Rise and Fall…On Mars

In April 2019, NASA’s InSight lander used its Instrument Deployment Camera (IDC) to capture a series of Martian sunrise and sunset images.

NASA’s InSight lander used its IDC camera to record the Martian sunrise on April 24, 2019. This image was taken around 5:30 a.m. Mars local time. Image credit: NASA / JPL-Caltech.

The first mission to send back such images was NASA’s Viking 1 lander, which captured a sunset on August 21, 1976. NASA’s Viking 2 then captured a sunrise on June 14, 1978. Since then, both sunrises and sunsets have been recorded by NASA’s Spirit, Opportunity and Curiosity rovers.

InSight’s IDC camera on the lander’s robotic arm snapped these photos on April 24 and 25, 2019, the 145th Martian day (sol) of the mission. In local Mars time, the shots were taken starting around 5:30 a.m. and then again starting around 6:30 p.m.

Much farther from Mars than it is from Earth, the Sun appears only about two-thirds the size that it does when viewed from Earth.

InSight used its IDC camera to image this sunset on Mars on April 25, 2019. This image was taken around 6:30 p.m. Mars local time. Image credit: NASA / JPL-Caltech.

Sometimes the Abyss Stares Back

Astronomers have produced the largest, most comprehensive ‘history book’ of galaxies in the Universe, using 16 years’ worth of observations from the NASA/ESA Hubble Space Telescope. The endeavor is called the Hubble Legacy Field. The image, a combination of nearly 7,500 separate Hubble exposures, contains roughly 265,000 galaxies and stretch back through 13.3 billion years of time to just 500 million years after the Universe’s birth in the Big Bang.

Pictured: EVERYTHING

The Hubble Legacy Field combines observations taken by several Hubble deep-field surveys. In 1995, the Hubble Deep Field captured several thousand previously unseen galaxies. The subsequent Hubble Ultra Deep Field from 2004 revealed nearly 10,000 galaxies in a single image. The 2012 Hubble eXtreme Deep Field was assembled by combining ten years of Hubble observations taken of a patch of sky within the original Hubble Ultra Deep Field.

The new set of Hubble images, created from nearly 7,500 individual exposures, is the first in a series of Hubble Legacy Field images.

Hello From the Other Side

Looking up at the Moon, you might recognize familiar shadows and shapes on its face from one night to the next. We see the same view of the Moon our early ancestors did as it lighted their way after sundown.

Only one side of the Moon is ever visible from Earth, it wasn’t until 1959 when the Soviet Spacecraft Luna 3 orbited the Moon and sent pictures home that human beings were able to see the “far side” of the Moon for the first time.

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A phenomenon called tidal locking is responsible for the consistent view. The Earth and its Moon are in close proximity (relatively speaking) and thus exert significant gravitational forces on each other. These tidal forces slow the rotations of both bodies. This locked the Moon’s rotation in sync with its orbital period.

Now the Moon takes one trip around the Earth in the same amount of time it takes to make one rotation around its own axis: about 28 days. From Earth, we always see the same face of the Moon; from the Moon, the Earth stands still in the sky.

The near side of the Moon is well studied because we can see it. The astronauts landed on the near side of the Moon so they could communicate with NASA here on Earth. All of the samples from the Apollo missions are from the near side.

With modern satellites, astronomers have completely mapped the lunar surface. A Chinese mission, Chang’e 4, is currently exploring the Aitken Basin on the far side of the Moon, the first such mission ever landed there. Researchers hope Chang’e 4 will help answer questions about the crater’s surface features and test whether things can grow in lunar soil.

A privately funded Israeli mission, Beresheet, started as a mission to compete for the Google Lunar X Prize. Despite crashing during an attempted landing earlier this month, the Beresheet team still won the Moon Shot Award.

Being shielded from civilization means the far side of the moon is “radio dark.” There, researchers can measure weak signals from the universe that would otherwise be drowned out. Chang’e 4, for instance, will be able to observe low-frequency radio light coming from the Sun or beyond what’s possible to detect here on the Earth due to human activity, such as TV and radio broadcasts and other forms of communication signals. Low-frequency radio peers back in time to the very first stars and the very first black holes, giving astronomers a greater understanding of how the structures of the universe began forming.

Rover missions also investigate all sides of the Moon as space scientists prepare for future human missions, looking to the Moon’s resources to help humanity get to Mars. For instance, water, discovered by NASA’s LCROSS satellite beneath the Moon’s north and south poles in 2009, can be broken up into hydrogen and oxygen and used for fuel and breathing.

It’s Cold Out There

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Pluto is the smallest, coldest and most distant dwarf planet with an atmosphere in the Solar System. It orbits the Sun every 248 years, and its surface temperature is between -378 and -396 degrees Fahrenheit (-228 to -238 degrees Celsius). Its atmosphere consists of nitrogen, with traces of methane and carbon monoxide.

Scientists aimed to record the seasonal evolution of Pluto’s surface pressure by observing ground-based stellar occultations to gain the atmosphere’s profile including density, pressure and temperature. They were able to construct seasonal models of Pluto and how it responds to changes with the amount of sunlight it receives as it orbits the Sun. What they found was when Pluto is farthest away from the Sun, and during its winter in the northern hemisphere, the nitrogen freezes out of the atmosphere.

The atmospheric pressure has tripled over the past three decades, but as the dwarf planet orbits, the modeling showed that most of the atmosphere would condense to the point that there is almost nothing left.

What the predictions show is that by 2030 the atmosphere is going to frost out and vanish around the entire planet. If it does freeze over, Pluto may appear brighter in the sky due to sunlight reflecting from it.

The findings will be published in the journal Astronomy & Astrophysics.

Marsquakes

NASA’s robotic probe InSight detected and measured what scientists believe to be a “marsquake,” marking the first time a seismological tremor has been recorded on another planet, the Jet Propulsion Laboratory in California reported on Tuesday.

The breakthrough came nearly five months after InSight, the first spacecraft designed specifically to study the interior of a distant world, touched down on the surface of Mars to begin its two-year seismological mission on the red planet.

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The faint rumble was roughly equal to a 2.5 magnitude earthquake, was recorded on April 6, the lander’s 128th Martian day, or sol.

It was detected by InSight’s French-built seismometer, an instrument sensitive enough to measure a seismic wave just one-half the radius of a hydrogen atom.

Scientists are still examining the data to conclusively determine the precise cause of the signal, but the trembling appeared to have originated from inside the planet, as opposed to being caused by forces above the surface, such as wind.

The size and duration of the marsquake also fit the profile of some of the thousands of moonquakes detected on the lunar surface between 1969 and 1977 by seismometers installed there by NASA’s Apollo missions.

The lunar and Martian surfaces are extremely quiet compared with Earth’s, which experiences constant low-level seismic noise from oceans and weather as well as quakes that occur along subterranean fault lines created by shifting tectonic plates in the planet’s crust.