One Year Mission on the ISS Begins!

When Canadian Astronaut Chris Hadfield was in space, on the International Space Station (ISS), he stayed there for six months, the standard length of stay for an astronaut.  On the ISS, three of the six-person crew are replaced every three months.  After returning to Earth, Hadfield could barely walk.  He had lost bone density and muscle mass, his immune system weakened, cardiovascular functions slowed, and he produced less red blood cells.  The lack of gravity is bad for humans,  The longest a human being has ever been in space was Russian cosmonaut Valeri Polyakov, who was in space for a staggering 437 days, and when he came back to Earth he opted to walk a few feet between the landing capsule and the transport, showing that long-term human space flight is possible.  Was Polyakov a special case? Or can any person survive longer trips to other worlds such as Mars?

Credit: NASA/Bill Ingalls

This is exactly what humanity hopes to find out with the launch of NASA astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko yesterday, who will each spend one year living in weightlessness aboard the ISS.  This will be a record for American space flight as the previous American record holder was Michael López-Alegría, who stayed in space for 215.4 days back in 2006.

Mars is not going to be an easy journey for future astronauts.  The trip is 8 months one way at the limits of our current technology, and that’s when Mars is close to the orbit of Earth.  It’s another 8 months back, and that’s if Mars and Earth are aligned, which they won’t be.  So unless we develop technology to make the trip shorter (which is planned), we will be sending humans into space for record-breaking flights just to get to Mars for the first time.

Knowing this, the mission with Kelly and Kornienko is underway so that humanity can determine the true effects of long-term space flight on the human body, and determine what is needed to support astronauts on the long trip to Mars.

If there’s one thing we have going for us (and against us) it’s that Mars has gravity.  When astronauts hope to land on Mars, the lower gravity will restore some of the normal body functions and lead to a partial replenishment of bone density and muscle mass.  But launching from Mars poses a new problem – It’s much bigger than the Moon and it has an atmosphere, meaning a rocket lander has to have a lot more power to escape Mars when eventually heading back to orbit and then back to Earth.  It’s no easy task.

Between our scouting of Mars by the Rovers and the Kelly / Kornienko mission, we are taking a big step toward human exploration of Mars.  It’s coming, it just might be a while.

Dark Matter is Darker than we Thought?

We call it dark matter because it doesn’t give off light, right? Well there is a lot of matter than doesn’t radiate, but the difference is that whatever the stuff is that we call dark matter doesn’t interact with anything through the small-scale fundamental forces.  The only way we have been able to detect it’s presence is through large-scale gravitational interaction.  Dark matter is ‘dark’ because it doesn’t interact with anything in a way that lets us figure out what it’s made of.   Well now that we’ve got that out of the way, we can look at the new data that suggests it’s even ‘darker’ than we previously thought; It interacts less than we expected based on prior observations.

This collage shows NASA/ESA Hubble Space Telescope images of six different galaxy clusters. The clusters were observed in a study of how dark matter in clusters of galaxies behaves when the clusters collide. 72 large cluster collisions were studied in total.

By looking at galaxy clusters we can see how matter is interacting.  Galaxies are made of stars, gas, and dark matter.  During a collision of two galaxies, the stars pass right by each other with little friction since the distances between them are so much larger than their individual sizes.  The gas in each galaxy will collide like two cars in a head-on collision, causing massive amount of friction, and spurring rapid star formation that we call a ‘starburst.’

But how about the dark matter? How does it behave? A team of astronomers using the Hubble Space Telescope and NASA’s Chandra X-ray observatory have studied a population of 72 colliding galaxy clusters to see what happens to the dark matter, giving insights into it’s composition.  According to their results, the dark matter behaves a lot like the stars, with little to no interactions.

However, dark matter is not as spread out as stars, and the leading theory characterizes it as being spread more or less uniformly throughout a galaxy cluster instead of in dense pockets.  So close interactions of bits of dark matter are likely, yet the results from the study show they still don’t interact.  This means that dark matter must be even ‘darker’ than we thought, giving rise to little or no frictional forces.

Galaxy cluster MACS J0717.5+3745 with dark matter map. Credit: Image courtesy of ESA/Hubble Information Centre

These results only rule out frictional forces in dark matter interactions, meaning the dark matter won’t slow down as it collides.  There are still several other types of interactions to study in order to fully characterize how dark matter is behaving.  As we continue probing the universe with better technology we find new ingenious ways of figuring out what this elusive matter is made of.  We still have a lot to do, since we only know what about 5% of our Universe is actually made of.

Best View Yet of Gas Cloud Passing Milky Way Black Hole

A few months ago I talked about Astronomers seeing the gas cloud known as G2 passing the central black hole of the Milky Way, called Sagittarius A*, and how we had hoped to watch the black hole destroy it in order to learn about the behaviour of supermassive black holes.  As we all sat and watched the passage of the cloud over the course of a few months, we were surprised to find that the cloud remained intact and passed straight by Sag A*.  When we last checked in, the leading theory was that the ‘cloud’ actually was a dense super-star, so massive that it has an extended dusty envelope.  Let’s see what has happened since then.

Series of images showing the cloud G2 pass close to the black hole Sag A*, shown as the cross in the image. Each image is false-coloured to show the motion of the cloud, redder is moving away from us and blue is moving toward us. Credit: ESO/A. Eckart

It was expected that the cloud would be elongated by the incredible gravitational tidal forces of the black hole, splitting it into a long stream, some of which would fall into the black hole.  This was a promising scenario for astronomers viewing from Earth because we would see a black hole actually swallow up material.  By looking at how this process occurred we would have been able to learn about the mechanisms involved in black hole accretion, and see how it would affect the black hole in the process.

