Could we detect and intercept RAMA with today's tech?

[alokmohan]

Icarus,greek man who flew to sun.

 

[halman]

willpittenger,<br /><br />While what you purpose is true, the gravity flucutations caused be objects massing only a few kilotons are going to be extremely difficult to detect, and would require establishing a huge database, in my opinion. Even a close pass by an asteroid a couple of kilometers in diameter will not significantly perturb a planet, but that same asteroid has the potential energy of several gigatons of TNT.<br /><br />This is why I suggest construction and launching of what I would think would be fairly simple satellites, consisting primarily of very sensitive high definition infared detecters, and the solar cells to power them, as well as a transceiver for data transmission upon interogation. Station keeping is not an issue, just orientation, so a gyroscope would probably suffice instead of thrusters. Any object within one Astronomical Unit of the Sun is going to radiate strongly in the infared, while more distant objects, even of planetary mass, will have signitures of a comparitively lower value. Because the scan would not depend on visible light, stars and asteroids outside of Earth's orbit will not raise the noise threshold. At least 3 satellites of this type would be needed, I believe, each with a minimum of a 120 degree scan field. By using triangulation, very precise locations of asteroids sunward of Earth could be generated in a fairly short time. Once the catalog is complete, the entries could be monitored with radar to update orbital changes, so the satellites do not need to have a long lifespan. Because the instrument package would be fairly small, and perturbation maneuvers could be used for final orbital injection, a launch vehicle the size of the Atlas would easily be able to place the individual satellites in the correct trajectory.<br /><br />For a total cost of perhaps 500 million, and about 8 years time, we could insure ourselves against being struck by a rock that we cannot see. This seems to me to be the simplest solution to thi <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[yevaud]

Not to be a naysayer, but Asteroids are generally dark, and that means in the Thermal and IR, as well as having low Albedos. <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>

 

[MeteorWayne]

And the sky, particularly the milky way is pretty bright in IR. <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>

 

[halman]

Yevaud,<br /><br />I have been of the understanding that dark objects tend to absorb heat energy more readily than light objects. I am fairly confident that any rock which orbits most of the time inside of the Earth's orbit is going to have a pretty high surface temperature. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[halman]

MeteorWayne,<br /><br />Yes, the Milky Way is comparitively bright in the infared band, but that is compared to empty space. When you are talking about an object a few millions of miles away, with a surface temperatuere of 100 degrees Celscius, you don't need supercooled detectors. This is the crux of my argument, that the bodies in orbits inside of the Earth's are going to be pretty warm. They will stand out quite easily in a near infared scan, without using any high tech detection. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[yevaud]

Halman, yes, true. Once it achieves our orbit. Don't forget that these things have somewhat regular but long-term eliptical orbits. As they approach us, they aren't <i>that</i> warm, and hence will be quite "Dark" to us. Or, it could be a one-pass on a hyperbolic trajectory; one in, once out, and thus lost to our solar system. We wouldn't even know to be looking for it.<br /><br />These things aren't that easy to image, even so. It really is hit-or-miss, and painstaking persistance. <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>

 

[halman]

Yevaud,<br /><br />Okay, I think that there is some confusion at work here. What I have been describing is a system specifically for detecting those asteroids which spend most of their time inside the orbit of the Earth. I am not suggesting that this system would be the best way of detecting rocks from the outer reaches of the Solar System, although, with some modification, it would probably work for that, too. But it is those asteroids which orbit to sunward of Earth, most of the time, which pose the greatest danger, because we cannot detect them using visible light. We could be hit without any warning whatsoever by a member of this group of space debris.<br /><br />This detection system would be a fairly cheap, quick way to catalog all bodies which orbit in the inner Solar System, which we could then track by radar. This is not a purposal for detecting inbound rocks from outside the orbit of Jupiter. That is an entirely different problem, but one which I don't think is quite as dire as the potential for being completely blindsided by something which we currently have no method of detecting. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[yevaud]

