Dawn Arrives at Ceres Today!

Today is the day that the Dawn Mission completes a long 7.5 year long journey that has taken it past the orbit of Mars and into the asteroid belt, studying the second largest asteroid Vesta before heading toward the dwarf planet Ceres, where it has now injected itself into orbit, as of 7:39 am EST.

Image Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

This marks the first time in history a spacecraft has seen a dwarf planet up close, and with New Horizons passing Pluto in July, Dawn won the race in an astronomical photo finish.

The Story So Far

Launching on September 27th, 2007, Dawn orbited the Sun and used its Ion propulsion thrusters to accelerate slowly out to the orbit of Mars.  Ion propulsion is a highly efficient form of thrusting in space, using minimal fuel but resulting in a slow and nearly continuous acceleration.  Dawn used its thrusters for approximately 80% of the time it was orbiting the Sun, before using Mars as a gravity assist  in 2009 to push it further out into the asteroid belt.

Credit: NASA/JPL – http://dawn.jpl.nasa.gov/

Two years later, Dawn arrived at Vesta, slowing down in order to insert into orbit around the ~500 Km asteroid.  It spent 14 months snapping photos and mapping the surface of Vesta in detail before leaving Vesta on September 4th, 2012, to head for Ceres.

Dawn images on approach of Vesta and ceres

Dawn images on approach of Vesta and ceres

Now that Dawn has begun its orbit of Ceres today, it will map the entire surface in detail, and begin studying surface features.  Over time it will determine if the surface features are changing, giving  evidence of any current geological activity.  Ceres is also about 25% water by mass, so astronomers on Earth hope to gather some insight into how water behaves on the dwarf planet, in contrast to the earlier observations of the much drier Vesta.

10:07 EST UPDATE: Mission Engineers received confirmation of the orbit injection at 8:39 am EST, with indication that the spacecraft had entered orbit as planned.

 

 

Haven’t Heard much from Mercury – But we Will Soon

With the MESSENGER probe set to crash into Mercury this month, it’s nice to look back on some of the finest data that it gathered during its tenure orbiting the smallest planet of the solar system.

Caloris Basin on Mercury. Image Credit: NASA, Johns Hopkins Univ. APL, Arizona State U., CIW

The image shows the Caloris Basin, the largest impact basin on Mercury and one of the largest in the solar system.  The result of a massive asteroid impact during the early days of the solar system, the 1,500 Km wide crater was filled with lava aeons ago when Mercury was geologically active (seen in orange).  Large impacts have punctured the surface of the basin since it filled, revealing the material beneath the 3 Km thick volcanic rock.

More on MESSENGER once it smashes into Mercury….

Tiny Distant Globular Cluster Discovered

It’s not often that we find new star clusters within our own Galaxy.  Technology has been good enough to see the stars in the Milky Way for decades, and the grunt work in identifying and cataloguing local clusters is more or less finished, but occasionally we get lucky.

GMOS image of Kim 2, in g band. The image is 4 arcminutes across. Credit: GMOS image/ Gemini Observatory

A tiny and extremely distant globular star cluster has been found in the outskirts of the far side of our home galaxy.  Currently named Kim 2, it pales in comparison to the other 150 Milky Way globular clusters, containing 10-20 times fewer stars and having less than half the stellar density.

The new star cluster was discovered by Dongwon Kim, a PhD student at the Australian National University (ANU), together with a team of astronomers (Helmut Jerjen, Antonino Milone, Dougal Mackey, and Gary Da Costa) who are conducting the Stromlo Milky Way Satellite Survey at ANU.

One theory of globular clusters is that they are the remnants of ancient protogalaxies that collided to form our much larger Milky Way.  Only the densest parts of the ancient galaxies survived, which today give us the tightly packed globular clusters that are spherically distributed about the bulge of our galaxy.

This discovery will help to shed light on the evolution of the Milky Way and other galaxies of the local group.

Science on the Ground Gives Clues to Planetary Formation

Astronomy is a science that is always associated with the sky, and rightly so.  But since the beginning of modern science there have been discoveries made on Earth that teach us about the formation and evolution of the Universe.  As telescopes become more powerful and allow us to look deeper into space, the technology to simulate outer-space conditions here on Earth has grown significantly.  In Albuquerque, New Mexico, a powerful tool called the Z machine generates quick high-energy pulses of electricity, which can be used to generate X-rays and Gamma rays to be used in experiments.

Credit: Randy Montoya

Outside of astronomy, the Z machine has been used to test the effects of nuclear blasts on a variety of materials.  But when astronomers use such a high energy simulator, it determines the conditions inside a star, or at the epicentre of a collision of two large rocky bodies.

