Posted on by Fraser Cain

How Long is a Day on Mercury

Using radio waves to calculate Mercury's orbit. Image credit: NASA

Mercury has very very long days. How long is one day on Mercury? Each day on Mercury lasts as long as 58 days, 15 hours on Earth. This is quite a feat, considering a whole year on Mercury is only 88 days.

I recommend you to read these amazing books for more information about the planet Mercury.

It gets even stranger, though. Because the orbit of Mercury is very eccentric, it reaches a point in its orbit when the speed of its orbital velocity matches its angular rotational velocity. When this happens, the Sun will appear to go backwards in the sky before it resumes its regular direction.

Astronomers used to think that Mercury was tidally locked to the Sun. In other words, its period of rotation matched its orbital period. In this situation, Mercury would always show the same side to the Sun. But in the 1960s, this was shown to be incorrect.

Cuánto tiempo es un día de Mercurio

Posted on by Fraser Cain

Phobos Might Only Have 10 Million Years to Live

Martian moon Phobos

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

Posted on by Fraser Cain

Rising Temperatures Could Shut Down Plate Tectonics

Venus is known as the Earth’s twin, but a better name might be Earth’s “evil twin” planet. Although Venus has a similar size and mass to Earth, it has a dramatically different surface and atmosphere. And one of the biggest differences is that fact that Earth has plate tectonics, and Venus doesn’t. New research indicates that prolonged atmospheric heat might be able to shut down plate tectonics, and cause our planet’s crust to be locked in place. Don’t worry, this isn’t something we’ll have to worry about for a few hundred million years.

This research was done by scientists from the US, Canada and Australia, and published in this week’s edition of the journal Earth and Planetary Science Letters. According to the researchers, large amounts of volcanic activity or increases in the Sun’s luminosity could reach a tipping point, where the system of plate tectonics just shuts down.

Don’t worry, this isn’t an article about the dangers of global warming. The kind of temperatures we’re talking about here are beyond anything scientists are expecting from human-induced climate change.

These findings help explain why Venus might have evolved differently from Earth. Although the planet has a very similar size and geological makeup, the atmosphere on Venus is rich in carbon dioxide, and almost 100 times more dense. It acts like a blanket, trapping heat from the Sun, and raising temperatures to more than 450 °C.

Plate tectonics are very important for keeping our mild temperatures here on Earth. The carbon dioxide is pulled out of the air and trapped on the floor of the ocean. This carbon gets returned to the interior of the Earth when a free-floating sections of crust called tectonic plates slide underneath one another.

Scientists think that the Earth’s plate tectonics are stable and self-correcting, assuming excess heat from inside the Earth can escape through the crust. The flowing mantle keeps the tectonic plates moving.

But if the surface of the Earth is heated up for a long period of time, it could make the flowing mantle more viscous, so it stops flowing. This would shut down plate tectonics on Earth.

“We found the Earth’s plate tectonics could become unstable if the surface temperature rose by 38 °C (100 °F) or more for a few million years,” said lead author Adrian Lenardic, associate professor of Earth science at Rice University. “The time period and the rise in temperatures, while drastic for humans, are not unreasonable on a geologic scale, particularly compared to what scientists previously thought would be required to affect a planet’s geodynamics.”

One interesting discovery is that the rise in temperature doesn’t need to boil away the Earth’s oceans. The tectonic shut down could happen, even though there’s still liquid water on the surface of Earth.

Original Source: Rice University News Release

Posted on by Fraser Cain

Lower Gravity Will Help Lunar Dust Get Deep Into Astronaut Lungs

Lunar dust covering astronaut Eugene Cernan. Image credit: NASA



Dusting the house might be a chore here on Earth, but when astronauts return to the Moon, they’ll need to be neat freaks. Their lives might depend on it! According to researchers at the National Space Biomedical Research Institute, the health of lunar astronauts will depend on how well they can keep the fine lunar dust out of the air.

