Tuesday, July 17, 2012

Star Trek: Supernovae and Element Scanning on Angel One

Star Trek the Next Generation (1987-1994) (Picture)
Season 1, Episode 13
Angel One

An away team beams down to Angel One in order to look for a lost freighter crew. The crew has apparently hidden away on the planet, so the Enterprise must use advanced scanning technology to locate them. There are elements not endemic to Angel One that the crew would have brought with them. By scanning the planet for platinum, the Enterprise is able to locate the freighter crew. How would such a scanning technology work, and is it realistic?

First let's ask an important question:

Is it realistic to believe a planet could have no platinum?

To that I am going to say yes. Planets are formed from swirling clouds of matter that are created from the detritus of old supernovae.

But what is a supernova, exactly? 

A supernova is a massive explosion that can occur when a star reaches the end of its life. It looks something like the image below.

 What a supernova might look like (Source)

When a supernova occurs there are conditions of intense heat and pressure. These conditions cause heavy ion fusion, meaning that two atoms of carbon, for example, can fuse together to create a new, heavier element. This is the process that is responsible for forming the heavy elements we have in the universe.

If stars did not die so spectacularly then there would not be the rich variety of elements we have around us today (including those that make up humans and all living things). 

Now back to platinum

I think it is realistic to believe that Angel One could have been formed from the remains of a supernova that was perhaps not energetic enough to produce a significant amount of heavy elements, including platinum.

 The periodic table of elements. Note how far down Platinum (Pt) is. (Source)

Platinum is a relatively heavy element, which can be seen from the periodic table. It is located near the bottom right of the transition metals (pink part of table) and it has the symbol Pt. All of the elements required for mammals to live are lighter than platinum, meaning that a planet theoretically formed without platinum or any elements heavier than it could support life for beings like humans. I believe the heaviest element the human body requires is Iodine (I), which is on the far right of the periodic table. It is important because it enables the thyroid to produce hormones. 

Now that we believe it is possible for a planet to be created without heavy elements like platinum and for life to exist without these heavier elements, it is important to return to the main question:

How might the Enterprise have scanned Angel One for platinum?

Assuming the Enterprise was only scanning the surface of the planet, I think this question has a pretty satisfactory answer: spectroscopy.


In its most common form, spectroscopy involves shining electromagnetic radiation on matter. If we look at the most well-used example, hydrogen, electromagnetic radiation is shone on a sample of hydrogen. Certain wavelengths are absorbed by the element and others pass right through. Those that are absorbed are equal to the energy difference between two energy levels of electrons.

Hydrogen energy level transitions with corresponding photon wavelengths absorbed. (Source)

The above image shows some of the energy level transitions allowed for an electron in orbit around a hydrogen nucleus (just a proton, in this case). The energy levels can be thought of as concentric circles around the nucleus. An electron usually lives in the one closest to the nucleus. In order to move up to a level further from the nucleus it needs to absorb a specific amount of energy. It only absorbs electromagnetic radiation that has the correct energy, and therefore the correct wavelength.

By shining all wavelengths of electromagnetic radiation on a sample and seeing which are absorbed it is possible to know the composition of what you are testing. After absorbing the electromagnetic radiation and moving up to a higher energy level, the electron eventually relaxes back down to its lowest energy state (ground state) by emitting electromagnetic radiation with energy equal to the energy difference between the two levels. Sometimes multiple transitions occur while an electron relaxes down to its ground state.

So, it works! 

In this case, the physics supports the possibility of the Enterprise finding the freighter crew using spectroscopy. Of course they need to have very powerful and sensitive equipment to notice a small piece of platinum on an entire planet (and to be able to scan the planet so quickly), but I think we can give that much to a ship that can travel through the universe at warp 9!

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