IPB

Welcome Guest ( Log In | Register )

5 Pages V  < 1 2 3 4 5 >  
Reply to this topicStart new topic
Possible Contamination, Bacteria hitched a ride to Mars
dvandorn
post Jul 19 2005, 09:13 AM
Post #31


Senior Member
****

Group: Members
Posts: 3227
Joined: 9-February 04
From: Minneapolis, MN, USA
Member No.: 15



No, not impossible -- but such life would have to have developed protections against the radiation environment that would make it vanishingly close to impossible that any terrestrial life form *not* adapted to the radiation environment would be capable of competing with it. Or even capable of surviving.

I always liked the way Mike Collins referred to the extra-terrestrial contamination issue. Of course, he was referring to the remote possibility that lunar materials might pose a threat to the Earth's biosphere, but his remarks apply here, as well.

Collins said that if you take the possibility of a profound threat from contamination by extra-terrestrial organisms (very, very small) and multiply it by the potential damage such contamination can cause (very, very large), you come up with a reasonable number that defines how much attention you give to the problem.

Now, when we start sending probes to dig more than a foot or two into the Martian soil, I think we need to take special care to sterilize any part of the spacecraft that reaches into a realm where terrestrial organisms could survive. But until then, I think the present sterilization procedures (which make the possibility of carrying significant amounts of terrestrial life to Mars very, very unlikely) makes the first part of Collins' equation a very small number. As long as that number remains very, very small, I think the risks of continuing to explore the surface of Mars are acceptable.

Besides, unless we're willing to take the risk, we'll never know whether or not there is any Martian life that needs protecting. Like I said, observing something affects it. And human technology is not infallible, so it is impossible to guarantee that all Mars landers will be *completely* free of terrestrial organisms. You *must* risk some small contamination possibility just to find out if there is any Martian life out there that could be at risk. If you insist on the presence of Martian life, and if you further insist that even a single bacteria carried to the surface will *definitely* contaminate or even destroy that life, then you're forced into the position that we must immediately cease *all* exploration of Mars. Including orbital exploration (since orbiters eventually crash). And you have to admit that your worst fears must already have been realized, since we've already landed and crashed imperfectly-sterilized craft on Mars.

Since we can't even *guess* at where life might presently exist on Mars, or under what conditions it may flourish, we have to do a lot more exploring there, including many more landings and even sample-return missions, to *ever* expect to find it. If it exists. Insisting that even the *possibility* of life on Mars means that we must stop *all* possibility of contaminating it means that we'll never, ever know if that life exists or not.

The most important thing about finding life on other worlds is to see if it organizes in different forms and with different chemical compositions than life does on Earth. If we dare not even go look for it, we'll never have the opportunity to even ask those questions, much less expect to get answers.

-the other Doug


--------------------
“The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
Go to the top of the page
 
+Quote Post
Bob Shaw
post Jul 19 2005, 09:16 AM
Post #32


Senior Member
****

Group: Members
Posts: 2488
Joined: 17-April 05
From: Glasgow, Scotland, UK
Member No.: 239



QUOTE (mike @ Jul 18 2005, 11:09 PM)
At some point it's absurd, and personally I can live with a few puny organisms accidentally destroyed if it means learning new things and gaining access to useful minerals/artifacts/whatever.  If I were worried about killing anything, I'd never take a shower, I'd never cook my food, I wouldn't kill fruit flies, etc. etc. etc.
*


I stand by the old Star Trek adage - 'We come in peace - shoot to kill!'.

Oh, there's Klingons on the starboard bow...


--------------------
Remember: Time Flies like the wind - but Fruit Flies like bananas!
Go to the top of the page
 
+Quote Post
dvandorn
post Jul 19 2005, 09:59 AM
Post #33


Senior Member
****

Group: Members
Posts: 3227
Joined: 9-February 04
From: Minneapolis, MN, USA
Member No.: 15



QUOTE (Bob Shaw @ Jul 19 2005, 04:16 AM)
Oh, there's Klingons on the starboard bow...
*

OK -- just so long as they're not circling Uranus...

ohmy.gif

-the other Doug


--------------------
“The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
Go to the top of the page
 
+Quote Post
Jeff7
post Jul 19 2005, 12:31 PM
Post #34


Member
***

Group: Members
Posts: 477
Joined: 2-March 05
Member No.: 180



QUOTE (dvandorn @ Jul 19 2005, 04:59 AM)
OK -- just so long as they're not circling Uranus...

ohmy.gif

-the other Doug
*


Quick, call the starship Enterpoop!
Go to the top of the page
 
+Quote Post
Bob Shaw
post Jul 19 2005, 03:16 PM
Post #35


Senior Member
****

Group: Members
Posts: 2488
Joined: 17-April 05
From: Glasgow, Scotland, UK
Member No.: 239



You're all *so* funny, and puerile with it.

First one to mention the dark rings around Uranus won't surprise me at all!

