10th Rock From The Sun?

[Dr Mordrid]

http://www.space.com/scienceastronomy/050729_new_planet.html

Dr. Mordrid

[KvHagedorn]

I guess every fist-sized rock with the Sun as its orbital center is a planet. Funny how Ganymede, Callisto, Triton, and Titan, which are roughly the size of Mercury are accorded a lesser status..

[Nowhere]

Perhaps how it was formed could be decising factor.
Which brings problems with Earth, because either we won't include it, or include Moon as well (well...I don't have a problem with "double planet")

[Dr Mordrid]

Planets are usually something orbiting the sun in their own orbit, not whirring about anohter larger object. As for the status being accorded to Kuiper objects, I have no objection as long as they are Mercury/Pluto sized or larger.

Dr. Mordrid

[Nowhere]

So...where you'll drove the line? Why Mercury/Pluto size? Or perhaps...beeing able to have spherical shape under force of its own gravity? Either way, there could be thousands of such objects...

[Lizzard[MPE]]

this planet they are bitching about not being a planet probably has life on it and in 100 years when we decide to get the space program off the ground again they will find that out.

i mean if its bigger then pluto i dont see the big deal.

[Dr Mordrid]

So...where you'll drove the line? Why Mercury/Pluto size? Or perhaps...beeing able to have spherical shape under force of its own gravity? Either way, there could be thousands of such objects...

Because they're the smallest bodies already classified as planets, so why not make that the cutoff line? It's as valid a criteria as anything else I've read, arbitrary as it may be.

Dr. Mordrid

[Lizzard[MPE]]

Whats the reasons for us not exploring more of our solar system?

not enough fuel to go for a joy ride?

[Nowhere]

Because they're the smallest bodies already classified as planets, so why not make that the cutoff line? It's as valid a criteria as anything else I've read, arbitrary as it may be.

Dr. Mordrid

Perhaps I've meant something more among the lines: you can't get Plutos radius and say that's the borderline and anything below it (even few km) isn't a planet. So, what X do you propose in R+/-X (R - Pluto radius)

[Nowhere]

Whats the reasons for us not exploring more of our solar system?

not enough fuel to go for a joy ride?

Something like that...
With our current chemical rockets technology we can go there only using gravitanional "catapult" of planets (even than trip takes a while...) and we can't go back...

[Dr Mordrid]

Lack of an adequate power system for large payloads.

Chemical rockes provide a huge initial impulse, but no thrust after that. From that point on one has to use a gravity slingshot using planets or large bodies to gain trajectory to the outer planets etc. This is why the probes to the outer planets take several years to get there, which makes such missions pretty much impractical for humans.

The new Ion Drive electric engines provide very low thrust but can maintain it for YEARS on end, allowing small craft like Deep Space One (DS1) to cruse all over the solar system on just a few pounds of fuel. This provides very low acceleration but it's on 24/7/365 which in the end gets you going much faster over weeks and months of flight. Great for probes, but not really for human space flight.

Chief among the future candidates for human space flight are nuclear powered engines like VASIMR: Variable Specific Impulse Magnetohydrodynamic Rocket. VASIMR would use a small nuclear reactors electric output (probably a pebble bed reactor for safety) to ionize gas into a plasma then accelerate it to extreme velocities using superconducting magnets. After this it would be ejected as in a conventional rocket, but like an Ion Drive it could run for extended periods but at relatively high levels of thrust.

Fuels for VASIMR would be hydrogen, helium, deuterium etc. The design itself borrows a bit from the TOKAMAK fusion reactor design, except it's linear and not toroidal. These babies could get you to Mars in weeks instead of the months to years time of a chemical rocket.

Another option would be thermal nuclear drive. In this a 50-100 megawatt nuclear reactor would have liquid fuel passed through it for super-heating then ejection as in a very high powered rocket exhaust. Tests on such systems were done in the 50's and 60's and they went VERY well, but the nuclear test ban treaty put the project out of business because they were primarily targeted as drives for hypersonic nuclear cruise missiles....mainly because the H-Bombs of the day were the size of a semi and needed the power

There has been a lot of talk about reviving the thermal nuclear program of late for earth orbit to interplanetary trajectory insertion, probably followed by a VASIMR as the mission drive.

Dr. Mordrid

[Nowhere]

Orion would be something...8 Mt to LEO...

Or medusa

[Dr Mordrid]

This site may be of interest;

http://www.nuclearspace.com/

Pratt & Whitney's TRITON engine;

http://www.nuclearspace.com/A_PWrussview_FINX.htm

Dr. Mordrid

[Dilitante1]

The ships will have to be HEAVILY armored to survive hi speed impacts from small-large items....thus making them heavy/expensive. The expandable habitats wont cut it.

Shame we (the world as a whole) has not pushed for more exploration once we landed on the moon. We should find out if there is life locally, and if not, decide if we want to harvest materials from the solar system to help this planet out or not (terraforming). Population growth is exploding here, we need to think ahead before it is too late and the world is too screwed up to save.

[GT98]

Shame we (the world as a whole) has not pushed for more exploration once we landed on the moon. We should find out if there is life locally, and if not, decide if we want to harvest materials from the solar system to help this planet out or not (terraforming). Population growth is exploding here, we need to think ahead before it is too late and the world is too screwed up to save.

Well depends...look at the huge impact that birth control has made and the smaller family size that has come of it. If the developing world can get BC cheap enough, the worlds popluation could start to shrink in another 100-150 yrs.