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Rosetta snaps a selfie. Courtesy ESA/Rosetta/Philae/CIVA.
Rosetta snaps a selfie. Courtesy ESA/Rosetta/Philae/CIVA.

Why Did We Land on a Comet?

Rosetta snaps a selfie. Courtesy ESA/Rosetta/Philae/CIVA.
Rosetta snaps a selfie. Courtesy ESA/Rosetta/Philae/CIVA.

Earlier today, as part of its Rosetta mission, the European Space Agency landed its Philae probe on Comet 67P/Churyumov-Gerasimenko—the first time in history this feat has ever been achieved. But why land a probe on a comet?

The Rosetta spacecraft launched in March 2004 and began its 10-year journey across the solar system into deep space—more than five times the distance between the Earth and the Sun—to rendezvous with Comet 67P/Churyumov-Gerasimenko, which occurred on August 6, 2014. The lander deployed today contains 10 scientific instruments; its batteries, which will drain after 64 hours, will be recharged by solar panels, allowing for one hour of exploration every two days. While the probe is exploring, the Rosetta spacecraft will continue to orbit the comet’s nucleus, following the celestial body on its path around the Sun (another historical first). The mission concludes in December 2015.

One of Rosetta’s goals is simply to observe a comet up close. “We have only observed comets from afar,” Joel W. Parker, a planetary scientist at the Southwest Research Institute in Boulder, Colorado, and the deputy principal investigator for an ultraviolet spectrograph instrument on the Rosetta spacecraft, told the New York Times. “Even the previous spacecraft flybys have been brief and could only study the comet by what they saw remotely. It is like the difference between what you can learn taking pictures from an airplane versus a geologist digging directly into the ground.” Scientists will also look at what happens to a frozen comet when it encounters the warmth of the Sun.

But the mission’s name holds some clues to its primary purpose: The Rosetta Stone, which helped us decipher hieroglyphics, and thereby understand the civilization in Ancient Egypt. The Rosetta spacecraft will help scientists understand comets, the oldest and most primitive bodies in the Solar System (at least, as far as we know). And by understanding comets, scientists hope to find out a little bit more about how our Solar System and its planets came to be.  From the website:

Rosetta's prime objective is to help understand the origin and evolution of the Solar System. The comet’s composition reflects the composition of the pre-solar nebula out of which the Sun and the planets of the Solar System formed, more than 4.6 billion years ago. Therefore, an in-depth analysis of comet 67P/Churyumov-Gerasimenko by Rosetta and its lander will provide essential information to understand how the Solar System formed.

There is convincing evidence that comets played a key role in the evolution of the planets, because cometary impacts are known to have been much more common in the early Solar System than today. ... Previous studies by ESA’s Giotto spacecraft and ground-based observatories have shown that comets contain complex organic molecules. These are compounds that are rich in carbon, hydrogen, oxygen, and nitrogen. Intriguingly, these are the elements that make up nucleic acids and amino acids, essential ingredients for life as we know it.

With this mission, scientists hope to determine whether life on Earth began with the help of a comet impact (or “comet seeding”). And even if Rosetta doesn't provide an answer, it will still provide scientists with a lot to study. You can follow the progress of the mission here, and keep up with the Philae probe's activities on the comet's surface here.

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Feeling Anxious? Just a Few Minutes of Meditation Might Help
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iStock

Some say mindfulness meditation can cure anything. It might make you more compassionate. It can fix your procrastination habit. It could ward off germs and improve health. And it may boost your mental health and reduce stress, anxiety, depression, and pain.

New research suggests that for people with anxiety, mindfulness meditation programs could be beneficial after just one session. According to Michigan Technological University physiologist John Durocher, who presented his work during the annual Experimental Biology meeting in San Diego, California on April 23, meditation may be able to reduce the toll anxiety takes on the heart in just one session.

As part of the study, Durocher and his colleagues asked 14 adults with mild to moderate anxiety to participate in an hour-long guided meditation session that encouraged them to focus on their breathing and awareness of their thoughts.

The week before the meditation session, the researchers had measured the participants' cardiovascular health (through data like heart rate and the blood pressure in the aorta). They evaluated those same markers immediately after the session ended, and again an hour later. They also asked the participants how anxious they felt afterward.

