About the name of planets, I think the naming them by numbers could work only if the structure of the solar system is known by everyone. {pavyplini} or {plini.xipa} (the . is mandatory since {plinixipa} might be mistaken for a fu'ivla) could work. In fact, jbovlaste already has {pavyplini} and friends.
It's not that it *might* be mistaken; morphologically, {plinixipa} is a zi'evla. Rather than a {.}, a space is also just fine. Also, I don't see why the use of {xi} jumps to mind so suddenly, especially when we have {moi} for making ordinals: {lo plini pamoi} -> "mercury".
That said, I don't like this naming scheme very much, I'd like to have some cmene for planets in our solar system. I would be tempted to use the greek/latin names as basis but I would really like to have someone who could inject some Arabic or Chinese into it.
Our moon has already a lojban word {lunra} that means "x1 is a major natural satellite/moon of planet x2" (by default our Moon). Jbovlaste also offers a word (a fu'ivla) for a generic satellite: {mluni} "x1 is a satellite/moon orbiting x2".
{mluni} isn't a fu'ivla, it's a gismu of the form CCVCV. (fu'ivla can't be five letters long, as that's a criterion for being a gismu.) {lunra} refers only to major natural satellites, namely moons, whereas {mluni} refers to essentially anything in orbit around a planet or something basically equivalent. {la sorgu'e ke kensa stuzi (my (bad) description of "international space station") cu mluni la terdi}.
If you like the numbering scheme probably {lunra.xivore} could be the second moon of Mars. What I don't really like of using numbers is that it assumes a precise knowledge of the entire system: which moon of Jupiter is Io ?
Using {lunra xi vo re} for the second moon of Mars isn't a very good idea; what if we want to refer to the thirteenth moon of the eleventh planet? {lunra xi pa pa pa ci}? Seems ambiguous... Could be the 113th moon of the first planet. Or the third moon of the 111th planet. Anyway, the point is that if you're going to use the xi-system, you need to use pi'e to separate moon-number from planet-number: {lunra xi vo pi'e re}. Why not just use the structure of lunra though? {lunra xi re lo plini xi vo}
Still, the moi-system seems far more appropriate here: {.i lo remoi co lunra be lo plini vomoi} We can use a big ol' tanru to represent this, too: {.i lo plini vomoi ke lunra remoi}. This system can also produce lujvo: {.i plinyvonmoikemluryrelmoi}.
As for this system requiring a precise knowledge of the solar system... it's an argument that doesn't work if these words become commonplace. You have to think that if these number-based words were the common terms for all these celestial objects, then by virtue of knowing the object's *name* you would know its position. This is a *feature* of the system, rather than an issue. If, since birth, we always referred to the planets this way, we wouldn't have to *learn* the order of the solar system, as the order would be integral to the naming system.
I can, however, see one major issue with the numeric system: what if we discover a new planet between two existing ones? What do we call it? If it's discovered between planet 3 and 4, do we call it planet 3.5 ? Do we shift all the other planets back and call this new planet planet 4 ? As far as I can tell, this is the only real shortcoming of this system.
A carbon nanotube could be a {navtabytu'u} and a space elevator a {kensa galgau}.
Elevators are machines rather than agents, and I'd suggest {galzenrikmi'i} "height increase physical-cause machine". Perfectly jvajvo. As for carbon nanotube, I don't think that a lujvo is ideal for this concept. (Due to it being extremely naljvajvo, as in practically 0% jvajvo.) Why not just use a tanru? {.i tabno ke nanvi tubnu}.
For the asterorid belts, I would try {plinyspi djine} (ring of planet fragments).
ie. Although, if we want to emphasize that the belt is composed of many objects -- or rather, if we want to specify how "dense" the belt is -- we can throw in {so'Vmei} -> {plinyspi so'imei djine}. Looks like this tanru could equally be used to describe the rings around planets such as Saturn. Throwing in {fi'o se sruri lo solri} or {fi'o se sruri lo plini xamoi} fixes that.
Lastly (take it "cum grano salis") {lo nundoifli cu mibysnadygau} for "your failure makes my success.
I disagree that gasnu1 can be an event (which is effectively what your bridi states.) I'd suggest {lo nu do fliba cu nu mi snada}. No need for lujvo here.
remod
btw, does you Sci-Fi occours inour solar system?