"One of the main uses of the James Webb Space Telescope will be to study the atmospheres of exoplanets, to search for the building blocks of life elsewhere in the universe"
Fascinating - the first exoplanet was discovered in 1988, and now there are more than 2.000 known ones [1]. Plus, for all we know, there may be billions more to discover [2]. Even though we're never going to reach one in our lifetimes, these are still interesting times to live in...
I don't think there is any doubt whatsoever there are billions more to discover, in this galaxy alone. And then of course there are billions of galaxies.
If they are able to properly orient the spacecraft using solar pressure alone, couldn't this approach be purposely engineered for discharging momentum from reaction wheels in other craft, instead of expending propellant?
Is there any reasoning why the distribution of planet sizes aren't following a bell curve or similar pattern? Maybe due to what materials the planets are composed of puts them into separated size categories?
The main reason Kepler can only see specific kinds of planets is that you need to see three transits before you confirm it, and that the further out a planet is from it's star, the less likely it is that it will ever transit.
These two combine to make planets closer to the sun much more likely to be seen. If there was another Sol in a perfect place and at perfect alignment and Kepler had been looking straight at it, by now we would have detected Mercury, Earth, Venus and Mars but nothing else.
The graph isn't uniformly distributed by radius, for one thing, as it has 0.5R-3.1 Re divided into four different bars, with 3.1-22 Re divided into the other four, so it wouldn't look like a bell curve even if they were normally distributed as it's designed to highlight planet sizes that are closer to earth sized.
Also, as someone mentioned, Kepler is only likely to find planets fairly close to their star. And if you have several large planets that are close to their star, they are more likely to interact and be knocked out into a higher orbit until only one is left to dominate the orbits close in. Smaller planets are less likely to disturb the orbits of their neighbors which means a system is more likely to have several smaller planets closer into the star, which again, makes them more likely to be detected by Kepler.
As with the sibling post, I'd also wonder if it's because of the failures that Kepler has had. Right now it can only point at a really small part of the sky and it's possible that that star forming region just happened to form mostly smaller planets.
Horrible armchair speculation: the graph ALMOST looks like there's two bell curves summed together. a larger planet forming one and a smaller planet forming one, might indicate that there's some threshold for making larger planets that has to be crossed first.
This would be very interesting to analyze. Any way to get some data about all these planets in the same place? planet Mass, planet orbit radius, star category, etc?
so are there any em spikes coincident with the transit of each planet? I mean if there was a civilization broadcasting into space with analog, we might hear them. And since they are using radio, we can be pretty sure they would be technologically inferior to us and unlikely to come over and eat us if we said hello.
It's so expensive in energy to do this that it's unlikely.
Even the moon, if it was made of gold bars stacked at the ready to be picked up and brought back to Earth, it wouldn't be worth it.
Even if you had technology to transport a significant force across the span of light years, why endanger that with the risk of resistance? Just go to one of the billions of habitable planets that don't have complex, radio transmitting intelligences on it.
Why would there be a spike with the transit of the planet? You still have line of sight to the planet before and after. What should be detectable is a drop in EM when the star is in front of the planet, but good luck discerning it from the noise of the star.
Kind of unrelated, but Ultra Wideband [0] is a way to communicate with quick electromagnetic pulses over big parts of the EM spectrum, which is indistinguishable from noise [1]. We could just be the only beings stupid/unlucky enough to make all our radio communication so obvious.
Let's see. Using current tech to get to our closest neighbour, Alpha Centauri, if you leave this afternoon, you should be arriving sometime in the year 102,016.
How about we skip this dream, along with world peace, and make baby steps, like everybody using their indicators while driving?
AC is only 4.5 years away. If we really wanted to go there we could most definitely build something that can travel at 0.5c and get there at, say, 6 to 7 years. It's not hard to keep accelerating and decelerating for 1m/s for 15 years with current tech.
> It's not hard to keep accelerating and decelerating for 1m/s for 15 years with current tech.
Just to put some numbers to this, I went to my go-to quick reference for these types of problems is the Usenet Physics FAQ article on the equations for relativistic rockets:
The key numbers are the trip time T according to the ship's clocks, the trip time t according to clocks on Earth or Alpha Centauri, the maximum velocity v achieved by the ship, and the mass ratio M, or kg of fuel needed per kg of payload. Assuming that we accelerate for half the distance and then turn around and decelerate for the other half, and that we use an ideal rocket that converts fuel to energy at 100% efficiency and exhausts all that energy out the back with perfect collimation (so it all goes into changing the rocket's momentum and not into heat or some other waste product), the formulas for these are:
T = 2 (c/a) arccosh (ad/2c^2 + 1),
t = sqrt((d/c)^2 + 2d/a),
v = at/2 sqrt(1 + (at/2c)^2)
MR = exp(aT/c) - 1,
where a is the acceleration, d is the total distance traveled, and c is the speed of light. The equation for T, assuming that we accelerate halfway, then turn around and decelerate to arrive at the destination at rest, is
Plugging in a = 1m/s^2, d = the distance to Alpha Centauri, or about 4 x 10^16 meters, and c = 3 x 10^8 m/s, we get
T = 3.9 x 10^8 s, or about 12.7 years,
t = 4.2 x 10^8 s, or about 13.6 years,
v = 1.7 x 10^8 m/s, or about 0.57 c,
MR = 2.7
This is a pretty small mass ratio, but of course it was derived using highly idealized assumptions. More realistic assumptions would result in a much larger mass ratio. Also, a maximum speed of more than half the speed of light would create huge radiation issues requiring heavy shielding, so the payload mass would be very large.
Yeah, hard is clearly an understatement. However, if it were critical to the human race, and the top 20 economies put a trillion dollars and some of their best scientists behind it starting today, there is absolutely zero question that a ship capable of that could be built and launched within 20 or 30 years.
Alternatively, Bezos will probably have $100 billion to play with in the next 12 to 24 months or so ($61 billion today, most projections have Amazon climbing quite a bit higher yet, new price targets have it at $1,000 per share; whether it takes a year or six years, it'll very likely get there). He just sold off $671 million worth of shares the other day, I'd expect his sales will continue as the price climbs. So maybe he'll fund it by himself in the coming two decades.
It gets easier year by year. Now we have ion drives. Maybe in 100 years we will stumble upon a breakthrough technology that allows us to build antimatter rockets: https://en.wikipedia.org/wiki/Antimatter_rocket
That would be a direct invitation to other stars in a lifetime.
http://jwst.nasa.gov/origins.html
"One of the main uses of the James Webb Space Telescope will be to study the atmospheres of exoplanets, to search for the building blocks of life elsewhere in the universe"