During the Apollo lunar missions in the 1960s and 1970s, astronauts realized how much this lunar dust was a hassle to their exploration of the Moon. The tiny particles clung to everything, and when the astronauts returned to their lander, it made a real nuisance. By the end of their missions, the astronauts said there was so much dust in their vehicles that they could smell it.

There are no known illnesses associated with the dust today; but the astronauts just weren’t exposed to it long enough. But scientists studying it back on Earth found that the dust was very similar to fresh-fractured quartz, which is highly toxic to humans. When astronauts return to the Moon in the next decade, they could be on the Moon for months, and exposed to much larger quantities of the dust.

And there’s another problem. Because of the reduced gravity on the Moon, and the tiny size of the dust particles, our respiratory system might not be able to handle the particles as well as we do on Earth. Here’s Dr. Kim Prisk, an adjunct professor in the Department of Medicine at the Department of Medicine at the University of California, San Diego:

“In the moon’s fractional gravity, particles remain suspended in the airways rather than settling out, increasing the chances of distribution deep in the lung, with the possible consequence that the particles will remain there for a long period of time.”

To conduct their research, the scientists are taking participants on NASA’s Microgravity Research Aircraft. This is a special aircraft that flies on a parabolic path. At the height of each arc, people on board the aircraft experience a brief period of low gravity, or even weightlessness.

When the gravity is lowered to the same as the Moon, the participants breath in small particles, which the researchers then study as they move down the airways. They want to know how many end up in the lungs. The deeper the dust goes into the lungs, the more dangerous it’ll be.

Again, here’s Dr. Prisk:

“With the reduced-gravity flights, we’re improving the process of assessing environmental exposure to inhaled particles. We’ve learned that tiny particles (less than 2.5 microns) which are the most significant in terms of damage, are greatly affected by alterations in gravity.”

The next step will be to figure out how to limit the amount of exposure to the dust. The more dangerous the dust is, the more complicated an engineering task it will be to keep it all out.

Original Source: NSBRI News Release

Posted on by Fraser Cain

It’s Almost Time for the Mars Phoenix Landing

You probably already forgot, but NASA has a spacecraft heading to Mars right now. The Phoenix Mars Lander has been traveling for almost 10 months, and it’s going to be landing on the surface of Mars in just a few days. Mark your calendar for May 25, 2008. it’s going to be an exciting day.

If everything goes according to plan, the NASA’s Phoenix Mars Lander will enter the Martian atmosphere traveling 21,000 km/hour (13,000 mph). It must then slow itself down using a variety of techniques (aerobraking, parachutes and retro-rockets), so that it can softly touch down on the surface of Mars.

Assuming the spacecraft isn’t somehow destroyed during the descent (like what happened to the Mars Polar Lander), the first signals could come back from the Mars Phoenix Lander as early as 2353 UTC (7:53 p.m. EDT).

One of the big concerns to mission planners are large boulders in the landing area. If the Mars Phoenix Lander comes right down on a boulder, it could tip over, or prevent the lander’s solar panels from opening properly. To deal with this risk, mission planners have imaged every meter of the potential landing area using the HiRISE instrument on the Mars Reconnaissance Orbiter, and haven’t found many dangerous rocks.

“We have blanketed nearly the entire landing area with HiRISE images,” said Ray Arvidson of Washington University in St. Louis, chairman of the Phoenix landing-site working group. “This is one of the least rocky areas on all of Mars and we are confident that rocks will not detrimentally impact the ability of Phoenix to land safely.”

When it finally gets down to the surface, the Mars Phoenix Lander will use its 2.35 meter (7.7 foot) robotic arm to scoop up samples of ice located underneath the ground. It has an on-board laboratory capable of analyzing the samples.

Scientists want to know of the region was ever compatible for microbial life. For example, there could be evidence that the ice freezes and melts over the course of the Martian year. This would give Martian bacteria access to liquid water. It might also be possible to find samples of carbon-based chemicals that would be the building blocks and food for life.

The mission is expected to last 3 months.

So like I said, mark your calendars. We’re less than 2 weeks away.

Original Source: NASA News Release

Posted on by Fraser Cain

What is Venus Made Of?

