Printer Friendly

Look to the nitrogen.

I wish to comment on Emily Lakdawalla's article on NASA's new Mars rover Curiosity and the search for life (S&T: December 2011, page 22). The very first thing that investigators should look for, on Mars or any other planet, is a nitrogen cycle. Nitrogen is an essential component of all DNA, RNA, and proteins. Its unique properties provide the glue--or, perhaps more aptly, "Velcro"--that holds DNA in a spiral helix yet allows the helix to partially unzip for duplication or RNA transcription.

On Earth, a major abiotic system for nitrogen fixation is the combination of an oxygen-nitrogen atmosphere and lightning. This combination produces nitric acid, which on the ground is neutralized by metal oxides and carbonates to form nitrate ions that plants can use as a nitrogen source. Some microorganisms also produce nitrate directly in an oxygen-nitrogen atmosphere without the need for abiotic sources. For example, the bacterium Pseudomonas radicicola forms nodules on the roots of some plants, particularly legumes. This is a symbiotic relationship: Pseudomonas supplies nitrate, and the plant returns sugar.

If there is no life on Mars today, it may mean there's no nitrogen cycle. And if there never was a stable, long-lived nitrogen cycle--long enough for life to emerge--there probably never has been life on Mars.

Donald Simons

Wilmington, Delaware

COPYRIGHT 2012 All rights reserved. This copyrighted material is duplicated by arrangement with Gale and may not be redistributed in any form without written permission from Sky & Telescope Media, LLC.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2012 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:Letters
Author:Simons, Donald
Publication:Sky & Telescope
Article Type:Letter to the editor
Date:Mar 1, 2012
Previous Article:Planetarium workshop.
Next Article:No Bok globule.

Terms of use | Privacy policy | Copyright © 2021 Farlex, Inc. | Feedback | For webmasters