Jackpot: astronomers tag Goldilocks planet While the Kepler mission turns up its ever-growing crop of exoplanets, a group of astronomers has announced an exciting find closer to home: looking towards Scorpius, there’s a super-Earth-sized planet just 22 light-years distant, with a habitable-zone orbit. Planets with the right orbit offer the best chance of harbouring …
I suggest that if it were important, it would not be too hard to develop a vehicle that could deliver a small probe to a planet 22 light years away in less that 100 years. It wouldn't take very long under a level of continuous acceleration currently achievable to reach 0.25c or faster.
The first hard part would be getting that much fuel into Earth orbit, but maybe a nuclear heater and a big block of something like CO2 or ice could be made to work.
The second hard part would be steering the probe when it got there - I guess it would have to be autonomous enough to find the planet and land (crash gently).
At least the 'Got Here' message would only take 22 years to get to us...
Surely it could only accelerate continuously for the first half of the trip, and then it would need to decelerate continuously for the other half. Otherwise it would arrive in the target system at 0.25c and fly straight through it in a matter of (hours/days/weeks?), not giving it much chance to do much discovering of stuff...
Also, what if it meets something on the way, going at 0.25c? Even the smallest bit of interstellar dust or ice is not going to leave much spacecraft left.
...so speeding up and slowing down are both accelerations in the language of physics.
As far as collisions, yes, dust particles hitting the leading edge at relativistic speeds would emit X rays or gamma rays, and a good sized rock would make a big explosion. You would need a really serious shield.
Why not use your fuel? If you have a fusion motor, your fuel could be a huge ball of ice. If you basically have a cue-ball of ice for fuel with a fusion ion drive attached to it, you can use the fuel as a debris shield without worries about explosions being catastrophic events.
Plus, you can get lots and lots of water ice already in orbit; capture a cometary nucleus in the outer solar system and Bob's your uncle.
Indeed so, and so any design for getting up into the tenths lightspeed regime must cope with carrying enough fuel to <i>decelerate</i> at journey's-end (unless you just want to send home a few blue-shifted pics as you hurtle past). If you travel halfway with your fuel in front as a shield, you can't just do a quick one-eighty and decelerate for the other half.
Why do I have a vision of a future astronomer hunting for software that can decode a raw CCD image file transmitted from a device that hasn't been manufactured for a hundred and fifty years?
... but you could shut off the engine halfway[1] and then disconnect the engine and reattach it at the front. You could also, in the early stages of the flight, excavate fuel from the cometary nucleus such that the instrument package is buried deep inside; and the fuel would be removed from the aft end to maintain as much shielding as is feasible for the high-speed part of the journey. The goal would be, upon arrival, to have a slender chunk of fuel left over (reinforced by fuel delivery tubes), with the engine at the fore end and the now-uncovered instruments aft. There is really nothing that could be done to absolutely protect the engines in the deceleration phase of flight; there would have to be enough small-ish engines that redundancy could handle the loss of a few from collisions whose damage can't be repaired.
[1] You would actually continue positive acceleration past the exact midway point, since the decreasing fuel mass would result in much greater acceleration magnitude at the end of the flight.
"It wouldn't take very long under a level of continuous acceleration currently achievable to reach 0.25c or faster."
No, but it would take a lot of kinetic energy; 0.25c, even with simplified Newtonian calculations, is 2.8 x 10 ^ 15 Joules per kilogram of mass. This is about the same energy as moving an aircraft carrier (100,000 tonnes) at 7,500 m/s. So each kg of vehicle moving at 0.25c is roughly the same as putting the USS Nimitz into Low Earth Orbit.
And this is just the basic energy of the result; factor into this the actual fuel load required to achieve this speed and that you need to accelerate the fuel with the vehicle, with the total mass reducing as the reaction mass is ejected and you actually need a lot more energy. A Saturn 5 burns about 2,000 tonnes of fuel to put a 100 tonne payload into LEO.
Even with VASIMIR at 1,400 MJ per kg of fuel you need 2,000 tonnes of propellant to get enough kinetic energy into 1kg of vehicle; but this doesn't take into account the mass of the propellant, which is also being accelerated along with the vehicle until the point that it is used, so you need to integrate the combined propellant mass/speed to get the full result (I'm supposed to be working so I haven't done this yet). The result will be FUCKING HUGE!!!
I'm afraid basic physics shows that an interstellar probe is really a long way off; the scale of the Universe is just too big for most humans to even conceive, let alone engineer for. (but I'd be happy to see future generations of physicists and engineers try to meet the challenge)
Yeah, we'd all like to see future generations of anybody doing anything at all (almost), but luckily for the future generations, it ain't going to happen.
