MadSci Network: Astronomy
Query:

Re: Why is luciferin used by space probes searching for life on other planets?

Date: Sat Sep 30 14:35:29 2000
Posted By: Neil Sandham, Secondary School Teacher, Science Teacher and Career and Technology Studies Coordinator, Chestermere Middle School
Area of science: Astronomy
ID: 970110133.As
Message:

Good to hear from a fellow Calgarian.  

Luciferin is used to search for life on other planets because when it comes 
in contact with a special substance called Adenosine Triphosphate (or ATP)
it starts glowing.  ATP is only found in living tissues and is used to 
distribute energy throughout the cells of all organisms.  Using the 
assumption that living cells throughout the universe would also use ATP for 
energy distribution, it is a logical conclusion that the presence of alien 
life forms would cause a similar reaction in Luciferin.  This reaction is 
so acute that it will occur in the presence in as few as 1 000 cells.  

By examining the spectra of light given off, scientists can even tell the 
difference between microbial ATP and mammalian ATP, thereby giving an 
indication of what sort of life-form released these particles.  
Unfortunately, as dead cells decay, the ATP also decays.  This means that 
this process can only be used for detecting current life, not past life in 
the area.  Detectors using this process are incredibly small (see the 
picture links below) and are now included in many remote planetary probes.  
They are mostly used for detecting the presence of ATP in soil samples as 
soil below the permafrost layers (a few meters on most planets) can 
preserve traces of ATP for long periods of time.

New research in this area is looking for ways to make the Luciferin 
reaction last longer (often it only glows for seconds), to make it more 
sensitive to ATP (it can take anywhere from 30 seconds to 10 hours for the 
reaction to occur), and to determine the effect of cosmic radiation on the 
necessary chemicals to make sure that extended periods of space travel will 
not affect the efficacy of the process.

Most of this information came from a highly technical website detailing the 
work of R K Obousy and A C Tziolas, M R Sims.  You can check it out 
yourself at the following link; 

http://www.ugcs.caltech.edu/~andreas/Aris/Exobiology/Paper/extant.htm PICTURE LINKS - check out these pictures of two designs currently being used;

http://www.ugcs.caltech.edu/~andreas/Aris/Exobiology/Paper/image162.jpg http://www.ugcs.caltech.edu/~andreas/Aris/Exobiology/Paper/image164.gif I hope this helps.


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