Historic Photos Reveal a Mercury Never Seen Before

NASA's MESSENGER spacecraft on Tuesday and Wednesday captured and delivered to Earth the first photographs of Mercury ever taken from within the planet's orbit.

The crater near the bottom of this image is a beautiful example of a relatively small, simple, fresh impact feature on Mercury. (Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)

Taken at 5:20 am EDT Tuesday, the historic first photo was soon joined by 364 more of the solar system's innermost planet, and several of them were released on Wednesday. Photos were taken by MESSENGER's Mercury Dual Imaging System as the spacecraft sailed high above the planet's south pole, providing a glimpse of portions of Mercury's surface that had not previously been seen by humans.
"The entire MESSENGER team is thrilled that spacecraft and instrument checkout has been proceeding according to plan," said MESSENGER Principal Investigator Sean Solomon of the Carnegie Institution of Washington.
"The first images from orbit and the first measurements from MESSENGER's other payload instruments are only the opening trickle of the flood of new information that we can expect over the coming year," Solomon added. "The orbital exploration of the solar system's innermost planet has begun."
Orbiting Every 12 Hours
NASA's MESSENGER -- short for "MErcury Surface, Space ENvironment, GEochemistry, and Ranging" -- on March 17 became the first spacecraft ever to enter Mercury's orbit after completing more than a dozen laps within the inner solar system over the past 6.6 years.
The probe will continue to orbit the planet once every 12 hours for the duration of its primary mission. On April 4, the yearlong science phase of the mission will begin, and the first orbital science data from Mercury will be returned.
In the meantime, thousands more images will be captured and studied in order to better understand the planet.
Newly Imaged Terrain

A color version of the first image acquired by MESSENGER from orbit around Mercury. (Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)

In addition to the first image taken on Tuesday, a series of several more were released on Wednesday, including a color version of that first photo. Visible in the upper portion of the historic image is a rayed crater known as Debussy. The smaller crater Matabei is visible to the west of Debussy and is notable for its unusual dark rays. The bottom portion of the image is near Mercury's south pole and includes a region of Mercury's surface not previously seen by spacecraft. That newly imaged terrain can be seen by comparing the new image with the planned image footprint.
Mercury's diameter is 3,030 miles. Simulated views on the MESSENGER website provide a glimpse of the spacecraft's current position.

One of 4 Rocky Planets

'They've had pictures of Mercury before, but this is the first time they've gone completely around the planet," Paul Czysz, professor emeritus of aerospace engineering at St. Louis University, told TechNewsWorld.
Mercury is of interest to scientists because it is one of only four rocky planets identified so far in our solar system. Joining it on that list is also Earth, of course, as well as Venus and Mars.
Among those planets, Mercury is the smallest, the densest (after correcting for self-compression), the one with the oldest surface, the one with the largest daily variations in surface temperature, and the least explored. So, developing a better understanding of Mercury is a key to understanding how the planets in our solar system formed and evolved. [*Editor's Note - March 30, 2011]

'One Side Is Blasted Bare'

Making Mercury particularly interesting is its proximity to the sun, and the fact that one side of the planet faces the sun most of the time, Czysz noted.
"One side is blasted bare" by the sun, while "the other side is dark and cold," he explained. "It takes years for it to do a complete revolution."
In fact, the extremely high temperatures on the sun-facing side of the planet meant that MESSENGER had to be designed carefully to be able to withstand such heat, Czysz noted. "They've designed the craft so a lot of the sensitive stuff is shielded behind, in the shadow of the sun."
Whereas the Juno probe slated to visit Jupiter later this year had to be designed to withstand that planet's nuclear radiation, MESSENGER's challenge was radiation of the thermal kind, he pointed out.

Looking for a Magnetic Core

MESSENGER's wide-angle camera (WAC) is not a typical color camera. It can image in 11 colors, ranging from 430 to 1020 nm wavelength (visible through near-infrared). (Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)

Insights that could be gained from a deeper understanding of Mercury include a better idea of the solar system's origins, Czysz said.
Our current understanding is that Earth is distinct among the solar system's four rocky planets in that it has a significant magnetic field, resulting from its molten nuclear core. Though neither Mars nor Venus has anything comparable today, there is evidence that suggests Mars may have had something similar at one time, he added.
Mercury, then, could be our last chance to find another rocky planet with at least the vestiges of a magnetic core like Earth's, Czysz explained.
"The only reason we have an atmosphere and don't die is because of our magnetic field," he pointed out. That's because the magnetic field is what deflects the solar winds and radiation that are constantly trying to bombard our planet.

'The Largest Nuclear Reactor Ever Conceived'

"We're trying to put the pieces together as to why some rocky planets have magnetic fields, or nuclear cores, and why some don't," Czysz noted.
Such information is particularly timely in the wake of the nuclear disaster currently facing Japan, Czysz added.
"We're all afraid of what happened in Japan," he pointed out.
In fact, Czysz said, "we're sitting on the largest nuclear reactor ever conceived -- it's called the core of the Earth."

Beyond the Point of No Return: Is There Life in Black Holes?

Few ideas convey the mystery and awe-inspiring nature of space better than the black hole.

Dark, vast and little understood, black holes in many ways represent all that we still don't know about the universe. With their seemingly infinite emptiness and general unexplorability, they're also more than a little terrifying.

