A fresh satellite image of Mars collected by the Mars Reconnaissance Orbiter shows an unusual site where sediments have eroded over time and exposed an ancient channel that stretches for a few miles. The f e a has b e c more o b v as t planet h dried u , especially w h viewed f r a height o about 250 m i . The feature may reveal something about the ancient past on Mars across millions of years of the planet's history.

"The images of Mars taken by the Mariner 9 probe indicate the presence of valleys that looks like the stream beds on Earth. The images also show that Mars once had an atmosphere that was thick enough to trap Sun's heat. If this is true, something must have happened to Mars billions of years ago that stripped away its atmosphere."This paragraph supports which of the following statements:-Mars has little or no atmosphere.Mars once had an atmosphere thicker than Earth's atmosphere.Mariner 9 probe took the first picture of Mars.Mars is closer to Sun than Earth.

(Venus, Mars) has evidence that water is or was once present.

That the Tharsis region on Mars has so few cratersGroup of answer choicesis due to annual flooding and water erosion.suggests it is at the center of a particularly strong magnetic field.proves tectonic activity is taking place.suggests it is the youngest region on the planet.is due to the regions very low elevation.

What is true of Mars?Group of answer choicesDefinite microfossils have been found.Its atmosphere is mostly water vapor.Iron oxide on the surface is responsible for its reddish color.A pool of water was discovered by the Mars Rover.Its magnetic field is stronger than Earth's

Contrast the mountains on Mars and Venus with those on Earth and the Moon.