# Rocketry question **URL:** \ **Category:** Factual Questions\ **Created:** [May 15, 2007, 8:15pm UTC](https://boards.straightdope.com/t/rocketry-question/404229 "2007-05-15T20:15:09Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![Hypno-Toad](https://avatars.discourse-cdn.com/v4/letter/h/b2d939/32.png) [@Hypno-Toad](https://boards.straightdope.com/u/Hypno-Toad)\ **Post date:** [May 15, 2007, 8:15pm UTC](https://boards.straightdope.com/t/rocketry-question/404229/1 "2007-05-15T20:15:09Z")
Lets say a submarine in the middle of the Pacific Ocean launches a missile into orbit. How big a radius is required to keep ground observers from seeing the launch? This is assuming that there is no obstruction by intervening terrain or atmospheric conditions. Also, I’m excluding airborne or orbital observation. I have seen shuttle launches from the roof of a 6-story garage in Fort Myers, 3-4 hours SW of Cape Canaveral. But even haze can significantly reduce observation. ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [May 15, 2007, 8:36pm UTC](https://boards.straightdope.com/t/rocketry-question/404229/2 "2007-05-15T20:36:25Z")
I am not aware of any submarine-launched missiles that are capable of orbit. Not relevant if this is a hypothetical question, except that a missile capable of orbit would have a longer boost phase than a conventional [submarine-launched ballistic missile](http://en.wikipedia.org/wiki/Submarine-launched_ballistic_missile), and thus be visible from a longer distance. ---
**Author:** ![Hypno-Toad](https://avatars.discourse-cdn.com/v4/letter/h/b2d939/32.png) [@Hypno-Toad](https://boards.straightdope.com/u/Hypno-Toad)\ **Post date:** [May 15, 2007, 9:37pm UTC](https://boards.straightdope.com/t/rocketry-question/404229/3 "2007-05-15T21:37:55Z")
[QUOTE=Fear Itself] I am not aware of any submarine-launched missiles that are capable of orbit. Not relevant if this is a hypothetical question, except that a missile capable of orbit would have a longer boost phase than a conventional [submarine-launched ballistic missile](http://en.wikipedia.org/wiki/Submarine-launched_ballistic_missile), and thus be visible from a longer distance. [/QUOTE] Yes, it’s hypothetical until I’m authorized to say otherwise. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [May 15, 2007, 10:08pm UTC](https://boards.straightdope.com/t/rocketry-question/404229/4 "2007-05-15T22:08:20Z")
I don’t think I understand the question; how big of a radius of what? **Fear Itself** is correct in stating that SLBMs are not designed for and not capable of orbital launch. Even if they were, though, it’s not as if the booster goes straight up; although it is initially fired in the vertical orientation to get it up above the thickest bit of atmosphere, as soon as aerodynamic loads will permit it is pitched over at an angle in order to get enough tangential speed to get the payload into whatever orbit it is trying to achieve. I’ve seen evening polar orbit launches out of Vandenberg AFB from Los Angeles. You can see the ISS in orbit, even during the day depending on clarity and the position of the Sun. So it’s not a matter of it being at a certain altitude and disappearing. Stranger ---
**Author:** ![633squadron](https://avatars.discourse-cdn.com/v4/letter/6/ee59a6/32.png) [@633squadron](https://boards.straightdope.com/u/633squadron)\ **Post date:** [May 15, 2007, 10:33pm UTC](https://boards.straightdope.com/t/rocketry-question/404229/5 "2007-05-15T22:33:38Z")
[QUOTE=Hypno-Toad] Lets say a submarine in the middle of the Pacific Ocean launches a missile into orbit. How big a radius is required to keep ground observers from seeing the launch? This is assuming that there is no obstruction by intervening terrain or atmospheric conditions. Also, I’m excluding airborne or orbital observation. I have seen shuttle launches from the roof of a 6-story garage in Fort Myers, 3-4 hours SW of Cape Canaveral. But even haze can significantly reduce observation. [/QUOTE] I think you’ve left too much undefined. What constitutes “seeing the launch”? Do you not want them to see the liftoff itself, do you not want them to see the vapor trail? I have seen contrails from launches at Point Mugu/Vandenberg AFB all the way up in SF Bay Area, several hundred miles away. I didn’t see the rocket itself, but it was immediately evident that it **was** a rocket and had at least two stages. An orbital rocket doesn’t go straight up anyway. It will be several hundred miles “east” of the launch point by the time it reaches orbit, assuming that it uses the Earth’s rotational “boost” and is heading for a roughly equatorial orbit. The rocket itself will be invisible long before its exhaust trail. The exhaust trail will describe a roughly hyperbolic curve. You can’t just use assumptions about Earth’s curvature “hiding” the launch. ---
