Category: Astronomy

Map generators like Mapquest and Yahoo! Maps have bailed me out quite a few times, helping me get where I needed to go. So imagine in the future, navigating on other bodies in our solar system and having the ability to find landmarks and destinations to point you in the right direction. This type of technology is now under development and could create three-dimensional “super roadmaps” of other planets and moons. In addition it could also provide robots, astronauts and engineers details about atmospheric composition, biohazards, wind speed and temperature, and could help land future spacecraft and more effectively navigate roving cameras across a Martian or lunar terrain.

The Rochester Institute of Technology’s Rochester Imaging Detector Laboratory (RIDL), in collaboration with Massachusetts Institute of Technology’s Lincoln Laboratory are developing a new type of detector that uses LIDAR (LIght Detection and Ranging), a technique similar to radar, but which uses light instead of radio waves to measure distances.

This is a new generation of high resolution, low power consuming optical/ultraviolet imaging LIDAR detectors that will significantly extend NASA’s science capabilities for planetary applications by providing 3-D location information for planetary surfaces and a wider range of coverage than the single-pixel detectors currently combined with LIDAR.

The LIDAR imaging detector will be able to distinguish topographical details that differ in height by as little as one centimeter.

“The imaging LIDAR detector could become a workhorse for a wide range of NASA missions,” says Donald Figer, director of the RIDL. “You can have your pixel correspond to a few feet by a few feet spatial resolution instead of kilometer by kilometer,” Figer says. “And now you can take LIDAR pictures at fine resolutions and build up a map in hours instead of taking years at comparable resolution with a single image.”

The device will consist of a 2-D continuous array of light sensing elements connected to high-speed circuits. The $547,000 NASA-funded program also includes a potential $589,000 phase for fabrication and testing.

LIDAR works by measuring the time it takes for light to travel from a laser beam to an object and back into a light detector. The new detector can be used to measure distance, speed and rotation. It will provide high-spatial resolution topography as well as measurements of planetary atmospheric properties: pressure, temperature, chemical composition and ground-layer properties. The device can also be used to probe the environments of comets, asteroids and moons to determine composition, physical processes and chemical variability.

The imaging LIDAR detector will be tested at RIDL in environments that mimic aspects of operations in NASA space missions.

Orginal News Source: EurekAlert

Astronomers have found the remains of the youngest supernova, or exploded star, in the Milky Way Galaxy. The supernova occurred in 1868, but was hidden behind a thick veil of gas and dust. Using the Very Large Array (VLA) and NASA’s Chandra X-Ray Observatory, which could peer through the veil, astronomers have now found “G1.9+0.3,” the first example of what scientists believe are a “missing population” of young supernova remnants. This is NASA’s long awaited announcement, and astronomers have been searching for over 50 years for this type of young supernova.

From observing supernovae in other galaxies, astronomers estimate that about three such stellar explosions should occur in our Milky Way every century. However, the most recent one known until now occurred around 1680, creating the remnant called Cassiopeia A. The newly-discovered object is the remnant of an explosion only about 140 years ago.

“It’s great to finally track one of them down,” said David Green of the University of Cambridge in the UK, who led the VLA study.

Supernovas mark the violent death of a star, and release tremendous amounts of energy and spew heavy elements such as calcium and iron into interstellar space. This seeds the clouds of gas and dust from which new stars and planets are formed.

The lack of evidence for young supernova remnants in the Milky Way had caused astronomers to wonder if our Galaxy, which appears otherwise normal, differed in some unknown way from others, or if our understanding of the relationship between supernovae and other galactic processes was in error.

Cassiopeia A supernova remnant — from the year 1680.

The astronomers made their discovery by measuring the expansion of the debris from the star’s explosion. They did this by comparing images of G1.9+0.3, made more than two decades apart.

In 1985, astronomers led by Green observed G1.9+0.3 with the VLA and identified it as a supernova remnant. At that time, they estimated its age as between 400 and 1,000 years. It is near the center of our Galaxy, roughly 25,000 light-years from Earth.

In 2007, another team of astronomers, led by Stephen Reynolds of North Carolina State University, observed the object with the Chandra X-Ray Observatory. To their surprise, their image showed
the object to be about 16 percent larger than in the 1985 VLA image.

“This is a huge difference. It means the explosion debris is expanding very quickly, which in turn means the object is much younger than we originally thought,” Reynolds explained.

However, this expansion measurement came from comparing a radio image to an X-ray image.

To make an “apples to apples” comparison, the scientists sought and were quickly granted observing time on the VLA which confirmed the supernova remnant’s rapid expansion.

The object already has provided surprises. The velocities of its explosion debris and extreme energies of its particles are unprecedented. “No other object in the Galaxy has properties like this,” said Reynolds. “Finding G1.9+0.3 is extremely important for learning more about how some stars explode and what happens in the aftermath.”

Original News Sources: Chandra site , National Radio Astronomy Observatory

You can breathe easily. The Moon is slowly receding away from the Earth at a rate of 3.7 cm/year (1.5 in/yr). But the Martians aren’t so lucky. Their moon Phobos is known to be doing exactly the opposite. It’s spiraling inward, and in the distant future it will crash into the surface of Mars. Researchers originally thought that Phobos has about 50 million years to go, but an Indian researcher has re-run the calculations and thinks Phobos only has about a quarter of that time to live.

It was originally believed that Phobos would take about 50 million years to crash into the surface of Mars, but according to Bijay Kumar Sharma, an Assistant Professor at the National Institute of Technology in Bihar, India, it might happen much more quickly. Dr. Sharma has revised the calculations for Phobos’ destruction in his new paper, Theoretical Formulation of the Phobos, moon of Mars, rate of altitudinal loss.

According to Sharma, Phobos will actually be destroyed about 10.4 million years from now, and not the 50 million years the researchers had previously calculated.

Phobos is believed to be an asteroid that Mars captured early on in its history. it’s one of the least-reflective objects in the Solar System, and thought to be similar to a D-type asteroid. It currently orbits Mars at an altitude of about 9,380 km (or about 6,000 km above the Martian surface).

Why does the Earth’s moon spiral outward, while Phobos is spiraling inward to Mars?

The Moon formed billions of years ago when a Mars-sized object crashed into Earth and sprayed material into orbit. This material pulled back together from mutual gravity to form the Moon, and this debris received a gravitational slingshot from the Earth.

They key is that the material was tossed into a high enough orbit, above what’s known as the synchronous orbit. This is where the Moon completes an orbit slower than the Earth takes to rotate once. Since the Moon ended up higher than this orbit, it’s spiraling outward. If its orbit was less than the length of a day, it would spiral inward.

And this is what has happened to Phobos. It orbits below this synchronous orbit, where it completes an orbit around Mars faster than the planet itself turns. It’s spiraling inward instead of outward.

Once Phobos gets down to an altitude of only 7000 km above the center of Mars (or 3,620 km above its surface), it will enter what’s known as the Roche limit. At this point, the tidal forces of Mars will tear Phobos apart, turning it into a ring that will continue to spiral into Mars. According to Dr. Sharma, this will happen in only 7.6 million years from now.

To know exactly how long Phobos has to live, Dr. Sharma suggests that a mission should be sent to Phobos to land on its surface and then use radar to measure the changing distance to Mars.

Original Source: Arxiv