A View From Mars

earth-from-mars-hiresA telescope in orbit around Mars took this view of Earth and its Moon, showing continent-size detail on the planet. The image combines two separate exposures taken in November, 2016, by the High Resolution Imaging Science Experiment (HiRISE) camera on the Mars Reconnaissance Orbiter. The images were taken to calibrate HiRISE  using the known value of reflectance for the Earth-facing side of the Moon. The exposures used to make this composite image were processed separately to optimize detail visible on both Earth and the Moon. The Moon is much darker than Earth and would barely be visible if shown at the same brightness scale as Earth.

The combined view retains the correct positions and sizes of the two bodies relative to each other. The distance between Earth and the Moon is about 30 times the diameter of Earth. Earth and the moon appear closer than they actually are in this image because the observation was planned for a time at which the Moon was almost directly behind Earth as seen from Mars so that the Earth-facing side of the Moon would be visible.

The reddish feature near the middle of the face of Earth is Australia. Mars was about 205 million km from Earth when the images were taken, so nude sunbathers are not visible in this image.

Image Credit: NASA

Odd Craters on Mars

Last October, the HIRISE instrument aboard the Mars Reconnaissance Orbiter grabbed this picture of a crater in the northern Arabia Terra region of Mars. This crater and several others in the same region contain oddly shaped deposits usually on the south side of the craters. All the odd craters are large, at least 600 m in diameter. The best guess (so far) is that the features were formed by the sublimation of water from ice-rich material stirred up by the substantial impacts which created the craters.

Image Credit: NASA

Frosty Mornings

We had a overnight freeze warning earlier this week here in Westminster. That can happen in the early Spring, but even our coldest mornings in the winter don’t compare to winter mornings on Mars. The white stuff in the photo above is dry ice—frozen carbon dioxide.

Image Credit: NASA

Elysium Mons

This image shows a cross section of Elysium Mons, including the entire summit caldera of the Martian volcano. It’s taller than Mt. Everest, standing about 12.6 km (41,000 ft) above its base and about 14.1 km (46,000 ft) above the Martian datum. It’s only the third tallest Martian mountain in terms of relief and the fourth highest in elevation.

Image Credit: NASA

The Martian Moons

moons_apparent-sizesThe Curiosity rover on Mars used its cameras to take the series of pictures stitched together to make this video. These are the first images from missions on the surface which have caught one moon eclipsing the other. The images were taken on 1 August, 2013, but some of the full-resolution frames were not downlinked until more than a week later, in the data-transmission queue behind higher-priority images being used for planning the rover’s drives.

The picture on the left shows how big the moons of Mars appear to be, as seen from the surface of Mars, compared to the size that Earth’s moon seen from the surface of Earth.

Image and Video Credits: NASA

A Helicopter on Mars

Nighttime temperatures at Jezero Crater on Mars can drop to -90 C which can damage unprotected electrical components and ruin batteries. However, the Ingenuity helicopter survived its first night after being deployed from the Perseverance rover on 3 April. If all goes well, Ingenuity will be the first aircraft to attempt powered, controlled flight on another planet.

Image Credit: NASA

A Landing Site on Mars

The day after the Perseverance rover landed on Mars, the Mars Reconnaissance Orbiter took this picture of the landing site. The image shows the location of the Mars 2020 mission descent stage, heat shield, and parachute and back shell that delivered Perseverance to the surface of Mars as well as the rover itself on the floor of Jezero Crater. Each the inset box spans is about 200 m across. Perseverance is located at the center of the pattern created by rocket exhaust from the the descent stage while it hovered and lowered the rover to the surface. After lowering the rover, the descent stage itself flew off, crashing a safe distance from the rover. After their separation in the landing sequence, the heat shield, parachute, and back shell fell to their own impact sites.

Image Credit: NASA

Looking at Mars at Night in UV

This obviously false color animation of Mars shows how its atmosphere glows and pulsates in ultraviolet light every night. It was assembled from months of data taken by the MAVEN spacecraft orbiting Mars. The nightglows occur three times during each rotation of the planet about 70 km above the surface. All three occur at sunset (which is on the left limb of the planet in this view). The pulsations are believed to be caused by downward winds creating nitric oxide in the atmosphere which glows in the UV spectrum. The fact that the three glows occur in data averaged over several months indicates that they are a nightly occurrence.

Video Credit: NASA