Tuesday, December 18, 2012

Getting There

How many different ways could we get to Alpha Centauri Bb, and how long would it take?

“Bb.” “Bb.” Where do we come up with this stuff?

Alpha Centauri is a binary star system, like many in our galaxy, and to distinguish between the two stars we assign them capitol ‘A’ and ‘B’.  These denote the larger and smaller stars in a double star system respectively.  Alpha Centauri ‘B’ is therefore the smallest of the binary pair. At their closest approach they are separated by just 11.2 AU, similar to the distance between the Sun and Saturn, and at their furthest they stretch out to the orbit of Pluto at around 36 AU. 

This system, however, is special. Not only is Alpha Centauri AB the closest star system to our own, it is also the closest planetary system as well. In November this year an article was published in Nature reporting the discovery of an Earth-mass planet orbiting Alpha Centauri B. Alpha Centauri Bb, or α Cen Bb, was discovered using the radial velocity method to be 1.13 times the mass of the Earth in an orbit of just 3.5 days orbiting its star at a distance similar to that of Mercury. The exoplanet community has adopted a lowercase ‘b’ to name the ever-growing population of planets in our galaxy, and hence the slightly awkward names.

So as Alpha Centauri is the closest planetary system to us, and although the planet would sadly not be habitable, what would it take to get there?

The system is a meager 4.09 light years away; that means that it takes the light leaving the star 4.09 years to reach us here on Earth. Therefore if we were able to travel at the speed of light in just over 4 years we could be vacationing on a not so comfortably warm world. But most of us drive or take a plane to get to our holiday destinations. How long would it take then? 
If we were to drive in a car at an average of 60 mph traffic permitting and without having to stop for gas in just 46 million years we could be there. That is almost as long since the dinosaurs were wiped out. What about a plane then, a Boeing 747 has a cruising speed of 570 mph cutting your travel time down to just 5 million years only twice the time it took our genus, Homo, to evolve on the Earth.

Let’s be more realistic now, what about a rocket how fast could that make us go?
Conventional rockets are funnily enough designed to go only as far as they need to and that then dictates the speed at which they travel to get there. Perhaps the easiest destination from the earth would be to the International Space Station in low Earth orbit. To get there you would need a rocket that travels at a minimum of 17,000 mph, although this would bring your trip to Alpha Centauri down to a more imaginable 170,000 years we are still not quite within the realms of the plausible. What we really want to know is what it would take to leave the solar system and the gravitational grasp of the Sun. For that we require more fuel, the only problem is that with more fuel comes more mass and this does not follow a nice smooth relationship. The more mass we add soon out ways the effect it has on the speeds we can reach and the reasonable distances we can then travel. A solar escape rocket like those used for the Voyager missions needs to be travelling at over 36,000 mph. Voyager 1 and 2 were launched in the 70’s and have barely made a dent in the 10 trillion miles to Alpha Centauri, negating the fact that they would have to stop on the way and ask for directions.

Solar Probe+
Though Voyager 1 and 2 are among the fastest manmade objects we have launched out into the solar system another type satellite has gravity on its side and beats them hands down. Helios II currently holds the tile of ‘fastest man-made object’ traveling at an astounding 160,000 mph; that means that in one hour it could circumnavigate the Earth six and a half times. This, however, will be surpassed by another solar probe, which will reach speeds of 200 km/s with the help of the Suns gravitational pull, that’s nearly 450,000 mph, and is brilliantly named Solar Probe Plus. At this speed it would only take 6,400 years to reach Alpha Centauri an admittedly enormous stretch of time but significantly smaller than the 46 million years we started off with.

In all honesty the most realistic speed we would need to accomplish in order to make it to the system within a lifetime of a standard space crew would be one-tenth the speed of light. Light can travel 300 million meters in one second one-tenth of this is the equivalent of 68 million miles per hour, over 150 times the speed of Solar Probe+.  At that speed we would get there in just 40 years and a mission to Mars will look like a walk in the park.

Alpha Centauri Bb is just the closest in a myriad of stellar systems out there to explore. So get on it engineers and build us a ship we have places to go a planets to see.

Check out the discovery article in Nature of Alpha Centauri Bb

Also look at this great post about the fastest spacecraft we've ever built

Image Credit: ESO/L.Calcada, NASA

Tuesday, December 11, 2012

What's it all about?

