Major Scientific Discovery on Extrasolar Planets

[mcbethcg]

I think it has been satisfactorily shown mathematically, that the bussard ramjet is a dead end, sadly.<br /><br />Magnetic scoop drag would overcome any likely thrust.

 

[priusguy]

<b>I think it has been satisfactorily shown mathematically, that the bussard ramjet is a dead end, sadly.<br /><br />Magnetic scoop drag would overcome any likely thrust. </b><br /><br />Unfortunately, yes.<br /><br />That is, if we are limited to D-D, D-T and D-He3 fusion. Which seems more than likely. Larry Niven's "Known Space" stories featured many Bussard ramjets, but they utilized H-H fusion. Which now seems impossible in anything smaller than a star. (Come to think of it, even at the temperatures and pressures of a Sun's core, H-H fusion has a pitiful efficiency. It will take the Sun <b>ten billion years</b> to burn through its supply!)

 

[yevaud]

Huh. Wasn't aware of that finding.<br /><br />I live and learn. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[priusguy]

Yes. The reason is that fusable materials -- deuterium and helium-3, -- comprise about 0.001% of interstellar gas. They would provide far too little energy to overcome resistance of remaining 99.999%.

 

[yevaud]

You know, I know that but never considered it. It seemed plausible that impacts per/second on the scoop would increase as velocity increased. Even the friction effects wrt to the interstellar medium were taken into account. Clearly a lot has changed in that arena since I last had an interest in it.<br /><br />As I said, I live and learn. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[toymaker]

So steve what would be your bet.

 

[toymaker]

A planet 5times the mass of the Earth. 20thousand light years away(!).It orbits about 2AU from the Star(If I heard correct) They used some kind of new microlensing.

 

[mikeemmert]

This just in.. It appears the new planet is 5.5 Earth masses and orbiting a red dwarf.<br /><br /><font color="yellow">This planet, dubbed OGLE-2005-BLG-390Lb, appears to orbit its star at a distance about 2.6 times greater than between the Sun and the Earth. But the red dwarf shines so weakly compared to the Sun that the planet's surface is thought to hover at about -220°C, as frigid as Neptune and Pluto."<font color="white"><br /><br />Well, there's the annoucement. I hope some other sources will come up. I guess New Scientist got the news out fastest.</font></font>

 

[toymaker]

Space.com has the story also now<br />http://space.com/scienceastronomy/060125_smallest_planet.html

 

[Philotas]

So instead of friggin hot; it`s friggin cold. But we won`t give up that easily.. <div class="Discussion_UserSignature"> </div>

 

[mlorrey]

I support Vogon. It all depends on how long you are willing to wait. One of Dysons Orion Project concepts involved an interstellar Orion ship that could achieve something like 2-4% of light speed. <br /><br />That is certainly sufficient to send missions to the Alpha Centauri system. Certainly not manned unless we are willing to scale Orion up to build a generation ship, since that is about a 105-240 year trip, with 60 year old fission technology. Fusion detonation design concepts could reach something like 5-8% of c, so that would take 53-84 years, so that would be possible with a manned mission, provided we send some young geniuses who are willing to fritter most of their lives away watching tv and screwing off, and willing to risk being passed by newer technology a few decades into the trip...<br /><br />If Heim Theory-derived technology becomes possible, of course, all bets are off, I'd be happy signing on as a ships cook for the land rush that would follow.

 

[mlorrey]

mcbethcg says:<br />"I think it has been satisfactorily shown mathematically, that the bussard ramjet is a dead end, sadly. "<br /><br />No, though that is the conclusion that people who do not read the literature tend to conclude from quick scans of reviews.<br /><br />Zubrin and another co-author of his examined a certain class of Bussard Ramjet concepts (not all of them), and made some assumptions about interstellar gasses which are now proven somewhat wrong. Based on their assumptions and the class of ramjet they chose to examine, they showed that that particular design could not work.<br /><br />This is a lesson for those who speedscan the scientific literature.<br />

 

[mikeemmert]

The main problem with Bussard ramjets is that hot stars and supernovae in the Hercules cluster have blown a great deal of the interstellar medium away from the Sun. (A star generates as much wind energy in it's presupernova phase as it does when it explodes). Bussard was going with the average density of the solar medium in the Milky Way, which was known at the time. <br /><br />For a while, they did not bother to do observations in the extreme ultraviolet. These are wavelengths shorter than 760 angstroms where hydrogen is ionized. The ionization absorbs the photon. However, somebody made an EUV observation concerning the solar system and discovered to his amazement that he could see white dwarves. Thus was born the Extreme Ultraviolet Explorer It did not see very many astronomical objects because it couldn't see past the bubble blown by the Hercules cluster.<br /><br />The low density of the local interstellar medium poses gigantic technological challenges to a Bussard ramjet.

 

[yurkin]

I think this new planet is actually not a bad candidate for life. The size means its probably very geologically active. So if its covered in ice then there must be underground reservoirs kept liquid by the volcanic heat.

 

[dragon04]

"Probably" very geologically active? Pretty bold assertion considering we have precious little data, <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[robnissen]

A long, long, long, long shot. But it might be worth a little bit of time on the Allen SETI telescope to point it at that star.

