Wednesday, September 28, 2011

World of Two Suns

Planets orbiting a binary star
Rocketpunk Manifesto has never claimed to be a space news blog, so I make no apology for being the last space blog in the known universe to mention last week's report of a planet found orbiting both components of a double star. (There is no indication - yet - of more than one planet in this system; see illo note at the end of this post.)

I will apologize for slower posting of late, the excuse being a couple of new work gigs I'm still breaking in.

But back to the world of two suns. The interesting thing about this - apart from the discovery itself - is that when I was growing up, and for long afterwards, the standard wise advice for any SF writer aiming for a speck of hardness was to avoid binary-star planets like the plague.

Any such planet was liable to be hurled out of its birth system. Even more to the point it was unlikely to form in the first place, disrupted before birth by the processes that formed a binary star in the first place. Which meant that in hard SF perspective, any planet of a binary might as well be 1930s baroque, with the blue sun rising as the red sun was sitting and the orange sun was at midafternoon.

Not for the first time - and surely not for the last - elegant inference has been trumped by observation.

Certainly not for the first time in the history of extrasolar planet discoveries. The first such worlds to be found, in 1993, were so hard to wrap our collective mind around - three planets orbiting a pulsar - that they were not fully acknowledged as 'real' planets.

Then came 51 Pegasi b, in 1995. The star is suitably sunlike, but no one expected a planet comparable in mass to Jupiter to be orbiting several times closer in than Mercury. And basically things have stayed weird ever since.

Before 1995, I'd venture that most people (who thought about it at all) expected more or less the same thing I did. Extrasolar planetary systems, when we found them, would mostly have the same overall organization as the Solar System. They'd have some rocky terrestrial inner planets between about 0.3 and 3 AU, and some gas giants out beyond the 'snow line.' Beyond the gas giants would be nothing much.

Details would vary, of course. Some systems might have only two or three planets, others well over a dozen. A few with planets bigger than Jupiter - even approaching brown-dwarf mass - and other systems with only Saturns or Neptunes. Most of these planets, big and small, would be on near-circular orbits, in striking contrast to the highly eccentric orbits typical of binary and multiple stars. The spacing of their orbits would likely be suggestive of 'Bode's law.'

By the current more or less official count of the Paris Observatory there are now 687 confirmed extrasolar planets. And precisely none of them are in systems with an overall architecture like I just described.

As I have noted here before, this is (probably) at least in part an artifact of observational 'selection effects.' Most of those 687 planets have been discovered by techniques that have a technical bias in favor of large planets close to the parent star. Indeed, a duplicate of the Solar System would be only at the threshold of detectability.

All the same it is starting to be just a little bit odd that so few known extrasolar planetary systems are even kinda sorta like the Solar System. Looking at the Paris Observatory website, there is just a hint that planets are more common around 5 AU - Jupiter distance - than around 4 AU or 6 AU. Some even have fairly circular orbits.

But all in all, the planets and planetary systems we have been finding have amazingly little in common with the ones we expected.

I don't want to draw very many large conclusions from this, except perhaps that 'large conclusions' are likely to be wrong. In particular, note that this particular discussion is entirely about the physical (and observational) facts about astronomical bodies, not about future human societies that might investigate those worlds, or seek to do more than investigate them.

But they are interesting, in themselves and for their possible place in human affairs, SFnal or otherwise.


The image comes from - but just to keep things interesting, it illustrates a discovery made last fall, not last week.

Tuesday, September 13, 2011

At the Speed of Story

Shuttle Endeavor docking to the ISS
Spaceships in science fiction, as was first noted by a commenter in the early days of this blog, always travel at the speed of plot. This observation is recurrent, including in comments on the previous post.

The title is a mashup of this principle with Teresa Nielsen Hayden's dictum that plot is a literary convention, while story is a force of nature.

All of which goes to explain why this blog is, in some respects, a futile effort. When story collides with other considerations (such as realistic space travel), story invariably wins.

I have first-hand experience of this problem, which I will be delving into further in upcoming posts. Suffice it for now to say that when a cool technology led me to a story, the story took over completely. And I mean completely. Among other things, not one but two battle sequences ended up on the cutting room floor. They had become distractions from the story; therefore they had to go.

There are, at best, some limited protective measures. The most obvious is to go with the flow. If your story calls for fighter jocks, you are going to need fighters for them to fly. These don't necessarily have to be space fighters - if a planetary atmosphere is handy, air fighters are legit - but you will certainly need fighters of some sort.

The implausibility of space fighters won't get you off that hook. You'll have to either make them plausible - or else say the hell with it and go with implausible ones. This is an eminently safe option. The great majority of readers will neither know nor care. Of the relatively few who do care, most will forgive you. Especially if they like the story.

Other options are available. A radical but straightforward one is to avoid telling a story. This is the strategy I have followed in this blog. I've posted only a handful of fiction snippets here, and most of those had nothing to do with space. (My only actual rocketpunk SF has been a couple of paragraphs in a very early post.)

There is a modest but real interest in 'nonfiction' space speculation. It is not too hard to find blogs or other websites that discuss and describe imaginary spacecraft without trying to tell stories in which they figure. But such is the power of story that it is always lurking, waiting for a chance to intrude. To identify your laser star or killer bus as belonging to the Zorgon Empire is to invite speculation about where or what Zorgon is and how it became an empire. Warning lights flash and sirens warble, because you are now under intrusion by an incipient story.

I ought to note here that all of this applies not just to the details of spaceships and the like, but to the entire setting. I have mentioned a few times here that there are plausible space futures that are simply not very story-conducive. But the comment threads for those posts always veer toward how to get a story out of it.


Last post I mentioned that there are no known cases of spacecraft docking maneuvers being filmed from a third spacecraft. There turns out to be an almost-exception: The image of the Shuttle Endeavor - on its final mission - docked up to the ISS comes was filmed from a nearby Soyuz. It comes from this rather interesting blog.