No, anything you launch from the Earth will also have Earth’s orbital velocity. If you just lift it free of Earth’s surface, it will still be in the same orbit as Earth, and at [effectively] the same velocity. To get closer to the Sun, you need to kill that velocity.
Just getting out of the Earth’s gravity well will put you in an orbit very similar to Earth’s, and the Earth, of course, does not hit the Sun. The Apollo missions didn’t loop back up to the Moon, because they didn’t just point directly back at Earth, they pointed backwards along the direction of the Moon’s orbit to reach Earth, and on reaching Earth, they basically collided with the planet to kill their speed.
If an Earth-sized body is orbiting the Sun at the surface of the Sun, it’s directly disturbing the gasses in a strip one Earth-diameter across, circling the Sun. One earth-diameter is about 1 degree for a circle as big as the Sun.
If you just point a spacecraft at the sun and give it a push, it’ll just go into an elliptical orbit around the Sun whose perihelion (lowest point) is slightly closer to the Sun than the Earth. You have to completely kill the orbital speed before it’ll fall all the way to the Sun.
It’s the same reason manned spacecraft have elaborate heat shields. The spacecraft has to kill its orbital speed before it drops to the ground. You can’t just aim the spacecraft at the ground and give it a little push.
Oh, come on.
I can’t be the only one thinking of Nuclear Man from Superman IV.
Clearly, he’s enough of a reason to avoid shooting stuff at the Sun…except for all copies of Superman IV, of course.
For the second question, I’d guess throwing somewhere around an Earth-sized lump of non-fusible iron into the Sun MAY (keyword is may) cause it to halt fusion and go Supernova* on us.
I should intensify that we honestly aren’t entirely sure whether throwing that (comparatively) small an amount of material into the Sun would do anything in the short term or not, but I’d wager it’s at least possible (if unlikely).
*Type Ib or Ic I think. It’s actually quite close to what happens in stars with 9 solar masses or above that generate a core of iron themselves and go type II supernova when they can’t sustain themselves from it anymore. I say “I think” because I’m not certain if an outside force contributing to the lack of fuel at the core makes the requirements count or if it has to generate the fuel deficiency all by its lonesome.
I don’t think I’ve ever heard of a space elevator that used rockets. Most of the speculative designs climb their tower with electric motors.
LiftPort Group, which is actually trying to put together the necessary technology, plans to use a climber on a carbon nanotube ribbon. The climber would have photoelectric panels to power the motors, which would collect energy beamed from the Earth’s surface with lasers.
Ah, I understand you now. The Earth-band would cover about .9% of the surface area, as you said. Still, communication of any sort between the core of the Sun and the outer layers is extremely slow, so I don’t imagine that any surface disruption would do anything more than maybe tangling up the magnetic fields more that usual for the remainder of the current cycle.
I don’t know what would happen if the Earth sank to the core, but the Sun probably already has more iron in it than the Earth does, and I’m not even convinced the Earth would sink: It might vaporize and get caught up in the convection eddies before it reached the burning core.
I see what you’re getting at re the energy needed to get rid of the Earth’s orbital energy. Can we agree that maybe you’d like a do-over on the Sun being “the hardest place in the Universe to throw things into”?
Just another tidbit on the sun.
From Wikipedia:
“The principal component of the Solar System is the Sun, a main sequence G2 star that contains 99.86 percent of the system’s known mass and dominates it gravitationally. Jupiter and Saturn, the Sun’s two largest orbiting bodies, account for more than 90 percent of the system’s remaining mass”
That’s a lot. The Sun also burns/converts 400 million tons of hydrogen a second. And that’s been going on for 4.5 billion years. Those numbers are staggering to me. I just can’t fathom that we can do/throw anything at the Sun that would affect it.
Chronos, in order to empty things into Alpha Centauri from here, aren’t we going to have to kill whatever tangential velocity we have on our approach? Isn’t this not necessarily less than the energy required to hit our own star?
No. It’s like shooting down a plane; you aim for where it will be at the momment the projectile arrives. In practice, we’d also have to allow for the star’s gravity–something which is negligible for aircraft–but the general principle remains identical.