Other studies have looked at the benefits of mindfulness after extended periods, but this one suggests that the effects are immediate. The participants showed significant reduction in anxiety after the single session, an effect that lasted up to a week afterward. The session also reduced stress on their arteries. Mindfulness meditation "could help to reduce stress on organs like the brain and kidneys and help prevent conditions such as high blood pressure," Durocher said in a press statement, helping protect the heart against the negative effects of chronic anxiety.

But other researchers have had a more cautious outlook on mindfulness research in general, and especially on studies as small as this one. In a 2017 article in the journal Perspectives on Psychological Science, a group of 15 different experts warned that mindfulness studies aren't always trustworthy. "Misinformation and poor methodology associated with past studies of mindfulness may lead public consumers to be harmed, misled, and disappointed," they wrote.

But one of the reasons that mindfulness can be so easy to hype is that it is such a low-investment, low-risk treatment. Much like dentists still recommend flossing even though there are few studies demonstrating its effectiveness against gum disease, it’s easy to tell people to meditate. It might work, but if it doesn't, it probably won't hurt you. (It should be said that in rare cases, some people do report having very negative experiences with meditation.) Even if studies have yet to show that it can definitively cure whatever ails you, sitting down and clearing your head for a few minutes probably won't hurt.

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Ted Cranford
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Scientists Use a CT Scanner to Give Whales a Hearing Test
Ted Cranford
Ted Cranford

It's hard to study how whales hear. You can't just give the largest animals in the world a standard hearing test. But it's important to know, because noise pollution is a huge problem underwater. Loud sounds generated by human activity like shipping and drilling now permeate the ocean, subjecting animals like whales and dolphins to an unnatural din that interferes with their ability to sense and communicate.

New research presented at the 2018 Experimental Biology meeting in San Diego, California suggests that the answer lies in a CT scanner designed to image rockets. Scientists in San Diego recently used a CT scanner to scan an entire minke whale, allowing them to model how it and other whales hear.

Many whales rely on their hearing more than any other sense. Whales use sonar to detect the environment around them. Sound travels fast underwater and can carry across long distances, and it allows whales to sense both predators and potential prey over the vast territories these animals inhabit. It’s key to communicating with other whales, too.

A CT scan of two halves of a dead whale
Ted Cranford, San Diego State University

Human technology, meanwhile, has made the ocean a noisy place. The propellers and engines of commercial ships create chronic, low-frequency noise that’s within the hearing range of many marine species, including baleen whales like the minke. The oil and gas industry is a major contributor, not only because of offshore drilling, but due to seismic testing for potential drilling sites, which involves blasting air at the ocean floor and measuring the (loud) sound that comes back. Military sonar operations can also have a profound impact; so much so that several years ago, environmental groups filed lawsuits against the U.S. Navy over its sonar testing off the coasts of California and Hawaii. (The environmentalists won, but the new rules may not be much better.)

Using the CT scans and computer modeling, San Diego State University biologist Ted Cranford predicted the ranges of audible sounds for the fin whale and the minke. To do so, he and his team scanned the body of an 11-foot-long minke whale calf (euthanized after being stranded on a Maryland beach in 2012 and preserved) with a CT scanner built to detect flaws in solid-fuel rocket engines. Cranford and his colleague Peter Krysl had previously used the same technique to scan the heads of a Cuvier’s beaked whale and a sperm whale to generate computer simulations of their auditory systems [PDF].

To save time scanning the minke calf, Cranford and the team ended up cutting the whale in half and scanning both parts. Then they digitally reconstructed it for the purposes of the model.

The scans, which assessed tissue density and elasticity, helped them visualize how sound waves vibrate through the skull and soft tissue of a whale’s head. According to models created with that data, minke whales’ hearing is sensitive to a larger range of sound frequencies than previously thought. The whales are sensitive to higher frequencies beyond those of each other’s vocalizations, leading the researchers to believe that they may be trying to hear the higher-frequency sounds of orcas, one of their main predators. (Toothed whales and dolphins communicate at higher frequencies than baleen whales do.)

Knowing the exact frequencies whales can hear is an important part of figuring out just how much human-created noise pollution affects them. By some estimates, according to Cranford, the low-frequency noise underwater created by human activity has doubled every 10 years for the past half-century. "Understanding how various marine vertebrates receive and process low-frequency sound is crucial for assessing the potential impacts" of that noise, he said in a press statement.

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