chemical reactor, the researchers said.

And, as far as we know, there are no living beings on Mars. But we still keep sending spacecraft to look for life. Sending a cargo of tardigrades to Mars would be irresponsible, even if we don’t believe they would survive.