Venus is often called Earth’s twin planet. And when it comes to the composition, Venus is very similar to Earth. But it does have a few significant differences.

The diameter of Venus is just 650 km less than the Earth’s, and its mass is 81.5% of planet Earth.

Looking inside Venus is much harder. Here on Earth, scientists probe the structure of the Earth’s core by studying how seismic waves from earthquakes bounce off the interior of the planet. Only a few landers have reached the surface of Venus, and they didn’t last long.

Since Earth and Venus have similar size and density, scientists assume that Venus has a similar internal structure to Venus, with a core, mantle, and crust. The interior of Venus is probably at least partially liquid.

One big difference between Earth and Venus; however, is the fact that Venus has no plate tectonics. This is probably because the surface and atmosphere of Venus are so dry and hot. This reduces the amount of heat lost from the interior of the planet, and prevents it from cooling. This might also explain why Venus doesn’t have an internally magnetic field; such as the one generated by Earth.

Posted on by Fraser Cain

Scientific Data Recovered from a Hard Drive that Crashed With Columbia

It would be amazing to think that anything could have survived the fiery destruction of the space shuttle Columbia, which broke up above Texas on February 1st, 2003, killing all 7 astronauts. Amazingly, tiny worms survived the break up and crash. And now, data recovery experts announced they were able to salvage scientific data from a charred hard drive.

The announcement was made last week by data recovery company Kroll Ontrack Inc. When they received a smashed up hard drive from NASA, it just looked like a hunk of metal. But after painstaking work, they were able to recover 99% of the information stored on the hard drive.

The hard drive was part of study of the critical viscosity of xenon gas. As the data were being gathered on board Columbia as part of its mission, they were being transmitted back down to Earth. They had only transmitted part of the data, enough to tell researchers that the experiment was working. They were going to wait until Columbia landed to get the rest. Of course, Columbia never landed.

What NASA sent to Kroll Ontrack was almost unrecognizable as a hard drive. Jon Edwards, a senior clean room engineer at the company said that the circuit board on the drive was burned beyond recognition and that all its components had fallen off. Every piece of plastic on the 400 MB Seagate hard drive had melted, and the chips were burned.

Unfortunately, two other drives that crashed with Columbia were so damaged that no data could could be extracted from them. One of the Seagate’s keys to its survival is that it was actually quite old and had a much lower data capacity. The 400 MB drive was about 8 years old in 2003. It had much more fault tolerance and durability that current hard drive capacity.

Engineers were able to remove the hard drive platters from the destroyed drive and transfer them to a new drive. From there they were able to reconstruct 99% of the data.

Original Source: Scientific American

Posted on by Fraser Cain

Help Find the Mars Polar Lander

NASA’s Mars Phoenix Lander is just a few weeks away from landing on the surface of Mars. NASA really hopes that this spacecraft doesn’t fallow in the doomed path of the previous Mars Polar Lander. What happened to the Mars Polar Lander? Nobody knows. NASA assumes it’s smashed up somewhere on the surface of the Red Planet. Now you can help search for it, by looking through high resolution images of the potential crash site.

The Mars Polar Lander should have landed on the Red Planet back in 1999. But instead of touching down gently on the surface of the planet, it just stopped sending back signals once it reached the Martian atmosphere. After an investigation into the crash, the best theory is that the vibration of the lander’s legs extending tricked the software into thinking it was on firm ground, and not 40 metres above the surface. The software cut off the main engine, and the lander plummeted down to the ground – a fall it couldn’t survive.

The spacecraft in orbit around Mars didn’t have the resolution to see the tiny lander on the surface of Mars. But the next generation Mars Reconnaissance Orbiter does have the resolution. If the lander is down there – in one piece, or in a field of debris – MRO’s high-resolution camera might be able to turn it up.

The problem is that there’s an immense amount of ground to cover, so the team responsible for the Mars Reconnaissance Orbiter’s main camera system is looking for some help. They’ve made images of the entire potential debris area.

