Question about speed in space

[johnrambo]

Bare with me im very new to astronomy.<br />My question is how fast we can travel in space today and what stops us from traveling faster than the current speed? <br />I meen if we really tryed to send a unmanned orb/rocket(to mars) with the max speed possible how long would it take?<br />thx

 

[vogon13]

Speed is relative, my young Padawan learner . . . <br /><br />Highest earth escape speed so far was (IIRC) New Horizon.<br /><br />To go faster, need a smaller payload on a given rocket, and/or a bigger rocket.<br /><br />Or a more efficient rocket. Like the ion thruster on the Dawn mission.<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[lukman]

200.000kph, what stoping, not enough thrust and need shield like star trek. <div class="Discussion_UserSignature"> </div>

 

[nyrath]

This site explains it, a bit<br />http://www.projectrho.com/rocket/index.html

 

[weeman]

The time it takes for a craft to reach Mars is still several months. <br /><br />As for now, Stargates are the fastest form of space travel, just ask Kurt Russell <img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /> <div class="Discussion_UserSignature"> <p> </p><p><strong><font color="#ff0000">Techies: We do it in the dark. </font></strong></p><p><font color="#0000ff"><strong>"Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.</strong><strong>" -Albert Einstein </strong></font></p> </div>

 

[jgreimer]

I'll leave the other questions to others but will take a stab at "what stops us from traveling faster than the current speed?" The max speed of the spaceship depends on the ratio of fuel mass to payload mass and the exhaust velocity of the fuel. To go faster you either have to increase the ratio of fuel to payload which gets very expensive or increase the exhaust velocity which has already been optimized for the type of fuel used.

 

[dragon04]

First of all, don't think in terms of "speed". That's really an inaccurate description of what's going on.<br /><br />The correct term is <b>velocity</b>.<br /><br />Speed is how far you travel over time.<br /><br />Velocity is speed in a particular <b>direction</b>.<br /><br />That's important because of the effects of gravity.<br /><br />Raw velocity alone isn't the solution. New Horizons is by far the "fastest" space probe we've ever launched.<br /><br />The Apollo missions took (IIRC) about 3 days to reach the Moon. New Horizons did it in like 9 hours, I think.<br /><br />The problem in sending spacecraft to Mars (or wherever) is having the ability to slow them down enough for the target's gravity to capture them. IOW, there has to be a way to slow them down rapidly enough when we get "there".<br /><br />That would require a lot of propellant and thrust to go from "60 to 0" in a very short amount of time.<br /><br /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[usn_skwerl]

which is where aerobraking comes in handy....of course, thats if target object has an atmosphere.<br /><br />we dont yet have the technology to slow down using terra braking from 100's of kp/s and have the spacecraft survive. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> </div>

 

[ashish27]

<blockquote><font class="small">In reply to:</font><hr /><p> That would require a lot of propellant and thrust to go from "60 to 0" in a very short amount of time <p><hr /></p></p></blockquote><br /><br />Can't the spacecraft reverse itself while in motion?

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>we dont yet have the technology to slow down using terra braking from 100's of kp/s and have the spacecraft survive.<p><hr /></p></p></blockquote><br /><br />Some jokingly call that "lithobraking". <img src="/images/icons/tongue.gif" /> It was (inadvertently) employed by the Genesis spacecraft (though arguably it also employed aerobraking through entry interface, and thus hit the Earth at its terminal velocity). It was used seriously by the first spacecraft to land on the Moon. However, this was done with the full expectation that they would not survive the experience. (And indeed, they didn't.) <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[MeteorWayne]

Surveyor, right? <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[nexium]

At an average velocity of 50,000 miles per hour, we could zip past or crash into Mars in 1000 hours = 42 days, but we would not have enough fuel left to make a gentle landing or orbit Mars, with any space craft presently available. Possibly we could land one kilogram on Mars, that quick, if we built a 5 stage rocket. That is my guess. For a manned flight, we need enough fuel left to return to Earth, so even 6 months is very optimistic with present rockets. Neil