26th April 2011 Bacteria in Space

In a fascinating article [1], Ed Yong explains how experiments in space are providing insight into disease on Earth. It's well worth a read.

Extreme Conditions

In extreme conditions, we can learn much about how bacteria functions. In hot undersea vents, studying bacterium led to the discovery of an enzyme which could create pieces of DNA at high temperature.  This enzyme gave rise to the polymerase chain reaction which is used to multiply DNA in the lab.[2]

For many years it was believed that bacteria could not live in the harsh conditions of the stomach but, against much disbelief and scorn, two Australians, Barry Marshall and Robin Warren, showed that Helicobacter pylori bacterium is a major factor in stomach ulcers.[5]

Bacteria in Space

Scientists led by Cheryl Nickerson have found that salmonella bacteria are far more virulent in microgravity (almost zero gravity) than they are on earth. They clump together more easily, which forms a biofilm which is more prone to cause disease. It is thought that this clumping is triggered easier by the reduced force of the liquid over the bacteria, which would usually indicate to the bacteria that they have reached the calmer regions of the body where they are adapted to reproduce.[ 1, page 3]

The mechanism which controls the changes in salmonella is a protein called Hfq. This switched genes on and off. If something to target Hfg could be found, it could lead to a weapon against not only salmonella but other bacteria too.

Weakened Immune Systems

In space, astronauts' immune systems are weakened since the white blood cells do not activate properly. Putting this together with the stronger bacteria and lack of medical facilities and care, it adds up to a hazardous situation for those travelling in space.

Update: Rosie Redfield (University of British Columbia) has some doubts as to the rigor of the paper the article is based on.[10]

Sources

1. Wired Magazine: Space Medicines Final Frontier
2. Wikipedia: Micro-g Environment
3. Wikipedia: Polymerase Chain Reaction
4. Wikipedia: Hfq Protein
5. Wikipedia.: Timeline of peptic ulcer disease and Helicobacter pylori
6. Wikipedia: Barry Marshall 
7. Wikipedia: Robin Warren
8. Wikipedia: Helicobacter pylori
9. Sciencemuseum: Spacebacteria
10. Rosie Redfield: Do bacteria become superbugs in space?

9th April 2011 Yuri Gagarin

Yuri Gagarin and Orbits - Sixty Symbols

The first man in space was in April 1960 when Yuri Gagarin, from the USSR, completed a low earth orbit of the earth.  There were rules established to define an orbit of the earth, which included that the astronaut must be stay in the space shuttle the whole time.  Gagarin actually parachuted out of the rocket as it was thought to be safer. This was kept as a secret for about a decade by the Soviets so they'd get the record.


Newton worked out that with the curvature of the earth, through thinking about a canon ball falling to earth but because of the curvature of the earth falling further than expected.  He worked out that if you put more gunpowder in, the ball would end up not getting any closer to the earth because it would be falling at the same rate as the curvature of the earth falls away.    Even more powder and it will have an elliptical orbit, going away from the earth before coming back in. With more, it would escape completely.

This wouldn't work because

• air resistance would slow the canon ball down and it would fall to earth,
• you'd need the canon ball to leave the canon at 6km/h. A modern rifle shot is only 1km/h.. 

 It required the invention of the rocket engine.


Low earth orbit: space shuttle can only get this high. Needs a booster rocket to go further.  Hubble telescope is in a low earth orbit.

Geostationary orbit: 36000km: geostationary orbit takes about 24 hours (23 hours 57 minutes)

Moon orbit: 400 000km: 28 days to orbit