A team from UC Davis has used the Z machine to give insights into the formation of the Earth and Moon.  The leading theory in the Moon’s formation is that 4.5 billion years ago during the formation of the solar system, a Mars-sized chunk of rock smashed into the younger, larger Earth, blasting out material that was pulled together by gravity to form our Moon.

The team, led by Sarah Stewart, UC Davis professor of Earth and Planetary Sciences, used the Z machine to subject Iron to high shock pressures by slamming Aluminum plates into the samples at high speeds.  Using this method they were able to determine the critical impact conditions needed to vaporize the Iron.

They determined that the shock pressure needed to vaporize the Iron was much lower than expected.  This would mean that more Iron was vaporized during the Earth’s formation than was previously thought.  This Iron vapour would spread out during collisions in the early solar system, mixing with the Earth’s mantle, whereas solid chunks of Iron would be heavier and sink toward the core.

This process could also explain why the Moon lacks Iron-rich material despite being exposed to similar extreme conditions.  The Iron vapour could have flown away from the Moon and been pulled toward the Earth’s stronger gravity, before condensing and falling onto the Earth.

“The timing of Earth’s core formation can only be determined via chemical signatures in Earth’s mantle, a technique that requires assumptions about how well the iron is mixed. This new information actually changes our estimates for the timing of when Earth’s core was formed,” says Lawrence Livermore National Laboratory scientist Richard Kraus, co-author of the study.

This is the essence of Science.  We have good theories in place that the evidence leads us to, and then something changes, so we update our theories, and come up with updates models to fit what we find.  As we are able to build better machines to test the conditions of the energetic past, we will continue to probe deeper into the secrets of the Universe.

Motivation Monday: Take a Break to Recharge

One of the best things about being focussed and working hard is that it builds.  You gain momentum. You have been making that small adjustment daily and things haven’t stopped moving forward.  It feels great!  But all of this forward motion comes at a cost.  It takes a lot of mental and emotional toll on a person to constantly fight a bad habit and establish new ones.  It becomes easier once the new habit becomes the path of least resistance, but the time it takes to get there is different for every person and every habit.  Sometimes, you feel you’ve run out of energy and it becomes harder to fight to keep yourself in check.  So what can you do to get back on track?

Credit: essentialjoy.lorig.me

I believe that being honest with yourself about your fatigue is important.  For some reason we feel like we are all superhuman, that we should be able to just start doing something, and if we stop for even a small break we are complete failures.  Everyone who fights for positive change in their lives has experienced the mental exhaustion, but its the ones who learn to expect it that can use it to their benefit.

I’ll use exercise as an example as its a goal that many people have.  I have always had the desire to exercise daily.  It feels good, and pretty much every scientific study shows that daily exercise is beneficial.  I used to go to the gym and just work away for an hour or two.  It felt great, but after a couple of days I was exhausted and would give up for a couple weeks before repeating the cycle.  Later, I would try to go to the gym every other day in hopes of working up to a daily routine.  Again, no dice, I would give up after a few weeks or months.  I could sustain it longer, but I would still tire out and give up.  Now, I’m approaching it differently.  I’m exercising every day, for about 5 minutes.  I don’t mean that stupidly intense kind of program where the super buff fitness instructor tells you they exercise for 5 minutes a day and then proceed to show you an hour long workout condensed into ‘5 easy minutes.’  I mean a few push-ups, crunches, and squats – every day, it goes back to my article on small changes.

Credit: phoenixrising.me

Even with the 5 minutes a day, I still find myself fatigued once in a while, not wanting to do even a little bit.  Maybe I’m out with my family for the day or I just want to relax and separate myself from my work life, really let go.  It’s more that I’ve used up the fuel in my tank, and I need to step back.  It’s the ‘two steps forward, one step back’ philosophy.

I’ve learned to allow myself the break, and there have been about 3-4 days so far this year where I haven’t done any exercise.  Now you might be saying ‘wow you’ve exercised every day this year save for 3-4 days, that’s incredible!’  The perfectionist in me doesn’t see that, it sees the 3-4 days as failures.  But what I’ve learned is to not give up after a self-proclaimed ‘failure’.   Learn to realize that a break is a way to refill our reservoir of mental and emotional energy, a chance to ‘reset’ and then continue on our journey.  It makes sure we don’t waste all of the hard work we’ve put in.

The interesting part is that I’ve slowly increased the number of exercises I do each day, and the biggest boosts come right after rest days.  This isn’t just true of exercise, but of everything.  You may have noticed that since October, I have posted, on average, once per day on this blog.  An unbroken streak.  But some of the posts have just been images with a quick description.  It’s because I needed a break.  I kept the streak going, but with almost no effort, and then the next day I came back with a fully refreshed mind and a much more complete post.

So no matter what you are trying to accomplish, let yourself take a break, and treat it as a reset and not a failure, so that when you get going again you will be able to continue along your path instead of feeling like you’re back at the beginning.