Everyone’s jumping on my analogy; I don’t think they understood what I meant. I was referring to nuclear waste being dumped into the sun as spitting into a lake, not dumping the whole Earth into the sun.
Right, but if you’re off by more than a stellar radius, you’re going to enter a highly-energetic hyperbolic orbit, right? So you’ve pretty much have to be dead-on in order to make Alpha Centauri more efficient than hitting the Sun - anything short of a perfect shot would be completely inefficient.
Also, what are the differences in energy for exiting the Solar System and for crashing into the Sun? I left my undergraduate texts in the US…
This isn’t the two-decimal place answer, but here’s a rough figure to get you started:
To exit the solar system from Earth orbit, you need to get near the escape velocity for the Sun’s gravity well. (In reality, sending something to Alpha Centauri doesn’t require quite the full escape velocity, because rather than trying to reach infinity, you only need to get about halfway to the other star. But the difference is slight.) If you’re already at the distance of the Earth’s orbit, you have to reach a speed of 42.1 km/s relative to the sun. Since the Earth is already moving at 29.8 km/s in its orbit around the Sun, launching yourself tangentially fast enough to escape the Sun only requires adding 12 km/s.
However, if you want to fall into the sun, you have to lose all that orbital speed. That requires enough energy to kill almost 30 km/s of orbital speed. So it’s about 2.5 times hared to launch something into the Sun than it is to launch it into interstellar space.
(Okay, so you don’t have to lose all of your orbital speed to impact the Sun. Keeping a tiny bit of remaining tangential velocity will still put you in an orbit with perihelion inside the Sun’s volume, therefore impacting it. But there is a negligible difference between that crazy ellipse and the full stop to fall directly to the Sun’s center. Close enough for our purposes.)
ETA: According to this part of the Wiki article on escape velocity,the combined effect of the Earth and Sun requires launching at 16.7 km/s, instead of the 12 km/s I quoted above. That’s obviously a more accurate answer. But it just means that it’s merely twice as hard to launch into the Sun, instead of 2.5x.
Oops, sorry. Misread the question. Or at least, didn’t read the whole thing.
Currently, Alpha Centauri is at -61° declination, putting it a looong way off the ecliptic. If you want to shoot for anything off the ecliptic, you don’t get the full benefit of Earth’s orbital velocity, meaning you need something more than 12 km/s delta-v.
I wanted to do the BOTE for how much, so I went looking for α Cen’s ecliptic latitude, since the actual distance off the ecliptic could be plus or minus 23.5° from its declination. I didn’t find that figure, but interestingly enough, I did find this page, which states that α Cen’s proper motion has it arriving in Gemini (very close to the ecliptic) and staying there around AD 176,000. But at that time, it will also be moving away from us at around 41 km/s, and be about 15.5 light years away.
Currently, α Cen is actually getting closer to us, with a close approach at 2.9 LY somewhere around the year AD 30,000, long before its proper motion puts it anywhere near the ecliptic. It will take approximately 21,000 years to go that far moving at solar system escape velocity.
*** Ponder
There is the risk that if we put a large enough amount of synthetic material in the sun that a hostile alien species could use that as a beacon to their next meal. :smack:
True, but for targets lightyears away, the difference is negligible. If you shoot a payload straight forward in the direction of Earth’s orbit, at just barely escape speed, then once it gets out into interstellar space, it’s going to be traveling at a snail’s pace. It doesn’t take much energy at all to turn a snail’s pace in one direction into a snail’s pace in another direction, so once you’re out of the bulk of the Sun’s gravity well, you just aim in the direction of your target star and give yourself a nudge.
True, unless you’re correcting your course along the way. But really, you don’t need to hit any star at all: A load of nuclear waste heading away in a random direction in the sky is just as gone as a load in the core of a star. All you need to do is make sure it doesn’t hit any populated planet, and the odds against that are so small it’s not worth worrying about, once you’re out of the Solar System.
If hostile or hungry aliens wanted a beacon to their next meal, why wouldn’t they use the radio signals we’ve been emitting copiously for most of the last century instead?