To get started, familiarize yourself with different kinds of debris and objects seen by Mars Reconnaissance Orbiter. Here’s a link (warning… it’s a 15 MB PDF). I really recommend you check out that file, it’s quite an impressive collection of spacecraft debris strewn around Mars.

And then you can start looking through high resolution images of the potential debris area looking for anything that looks like a crashed lander, parachute, backplane, etc. Feel free to report any Martians you see as well.

Click here to access that page that links to all the image sets.

You can then post comments onto the blog for any possible objects you see.

And let’s hope Mars Phoenix Lander lives up to its name, and helps the mission rise from the ashes to learn more about the subsurface ice on Mars.

Posted on by Fraser Cain

That’s WMAP, Seen from Earth



Okay, now astronomers are just showing off. See the three little multicolored dots in the upper right of this image? That’s NASA’s WMAP satellite, seen from a distance of 1.5 million km. The photograph was taken from the 2.2 meter telescope at the European Southern Observatory at La Silla, Chile. Apart from demonstrating some impressive imagine power and technique, the astronomers are testing out new tracking techniques for ESA’s upcoming Gaia space observatory.

The technique for finding your place in the Universe is called astrometry. Star Trek’s Enterprise would rely on this kind of information to navigate from star to star. In reality, though, astronomers compile this information to understand the Solar System’s position in relation to the rest of the Milky Way.

The last mission focused on this process was ESA’s Hipparcos mission, which wrapped up in the year 1993. Hipparcos measured the distance to 120,000 stars with great accuracy, as well as another 400,000 stars with less accuracy.

ESA’s new mission, due for launch in 2011, is called Gaia, and will travel to the Sun-Earth L2 Lagrangian point. From this vantage point, it’ll create a precise three-dimensional map of stars throughout the Milky Way galaxy, and beyond. All in all, it will eventually create a catalogue of 1 billion stars.

When Gaia finally launches, knowing its position accurately in the Solar System is everything. And so, astronomers on Earth will need to be able to track its position in the sky, and relay this data back to the spacecraft, so it can make its calculations.

By demonstrating that they can already track the WMAP spacecraft, currently at the L2 Lagrangian point, the astronomers have proven that they should be able to watch Gaia as well. In fact, Gaia should be brighter than WMAP.

You might be wondering why the WMAP image shows three different colours. The astronomers photographed the region three times in black and white, and then artificially coloured them red, blue and green. Since the stars don’t move, the three colours add up to make them appear white. The moving WMAP is clearly different from the background.

Original Source: ESA Image of the Week

Posted on by Fraser Cain

Hubble Image of the Colliding Antennae Galaxies (with Video)

Antennae Galaxies. Image credit: Hubble

It’s time for another beautiful image from the Hubble Space Telescope. And this time, there’s an added bonus… video. The latest images released by Hubble are based on research of the Antennae Galaxies, known as NGC 4038 and NGC 4039. Astronomers used to think that they were 65 million light-years away, but the new research puts them much closer; probably 45 million light-years away.

This image was captured by Hubble’s Advanced Camera for Surveys and Wide Field Planetary Camera 2, to observe individual stars spawned by the cosmic collision.

Here’s the Hubble video to help you get a sense of the scales involved (with pretty music too).

The astronomers targeted the object’s southern tidal tail, which was thrown away from the active central regions. This tail contains material hurled away from the main galaxies as they came together. Astronomers looked for older red giants to make the estimate for their distance. These red giants are known to always shine with the same brightness, and by knowing this brightness, they were able to calculate the galaxies as being 45 million light-years away.

Since this galactic merger is happening relatively close, it’s one of the best examples astronomers have to study this process. And now that the galaxies are closer than astronomers previously believed, it changes the size of many objects the astronomers are studying. For example, the size of the star clusters being formed by the collision match the size of other galaxy mergers, instead of being 1.5 times larger than they should be.

The Antennae Galaxies are named for the two long tails of stars, gas and dust thrown out of the collision that resemble the antennae of insects. They can be found in the constellation of Corvus, the Crow.

Original Source: Hubble News Release