It will be a problem to sell the idea of a multi-century exploration mission to your Parliament | Senate | Duma | Revolutionary Council [delete as appropriate] because none of us alive and tax-paying now will ever see a whisper of a result. Even more so when one of the great space-exploring nations inexplicably drops an intra-system exploratory vehicle into the Pacific Ocean.
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"Red dwarfs? That's the shitty part of the local neighbourhood.Your probes are likely to be jacked and stripped for parts by local alien minorities."
And that is what mankind will take to the stars. Prejudice. Racism. Hatred. And wait till a local earth boy falls in love with an alien chick and starts banging her... KKK? Evangelical Christians? Fundamentalists? Taliban?
You ain't seen nothing of how truly fucked up mankind is...
Here's hoping that your species never set foot outside your solar system.
Actually, there's very little reason that a biological system couldn't exist on, say, liquid arsenic just as well as water. It would take very little change to DNA for a species to be able to breath Sulpher Dioxide and drink Arsenic.
We look for water primarily because we have proof of water-requiring life-forms, but we should also recognise that we take this proof from a sample of only one. Us.
Indeed. From a historical perspective the ones that aren't poisoned by, nay thrive on dissolved or atmospheric oxygen are a recent innovation. Oxygen molecules floating about the place in reasonable concentration to be reliable didn't really happen until most of the metallic elements in the crust had been oxidised first. Which took quite a long period of biological activity to happen.
@Originone, the Earth may be unusually dense.
As Dani says, a system poor in heavier elements might have lower density planets anyway.
However, since rocky planets at about our orbit will have a very low % of hydrogen and virtually no helium I'm not sure it matters what their ratio is.
As I recall pretty much all the helium on Earth isn't from its formation, but from radioactive decay that happened to occur in places where it could be trapped, thus helium although it's the second most common element in the universe is actually probably rarer than gold on the Earth.
The current consensus is that the Moon was formed by a roughly Mars sized object hitting the Earth and splatting off a good chunk of the outer, lighter layers, leaving the Moon as a relatively less dense object and the Earth denser.
The material didn't come off in a blob. The proto-Earth and the impactor were both substantially vaporized by the energy of the collision which caused a cloud of matter to get flung up into the sky. Over time the stuff that had enough energy to stay up coalesced into a sphere, but it's on a near circular orbit now because that's the average trajectory of the particles it was composed of.
wtf is the point. really. it's a dirt ball. it's too far away to investigate in any viable way, barring a discovery on the unobtainium type, say, a gate that you can steer remotely to within a useable distance.. we're stuck here and all this escapism is an expense we really should divert elsewhere. i can't think of a practical use for this knowledge. Park the program for fifty years and use the cash to sort out something a little closer to home.
I'm all for research spending etc.., just into things that might make this kind of thing viable when it's more of an option. we've a few things to sort out on our own planet first.
Seriously Jelliphiish, no offence but you're an idiot. We, by our very nature, can't help but explore and look around the next corner, over the next horizon. It's part of what makes us human. Pure exploration isn't supposed to lead to any practical use but inevitably it does. This "discovery" adds fuel to the postulation that we are NOT alone in the universe and that we are NOT so damn special. We need an answer to that. We need to know if we're some random 1 a googleplex chance or if there are neighbours out there. It also increases our speculation about the ways planets and systems form and challenges previously held beliefs - god I love science (see what I did there? :) )
Oh, and on the water front (so to speak) any molecular biologists out there that can correct me or in some way fill in the blanks but as far as I remember one of the reasons we say that water is required for life is that as well as the very detailed and excellent explanation of Ken Hagan above; water has certain properties that cause the protein chains to loop round as they are attracted and repelled by the water molecules which enables amieno acids to form and hence DNA. No water, no DNA, no life as we know it. - I could be wrong. It's rare, but it happens.
The good news is that they'll have been watching our TV for the last 40-50 years.
Currently such delights as Bergerac and the Crystal Maze will be hitting their screens, as well as, conincidentally, Red Dwarf. Lucky them.
Presumably they've not been sending us their telly? How selfish! I reckon they could do a good line in "Dark Humour".
all they'll see is 3 different signals (or is there another one for B&W).
they can translate that into whichever frequencies they want.
We'll do the same, It'll be interesting how many different signals they'll send - will they be like dogs and see with fewer receptors? Or squid with far, far more?
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