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Planets at near stars?

Posted by: JonHogan - Sat Nov 02, 2013 12:23 am
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Planets at near stars? 
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Post Re: Planets at near stars?   Posted on: Sat Dec 07, 2013 10:21 pm
SuperShuki, even though the prospect of competitive commercial aerospace companies bringing down the cost of space transportation is exciting, non-profit public projects such as astronomical observatories employing private contractors for their development and deployment must still navigate labyrinthine governmental rules and procedures for public funding and oversight.

Lourens, why do you think probably not in our lifetime? Money or hardware?


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Post Re: Planets at near stars?   Posted on: Sun Dec 08, 2013 1:51 am
USJay wrote:
SuperShuki, even though the prospect of competitive commercial aerospace companies bringing down the cost of space transportation is exciting, non-profit public projects such as astronomical observatories employing private contractors for their development and deployment must still navigate labyrinthine governmental rules and procedures for public funding and oversight.


Maybe. But I think that if there is a big enough business interest in getting things to space, things will change, even for non profit stuff. Remember, we are talking about potential huge increases in the amount of stuff that gets to space, if reusebility is perfected (and the way things are going, chances are it will be). That means the cost of getting stuff to space will drop radically, and that will open up whole new markets, which means lots more stuff going to space. And the pressure to deregulate then will be huge.

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Post Re: Planets at near stars?   Posted on: Sun Dec 08, 2013 9:27 pm
I think it won't happen in our lifetime because there's very little interest in such fundamental science in society. Granted, as we've got richer over the years, interest has increased, but it's still tiny.

Now, us getting richer has been driven by population growth (more people means more work can be done) and technological advances (the same number of people can do more work). Population growth is already stagnating in the developed world, and is forecast to come to a halt globally by about 2050, and I don't see this happening before then, which everyone being busy with shifting economical activity to Asia, getting Africa sorted out, energy transitions, and preventing ecological collapse so we can continue to feed ourselves.

Technological development is running into the issue of machines simply not being smart enough to take over more work from humans, and while I'm not ruling out improvements in AI, it does look like they will require a lot more processing power, which is starting to run into physical limits as well. Then there's the increasing oil prices, running out of various other natural resources, which we'll have to deal with by becoming more efficient in terms of recycling and energy consumtion.

In short, I think that the world as a whole (if maybe not the West) will still become a marginally better place to live in during the rest of my lifetime (currently scheduled to end in around 2060), but I doubt that we'd have the resources to spare to invest such an amount of money into fundamental science.

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Post Re: Planets at near stars?   Posted on: Sun Dec 08, 2013 10:25 pm
Lourens, first let me offer my sincere condolences on the occasion of your “deadline” circa 2060. There’s plenty of living to be had in forty-seven more years though! As for the “decline and fall of western civilization” argument, that sounds suspiciously like a variation of the “present fiscal and political environment” argument which has been used to oppose virtually every large-scale governmental technological/scientific project since at least Project Apollo. These things keep getting built anyway and there is every reason to believe that will continue to be true.

Does this mean you see the obstacles as principally financial rather than technical?


Last edited by USJay on Sun Dec 08, 2013 10:40 pm, edited 1 time in total.



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Post Re: Planets at near stars?   Posted on: Sun Dec 08, 2013 10:35 pm
SuperShuki, “He who pays the piper calls the tune.” If the public is paying, then taxpayers will always reserve the right to “call the tune.” There will certainly be ever increasing opportunities for private enterprise in space wherever a sufficient return on investment can be realized, but public works will remain answerable to public oversight. That will not change. Deregulation applies to commercial activity, not public works. Owning a private astronomical observatory would never be likely to prove financially rewarding, but being the private contractor hired by the public to build or deploy one certainly can be.

Most of the private commercial space activity we are likely to see in the near term will involve either the placement of commercial satellites in orbit or transportation services for governmental (public) programs such as deliveries to the International Space Station and deployment of scientific instruments such as an astronomical observatory on the moon, to name a perfectly random example! Businesses always “follow the money” if they want to stay in business. For the foreseeable future, speculative exploration beyond Earth orbit to mine an asteroid or comet, for instance, is unlikely to yield a profitable return on the enormous investment required.