It is that time of year again. A time when you get together with your family, grandparents, aunties, uncles, and cousins that you haven’t seen in a year and they ask you the dreaded question; ‘why?’ What do they get out of the research you have tried to explain to them for the thousandth time?

So I thought I would ask around the department and other scientists to see what reasons we use to come to work everyday. What are we really looking for? As researchers and enthusiasts, when we look up at the sky and take measurements of the universe. What is the motivation behind it? How do we justify it to ourselves every day?
In all honesty those are not easy questions to answer and I cannot guarantee that this will satisfy them. They are purposefully vague and if asked differently can provoke a range of responses from defensive to finance, education and technology.

Astrophysics occupies a small subsection of research known as blue-skies projects, a region of scientific research where “real world” applications are not immediately apparent. A postdoctoral researcher at the University of Exeter said, “With blue-skies research it is hard to see its effects locally. We are hedging our bets and looking far ahead on things that might impact us one day in the future.”

We have direct evidence of what the future holds with so called blue-skies research. Space missions like Voyager built and deployed in the 1970’s are still sending us information back from the edge of the solar system and beyond. Their missions were designed for applications 15 years down the line. The Kepler mission, launched by NASA in 2009 to hunt for transiting extra-solar planets, began its design phase when the knowledge of exoplanets was in its infancy and yet today it has offered us a wealth of information in the field.

The future of science in this country is not us, we are working in the future those preceding us dreamed of, science in this country is dependent on the inspiration of others to continue to use and develop ideas we are not in the position to implement yet. 
“Our chief financial, socio-economical, goals is to get people into science. We take on a lot of researches as a field, we know that most cannot carry it on as a job but hopefully we get a lot of people interested in science and they then can go on and do a lot more useful things for society. “

University research departments no longer dominate the technology market, if we want a better camera we go to a technology company with their own research departments. So with knock on technology out of the picture what is it that we are really doing here everyday? Why does our curiosity continue to reach out to the stars with little or no application evident on the Earth to further mankind’s dominance of the planet?

One of the main reasons we are asked this question is based in the financial support from the government for funding.  This brings to mind a famous quote most often attributed to Sir Winston Churchill when asked about not cutting money for the Arts during the war was, “If we cut the money to arts and drama then what we are fighting for.” The amount of money that goes towards astrophysics research in this country, and the world for that matter is a luxury but it is a small one, a very small one in the grand scheme of things.  Astronomer Paul A. Wilson stated, “I find that astrophysics is sort of the same. It is necessary for humanity to be able to learn and to try and answer some of the most fundamental questions such as why we are here and where we came from?”

Along with the philosophical and existential questions that come to mind when identifying a motivation behind our research it always came back to the science. You have to go home at night and be proud of the work you have done, it is not a place for egos you don’t want to go home thinking, ‘yes I just crushed this guys research and nicked his funding,’ if you want to think like that you should go into politics. As a scientist it is all about discovery, is our research furthering our understanding. Is what we have been working on sparking the imagination of another child willing to look up at the stars in awe at what we know and what we have yet to discover.

I ask you then to question what it is that you are looking for when you look up at the sky with childlike glee and wonder. Did Douglas Adams get it right; is it the ultimate question to life the universe and everything? Is it the question rather than the answer that holds the key to knowledge and the nature of all things?

Saturday, December 1, 2012

Cosmic Christmas

Over two and a half thousand light years away, embedded in a glowing blue reflection nebula, lies a twinkling of stars known as the Christmas tree cluster.

This festive cluster was discovered by Sir William Hershel during his great sky survey in the late 18th century. The wisps of gas and dust that form the coniferous frame of the tree stretch over 40 light years across, covering an area of 1.5 full moons in the night sky just to the left of the deep orange shoulder of Orion.

The bright O star at the base of the tree can be seen with the naked eye and shines with the luminosity of over 8,000 suns.  As a string of over 20 bright young stars brighten up the gas above, like fairy lights highlighting thick shawls of dust tinseled through the sky. These are accompanied by a group of stellar newborns called the snowflake cluster hidden in the optical by the thick dust of the trees shell.

Adorned upon the top of the tree is the birthplace of stars, the great cone nebula, protruding downwards as if it were the tip of a giant ornament perched on the edge of the tallest branch. This star nursery, 65 times larger than the diameter of our solar system, is slowly eroding the surrounding gas as its hot, young stars excite the gas to the encompassing space.

But fear not, this Christmas tree will be lighting up the sky for millennia to come revealing new stars as they are born and sending out Christmas cheer across the galaxy.


