[ Keli/NASAChatHost - 51 - 14:20:54 ]
You may post questions for Dave here during the lecture--he will answer the most relevant questions "on the air" as time permits, while other questions will be answered in the chat room after the lecture. There might be a slight time delay as this chat is moderated. If your question is answered "on the air," you will not see a typed answer here.

[ Keli/NASAChatHost - 53 - 14:21:12 ]
Let us know what you think of this event by filling out our online survey at http://quest.arc.nasa.gov/ltc/survey.html

[ Keli/NASAChatHost - 54 - 10:04:12 ]
To view Dr. Peterson's lecture, go to http://quest.arc.nasa.gov/ltc/astrobio/index.html and click on one of the "technologies" link. From there you can get to his slides.

[ AbelMendez/UPRArecibo - 55 - 10:27:03 ]
Hi Dr. Peterson. I'm in biophysics doing research in the Growth Dynamics of microorganisms under Mars near-surface environments. Mi question is: How does life affects the nitrogen Levels? What's the atmospheric nitrogen history of the Earth?

[ Keli/NASAChatHost - 56 - 10:28:11 ]
Hi Abel, got your message and will pass it on to Dr. Peterson shortly!

[ Keli/NASAChatHost - 57 - 10:42:02 ]
RE: [Keli/NASAChatHost] Hi Abel, got your message and will pass it on to Dr. Peterson shortly!
Abel, hope you got the answer to your question on the air--if you have further questions, Dr. Peterson is now in the chat room.

[ Keli/NASAChatHost - 58 - 10:43:47 ]
RE: [Keli/NASAChatHost] Abel, hope you got the answer to your question on the air--if you have further questions, Dr. Peterson is now in the chat room.
He is also writing a typed answer to your question while we await further questions.

[ AbelMendez/UPRArecibo - 59 - 10:44:03 ]
Thank you for the reference Dr. Peterson.

[ Keli/NASAChatHost - 60 - 10:45:40 ]
We would love to know what you think of this lecture series. You can give us your opinion at the online survey at http://quest.arc.nasa.gov/ltc/survey.html

[ Keli/NASAChatHost - 61 - 10:47:00 ]
If you enjoyed this lecture, please be sure to tell others to come. Next week, Chris McKay will be talking about "What is the Potential For Biological Evolution Beyond the Planet of Origin?"

[ David - 63 - 10:48:30 ]
RE: [AbelMendez/UPRArecibo] Hi Dr. Peterson. I'm in biophysics doing research in the Growth Dynamics of microorganisms under Mars near-surface environments. Mi question is: How does life affects the nitrogen Levels? What's the atmospheric nitrogen history of the Earth?
Abel, Thanks for your question. I thought I could give you a bit more information and point you to the work of some of the scientists. One fellow you should contact is at UPR Mayaguez by the name of Roy Armstrong. Roy studies coastal plants and ecosystems including coral reefs and magrove forests and the effects of nitrogen on these systems due to increases in nitrogen input from human waste systems. Roy's office is in La Parguera. Also, you might want to do a search for the work of Peter Vitousek and Pam Matson on nitrogen and the role of microorganisms in regulating the N cycle. Virtually all of the soil N needed by plants comes from the results of microorganisms breaking down organic detritus, such as leaves, to get energy. When the organisms expire, they release the nitrogen into inorganic forms such as NH3 and NO3 which is useable by plants as part of the biogeochemical cycles. The Annual Meeting of the Ecological society of America always has special sessions devoted to the nitrogen cycle. I suggest you ask Chir McKay next week if he knows anything about the history of N on Earth or on Mars. Nitrogen gas has no greenhouse properties, though nitrogen oxides are important greenhouse gases though much less abundant than gases like methane or CO2. Now that you have brought this up I am going to go the literature myself to look it up. Best of luck with your research plans. Dave

[ David - 64 - 10:53:23 ]
RE: [AbelMendez/UPRArecibo] Do you know what percent of the plant intake CO2 gets converted to O2? Any suggestion to get relate info?
Abel, The answer I believe would be in the equation of photosynthesis. For each molecule of CO2 assimilated in photosynthesis, one molecule of O2 is liberated. Six moelcules of CO2 and 6 of H2O also create one molecule of glucose for energy use of the plant and the six molecules of O2. Of course, the plants release CO2 as part of their respiration as do the microbes. In that process they use oxygen to burn the metabolic products. Dave

[ Keli/NASAChatHost - 65 - 10:55:19 ]
Are there any further questions for Dr. Peterson? If not, I'd like to thank him in advance for sharing his time and expertise today and welcome you to join us next week when Dr. Chris McKay lectures on "What is the Potential For Biological Evolution Beyond the Planet of Origin?"

[ AbelMendez/UPRArecibo - 66 - 10:56:31 ]
Thanks again for the detailled answers. I will look the references. Bye.

[ Keli/NASAChatHost - 67 - 10:56:31 ]
Thank you for coming Abel!

[ Keli/NASAChatHost - 68 - 10:59:58 ]
Thank you to Netscape for helping to sponsor this event. See you next week!