Oops, just mentioned 'em.

Damn.

On second thoughts:

We're all *so* funny, and puerile with it!






Well, I'm off to the top of Husband Hill to scare the sheep.


--------------------
Remember: Time Flies like the wind - but Fruit Flies like bananas!
Go to the top of the page
 
+Quote Post
mike
post Jul 19 2005, 05:07 PM
Post #36


Member
***

Group: Members
Posts: 350
Joined: 20-June 04
From: Portland, Oregon, U.S.A.
Member No.: 86



If we were to find Earth-like organisms on Mars, we'd have no way of knowing whether they came from Earth-based meteors or whether they've been there for billions of years, regardless of whether probes had ever landed there or not.

As far as a tiny risk having profound consequences, that's true of everything that has some potential for great results - nuclear plants can melt down, jets can crash, gasoline trucks can explode, etc. etc. etc.

If we're not going to do things simply because they're dangerous we should not drive, not leave our house, not eat anything but tofu...
Go to the top of the page
 
+Quote Post
tty
post Jul 19 2005, 05:18 PM
Post #37


Member
***

Group: Members
Posts: 683
Joined: 20-April 05
From: Sweden
Member No.: 273



QUOTE (mike @ Jul 19 2005, 07:07 PM)
If we were to find Earth-like organisms on Mars, we'd have no way of knowing whether they came from Earth-based meteors or whether they've been there for billions of years, regardless of whether probes had ever landed there or not.
*


Oh, yes we could - the phylogenetic distance would give a good indication how long they had been isolated. Admittedly we don't have a good idea about how fast evolution works on Mars, but separating organisms arriving a billion years ago or in 1975 AD would be easy. Incidentally if there is life on Mars and it is distantly related to earthly life, then it is rather more likely that Mars has contaminated Earth rather than the other way around. smile.gif

tty
Go to the top of the page
 
+Quote Post
Sdetton
post Jul 19 2005, 10:46 PM
Post #38


Newbie
*

Group: Members
Posts: 6
Joined: 18-July 05
Member No.: 440



QUOTE (Edward Schmitz @ Jul 18 2005, 08:15 PM)
Where are you getting these "facts"?  "Thousands of years"?  How do you know that sterilization is superfluous?  Maybe the only earth microb that will survive on mars can't make the long journey on a rock, but the rovers are an exceptable transport. 

ed
*


What's so different about the rovers that make them better at transporting microbes than pieces of ejecta? The organisms might not survive if they were on the surface of the rock, but they have far better chances if they are inside the rock or maybe in frozen water/hydrocarbons. And the "facts" are actually assumptions based on evidence of how life on earth adapts and evolves. Call it more of an educated guess wink.gif .

And bravo to dvandorn for some excellent points.
Go to the top of the page
 
+Quote Post
Guest_Edward Schmitz_*
post Jul 20 2005, 03:53 AM
Post #39





Guests






QUOTE (Sdetton @ Jul 19 2005, 03:46 PM)
What's so different about the rovers that make them better at transporting microbes than pieces of ejecta?
*

How 'bout time? Seven months vs. seven million years. How 'bout shielding? Parts of the rover are shielded against radiation. How 'bout thermal protection? The WEB is insolated against thermal extremes. How 'bout matterial? vastly different composition. How 'bout food supply? Cork! How 'bout not being blast through the atmosphere by a multi-tera-ton blast?

That's what I came up with in about 2.5 minutes. I'll bet that there are even better differences that I don't even know about.

What's so different? Lots of stuff, that's what.

ed
Go to the top of the page
 
+Quote Post
Sdetton
post Jul 20 2005, 04:55 AM
Post #40


Newbie
*

Group: Members
Posts: 6
Joined: 18-July 05
Member No.: 440



QUOTE (Edward Schmitz @ Jul 19 2005, 10:53 PM)
How 'bout time?  Seven months vs. seven million years.

How 'bout shielding?  Parts of the rover are shielded against radiation.  How 'bout thermal protection?  The WEB is insolated against thermal extremes.  How 'bout matterial?  vastly different composition.  How 'bout food supply?  Cork!  How 'bout not being blast through the atmosphere by a multi-tera-ton blast? 

That's what I came up with in about 2.5 minutes.  I'll bet that there are even better differences that I don't even know about.

What's so different?  Lots of stuff, that's what.

ed
*


Ok, let's examine some of your points.

Time: Can vary. It doesn't always take ejecta millions of years to get there. It can happen within thousands or less depending on the circumstances. Also see the comment about food.

Shielding: The rock can have dense metals or other materials on the surface. Also depends on how deep the microbe is inside. There may also be pockets within to protect against the vaccuum.

Thermal protection: Once again, depends on the makeup of the rock, the amount of time to impact, and other factors. Could make the temps within warmer by maybe a few degrees - not perfect but helps survival.