This is what we expected…

Instead, the cloud was barely even altered as it swung around the central mass, showing only slight changes in shape.  And it was moving fast, 10 Million Km/h!  The only explanation is that the ‘cloud’ is actually an extended object with a dense core, like an incredibly massive star.  It’s the only way it could keep itself together.

The other piece of evidence is that there is no new activity from the black hole.  If black holes are suddenly swallowing up more material they tend to flare up and brighten throughout their accretion disk, as the collision of matter at high speeds produces bright radiation.  Whatever the accretion disk was doing before G2 passed by, it’s still doing it.

Its important to note that observations of this region are incredibly difficult.  The central region of our Milky Way is shrouded by thick layers of dust and gas, and so more observations are necessary to get good data and determine what is really happening.  As the cloud moves further away from the black hole we can get a better idea if the massive tidal forces had any impact on G2.

Measuring Saturn’s Speedy Rotation

How do we measure the rotation speed of a planet? Exactly as you would expect.  Watch the surface, look for markable features, and time how long it takes until those features pass the same point again in the future.  But how can we possibly nail down this information when the planet has little to no visible surface features.  Gas giant planets are great examples of this.  Jupiter is a bit easier since it has plenty of storms and separated cloud layers along the planet’s rotation axis, but the other three are much tougher.  Aside from hard-to-spot features, gas giants also sport different rotation speeds that vary with latitude.  A new method for measuring Saturn’s speed has been determined, and it gives us extra information important to our understanding.

Credit: NASA/JPL

In the past, astronomers have looked at fluctuations in radio radiation measurements resulting from the magnetic field of gas giants such as Saturn, but for Saturn this has resulted in different rotation speeds over a history of measurements.  The new method, from Tel Aviv University researcher Dr. Ravit Helled, utilizes a statistical work-up based on properties we already have figured out, such as Saturn’s gravitational field and shape.  By applying known properties to the equations to constrain the results, Dr.Helled’s team was able to narrow down the rotation period of the planet that matched the majority of solutions to the equations.

To test their solution, they applied the same equations to Jupiter, and found that their result matched the accepted and verified results for Jupiter.  It looks like everything is working perfectly.

The best part about Dr. Helled’s method is that the results give insights into other important properties of Saturn.  “The rotation period of a giant planet is a fundamental physical property, and its value affects many aspects of the physics of these planets, including their interior structure and atmospheric dynamics,” said Dr. Helled. “We were determined to make as few assumptions as possible to get the rotational period. If you improve your measurement of Saturn’s gravitational field, you narrow the error margin.”

The team hopes to apply their new method to Uranus and Neptune in the future, in order to better understand the gas giants that guard our outer solar system.

Jupiter Came in Like a Wrecking Ball! A New History of Our Home System

It’s difficult to determine the history of the Solar System.  The planets have been in their current orbits for Billions of years, and any signs of prior activity or configuration has to come from leftover geologies of smaller, rocky worlds.  It makes it especially difficult when the Billions of interloper asteroids and comets throughout history have to be accounted for, adding to the already complex task.  But if there is one thing humanity has going for us it’s the ability to theorize, model, simulate, and test scenarios here on Earth.  We can try new ideas and see if they match the observations of our solar system and other planetary systems in space.  If the theory answers all of our tough questions about what we see, then it becomes our most plausible theory of the formation of the solar system.

This snapshot from a new simulation by Caltech and UC Santa Cruz researchers depicts a time early in the solar system’s history when Jupiter likely made a grand inward migration.  As it moved inward, Jupiter picked up primitive planetary building blocks, or planetesimals, and drove them into eccentric orbits (turquoise) that overlapped the unperturbed part of the planetary disk (yellow), setting off a cascade of collisions that would have ushered any interior planets into the sun. Credit: K. Batygin/Caltech

In a new simulation by scientists from UC Santa Cruz and Caltech, the mighty Jupiter is actually a super-Earth killer.  In this scenario, Jupiter migrates into the inner solar system, tug boated in by the massive amounts of material present. At this point it used its massive gravity to kick a population of young super-Earths into the Sun, clearing out the inner solar system and paving the way for the smaller rocky planets present today.  But what stopped it from moving in? Saturn!  Saturn would have pulled it back out through a gravitational resonance.

When we look at other solar systems that we have studied so far, we find a lot of massive gas planets bigger than Jupiter that orbit close to their home star (Hot Jupiters).  If Jupiter formed early and was pulled in, there would have still been enough gaseous material in the outer solar system to form another smaller gas giant like Saturn which would pull it back out while leaving a small amount of material in the middle for the rocky planets.

This image shows a super-Earth exoplanet and its moons. Image credit: Luciano Mendez / CC BY-SA 3.0.

One of the biggest questions of our solar system answered by this theory is how the rocky planets have such small masses compared to the inner planets of other solar systems.  The most beautiful part of this theory is that it explains other solar systems with hot Jupiters.  Reading the article, found here, it’s clear that the simulations can explain a lot of the current properties of multiple planetary systems.

Currently we have found only a relatively small population of solar systems in our local region of the Galaxy.  Statistically we can make generalizations about all stellar systems from looking at a small population, but we also don’t have the best data on those systems.  For example, it naturally is more difficult to see the innermost parts of an exoplanetary system due to the brightness of the host star blocking out any small planetary signatures.  As we gather better data from other planetary systems we will be able to refine theories of how our own planets formed.

This theory shows how our solar system is an outlier, an uncommon configuration built by perfect timing and a wrecking ball gas giant.  But does this mean that life can only form in a solar system where this happens? And if so does this mean life is extremely rare? With the massive population of stars in the Universe, its likely we will someday find another planetary configuration like our own, but will it harbour life?