Interstellar probes. When, where, how?

[grooble]

I believe that this century will see us finding earth type worlds around other stars, by using new and advanced space telescopes. Such an event would lead to people wanting to send a probe of some sort. I think this is an inevitable scenario.<br /><br />Will we be able to send probes that relay information back to earth in a reasonable time, say within 30 years? People are still following the voyager mission, so that is a good sign that people will still follow such a long term project.<br /><br />Is there no way to increase communication speeds over great distances than what we have now? At the dawn of the 21st century, are we already at the speed limit for communication between a probe and earth?<br /><br />What sort of engines would the probe need, what materials would it have to be made of? <br /><br /><br /><br />

 

[najab]

<blockquote><font class="small">In reply to:</font><hr /><p>Is there no way to increase communication speeds over great distances than what we have now? At the dawn of the 21st century, are we already at the speed limit for communication between a probe and earth?<p><hr /></p></p></blockquote>The Speed of Light, not just a good idea, it's the law.

 

[larper]

The speed of communication is already maxed out. What we need to dramatically improve upon is bandwidth. <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>

 

[toymaker]

I have seen several plans of interstellar probes, ranging from quite realistic to very "sf like"<br />Here are some of them :<br />http://www.space.com/news/21c-exploration_991231.html<br />http://interstellar.jpl.nasa.gov/<br />http://sfwrg.org/d001.html<br />http://en.wikipedia.org/wiki/Project_Longshot<br /><br />Of this Project Longshot is the most feasible I think.

 

[odysseus145]

The Mars Telecomunications Orbiter is planned to carry a laser communications system, which would greatly increase bandwidth between Earth and Mars. IIRC, it would be around 10 times the current data transfer rate. <div class="Discussion_UserSignature"> </div>

 

[heyo]

The problem is no as much communication between Earth and the probe as it is getting the probe out to such vast distances within an average lifetime.<br /><br />I think with our fastest propulsion technology we might be able to get a probe to our very nearest neighbor star (Proxima Centauri) in about 700 years, IIRC.<br /><br />(The experts around here can probably give a better estimate)<br /><br />Proxima Centauri is not believed to have any planets. I don't know how near the nearest start with planets is.<br /><br />The bottom line is we will need to go much farther, MUCH MUCH faster if we are ever to get off of our own front porch.<br /><br />As it stands now, even if would could instantly teleport a probe to Proxima Centauri, it would be over 4 years before we would receive the first byte of data from it.<br /><br />If we had the technology to push something up to .5C or more, that would open up a few nearby star systems in the sense that a young group of scientists who worked to send the probe would live to get results back within a few decades.<br /><br />Heyo

 

[vogon13]

Even at a maximum velocity of 0.01C, it will only take humanity 10 million years to colonize the galaxy. Considering the galaxy is billions of years old, this (in the big cosmic scheme of things) does not seem excessive.<br /><br />Additionally, since we don't seem to see any alien colonists here, we have another piece of data to corollate with the Fermi Paradox.<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>

 

[adzel_3000]

From the BIS website:<br /><br />In 1973 the British Interplanetary Society started the Daedalus project. Its aim was to design a practical starship able to investigate a star system near our own. Although this may seem a far-fetched project, it is worth noting that in the 1930s the BIS designed a moon landing mission that bore some remarkable resemblances to the Apollo landings thirty years later. The project was led by the engineer Alan Bond, who had previously worked on the Blue Streak rocket and would go on to design the HOTOL spaceplane. A panel of about thirteen experts worked on the project, though contributions were made by many more.<br /><br />The project had clear guidelines: <br /><br />The spacecraft must use current or near-future technology. <br />The spacecraft must reach its destination within a human lifetime. <br />The spacecraft must be designed to allow for a variety of target stars. <br />These guidelines meant that the spacecraft would be practical, that scientists working on the project would have a good chance of being alive at the end of it, that the craft would not be overtaken by something more advanced, and that several close stars could be investigated using the same type of starship.<br /><br />The target chosen for the Daedalus study was Barnards Star, 5.91 Light Years distant. A spacecraft able to fly there would be able to reach Proxima Centuri in a shorter time, or Sirius in a longer period. Barnards Star was also chosen because evidence suggests that it has at least one planet orbiting it, giving the probe a chance to investigate another planetary system.<br /><br />To reach Barnards Star in a human lifetime, a speed of 12% the speed of light (36, 000 Km per second) would be needed. Conventional rockets, solar sails or ion drives would be insufficient to achieve this. There was, however, a newer method; Internal Confinement Fusion. In this, a pellet of deuterim/helium-3 is bombarded from all sides by lasers, resulting in a small fusion explosi