Food supply: Certain organisms can form a very durable spore (like anthrax for example) when the nutrients aren't at hand. They can even revive after hundreds of thousands of years in such a state ( BBC link )

The only thing the rover seems to have going for it is impact survival - the slow and safe landing of the rover does make it a better mode of transport over the ejecta. But besides that, nothing much.

Anything else?
Go to the top of the page
 
+Quote Post
edstrick
post Jul 20 2005, 08:24 AM
Post #41


Senior Member
****

Group: Members
Posts: 1869
Joined: 20-February 05
Member No.: 174



This whole discussion has been triggered by an apallingly clueless and unclueable piece of shoddy sensationalistic and controversy-mongering reporting.

There is absolutely no doubt that the rovers carried viable microorganisms to Mars,. as did Polar Lander, Pathfinder and the 1971 and 1973 Soviet Mars Landers.

The Soviets *CLAIMED* at the time that the landers were sterilized, as required by international planetary protection protocals, but unless new information has become available that I don't know, were later admitted to be merely a case of having been assembled under extra-clean conditions with decontamination procedures intended to reduce microbial loads on the spacecraft.... essentially like all Post-Viking missions.

Viking Landers were assembled "clean" like other missions, sealed inside "BIOSHIELD" cannisters, heat-shields and all, and heat sterilized at something like 240 F with the temperature ramped up, held at 240 for like 24 hours, and ramped back down over a 36 hour or 2 day period. Mission requirement was something like 1 chance in 100,000 of delivering a viable microbe to the surface of Mars.

Given the extreme hostility of the surface environment to survival and especially reproduction of terrestrial life, planetary quarantine restrictions were relaxed to the current 'spiffy clean' standard, except for hardware that can penetrate to ice that could possibly someday melt aand especially any water tables. Check Phoenix Lander mission stuff on their plans, since they're landing on icy soil and trying to dig down into it.
Go to the top of the page
 
+Quote Post
remcook
post Jul 20 2005, 01:48 PM
Post #42


Rover Driver
****

Group: Members
Posts: 1001
Joined: 4-March 04
Member No.: 47



My point was more to discuss what people think about the viability/use of these policies than to discuss the actual article
Go to the top of the page
 
+Quote Post
remcook
post Jul 26 2005, 09:47 AM
Post #43


Rover Driver
****

Group: Members
Posts: 1001
Joined: 4-March 04
Member No.: 47



more to add...

http://www.spaceref.com/news/viewpr.html?pid=17496

QUOTE
Over the coming decade, NASA should develop and implement new methods and requirements to detect and eliminate microorganisms on robotic spacecraft sent to Mars to prevent possible contamination of the planet, says a new report from the National Academies' National Research Council. If microbes aboard a spacecraft were to survive the trip to Mars and grow there, they could interfere with scientific investigations to detect any life that might be native to Mars. Existing techniques for cleaning spacecraft are outdated and typically eliminate only a fraction of microorganisms, said the committee that wrote the report.
Go to the top of the page
 
+Quote Post
Guest_Richard Trigaux_*
post Jul 26 2005, 11:05 AM
Post #44





Guests






I think that introducing mass of cork DNA, even dead, was a mistake: wind will carry it everywhere, and everywhere we will find Earth DNA. I think that other material than cork should have been used.

But will this hamper us to find genuine Mars life? I think not. Because if life appeared on Mars, it is very unlikely that it used exactly the same recipe as on earth. It could be another chemical than DNA; it could be other chemicals than the four bases; it could be another set of amino acids and another correspondance from DNA bases to amino acids. It could be eventually something completelly different. So finding no DNA is not an evidence that there is no life on Mars; finding some is no more an evidence that there is some. So looking for DNA is simply irrelevant.

Matters get worse if we consider life exchange between Earth and Mars (and probably also ancient Venus). In this case, a DNA on Mars could be anything from genuine marsian life from cork DNA and even technician skin cells. in this case, this DNA should be brough back on Earth and analysed with the methods used to assess the evolution links between species, which will eventually lead to a double evolutionnary tree with some connections.
Go to the top of the page
 
+Quote Post
algorimancer
post Jul 26 2005, 02:43 PM
Post #45


Member
***

Group: Members
Posts: 587
Joined: 20-April 05
From: League City, Texas
Member No.: 285



Personally I think that the search for life is overblown as a justification for Mars exploration. At this point it's pretty clear that the only life we're likely to find will be microscopic, and probably related to microbes carried from Earth by meteorites. It's also likely to only exist deep underground, where modern contamination isn't likely to affect it. I'm inclined to stop worrying about contamination and just get on with exploring the geology.

Europa may be a different matter.
Go to the top of the page
 
+Quote Post

5 Pages V  < 1 2 3 4 5 >
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 30th July 2014 - 09:17 PM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is a project of the Planetary Society and is funded by donations from visitors and members. Help keep this forum up and running by contributing here.