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Two Telescopes Linked To Find Planets
glinden writes: "Two telescopes at the Kech Observatory have been optically linked to form the Keck Interferometer. The resolving power of this combined telescope will apparently be sufficient to see earth-sized planets around nearby stars." quoll contributes a link to NASA's own version of the story, too.
COAST has five in it's array. It's first images were made in 1995.
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Moderator's essentials
Sounds easy? Think again!
1.chemical propellents - 10^137kg
2.fission - 10^17kg
3.fusion (inc orion craft) 10^11kg
4.ion/antimatter rocket 10^5kg
First of all, as you point out, a solar sail and a stationary laser would work quite well for sending probes out to other stars (though slowing down at the end would be quite a trick).
Secondly, I question some of these numbers. They're looking at only one range of the problem space - setting a time, and deriving a fuel/cargo ratio from there. The problem with doing this is that the fuel/cargo ratio will start to blow up once the amount of fuel becomes greater than your amount of cargo (it starts taking exponentially more fuel to reach a higher speed, because you're mostly hauling fuel).
A better question is, "given a certain fuel/mass ratio and a certain delta-V, how long would it take to reach Alpha Centauri?". My answers are as follows:
[Velocities and travel times are for a flyby; use half the velocity and double the time if you want to stop at the destination.]
Most of the energy of a matter/antimatter annihilation comes out in the photons (even if you're doing a proton/antiproton annihilation, the mesons get only a small fraction of the energy). Assume a 10% efficient conversion of mass to useful thrust, and thust/energy efficiency of a photon drive (horrible - 1/C N/J).
This could be built as a big block of lead/concrete/rock with the ship and fuel tanks on one side, and antimatter explosions happening just over the other side.
Velocity at 50% fuel: 0.05 C (100 years)
Velocity at 10% fuel: 0.01 C (500 years)
This assumes 1% conversion of mass to kinetic energy within the plasma (still inefficient at this energy density, but much better than photon drive efficiency).
Building a drive like this would be very difficult. You'd have to use one of the fusion reactions that doesn't produce gamma rays or neutrons, you'd need a great magnetic bottle, and you'd have to have your exhaust leave the rocket before it could radiate its heat as light. Good luck.
Velocity at 50% fuel: 0.07 C (70 years)
Velocity at 10% fuel: 0.014 C (350 years)
This assumes 0.3% conversion of mass to useful energy, and photon drive efficiency.
This could be built as a big block of lead/concrete/rock with the ship and fuel tanks on one side, and fusion bombs being set off in space on the other side (counting on the plasma radiating most of its energy as light before dispersing).
Velocity at 50% fuel: 0.15% C (3,300 years)
Velocity at 10% fuel: 0.03% C (16,700 years)
As with Good Fusion, but with 0.03% mass to useful energy conversion. Ship design is similar to Good Fusion.
Velocity at 50% fuel: 0.015% C (33,000 years)
Velocity at 10% fuel: 0.003% C (167,000 years)
This assumes 15 MJ of exhaust kinetic energy per kg of fuel. This is attainable with a good chemical rocket.
Velocity at 50% fuel: 0.0009% C (550,000 years)
A really good antimatter drive could bring humans to the next star within their lifetimes, if it was mostly fuel. An excellent fusion ship could do it within a few generations, though fusion ships would more likely take centuries (even if mostly fuel).
But the next leap forward is going to be European... ESO (European Southern Observatory) are constructing two identical telescopes in Chile and Hawaii (project Gemini.) How's that for a long baseline? ;p
And for bluesky "gee whizz" quotient, check out the Overwhelmingly Large Telescope (OWL)...
I've seen a chart somewhere (can't find a link - anyone?) charting aperture (light collecting capacity) of telescopes since Galileo. The Keck and other 10m class telescopes have moved the curve from a nice straight line to an exponetial curve - and that's not allowing for vastly increased computer power, active optics, and out-of-visible band stuff. Truly this is a fantastic time to be interested in astronomy, even (especially?) as an amateur. For a couple of thousand dollars you can do stuff in your yard that was the province of professionals only a few decades ago.
--
If the good lord had meant me to live in Los Angeles
Does this remind anyone else of SMP? :)
IANAPA (I am not a professional astronomer)
No, this instrument will not see Earth sized extrasolar planets. Read the article.
This has been thought of before, and not even this past century, but only recently (past 20 years) has the tech been there to actually DO this. The optics and the placement of them, esp in the delay line, has to be quite precise. We're dealing with fractions of wavelengths here.
Basically it works like this: You have two telescopes, and the two light beams are brought together accurately so that they create interference fringes (hence the name interferometer). The interference fringes tell you about the light at a specific spot in the sky, in a very narrow angle (well, a REALLY REALLY narrow angle). From this, maps can be made of spots on very active stars, etc. (None of this is seen directly). Effectively, what you get is the same resolution of a theoretical mirror that's the same diameter of your baseline. You just don't get the light grabbing ablity of that theoretical mirror.
Dim light is the bane of interferometry. In an ideal world with ideal funding, interferometers would be nuked in favor of full sized optics kilometers across, but who's going to foot the bill?
The longer the baseline, the narrower the angle you can see, hence more resolution. Keck is a good start, but the baseline is way too narrow for what people are speculating on this weblog. Maybe someday when someone finds the funding, we'll have a space based interferometer with big mirrors and a few thousand klicks in between for a baseline.
What next? Are they going to add a blue filter on one and a red filter on the other???
hmm... for fun I enjoy launching DDoS attacks against 127.87.42.5
The resolving power of this combined telescope will apparently be sufficient to see earth-sized planets
Whereas the article says:
The Keck Interferometer will be able to detect planets farther from their parent stars, helping to pave the way for future interferometers in space that will look for Earth-like planets, NASA said
To find Earths (at least directly) you have to go to space Don't expect this for another 10 years or so.
Space exploration has, to some extent, died off. We spend a lot of time heaving new shiny things into orbit, but we don't seriously talk about new colonies or settling other planets.
I wonder, if this telescope spotted an earth-sized planet, suitable for life, with an earth-like atmosphere, would space research undergo a rennisance? Would the idea that "we can go there!", with a very specific there in mind, a there you could point at in the heavens, somehow inspire the human race?
Maybe the state's highest function is to grind out insoluble problems. (Zelazny, Hall of Mirrors)
No, the goal of future pie-in-the-sky NASA missions like the TPF (Terrestrial Planet Finder) is to directly image other planets by nulling the light from the star. This is not the indirect wobble detection that Marcy and Butler are doing so successfully on the ground now: rather, you image the planet, maybe as a dot, get a spectrum, and - holy smoke - there's free oxygen in the spectrum!! Life! Little green men! More funding! :)
The Keck interferometer, OTOH - it's not going to resolve small earth-like planets. But its a step in the right direction, and should resolve brown-dwarf companions and maybe giant planets too...
(Yes, IAAAstronomer)
"I will take the Ring," he said, "though I do not know the way."