An array of mirrors on the far side of the moon, on the other hand, is exactly the sort of “huge...amount of stuff” a new and hungry commercial aerospace corporation would be eager to deliver on behalf of the government, thereby guaranteeing a reliable income over many years. The elements of the array would be identical, so the dozens of launches carrying “pallets” of mirrors would be essentially identical as well. Repetition is good for business. Streamlined routine operations mean fewer expensive surprises. Unfortunately at present, even though the technology currently exists to deliver the goods, the “shipping” cost is still too high. With increasing commercialization of space transportation, those costs should continue to trend downward until a lunar astronomical observatory is as workable financially as it already is technically.

The ultimate reduction in transportation cost is likely to result from the marriage of nuclear power and electromagnetic thrusters. Both nuclear technology and electromagnetic propulsion have undergone rapid advances recently which could revolutionize space transportation. A routinely reusable crewless nuclear-powered cargo “shuttle” traveling back and forth between Earth orbit and lunar orbit would reduce transportation costs to only a small fraction of present requirements. At some point taxpayers are likely to find the price to be low enough to allow public funds to be dedicated to the establishment of an optical observatory on the far side of the moon. Then we could finally get that “nice photo” of an extrasolar planet Jon Hogan is hoping to see in his lifetime.


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Post Re: Planets at near stars?   Posted on: Mon Dec 09, 2013 2:59 am
Finally, there's a need for a lunar colony. Why ship hundreds of mirrors from Earth to the moon when we could just build them there? :)


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Post Re: Planets at near stars?   Posted on: Mon Dec 09, 2013 4:29 am
Are you saying that the costs are . . . astronomical?
:mrgreen:

Elon Musk wants to go to Mars in his lifetime, and I don't see how that has a business interest. And yet, he believes he can afford to do it. So if someone rich decides to do it, why not?

Lourens: At the turn of the 20th century, it seemed that technology had reached its peak. But that turned out not to be the case. Why should it be different at the turn of the 21st?

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Post Re: Planets at near stars?   Posted on: Mon Dec 09, 2013 5:04 am
Dave, sending an astronaut into space costs about a thousand times what it costs to send an inanimate payload of equal mass because the payload doesn’t require multi-redundant life-support systems providing fresh oxygen, carbon dioxide absorption, heating and cooling, water, food, a toilet, sleeping accommodations, exercise equipment, “elbow room” and on and on. So sending just one 200-pound astronaut would cost about as much as sending a thousand 200-pound mirrors.

SuperShuki, if a billionaire wants to spend his money that way without being motivated by profit, great! Maybe you can persuade him to build the Elon Musk Lunar Observatory instead. Musk does not appear to be motivated by egotism though. I believe he actually wants to establish a “backup” population of the human race on a second planet to reduce the risk of extermination by global catastrophe, although living on Mars would probably only be slightly less difficult than living on the moon.


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Post Re: Planets at near stars?   Posted on: Mon Dec 09, 2013 10:01 am
I'd rather Musk sends people to Mars.

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Post Re: Planets at near stars?   Posted on: Mon Dec 09, 2013 1:22 pm
USJay wrote:
then taxpayers will always reserve the right to “call the tune.”


Unfortunately the taxpayer usually chooses tunes that are in their short-term self interest. Transfer payments (welfare) and public goods that they don't directly or immediately pay for. When long term or indirect benefit activities such as space exploration is funded it is done because a leader has had a "good idea", or is done by political machination (paying off industrial contributors and "jobs") disconnected from the direct will (and interests) of the bill-paying populace. Such is the double edged nature of representative democracy.

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An array of mirrors on the far side of the moon, on the other hand, is exactly the sort of “huge...amount of stuff” a new and hungry commercial aerospace corporation would be eager to deliver on behalf of the government...


