Monday, July 25, 2011

News from the solar neighborhood

The past week was a remarkable one for planetary science. Not only we had a probe arriving to an asteroid but also the solar family welcomed a new member.

In one side we have that the probe Dawn arrived to asteroid Vesta and is now in orbit around it. The story behind the whole mission is quite interesting. Actually the mission was cancelled many times and was only successful after the contractor (Orbital Sciences Corporation) offered to build the probe at cost. I certainly don't know of any other cases where the contractor ends up offering a whole probe at cost.

Vesta as seen from Dawn after it entered orbit.

The scientific program of this probe is quite ambitious. It plans to visit two of the biggest members of the asteroid belt, Vesta and Ceres, which were chosen as representative of "young" and "evolved" asteroids. Additionally, Vesta is (allegedly) the source of many of the micrometeorites that produce shooting stars in the sky which made it a particularly attractive target of study. This is also the first time a probe enters around the orbit of two objects. In previous "tours" like the Voyager missions the observations were made during flyby's. A similar option was considered a few years ago for Cassini with a potential transfer to Uranus which would had required a 20+ year cruise time. Eventually, that option was discarded and it was decided to send Cassini in a collision route with Saturn.

In a different development, it turns out that Pluto (the good old planet, now dwarf planet) system has at least three moons. This was spotted with the Hubble Space Telescope and the new satellite will be most likely studied by the probe New Horizons during its expected flyby of the system. 

The Pluto system as shown by latest Hubble observations.

If you add all this with the results that are being announced from EPS-HEP there is no doubt that the past week has been one of the most exciting in a long time.

Friday, July 15, 2011

What is the relevance of the JWST?

The James Web Space Telescope, the succesor of the Hubble Space Telescope is now under the very serious treat of termination due to budget cuts. The story goes like this: last week, the House Commerce, Justice, and Science Appropriations Subcommittee recommended the cancellation of the JWST project. This was followed when the full House Science, Space and Technology Committee approved the subcommittee's plan.

From a scientific standpoint this is a total disaster. We need the JWST if we are going to push the frontiers of current research to an epoch where the first stars and galaxies formed. The scientific case has already been well explained by Julianne Dalcanton in Cosmic Variance so I don't need to repeat it again.

But, from the point of view of the average Joe in the street, what is the justification for pouring truckloads of money in the JWST? Maybe the most poetic justification reads something like it will enhance our comprehension of the origin of cosmos and the existence of life in it. But nonetheless, I find that, while completely true, this kind of answers are easy to dodge by any opportunistic politician who wants to present himself as the "hero of the community" by "saving the hard earned money of the community from falling into this resources swamp". 

Well, this is utter nonsense. Let me tell you why. The principal outcome of massive scientific collaborations is not a stream of papers with the latest and greatest results about fundamental questions but a stream of highly trained people who goes and contributes to the society in countless ways. I can not really estimate how many people went on to get a PhD based on Hubble's data or research started by Hubble's observation and while a few of them remain in the academia most have gone into all other corners of life. Many of them have joined big corporations or started their own corporation and contributed to the development of many technologies that are now commercialized and now create jobs for the people producing and manufacturing them. That is not to mention the secondary sources of income that are created when this people go and spend their income. So please keep in mind that by shooting down the JWST you are not only shooting down the few professional astronomers in your district but actually the training of some of the most skilled people in the society, the kind of people who will later produce some of the best sources of income available in society.

If you are in the USA, please take five minutes of your time and contact your representative to keep the JWST alive, the vote of the congress is still required to terminate this project. 

If history can give us some clues as what can happen, let me mention the Superconducting Supercollider, the project that was supposed to lead experimental high energy in the late 20th and early 21st century. After its cancellation not only we as scientists remain with doubts about fundamental physics as the Higgs boson or superpartners but also the region of Texas where it was going to be built entered into a local recession and furthermore, now the advance of the field is led by the CERN in Europe, ending with decades of US dominance of the field. Please don't allow this to happen again.

Wednesday, July 13, 2011

Blog v3

As anyone of you reading this has undoubtedly realized, the site has been completely overhauled. This is an attempt to bring it up to date in web standards. We now have an atom feed for updates, latex to mathml translation for maths and a new theme. You won't see it, but also the backend editor is new and is supposed to produce cleaner code. Let me know if you find any glitch with the new design.

On an unrelated thing. Neptune was discovered almost 165 years ago by John Galle who was looking for it after Adams and Le Verrier had predicted its existence based on the effect of Neptune on the orbit of Uranus. Since the orbital period of Neptune is 164.79 years we can say today that we are celebrating Neptune's first birthday!

Happy "birthday" Neptune!

Interestingly enough, from his observational notebooks we know now that Galileo had observed Neptune in his telescope which was too rudimentary to actually show its disc and reveal it as a planet. Additionally, in a strike of bad luck he just happened to observe Neptune when its proper motion was less noticeable. Nonetheless, there is some evidence that he was at least aware that it moved to respect the background stars. Unfortunately, bad weather prevented him to pursue this issue further. It is interesting how a small set of circumstances shapes history, not only of science.

Tuesday, July 12, 2011

Linux kernel 2.38 and Ubuntu Natty: The devourer of laptops

Some of you have undoubtedly installed a Linux distribution featuring the kernel 2.38 (or a latter version). This kernel comes with Ubuntu 11.4 Natty Narwhal but also in Fedora 15 and some rolling release distributions like Arch or LMDE.

While installing a new fancy distro carries the advantage of bringing you with the latest packages including the new fool-proof desktop environments that have been recently in the spotlight (unity and gnome 3) it will also bring you to one of the most annoying bugs that I have dealt with.

All the Linux kernel versions starting with 2.38 made changes to the Active-State Power Management (ASPM) that have resulted in a dramatic power consumption increase. This might be not so evident for a desktop computer but can easily trounce the charge duration of a laptop by a third, not to mention the fact that it turns it into a portable pan.

To fix this we need to enable the pcie_aspm=force option. The downside is that this might turn some systems unstable or even prevent them from booting. Use this at your own risk.

A simple way to see if this fix will work for your recently turned into pan laptop is to enable this option for a single boot. In Ubuntu you need to select your Ubuntu system and press e in the menu that allows you to choose an operating system just after turning on your computer. This allows you to edit the boot options for this session. Locate something looking like quiet splash and add pcie_aspm=force inmediately next to it, separated by a space. If your computer boots and remains stable you will notice that it will heat considerably less and that  battery life is extended.

Now, to make this change permanent we need to edit the bootloader. Open a terminal and enter:

gksu gedit /etc/default/grub

which will ask you for privileges escalation (the password of the administrator). Then, look for this line

and change it to

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash pcie_aspm=force"

Make sure that this is indeed how the line looks like, we don't want to screw the bootup. After that we need to update the bootloader:

sudo update-grub

And that's it, you have rescued your laptop from becoming your next broiler. Just reboot and the change must be there permanently.