Wednesday, November 28, 2012

Not like the other one

When we look to other solar systems is it really so surprising that there is a huge diversity of planets and systems out there. We only need look at our own to see how wacky some of these places are. So I thought I would compile a feature on the weird and wacky things setting our own solar system planets apart from each other.

The messenger is the smallest planet in our solar system; land of the double sunrise; and home of the Caloris Basin. Mercury orbits the Sun in just 87 days while experiencing only one and a half of its own. After Pluto was excluded from the ‘Planet Club’ in 2006, it became the most eccentric planet in the solar system experiencing non-Newtonian motion as it approached perihelion each orbit.  This motion also causes a unique phenomenon, the double sunrise, when the speed of the planet as it orbits the Sun overtakes that of its rotation; casing the sun to set and then rise again when the planet passes the point of closest approach.

The goddess of love and beauty that will crush you down and melt your skin. Although not the closest to the Sun it is the hottest planet in the solar system, temperatures can reach up to nearly 500oC. This is due to high levels of volcanic activity on the surface and a surface pressure 92 times greater than that we experience on Earth; that is the equivalent of going 920 meters underwater nearly 3 times deeper than any scuba diver has ever gone. Labeled as Earth’s sister planet due to its similar size, its climate is anything but. With an atmosphere of over 95% Carbon dioxide, rain clouds of sulfuric acid, and little to no temperature variation between day and night it is a hellish place. 


Terra Firma. What more do I need to say about this weird and wacky world other than it has managed to produce a civilization of walking talking primates, who not only have an Internet of knowledge available at the click of a button, but who have ventured into space, beyond the realms of their heavenly home.  

Named after the God of War due to its vibrant rust red surface of iron oxide that covers a silica-rich dust bed. Mars is the most explored planet in the solar system, other than the Earth, with over 30 probes and satellites bound for the ‘Red planet’ since the 1960’s. Most of these missions, however, met their end before they had even begun. Those that have made it into Martian orbit, or successfully landed on its surface, have sent us staggering information about this not so distant world. And with three active satellites in orbit (Mars express, Mars odyssey, and Mars Reconnaissance Orbiter) and two live rovers on the ground (Curiosity and Opportunity), we are set to learn even more in the years to come. 

The largest planet in our solar system you could line up ten earths next to each other and it would still not stretch all the way across the face of this mammoth world. With an atmosphere of hydrogen and helium that stretches over 5,000 km in altitude it is truly the god of the Gas giants. Jupiters atmosphere is host to the largest storm in the solar system that was first recorded in 1665, The Great Red Spot. The storm rotates anticlockwise roughly every 6 Earth days and is big enough to swallow the Earth whole three times over. The center of the storm is hotter and redder than the surrounding area, although it is still not known what exactly causes the brick-red to pale salmon color of the gas as it swirls and processes around the planet. 

Apart from having a mean density less than water, meaning that with a bath tub big enough you would find yourself with a pretty impressive bath toy, Saturn is host to one of the most impressive sites in the solar system. Its rings. Saturn’s main ring system spans a distance almost as wide as the planet itself extending from around 6,500 km from the surface out to over 120,000 km. The latest ring was discovered in 2009 using the Spitzer space telescope and is the largest ring studied in the solar system with a thickness of 2.5 million km and reaching 50 times further out into space than the central rings.

The first and only planet in the solar system named after a Greek god, Uranus is the largest of the ‘ice giants’ with an atmosphere of frozen; water, ammonia and methane crystals. While the axial tilt of the Earth set at 23.5°, affords us a beautiful mix of four seasons a year. Uranus is tilted at a staggering 97.77° making it barrel roll around the Sun like a drunken uncle at a wedding. This means that it has the most extreme seasons in the solar system with each pole experiencing 42 years of continuous sunlight in the summer, followed by 42 years of darkness in the winter.

Aptly named after the God of the sea, Neptune gets its rich blue color from the methane in the atmosphere. Voyager 2 made the one and only fly-by of Neptune in August 1999 observing immense storm systems and winds wrapping round the planet with speeds approaching 600m/s, over 1,300 miles per hour. If you could stand on Neptune, without getting blown over or sinking into the atmosphere, you would weigh almost the same as you do on Earth with a surface gravity of 11.5m/s compared to the 9.81m/s here on Earth.

Each of the planets in our solar system are wonderfully unique, so I can’t begin to imagine what the hundreds of exoplanets out there have to offer us.