I see.<br /><br />Well, yes, it will be very useful indeed to assess and track all Earth-crossing objects within the inner solar system. Personally, that's not where I see the major problem arising from. It's those that approach from farther outwards that we don't yet know about. And they are truly difficult to locate; literally, to repeat what I'd said, "hit or miss" (a miss, I do hope!). They are terribly "dark," both optically and in the Thermal and IR bands.<br /><br />As far as Radar goes, the problem is that there is no singular Radar system in existence right now that could do so. Were we to build such (I am wholeheartedly for it), it would have to be space-based, and quite possibly the most powerful Radar system ever built. Sheer scale alone requires that. Else we would be detecting infalling objects only a few thousand miles distant, which would be effectively useless for our purposes. So a major project would be neccessary. <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>

 

[willpittenger]

Halman was talking about RADAR for <b>known</b> objects only. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[yevaud]

***/ Deleted pending a better reply to this issue/ *** <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>

 

[rocketman5000]

If we defined a distance we wanted to detect infalling opjects out to and described a minimum size we wished to detect (world killer size I would presume) wouldn't it be possible to design a system of space based radars that could cover the sky? You wouldn't need to know where the object would be at the time of the signal contacting it as what you are trying to detect are objects coming straight at your transceiver. <br /><br />Understandably this would either have to be a large system of small radars or small system of enormously powerful radars. I would prefer lots of small radars with each system's coverage overlapping 50% of its neighbors "airspace" This would provide a duplication of data and redundancy while reducing satelitte mass and power required. If a central processing unit was available between all satelittes you could use the receive the signal from one unit at another and potentially track objects moving perpindicular to your radar signal. If every radar station transmitted at a different frequency it might be possible make this idea a little more feasible

 

[halman]

Yevaud,<br /><br />Upon further research, I have discovered that there is a class of asteroids called Aten which have orbits that lie mostly inside of the Earth's, but which cross the Earth's on a regular basis. The recent scare about a possible collision in 2029 involved one of the few known Aten asteroids. There is a great deal of evidence that debris can be found all over the Solar System, some of it of considerable size. Granted, an infalling rock may have considerable destructive power, due to the velocity it aquires approaching the Sun, but a large rock cutting across the Earth's orbit at a sharp angle would also have substantial potential energy.<br /><br />Of the two, it is far more likely that something falling into the Sun's gravity well will be detected, as it is almost impossible to search for objects with orbits inside of the Earth's. One of the currently identified Aten bodies is listed as 'lost', due to the orbit not being calculated accurately in the observation window available.<br /><br />Be that as it may, my suggestion for using the Sun as the transmitter for a detection system is applicable to objects further out than Mars, and possibly as far as Jupiter, in that the Sun produces radiation across a broad spectrum. Certainly, some band of that radiation would be reflected by any object close to the Sun, just as visible light is. By building a series of satellites with detectors tuned to such a band, and placing them in a sphere surrounding the Sun, detection of practically every object in the Solar System above a set minimum size would be possible. We have little chance of equaling the output of the Sun in terms of radiation, even with nuclear explosions. Just as radar has evolved from using wavelengths of several centimeters to modern micrometer systems, so we should be able to find a suitable bandwidth in the Sun's emissions for use in detection of bodies within the Solar System. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[halman]

rocketman5000,<br /><br />Considering that we are talking about detecting objects approaching from any angle relative to the plane of the ecliptic, and at distances measured in hundreds of millions of kilometers, radar is just not an option, for reasons I have stated in earlier posts. Of course, pulses generated by thermonuclear explosions in the gigaton range are excluded from those constraints. However, we might have to deal with an ElectroMagnetic Pulse that wipes out all electronics not protected by substantial shielding if such means are used. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[halman]

newsartist,<br /><br />If we did indeed deploy a sphere of detector satellites around the Sun, say at 2 Astronomical Units distance from the Sun, even such a body as the one you describe could be detected. However, such a body would have to have terrific velocity, if it were not to be considerably deflected by the Sun. So, again, having detection capability for objects inside the orbit of Earth would be of paramount importance.<br /><br />But that begs the question; what would we be able to do about a rock headed our way? Blowing it into a bunch of small rocks (100 meters plus in diameter) would not be such a good idea. With our current and near future proposed launch capability, it is unlikely that we could intercept with a large enough payload to do any deflection.<br /><br />I still remember the feelings I experienced back in 1991 or 92 when I read about a 1 kilometer rock that was not detected until it was passing between the Moon and Earth. We still are subject to termination without notice. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>