Except that is a well that has run dry. There simply isn't the money to fund such a huge science project. Not even the Chinese could afford it.
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With increasing commercialization of space transportation, those costs should continue to trend downward until a lunar astronomical observatory is as workable financially as it already is technically.


This really is your pet obsession isn't it?



SuperShuki wrote:
Elon Musk wants to go to Mars in his lifetime, and I don't see how that has a business interest. And yet, he believes he can afford to do it. So if someone rich decides to do it, why not?


A socialist would have a handy answer for you.

Quote:
Lourens: At the turn of the 20th century, it seemed that technology had reached its peak. But that turned out not to be the case. Why should it be different at the turn of the 21st?


Technological advance depends on a healthy (but not necessarily wealthy or peak) society.


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Post Re: Planets at near stars?   Posted on: Mon Dec 09, 2013 2:54 pm
USJay wrote:
Dave, sending an astronaut into space costs about a thousand times what it costs to send an inanimate payload of equal mass because the payload doesn’t require multi-redundant life-support systems providing fresh oxygen, carbon dioxide absorption, heating and cooling, water, food, a toilet, sleeping accommodations, exercise equipment, “elbow room” and on and on. So sending just one 200-pound astronaut would cost about as much as sending a thousand 200-pound mirrors.

Who or what is going to set up the mirrors? I suppose we could use a robotic vehicle to set them up. However, I see a lunar colony as the first step toward going to Mars and beyond. So at some point we're going to need to establish a lunar colony. Once we do that we might as well give them something to do. Setting up mirrors can be one of their many tasks.


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Post Re: Planets at near stars?   Posted on: Mon Dec 09, 2013 6:34 pm
There basically aren't any Nearby stars on our scale. The closest one we know of is decades out at the speeds we could achieve without Relativistic effects robbing efficiency, (About .5c) and we can't reach those velocities with the technology we have the tools to create. (We barely got up to escape velocity from the Sun, with gravity whips off of the Gas Giants, which is 0.0006/c)

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Post Re: Planets at near stars?   Posted on: Mon Dec 09, 2013 8:21 pm
USJay wrote:
All in all, every aspect of the system, including deployment, is well within proven practical technical experience.

Now, about the money...

Perhaps these types of programs need to be sold on merits other than just the great pictures and scientific values. My family grew up on Aerospace/Defense, call it a publics work program if you will, but tens of thousands were directly employed as a result. Sure it was boom or bust between projects and contracts but it supported millions of families. Currently they are again discussing extending 'unemployment benefits' for another year...at what cost? State and federal government paid out $94 billion dollars for it last year. This translates into deeper cost/debt with little to show for it; even many negative sides effects...low self esteem, loss of current skills, drug abuse, etc. Providing jobs in grand long term projects such as this employ people, create and support businesses and lead to new innovation furthering growth in other sectors. All of these find favor in the two political factions controling government funding. The money is there, it takes education to show people the need for a different way of using it.
USJay wrote:
In terms of cost effectiveness, a lunar observatory would be useful for much more than just imaging planets around other stars. Objects in our own neighborhood could also be examined with unprecedented clarity. Thousands of asteroids, comets, Kuiper Belt Objects and more could be as sharply photographed as our own moon. A single enormous telescope could gather as much data as thousands of fly-by space probes at a fraction of the price.

How true; recently there is a lot of interest, ideas, talk, etc about preventing the earth from getting a hit by comets and such. Having such a lunar telescope, especially when it grows to a large size, could be used to help not only detect but but maybe even deflect such an incoming object (boil off volatiles and emission of thermal photons) when it was still millions of miles distant from the earth.
davehein wrote:
Finally, there's a need for a lunar colony. Why ship hundreds of mirrors from Earth to the moon when we could just build them there?

