A map of all the space junk that has re-entered over Australia

Today someone wrote to me to ask for help in identifying a piece of space junk which had been found in Queensland some years ago. Dr Space Junk is always happy to help, so I sent off a brief explanation.

This made me think, though, of how interesting it would be to map the location of all known re-entry events. There'd be a whole bunch of Skylab in Western Australia, some material from the Europa launches from Woomera in the 1960s in the Northern Territory and Queensland, and many pressure vessels used in rocket fuel systems - globally, these are the most common component to survive re-entry as they're usually made from titanium, stainless steel and/or carbon-carbon. Because of Australia's location, many rocket bodies fall back to Earth over our landmass. We're well situated for observing and tracking the LEOP (Launch and Early Orbit) phase of launch so it makes sense that the second and third stages are likely to re-enter in our vicinity.

You could compare the distribution of this junk with the meteorite entries being mapped by the Western Australian Fireballs in the Sky project, which asks citizen observers to send in data whenever they see some flaming object heading towards Earth. And of course there's also the tektite strewn fields.

I might just expand it to include anything that falls from the sky, as it's likely there's stuff that my Friday-arvo brain has forgotten about at the moment. The more I think about it, the more I think this could be an extremely interesting map to create and I wonder why I've not thought of it before. Such a deliciously simple idea that could lead to - well I don't really know just yet, but it's sure to be something!

Do objects and people cast shadows inside the International Space Station?

Do astronauts cast shadows in space?

Astronaut Mike Hopkins casts a spoon shadow. Image courtesy of NASA.

I've been thinking about shadows a lot, and also space stations. This has involved reading about habitability studies, an area I started to investigate when I was writing about Skylab a few years ago. The point of this line of enquiry is whether shadows are considered when the interiors of space stations are designed. Perhaps they contribute to creating a feeling of homeliness. Perhaps a lack of shadows is something characterising a laboratory environment, or a solitary confinement cell, or a padded cell, and hence to be avoided. Astronauts are, after all, under constant surveillance. You can hide things in shadows. Things can hide themselves in shadows.

It's worth observing that a shadowless environment can occur when you have no light, or when you have too much light.

Part of the answer to this is how, when, where and with what the ISS is illuminated. It appears that the lighting at present is a combination of fluorescent and LED.  

A perusal of images of the interior shows that there are certainly shaded areas, and more highly illuminated areas. The restricted interior space, and the curvature will also have an impact on the appearance of shadows. Have a look at this one:

Image courtesy of NASA

Of course, when we see images of the inside, they are generally illuminated. But the space station is also darkened at 'night'.  Recently astronaut Alexander Gerst took a series of rather spooky pictures with the lights turned off. Clock this and tell me it doesn't send chills down your spine:

Image courtesy of NASA

Do you see that the helmets are hooded? Is this from fear of what you might see if you looked through the visor?

Perhaps illumination inside the ISS is designed to avoid the ever-present uncanny, always just out of sight, in another module, or outside the window....