 

[bonzelite]

i largely agree with steve. i'm not euphoric or even remotely excited. <br /><br />and i find this part of the article typical of pop-sci cosmologists passing off rumor, hype, and theory as truth nearly right away:<br /><br /><font color="yellow">Because the newly discovered planet is only the third astronomers have detected using gravitational microlensing and already they have found a small, rocky body, the researchers believe there is a strong likelihood that rocky planets may be even more common than their gas-giant brethren. This prediction would agree with one of the models for solar system formation, core accretion, which suggests that small, rocky, "failed Jupiters" should be far more common than the massive gaseous planets.</font><br /><br />finding millions of rocky planets would not necessarily confirm or deny life or core accretion theory. if anything, it may deny core theory, if not already denied. many super jupiter gas giants orbit so close to the primary star that there is scarcely room for any other body within it's orbit. this violates the distribution by composition idea. <br /><br />i'd pass this whole story off as irrational exuberance. and a sort of "so what" factor. undoubtedly there are trillions of rocky planets, some with atmospheres, orbiting other suns. and who cares. this quest for another earth is a search for the holy grail. and if it is there, science will not know what it is really like unless a probe is sent. and that would be infeasible. <br /><br />this is martian canals and rivers and plants all over again. <br /><br />

 

[centsworth_II]

<i>"Probably" very geologically active? Pretty bold assertion considering we have precious little data</i><br /><br />Correct me if I'm wrong, but I'm under the impression that in any planet-sized chunk of generic rocky material radioactive heating is an unavoidable, physical fact. Given the mass of rock involved (five times that of Earth, minus the fraction due to water/ice) it may be more of a stretch to imagine how such a planet could <b>not</b> have a molten core. <div class="Discussion_UserSignature"> </div>

 

[centsworth_II]

<i>"the problem is that it can't be duplicated..." -- stevehw33</i> <br /><br />Even though it is a unique event, the observation is most definatly duplicated -- multiple times:<br /><font color="yellow">“The fact that they’ve got a whole bunch of folks using multiple telescopes all observing the same event and calibrating themselves self-consistently makes the data look very sound,” Boss said. “I think it’s a pretty solid detection.”</font>- from the space.com article<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[centsworth_II]

<font color="yellow"><i>"i'd pass this whole story off as irrational exuberance... and who cares. this quest for another earth is a search for the holy grail....this is martian canals and rivers and plants all over again." -- bonzelite</i></font><br /><br />Talk about hype!!! Where did you get all that??? <br /><br />I read an interesting article about a new way to search for extrasolar planets that may reveal a different population of planets than can be found by other methods. I read "most earthlike" (so far), not "earthlike". Sure, some wackos will read "earthlike" into the text, I didn't think you would be one of them.<br /><br />If you want to talk about a "holy grail" I suppose you could say the search for extraterrestrial intelligence would be it. And if we are looking for signs of life as we know it, it would make sense to look for it on planets similar to ours. So what's wrong with looking for them?<br /><br />But I don't think this new method of looking for extrasolar planets is all about looking for "another Earth". It's about identifying more extra solar planets. The longer the list of found planets gets, the more we learn about solar systems in general. What's wrong with that?<br /><br /> <br /> <div class="Discussion_UserSignature"> </div>

 

[centsworth_II]

<font color="yellow">"The Newscientist.com article about the microlensing method showed that it was one of a kind and the configuration quickly passed and was not repeatable"</font><br /><br />You must have inadvertently skipped over my post so I will repeat:<br /><br />Even though it is a unique event, the observation is most definatly duplicated -- multiple times: <br /><i>“The fact that they’ve got a whole bunch of folks using multiple telescopes all observing the same event and calibrating themselves self-consistently makes the data look very sound,” Boss said. “I think it’s a pretty solid detection.”</i>-- from the space.com article <div class="Discussion_UserSignature"> </div>

 

[toymaker]

"The Newscientist.com article about the microlensing method showed that it was one of a kind and the configuration quickly passed and was not repeatable"<br />The configuration was observable throughout the period of one month.

 

[centsworth_II]

<font color="yellow">"These events are very, very rare, so rare in fact, they cannot give necessary observations to any star, but a very tiny number of the literally hundreds of billions which need to be observed." -- stevehw33</font><br /><br />Rare, but apparently frequent enough to make the technique <b>more</b> productive than others according to at least one astronomer.<br /><br />Also from the space.com article:<br /><font color="yellow">"...thousands of star systems can be screened in a relatively short period of time compared to other techniques.</font><br />'You can’t learn a whole lot about the details of individual systems … but it’s a wonderful alternative for learning about what the mass distribution of extrasolar planets might be and the frequency at which they occur,' said David Latham, an astronomer at the Harvard-Smithsonian Center for Astrophysics who was not part of the study."<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[centsworth_II]

The time during which the planet could be detected is actually a few hours. Still plenty of time to get multiple observations from around the world. <br /><br />From the NewScientist article:<br /><i>"Light from the background star is gravitationally bent and magnified for a period of days to weeks during the event. But if the nearer star hosts a planet, the planet's gravity can give an added boost to the background star's light for a few hours."</i> <br /> <div class="Discussion_UserSignature"> </div>

 

[bonzelite]

cents, the whole planet finder telescope and all of this nonsense to find "another earth" is the hunt for the great white elephant. and this gravitational lensing thing is yet another stretch of this premise.<br /><br />gravitational lensing is over-hyped as well, given too much credit for proving anything. it may not even exist in some cases where cosmologists say it is effectively bending light and/or creating multiple images of distant objects. it's another thing that has a seed of truth and is grown into a giant bulls000 tree. the detection of this planet is no different. it may not even exist. <br /><br />very soon, the planet finder will locate perhaps thousands of planets. and that is all good. exploration is part of the human experience. but they're not finding earth again.