Having grown up with Apollo, I would really love to see us place a permanent station on the lunar surface but that is past my lifetime but not for the students I mentor. Sure, the costs would be high but could come down to preserving human life if a catastrophe was to hit the earth. The Amundsen-Scott South Pole Station is about as remote a place that humans can have on earth yet is utilized more every year in spite of its cost. Though set up for the IGY, it has been continuously occupied and enlarged since and has now seen uses over and above its original design. The ISS has a limited life before it will be deorbited like the Salyuts, Skylab, Mir and Tiangong to be replaced with yet another temporary structure...let's go permanent.

The mirrors could be initially placed autonomously but what if a large impact occurred depositing enough 'dust' to render them useless? People there could be pressed into use as maintenance people for cleaning them off...there will always be a need for maintenance people, think Hubble (jobs for everyone).


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Post Re: Planets at near stars?   Posted on: Wed Dec 11, 2013 4:00 am
Wow! Lots of great thoughts.

SuperShuki, it looks like you are about to start a new thread contemplating the colonization of Mars.

Dave, the mirrors as imagined would be small enough not to require any set up. Mass-produced mirrors on mass-produced miniature landers resembling Apollo landers or Mars landers would autonomously touch down far and wide, run a few diagnostics and then open for business. Cooperative software would allow the mirrors to communicate with each other through the relay at the Earth-Luna L2 point and organize themselves for whatever the next observation requires.

The premise of what has become this greatly extended conjecture is that acquiring Jon Hogan’s “nice photo” of an extrasolar planet could be accomplished using existing established technology. A lunar colony is the hope of very many people who believe humanity must become a multi-planet species and there is little doubt that goal can eventually be achieved, but not with present technical capabilities. Too much would need to be invented first. On the other hand, a lunar optical telescope could probably be built “today” but for the lack of money. We already know how to make all the parts, how to deploy them and how to get them to work together.

Money. Rick, you are absolutely right. Great pictures and abstract science are not enough to sway public opinion, but job creation always wins votes. Projects like this always create jobs requiring skills that are readily transferable when construction is complete and drive industry with new products and new processes. Saving money by taking the place of much more expensive forms of space exploration is also a selling point appealing to taxpayers.

Additionally, the concept is also financially appealing is because the array is modular instead of all or nothing like the James Webb Space Telescope. A modular design on this scale has never been used for a space-based observatory. The first cluster of mirrors would immediately be able to provide better images than any previous observatory could. As more mirrors were added imaging capability would continually improve until truly breathtaking portraits of extrasolar planets would become possible. A modular design allows a pay-as-you-go budget, which taxpayers might find easier to support. The public would be able to decide when enough is enough. If the “customers” paying for the equipment like what they see they are more likely to approve continuing comparatively low-cost enhancements.

“Disasteroids.” Focusing the array with precision on a point at L2 “only” 36,000 miles above would be just within the realm of technical feasibility, but focusing sunlight on a planet-killer comet or asteroid millions of miles away “to save Earth from certain destruction!” sounds like much more fun! I doubt it could be done, but that doesn’t mean we should deny ourselves the adventure. Just be sure to work the Space Fellowship into the screenplay.

Hollywood aside, objects with very high apparent magnitude (very low brightness) which might truly threaten our safety are notoriously difficult to spot and track. The immense light-gathering capacity of a very large lunar optical array would allow detailed study of all “Earth-crossing” objects, of any apparent magnitude, which might require surgically accurate “persuasion” to pass us by, an other point that might impress voters. Sounds like yet an other thread too.

Maintenance. What meaningful maintenance astronauts might be able perform on the lunar surface is difficult to imagine. There would really be nothing for them to do. The reflecting surfaces would be slowly and irreparably degraded by micrometeorite impacts and microscopic scoring from the repeated removal of dust. Replacement of components such as batteries or electronic modules for so many units spread over such a wide and treacherous area seems impractical. Simply soft-landing upgraded autonomous replacement mirrors as older worn-out units are decommissioned would actually cost much less. I understand the desire to use an installation such as this as an impetus to establish a permanent presence on the moon, but routine human maintenance for this particular concept would be just too dangerous, too expensive and too slow. There are other proposals for lunar installations where the human touch would be much more meaningful.

