Monday, October 14, 2013

Wanderlust: Crawling on hands & knees

The European Space Agency writes to say
The applicant must have the normal range of motion and functionality in all joints.

Historically, IMHO, astronauts came from a flight/test-pilot background. Physical fitness may have been mandatory for orbital flight, and for the lunar programme. It may even be necessary for any missions that involve actually landing on a body exhibiting significant gravitational attraction. It might _not_ be necessary, say, for a mission to Phobos.

I'm sure NASA and other Space Agencies have similar physical mobility requirements for their astronauts.

In this context, Wikipedia writes to say
What began as the selection of military fighter and test pilots in the 1960s, with a considerable focus on physical capability, has evolved into a selection that now selects for aptitude in engineering, sciences, life sciences, and mathematics

Say instead the astronaut is headed to the ISS where she/he is expected to be in free-fall most of the time. A person with a reduced range of motion (I'm specifically of the mind of restricted movement of the lower-limb) might actually be better suited for free-fall - as long as other physical, social, mental health parameters are met. About the only time I imagine full-range of motion in the lower-limb/s might be necessary would be at launch/landing.

I've never been an astronaut, or even close to medicine let alone space-medicine so I may be wrong. Feel free to poke me in the rib if my premise is flawed!

Is the physical fitness requirement that an astronaut prove full-range of mobility in all limbs relevant to astronauts headed to the ISS, or low-gravity bodies such as an asteroid?


Saturday, October 05, 2013

Wanderlust: A doe-eyed toddler

There's a lot of hullaballoo about the sky falling on our heads.
It all started when someone in the Space Program read an Asterix comic ... no, it didn't really. But there is some truth to the sky falling on our heads; except that it is about orbital debris.

According to wikipedia -
Currently, about 19,000 pieces of debris larger than 5 cm (2.0 in) are tracked, with another 300,000 pieces smaller than 1 cm below 2000 km altitude.

Now 5cm, and 1cm seem to be laughably small - and they would be laughably small under normal circumstances. In orbit though, there is no such thing as laughably small. What makes orbital debris dangerous is that an object in orbit travels at extremely high velocity! What's your first guess? 100km/h? 200km/h? 1000km/h? Objects in orbit travel at a velocity of over 25000 km/h!

For instance, the heaviest artifact in orbit at present is the International Space Station. This has a mass of 450,000 KG ... and an average velocity of 7.66km/s OR approximately 27576km/h!

For the sake of comparison, the fastest bullet (well, it can be called a bullet!) fired by a tank gun is around 1.7km/s.

In case you think this 7.66km/s is fast, let me point out to you Voyager 1 (now out of the Solar System) is toddling along at over 17km/s . Given the immensity of interstellar space and huge distances between objects in space, even this 17km/s is slow! Remember that Voyager 1 was launched over 36 years ago - about the time I was born. So in my lifetime, Voyager 1 has only gone out of the Solar System! It will take 40000 (yes, Forty thousand) years to even get close to another star!

The good thing about orbital debris being small is that if it encounters Earth Atmosphere, it will burn away as a meteor! Besides, space is so immense an object may spend an infinity in orbit without anything eventful happening.

But these artifacts are scattered beginning from around 200km above Earth to 36000km above Earth. The renewed interest in space exploration promises to increase the population of objects orbiting Earth. As an example, Kicksat is a program to launch miniature personal satellites!

But what can be done about this situation? Why not turn the debris into an advantage? Easier said than done, I know ... and I'm no space scientist so my take could be wrong.

Having made that qualification, I shall now proceed to put my foot in it -

The ISS is up there anyway ... can all this debris be collected to construct a small module - assembled in orbit? The ISS uses fuel to balance it's orbit anyway; we may perhaps even haul fuel, and cannibalize an engine from the ISS instrumentation to send the module elsewhere out of Earth orbit! This could also be an experiment for the Pir module due to be undocked in 2014