This artist's concept shows a supermassive black hole at the center of a remote galaxy digesting the remnants of a star. NASA's Galaxy Evolution Explorer had a "ringside" seat for this feeding frenzy, using its ultraviolet eyes to study the process from beginning to end. The artist's concept chronicles the star being ripped apart and swallowed by the cosmic beast over time. First, the intact sun-like star (left) ventures too close to the black hole, and its own self-gravity is overwhelmed by the black hole's gravity. The star then stretches apart (middle yellow blob) and eventually breaks into stellar crumbs, some of which swirl into the black hole (cloudy ring at right). This doomed material heats up and radiates light, including ultraviolet light, before disappearing forever into the black hole. The Galaxy Evolution Explorer was able to watch this process unfold by observing changes in ultraviolet light. The area around the black hole appears warped because the gravity of the black hole acts like a lens, twisting and distorting light. Credit: NASA/JPL-Caltech

Imagine what it would be like, then, to learn that life exists in these expansive regions of no escape. Sounds like something from science fiction, doesn't it?
It may not be quite as far-fetched as it seems, however. In a paper recently written for the Journal of Cosmology and Astroparticle Physics, Russian physicist Vyacheslav Ivanovich Dokuchaev proposes just such a possibility.
The 'Gravitational Singularity'
Black holes are essentially regions of space whose gravitational pull is so strong that nothing -- not even light -- can escape. It's for that reason that the phenomena are called "black," since all light hitting them gets absorbed, leaving nothing for the viewer to see.
Black holes can be either rotating or non-rotating, according to current theory, but either way, a "gravitational singularity" lies at the center.
Surrounding each black hole, meanwhile, is an invisible boundary known as the "event horizon" that essentially marks the point of no return. Anything that reaches a black hole's event horizon is expected to get sucked toward its singularity, with no hope of escaping again.
Though much of our current conception of black holes comes from Einstein's theory of general relativity, there is a growing consensus that supermassive black holes exist at the center of most galaxies -- including our own Milky Way.

Death by 'Spaghettification'

As one might expect, the fate of objects that get sucked into black holes is not typically considered a happy one.
Possessing infinite density, the gravitational singularity is theorized to subject any matter passing through to a process known as "spaghettification." That evocative name alone should be enough to strike terror into even the bravest of hearts, and with good reason, for it's essentially just what it sounds like.
It's conceivable, though, that living matter might be able to exist within a black hole without being consigned to that harsh and eternal oblivion.

'Advanced Civilizations May Live Safely Inside'

So argues Dokuchaev, who suggests that there are stable, periodic planetary orbits inside black holes that neither begin nor end in the black hole's gravitational singularity. Rather, they orbit around and around somewhere between the event horizon and the singularity without ever approaching the singularity or its life-threatening "spaghettifier."
Such stable periodic orbits exist inside black holes for photons, and they may exist for planets as well, Dokuchaev writes.
"Advanced civilizations may live safely inside the supermassive black holes," he explains. "Stationary observers may exist just as anywhere on the planet Earth ... . The only thing needed is to put your vehicle or your planet to a stable periodic orbit inside the black hole."
In this intermediate ground between the black hole's inner and outer parts, then, there could be a safe ground for life to exist.

'No One Really Knows'

It's nothing if not a compelling theory, and science fiction books are no doubt being written even now about the intriguing possibilities.
For now, though, the unfortunate fact is that -- like so many theories of its kind -- Dokuchaev's proposition is currently more or less impossible to test.
"It's a conjecture, because no one really knows," Paul Czysz, a professor emeritus of aerospace engineering with St. Louis University, told TechNewsWorld.

'Nothing We'd Recognize'

It's almost impossible to guess what it would really be like inside a black hole, Czysz asserted.
"Even [Stephen] Hawking retracted his statement as to what the conditions would be like," he explained. "All we know is that as you approach the edge of the black hole where the boundary is, the gravity is so high that even light can't escape."
Temperatures and pressure would probably also be extremely high, he pointed out.
"I don't know if anything could survive," Czysz added. "If it can, it would look like nothing we'd recognize here on Earth."

'Probably Too Extreme'

Indeed, the "existence of periodic orbits may be necessary but is certainly not a sufficient condition in itself to sustain life -- at least organic life as we know it," agreed Manasse Mbonye, a professor in the physics department at the Rochester Institute of Technology.
For example, "you can have a stable periodic orbit, say, very close to the sun, but other conditions -- like temperature and strong electromagnetic fields -- would probably be too extreme to support organic life," Mbonye told TechNewsWorld. "Some of these conditions are likely to be even more extreme inside black holes."
On the other hand, "if one is talking of life forms that are not organic and which we obviously don't know anything about, then our very ignorance about them puts no condition on where they can survive, including inside black holes," Mbonye concluded.

'Enormous Tides'

Similarly, "even if this is correct, I would still have thought that this would be one of the most inhospitable environments for life I can think of," Mario Livio, a senior astrophysicist with the Space Telescope Science Institute, told TechNewsWorld.
"We are not even certain if life can develop on a planet that orbits its parent star in an elliptical orbit, so life in this black hole environment that suffers from enormous tides appears to be rather far-fetched," Livio explained.
Still, "examining these types of orbits could provide insights into the properties of spacetime in these extreme environments," he pointed out.

'Everything Is Possible'

However improbable Dokuchaev's theory might seem, the fact remains that even on our own planet, life has been discovered in places where we never thought it would be possible, such as in volcanic vents at the deepest parts of the oceans, Czysz noted.
"No one thought animals could have been alive in that hostile area; we assumed they needed oxygen to metabolize," he explained.
It turned out, however, that the organisms discovered could metabolize sulfur instead.
"No one would have postulated that until they saw it," Czysz added.
So could life exist in black holes in some form, even one not recognizable to us Earthlings?
"Everything is possible," Czysz conceded. "But is it probable? I doubt it."