 

[grooble]

Awesome, i wonder what those guys would have came up with if they used current and near term tech of this era, maybe they could have come up with something that travelled at 30-50% lightspeed. <br /><br />

 

[adzel_3000]

<br />I'm not sure about a speed above 15% of c with current technology (nano-probes shot from accelerators not included...)<br /><br /> BIS is still active and looking into this.<br /><br />The Daedalus design seems the most practical of the many I have seen. All the technology seems within reach. Still, the price tag would be huge.<br /><br />Also, the mission would be a fly-by of Barnard's Star. No braking or stopping.<br /><br />A cool concept though.<br /><br />--A3K<br /><br />

 

[grooble]

What is the speed limit for ION engines? At what point do they no longer produce any speed benefit?

 

[spacefire]

is there a way they could swing from solar system to solar system, kind of like we use gravity assist of the planets to giude and accelerate probes? <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[adzel_3000]

I am not sure what the outer theoretical limit is for an ion engine.<br /><br />NASA's DS- One probe is propelled by using electricity from solar panels to remove electrons from xenon atoms. These ions are then expelled at 30 km/s, providing the craft's propulsion. The specific impulse provided by this method is about 10X that of a chemical engine. Yet the thrust (and therefore the ramp rate to a given velocity) is much lower. This means that, although an ion engine accelerates slower than a chemical engine, its maximum speed as well as ability to efficiently convert its fuel are much better. <br /><br />Various groups, including at Sandia national Labs, have looked into this from time to time. I saw an estimate that suggested an ion engine could reach 1% of c. This is roughly 6.7x10^6 miles/hour. This would be great for interplanetary travel, but a tad slow for interstellar.<br /><br />--A3K<br />

 

[adzel_3000]

I would think that an interstellar flight could use some type of gravity assist. A good start to an IS flight might be to achieve high speed by first passing close to the Sun. At close approach some type of high-thrust rocket could be kicked in. Even a small increase in speed near the Sun could translate into a big increase in the ultimate velocity far away. <br /><br />But if this was not achievable (perhaps the probe cannot go near the Sun because of delicate electronics or even passengers). then another way to kick-off an IS mission to a far-off star system may be from a comet. Comets are neat in that they have orbits that already go to the very edge of the solar system. They could also provide resources for the ship or its crew. <br /><br /> Such boosts from gravity wells or resources (like comets) within our solar system might allow missions to nearby stars to get off to a good start. To reach more distant parts of the galaxy, however, may require swing-bys like those suggested with the Sun, but the IS ship would “skip” across many different solar systems. Dwarf stars exist which are as compact as Earth and as massive as the Sun, and perhaps some can be found that would form a “flight-line” for acceleration and even deceleration toward your target star. If so, dwarf stars might be a perfect target or targets for the type of maneuver I believe you are suggesting. <br /><br />--A3K<br />

 

[mrmorris]

<font color="yellow">"What is the speed limit for ION engines?"</font><br /><br />It's variable depending on the amount of power the engine has available to accelerate the ions. DS-1's engine expelled ions at about 30 km/sec. Voyager 2 by contrast is moving at about 17 km/sec.