**Author:** ![633squadron](https://avatars.discourse-cdn.com/v4/letter/6/ee59a6/32.png) [@633squadron](https://boards.straightdope.com/u/633squadron)\ **Post date:** [May 15, 2007, 10:36pm UTC](https://boards.straightdope.com/t/rocketry-question/404229/6 "2007-05-15T22:36:07Z")
[QUOTE=Stranger On A Train] I’ve seen evening polar orbit launches out of Vandenberg AFB from Los Angeles. You can see the ISS in orbit, even during the day depending on clarity and the position of the Sun. So it’s not a matter of it being at a certain altitude and disappearing. [/QUOTE] As I noted, I’ve also seen these launches, but I noticed the exhaust trail rather than the vehicle itself. If you can see the ISS during the day, it’s because of reflection not resolution; a dark-painted launch vehicle would hardly be visible. ---
**Author:** ![Jurph](https://avatars.discourse-cdn.com/v4/letter/j/50afbb/32.png) [@Jurph](https://boards.straightdope.com/u/Jurph)\ **Post date:** [May 15, 2007, 11:41pm UTC](https://boards.straightdope.com/t/rocketry-question/404229/7 "2007-05-15T23:41:54Z")
I’ll take exception, even though I know **Stranger on a Train** knows his stuff, and say that if your payload was small enough, you might be able to get it to low orbit with an SS-N-23. In fact, I was able to find a [source](http://nssdcftp.gsfc.nasa.gov/miscellaneous/spacewarn/spx.537) that claims it’s been done. Note the payloads are called “microsats”. Here’s another [source](http://www.spacetoday.org/Rockets/Plowshares/Submarine.html). You could also hire the chaps at [Sea Launch](http://www.boeing.com/special/sea-launch/) to head towards some equatorial area with little population – somewhere in the middle of the Pacific should work. As for exactly where, I’d need a copy of an orbit simulator and a map of all populated places, but there’s probably a spot near Hawai’i that would be okay. Let’s assume you’ve got a microsat coated in Handwavium, so that it can’t be observed from earth. :dubious: All we need to do is determine the diameter of a rocket plume, and from how far away it’s visible, and then wait to do your launch until an east-bound storm system passes over your position, or between you and the nearest population center. Surface as soon as the weather clears, launch eastward from the equator, and Bob’s your uncle. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 15, 2007, 11:52pm UTC](https://boards.straightdope.com/t/rocketry-question/404229/8 "2007-05-15T23:52:51Z")
I’ll make a few assumptions, here. First, by “see the launch”, I’ll assume that you mean “within line of sight of the spacecraft while the engine is burning”. Second, I’ll assume an orbit height of 200 km (which would decay rapidly). A rocket must make at least one burn at its final orbital height, so the question boils down to the distance of the horizon from 200 km. The radius of the Earth is 6371.1 km, so the angle on the Earth to the horizon would be acos(6371/6571), or 14.16 degrees. Converting that to kilometers, we get 1576 km. If instead you want a more durable orbit of 400 km, we get 19.78 degrees, or 2202 km. Incidentally, I’m pretty sure that I’ve heard that some Russian missile subs have been converted to launch commercial payloads into orbit, but I can’t find any information on such. Certainly, though, one could in principle launch from a vessel in the middle of the ocean. ---
