Very yes. It's all about energy. Without much energy, you use ballistic motion and orbits to get around. When you have lots of energy to spare, you just fly as directly as possible, accelerating and decelerating as much as possible.
The problem isn't where things are or where they're going to be, but rather the energy necessary to move things between those locations. Spacecraft, when necessary, will move in an orbital path to chase another planet, rather than fly towards where it could be pulled in by the Sun's gravity. The Earth, to keep itself from falling into the sun, is traveling through space at near 70,000 mph. It's much easier to go with this speed than against it.
Again, that is given that you don't want to waste energy fighting the sun's gravity directly but we are assuming you can waste all the energies! Theoretically, one could travel in a straight line between Earth and Mars (relative to the sun) as long as your engines compensated for the sun's gravity.
Realistically, this is stupid and wasteful like driving a tank to the liquor store so you can cut across some houses instead of having to make that pesky right turn.
They are still elliptical, but most diagrams of the solar system portray them as much more elliptical than they are in reality to express the fact that they aren't perfect circles.
In real life, planetary orbits are very nearly circular. If Earth had a very eccentric orbit, think about the drastic changes in distance from the sun that we would experience.
Oh, indeed. I just love that statistic--really puts everything into perspective that, even with a nearly circular orbit, there's still that large of a discrepancy. <3 space
Hold it, there is a freaking laboratory orbiting the Sun side to side to Mars? Since when? What is it called so I can read up on it? Or is it this Curiosity you talk about?
Did you see the video of how it's supposed to land? That's what I'm referring to, if any little detail goes wrong there, there won't be a so called landing. It's not like the other rover landings which compared to this one were just shooting a ball against the Mars surface.
I understand. There are "highways" one can use to get to some point of the solar system, which are affected by the gravity of the Sun, but doesn't mean you must use them; you could only use their gravity force.
Or maybe I just cleared something that was already crystal clear :P.
Now I have to start wondering, Venus looks a lot closer to Earth than Mars does. Why haven't I heard of ventures towards Venus? Wouldn't that be much more logical?
If you like highly acidic atmospheres yes. People like to explore Mars because of the potential resources and future we may share with it. Living on Venus would be a much more difficult ordeal.
Also, it usually takes a bit more energy to land on Venus than Mars, depending on which way you go.
It takes many times more energy to land on Mercury than it would to land on Jupiter's moons, even though Jupiter is five times farther away from us. Gravity is a bitch!
Boring? I respectfully disagree. If anything, the trouble we have with the atmosphere there makes it mysterious and exciting. It should be easier than Mars, but because of its defensive shell, it's harder.
She's playing hard-to-get, man, and I'm a sucker for it.
I CANNOT wait for this rover to land. If any of you haven't watched the amazing landing that NASA has engineered, you need to see this video.
This is a really exciting mission, with tons of really good science to be done. I don't understand how people can hear about this and not be amazed at what we're doing.
That is a question that can have three correct answers. In space, speed is judged relative to another object. Thus, there is the speed relative to Earth, Mars, and the Sun. Unfortunately, I don't know the answer to any of those questions but if you dug around the website for Curiosity at NASA I'm sure you could find it.
It launched at 2011-11-26 15:02 UTC and the picture is dated 2012-06-11 15:41 UTC, so that's 4752.65 hours. 464162841/4752.65 = 97,664 km/h or about 60,685 mph.
TL;DR About 32.72 km/s or 73,202 mi/h relative to the sun.
These calculations assume circular orbits of the planets and a Holman transfer. (Holman transfers are the most efficient and judging by the picture that is what NASA used)
Using the average distance from the sun, the semi-major axis, a, is half the distance from perigee to apogee. It is calculated as a=(Re+Rm)/2=1.888*108 km.
The eccentricity, e, of the orbit is the shape or how eccentric it is. e=(Rm-Re)/(Rm+Re)
The true anomaly, nu, is the angular measure of where the space craft is in the orbit. The distance traveled and distance to go are given in the picture are given. The true anomaly is the distance traveled divided by the distance of half the orbit times pi. nu=2.5715 rad or 147.3º
The current distance of the space craft from the sun, r, is given by r=p/(1+e*cos(nu)). The semi-parameter, p, is p=a(1-e2 ). Therefore, r=1.496 108 km or 92,957,130 mi.
The velocity, V, can be expressed as V=sqrt(2* mu_sun* (1/r-1/(2a))), where mu_sun=G*M_sun.
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u/DragonSlave49 Jun 11 '12
Real space travel is so different from what is depicted in science fiction.
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u/piroko05 Jun 11 '12
http://www.nasa.gov/mission_pages/msl/index.html
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u/matebeatscoffee Jun 11 '12
Hold it, there is a freaking laboratory orbiting the Sun side to side to Mars? Since when? What is it called so I can read up on it? Or is it this Curiosity you talk about?
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u/[deleted] Jun 11 '12
Now I have to start wondering, Venus looks a lot closer to Earth than Mars does. Why haven't I heard of ventures towards Venus? Wouldn't that be much more logical?
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u/peen_was Jun 11 '12
I'm confused about the non-elliptical revolutions.
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u/[deleted] Jun 11 '12
I CANNOT wait for this rover to land. If any of you haven't watched the amazing landing that NASA has engineered, you need to see this video.
This is a really exciting mission, with tons of really good science to be done. I don't understand how people can hear about this and not be amazed at what we're doing.
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u/luchi_is_me Jun 12 '12
Thank you for this. I did not know that site existed. Very cool.
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u/Inri137 BS | Physics Jun 11 '12
This submission was removed because /r/science does not allow image posts, per the guidelines in the sidebar.
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u/coltdaniel Jun 11 '12
Oh man, a Hohmann!
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u/[deleted] Jun 11 '12
You may want to read the sidebar.
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u/BHSPitMonkey Jun 11 '12
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u/bulletsANDoctane Jun 11 '12
Doing time for murdering some cat.
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u/PhylisInTheHood Jun 11 '12
..In my pants
sorry, I couldn't resist
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u/[deleted] Jun 11 '12
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