 

[spacefire]

I thin ION thrusters have a limit called the characteristic velocity. <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[thalion]

Unfortunately, IIRC, gravitational deflection is proportional to both the mass of the deflector and the velocity of the incoming body. At .15 c, even the Sun could only slightly deflect a space probe. It probably couldn't impart any significant velocity to the probe, either, as that would have to be relative to the galactic center, and out here everything is traveling just about the same speed; any boost would probably be incrementally small compared to the overall .15 c velocity. <br /><br />A final problem is that space is very empty; I read once that if you extended a line out from the cornea of your eye to the edge of the observable universe, chances are that that line would never intersect the surface of a star. In short, if we sent an IS to Sirius (which I think would be an awesome target, btw), the chances of the probe making another close flyby to any other star system in the line of travel would be vanishingly small, not without a huge expenditure of fuel to significantly change the path once more.

 

[yevaud]

Some grist for the mill:<br /><br />It has been thought that no matter what drive system is used, that realistically, there's a "speed limit" of about 0.3C. Beyond that, it's thought, friction with the Interstellar medium would cause so much damage (primary, secondary and tertiary radiation, continual interaction with particles, etc.), that's it'd kill the crew.<br /><br />I don't know if this includes a Bussard Ramscoop, as it's able to "protect" itself, by virtue of it's magnetic scoop-field. Still theoretical at this point anyways. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[mental_avenger]

<font color="yellow"> there's a "speed limit" of about 0.3C. Beyond that, it's thought, friction with the Interstellar medium would cause so much damage ……<br /><br />I don't know if this includes a Bussard Ramscoop, as it's able to "protect" itself, by virtue of it's magnetic scoop-field. Still theoretical at this point anyways. </font><br /><br />That would be dependent upon magnetic deflection of the particles/plasma. I did a quick estimate on deflection at 1/3c. If you see any math errors here, let me know. <br /><br />1/3c is about 100,000km/sec. Let's assume some dust at 1km ahead of the ship. At 100,000km/sec that would be .00001 seconds (10 microseconds) before the ship arrived at the dust. Assuming a magnetic deflection field 1 km ahead of the ship, the particles would begin lateral acceleration 10 microseconds before the ship arrived. With a ship diameter of 400 feet, what would be the acceleration needed to clear the path of particles? <br /><br />The particles would have to average 20,000,000 feet per second for the 200 feet from the center of the ship to the edge. That means that they would have to be accelerated from 0 to 40,000,000 fps in .00001 second. The lateral acceleration required would be extremely high. At 1 km from the ship, lateral acceleration of the particles would have to be 4,000,000,000,000 feet/sec/sec.<br /> <div class="Discussion_UserSignature"> <p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="2" color="#ff0000"><strong>Our Solar System must be passing through a Non Sequitur area of space.</strong></font></p> </div>

 

[ldyaidan]

It seems that it would be far more practical, at least at first, to try to send a "message" rather than to go there in person. If we discover earthlike planets, then if we were to scan it for radio/etc signals, and try to send a message on that same frequency, we would recieve results faster than to send a probe, with a lot less expense and risk. Granted, if we don't detect anything, then the probe would be the next best option. Even if we can't communicate with specifics due to language barriers, sending a signal that "we are here, too" seems like the first logical step. Just seems like it would be more polite to "call" before showing up on our neighbor's doorstep.<br /><br />Rae

 

[mental_avenger]

The probability of finding ET Aliens on any planet close by is extremely small, so making communication a criteria would be a waste of time. The probability of finding ET Aliens at a stage of development where they are advanced enough to reply, but not so advanced that they ignore us is even smaller. After the TPF, the only logical course is to send a probe with the capability of doing a close-up analysis of the likely planets, and the ability to transmit that data back to us. <div class="Discussion_UserSignature"> <p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="2" color="#ff0000"><strong>Our Solar System must be passing through a Non Sequitur area of space.</strong></font></p> </div>

 

[absolutezero]

For communications, it really comes down to this single point. Communications will have to take advantage of wormholes by sending the signal through the worm hole. Unless communicating within a solar system, the speed of light simply is not practical with any space craft travelling to other star systems.<br /><br />If we are to build a probe to another star system and we can't communicate via worm hole, the probe will have to be soley programmed to handle everything without the intervention of humans, but to me, whats the good of sending a probe to another star system if it will take thousands of years to ever to get anything back?<br /><br />Using wormholes to communicate is how I believe any civilization level II or up would communicate via worm hole.