**Author:** ![Crescend](https://avatars.discourse-cdn.com/v4/letter/c/b9bd4f/32.png) [@Crescend](https://boards.straightdope.com/u/Crescend)\ **Post date:** [May 16, 2007, 12:19am UTC](https://boards.straightdope.com/t/rocketry-question/404229/9 "2007-05-16T00:19:50Z")
[QUOTE=Chronos] Incidentally, I’m pretty sure that I’ve heard that some Russian missile subs have been converted to launch commercial payloads into orbit, but I can’t find any information on such. Certainly, though, one could in principle launch from a vessel in the middle of the ocean. [/QUOTE] That would be the Штиль (Shtil’) launcher, a converted R-29 SLBM. Wikipedia link [here](http://en.wikipedia.org/wiki/Shtil'). ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [May 16, 2007, 12:26am UTC](https://boards.straightdope.com/t/rocketry-question/404229/10 "2007-05-16T00:26:16Z")
[QUOTE=Jurph] I’ll take exception, even though I know **Stranger on a Train** knows his stuff, and say that if your payload was small enough, you might be able to get it to low orbit with an SS-N-23. [/QUOTE] Ach, I was restricting my thinking to American SLBMs (Trident C-4s and D-5s). I don’t know about the Russian boosters (except that those _Typhoon_-class boomers are massive boats) so I’ll defer to those more knowledgable on that. **633squadron** , I didn’t really make a distinction between the booster and the plume because if you can see the latter you can’t hide the former. Stranger ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [May 16, 2007, 1:51am UTC](https://boards.straightdope.com/t/rocketry-question/404229/11 "2007-05-16T01:51:49Z")
I once saw the ascent & leftover exhaust trail of a dusk Vandenberg launch from our cruise altitude over the KS/CO border. That’s a little over 1000 miles from my position to the launch site. I later read that the missile was targeted at Kwajalein, so it was heading away from me as it climbed. I wasn’t on the ground, so I’m out of bounds for the OP’s question, but it points out the difficulty of launching something to orbit wothout people seeing it. ---
**Author:** ![Hypno-Toad](https://avatars.discourse-cdn.com/v4/letter/h/b2d939/32.png) [@Hypno-Toad](https://boards.straightdope.com/u/Hypno-Toad)\ **Post date:** [May 16, 2007, 2:53am UTC](https://boards.straightdope.com/t/rocketry-question/404229/12 "2007-05-16T02:53:36Z")
Of course all the answers come while I’m away. To clarify: How far away would the launch have to be so that _no one knew that the launch occurred._ If they can see the plume, they’ll know something launched. **Chronos** gave me the information I wanted. The reason I asked is that I was speculating about what course history might have taken if the US had invented orbital launch capability during WWII. Was there a place in North America or the Pacific that would have been remote enough to guarantee that no one could observe the launch or even see it? ---
**Author:** ![Jurph](https://avatars.discourse-cdn.com/v4/letter/j/50afbb/32.png) [@Jurph](https://boards.straightdope.com/u/Jurph)\ **Post date:** [May 16, 2007, 9:51am UTC](https://boards.straightdope.com/t/rocketry-question/404229/13 "2007-05-16T09:51:10Z")
Wow, rolling back the clock to WWII makes a big difference. You don’t have any 747s full of civilians (with cameras) crossing the Pacific several times an hour. The shipping on the Atlantic is pretty much limited to U.S.-protected convoys. The biggest thing in your favor is that nobody is going to know what a rocket plume _is_. Launch from the U.S. southwestern desert and send a few FBI agents around to local towns to tell everyone that the long-range artillery test they witnessed was a failure, and for heaven’s sake to keep their mouths shut. Send a few more to ask if anyone saw the meteor trail, and did they have any idea where it landed, because the military wants to use the materials in it for a new weapon. You get the idea. ---
**Author:** ![Sapo](https://avatars.discourse-cdn.com/v4/letter/s/ec9cab/32.png) [@Sapo](https://boards.straightdope.com/u/Sapo)\ **Post date:** [May 16, 2007, 11:55am UTC](https://boards.straightdope.com/t/rocketry-question/404229/14 "2007-05-16T11:55:36Z")
\*\*Jurph \*\* got it, I think. Some people might see it, but so what? If they don’t know what they saw, they didn’t see it. Plus, if you choose your weather wisely, you might shield it from good swaths of land. ---
**Author:** ![MarcusF](https://avatars.discourse-cdn.com/v4/letter/m/67e7ee/32.png) [@MarcusF](https://boards.straightdope.com/u/MarcusF)\ **Post date:** [May 16, 2007, 9:25pm UTC](https://boards.straightdope.com/t/rocketry-question/404229/15 "2007-05-16T21:25:38Z")
You could always say it was a weather balloon 😃