Top 3 of this Week in Science

Dark Matter discoveredIt’s been a busy week in science (and in my life too…) so I’ll just put a brief links and descriptions for now… Let’s call it a Top 3 of the week!

  • Pluto is not a planet anymore: This story has been covered pretty much everywhere on the web, after the decision by the IAU to formally define what is a planet. Consequently, Pluto has lost its status of planet. It shall now be refered to as a dwarf planet. The definition of planet is still controversial, mainly because Pluto has a large lobby. Nowadays, a planet is a celestial body that is in orbit around the sun; has the shape of a body in hydrostatic equilibrium (nearly round); and has “cleared the neighborhood” around its orbit. One might want to include Pluto as an historical error, but I think this would be unlikely.
  • NASA Announces the discovery of Dark Matter: This one is pretty big news too. Scientists working with the Chandra telescope have found direct observational evidence of dark matter. It confirms the scientists in their view of the Universe and it also makes some pretty pictures like the one seen here at right. In that picture in false colors, the normal matter is in pink whereas the dark matter is in blue. The picture didn’t show like this originally, as the blue region is the result of a calculation of how mass is distributed in that galaxy cluster.This confirms the ratio of dark matter vs. normal matter that astrophysicists have been thinking about since the last ten years. You will find more reading here and here.
  • Proof of the Poincaré Conjecture and Fields Medal Saga: The Poincaré conjecture, in its simple form, stands as follows:

    Every simply connected closed (i.e. compact and without boundary) 3-manifold is homeomorphic to a 3-sphere.

    For most people, it doesn’t mean anything. However, no one has been able to make a proof of this statement since Henri Poincaré announced it in 1904. The Clay Mathematics Institute selected this problem as one of the seven Millenium problems, which were linked to a reward of 1,000,000$ each. In late 2002, a rumour started to arise that a russian mathematician, Grigori (Grisha) Perelman found a solution to the problem. In the ICM (international congress of mathematics) in August in Madrid, his 3 papers were on the agenda. They decided to award him (in part) the Fields Medal, widely considered as the Nobel Prizes for Mathematics. He however refused, but the reasons for his refusal were not made available. On top of that, the whole political world of mathematics and, by extension, of higher research is surfacing, which is not pretty at all.

    If you feel brave enough, you can check the Clay Institute Homepage, which now gives a detailed exposition about the Poincaré Conjecture and especially the works of Perelman.

    • August 27th, 2006 | General Science | 1 comment

    Making a SMART Move on the Moon

    SMART-1 Trapped by the MoonThe ESA is gearing up for the end of the mission of its first spacecraft towards the Moon. SMART-1 was launched on September 27, 2003, and it reached the Moon in November 2004 after a long spiralling around Earth. So far, the mission has been a success and will end in a dramatic fashion.

    Initially planned to last 6 months, the SMART-1 mission got a one year extension and further studies were completed. Now the delay is over and the spaceship will be a tool for one last experiment. Since the spacecraft is trapped by the Moon’s gravity, it will come down crashing on the Moon on September 3rd. The last bits of propellant were used to boost the orbit of SMART-1, giving it that one year extension. Out of xenon propellant, SMART-1 used its hydrazine thrusters to perform the last major manoeuvre at the end of June 2006 to further stretch the mission lifetime and win three more weeks of operations.

    SMART-1 first contribution was to show that its ion engine could be used efficiently for interplanetary travel (assisted by gravity slingshots). To cover the 385,000 km distance that separates the Earth from the Moon if one travelled in a straight line, this remarkably efficient engine brought the spacecraft on a 100 million km long spiralling journey on only 60 litres of fuel!

    SMART-1 also tested future deep-space communication techniques for spacecraft, techniques to achieve autonomous spacecraft navigation, and miniaturised scientific instruments, used for the first time around the Moon. Also, a small instrument on the satellite as shown the first detection from orbit of calcium on the Moon. This could help scientists determine if the Moon form from part of the Earth.

    (more…)

    August 18th, 2006 | Physics, Space | No comments