A long-standing concept for an observatory on the moon capable of resolving extrasolar planets is an optical interferometer comprising a precise array of full-function telescopes. These would occupy far fewer sites on the surface, making maintenance by astronauts more feasible, but each telescope would be roughly similar to the Hubble in terms of size and sophistication. Manufacturing and emplacing an array of telescopes for a lunar interferometer would be far more difficult and expensive than mass-delivering a swarm of small, mass-produced comparatively simple primary reflectors to the surface and keeping the one Hubble-like component “floating” safely at L2.

Among many other things, the Hubble Space Telescope has taught us how long a space-based observatory can remain operational with regular maintenance. Now, anything less must be recognized as substandard and unacceptable. Unfortunately, the Hubble has had to be maintained and repaired by hand by a total of sixteen very brave people in stiff clumsy space suits performing delicate and tedious operations hour after hour in the most lethally unforgiving working environment we have ever encountered because the world’s most famous astronomical observatory was never intended to be serviced at all. The “unfortunate incident” with Hubble’s optics forced us to figure out how to correct the mistake. Only then did we discover hands-on routine maintenance of the telescope might be possible. There have now been five service and repair missions. Had the Hubble been designed from the beginning to be serviced by remote operation, none of those lives would need to have been put at risk.

Servicing an observatory stationed at L2 by spacewalking astronauts is not likely ever to be practical, so less expensive and less dangerous autonomous robotic maintenance and repair would need to be incorporated with the plans from the beginning. The robotic work would have to be at least partially autonomous because entirely “telenautic” (Earth-based remotely piloted) operations would not be practical either, considering the time-lag for communication over such great distances. The L2 “receiver” would require refueling for its station-keeping reaction control system, replacement of gyroscopes or reaction wheels, upgrades to electronic components and so on. All such operations can be designed to be performed robotically.

Dust. I’ve thought a lot about the “dust” problem, which would be a serious concern for any optical telescope on the moon. Even a fairly common meteorite impact (think golf ball) could raise enough dust to significantly degrade a nearby mirror’s optical performance. Astronaut maintenance crews, however, are not the answer. Even with thousands of mirrors in the array, the individual mirrors would still be miles away from each other spread out over hundreds of miles. The only way astronauts could travel those distances over very rough terrain fast enough to be useful would be by rocket propulsion. The cartoon image of a crew of astronaut janitors meticulously cleaning a lone mirror and then blasting off with their jetpacks in a cloud of dust unavoidably comes to mind!

One of the reasons I favor simple open mirrors on the surface rather than fully functional telescopes (as with an interferometric array) is specifically because the mirrors could more readily clean themselves. In the airlessness and low gravity of the moon, all of the larger particles and most of the finer dust that might fall onto a reflecting surface could be removed simply by tilting the mirror as far as the mechanism allows, perhaps with a little vibration as well. Dust which clings electrostatically could also be removed electrostatically. Positively and negatively charged elements on the structure could work together to repel the remaining ultrafine particles. An other somewhat more radical way to remove the finest particles would be to spin the mirror, but this would be mechanically much more difficult and also seems more likely to cause scoring on the highly polished aluminum.

Large meteorite strikes are exceedingly rare. Any strike large enough to affect a significant fraction of the array is likely to destroy the mirrors with larger pieces of ejecta rather than just cover them with dust. This kind of disaster could happen to any lunar project. No amount of maintenance would make a difference then, but the great separation between neighboring mirrors which works against the feasibility of maintenance by astronauts does have an advantage. The most common meteorite strikes involve tiny impactors which could only ever affect one mirror at a time. Even then, the odds are against a strike large enough and near enough to any one mirror to cause serious problems. The “array” would be mostly wide open nothingness as far as the eye can see.


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Post Re: Planets at near stars?   Posted on: Wed Dec 11, 2013 4:18 am
Why need a rocket?

Look at hydrogen gas guns,

you could "shoot the moon"

Repeatably with your reflectors,

since there are no people,

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