The European Union’s probe, Smart 1, did a controlled collision with the moon. After doing some tests and stuff, they crashed it so that dust would fly into the air, giving earth telescopes the opportunity to study it.
While I think that is fairly cool and groovy on its own, it was another part of its mission that caught my interest.
From BBC News article Probe crashes into Moon’s surface:
Smart 1 was launched on an Ariane 5 rocket in September 2003 as a technology demonstrator.
It became Europe’s first space science mission to use an ion engine instead of chemical combustion to reach its destination.
The system drew power through the probe’s solar wings and then used this energy to propel the spacecraft forward by expelling charged particles of xenon. It was highly efficient, covering 100 million km in a series of looping orbits and using just 60 litres of “fuel”.
Down at the bottom of the article is this picture and explanation of the engine:
1. Xenon gas atoms are pumped into a cylindrical chamber, where they collide with electrons from the cathode. The electrons – which are negatively charged – knock electrons off the xenon atoms, creating xenon ions – which are positively charged.
2. Coils outside the chamber create a magnetic field, which causes electrons from the cathode to spiral and become trapped at the mouth of the chamber.
3. The build-up of negatively charged electrons at the mouth of the chamber attracts the positively charged ions, accelerating them out of the chamber.
4. The stream of accelerated ions leaving the chamber thrusts the spacecraft forward. Although the force is small, over time it creates great speed in the frictionless environment of space.
Now how cool is that? We live in a wonderful time, despite the US gov’t’s King George.
NOTE: Related linkage
- SMART-1 Prepares for Lunar Crash – Planetary News, The Planetary Society
- European Space Agency’s page for Smart 1 and another in their Science section
- Wikipedia – Smart-1
- Space.com – At the Moon Again!