Wishing and hoping doesn’t make it real

Credits: NASA/JPL-Caltech/T. Pyle

Credits: NASA/JPL-Caltech/T. Pyle

Look, I’m a space nut. It says so on the header up there. So when NASA announced the discovery of “Earth 2.0” I was as excited as the next space nut.

But let’s put this into context, people. What do we really KNOW about this planet, as FACT?

  • It’s in the constellation of Cygnus, 1,400 light years from Earth.
  • It orbits a star slightly larger than our sun, but of the same solar type.
  • The planet has an orbit of 385 Earth days.
  • It’s slightly larger than Earth.

And that’s it.

Let’s face it folks, astronomers have done a LOT of conjecturing on what amounts to a slight dip in the brightness of the star as the planet passes across its face. Science Alert has a rather good article about the discovery, with a little less hype.

We don’t know how long its day is. We don’t know the composition of its atmosphere. We might think it’s rocky but we can’t be certain. We certainly can’t suggest for a moment that its surface looks like the wonderful artist’s impression at top left. We should remember that Mars and Venus are in our sun’s habitable zone. Venus, in particular, could be seen as Earth’s twin – from a distance.

That said, (and to quote Captain Piett) it’s the best lead we’ve had. He was promoted to Admiral not long after that. Maybe we should send a star fleet to check Kepler 452b out. Maybe we’ll meet some Klingons.

 

 

Star Wars ISD – a good design, or not so hot?

https://en.wikipedia.org/wiki/Star_Destroyer

Oh, man. The majestic Imperial Star Destroyer.  I’ve said before it was one of the reasons I fell in love with Star Wars. Here it is in all its glory. Bristling with weapons, a space-going aircraft carrier cum assault ship. According to Star Wars: The New Essential Guide to Vehicles and Vessels, the 1.6km long ship carried 9,700 soldiers, 72 TIE fighters, 20 AT-ATs, 30 AT-STs and an assortment of barges, gunboats, transports, shuttles and Skipray blastboats. Look at it, all angles and details, with its huge bridge (complete with picture window) and shield generation domes. Be still my beating heart. I built the plastic model, of course, and added lots of spiky details. It was/is a thing of beauty, and a joy forever.

And yet, that’s not what the battle cruisers in my novels look like. Why is this so?

Not, as you might imagine, the copyright issue. Nor is it anything to do with streamlining. In space, streamlining is not an issue. (In fact, the space battles in the Star Wars movies were giggled at by most of us who know a little about space. Those fighters maneuvered as they would in atmosphere, diving and curving like World War I Sopwith Camels.) Getting back to the capital ships, provided they stayed out of a planet’s atmosphere, they could be any shape the mind can conceive. Let’s face, it that pointy bow is unnecessary, even if it looks cool. Same with the angled deck surfaces.

My reservations about the design are more about that bridge structure. Would you really put all your commanders in such an obvious place? I know it’s based on a sea-going ships’ superstructure but I think even in the world’s navies, the actual command centre is well-protected, within the ship. That great T-bone up there is an obvious target. Remember when, in The Empire Strikes Back, an asteroid collides with the bridge of one ISD and takes out the ship? Oops. And then the bridge of the great SSD Executor is hit by a rebel fighter in Return of the Jedi. Double Oops. What’s more, those shield generators must have a pretty mighty job to effectively blanket the whole ship from that position. Clearly, from the previous, with a certain lack of success.

So my ships aren’t pretty. They’re a bunch of rectangles stuck on top of each. The largest and lowest contains the hangars, the hydroponics, the artificial gravity generators, and down the far end, the engine rooms. The level above contains the troop accommodation and training areas, kitchens, workshops and the like, and the highest contains the bridge (although well down the decks) and Fleet accommodation. It’s a big ship, more like 5km long, plenty big enough to support a task force. And of course, it would usually have escorts to protect it. Although it carries quite a bit of its own protection in the hangars and the weapons (missiles and energy weapons) deployed around the decks. The shield generators are on the lowest level and carry charge to a network of emission sites over the hull.The ships have two drive systems, one for shift space when they travel enormous distances through different dimensions, and another for travel in normal space. Like Star Wars ships, they can make a jump within a system, arriving fairly close to a planet. The drives themselves use controlled nuclear fusion. Don’t ask me how. Just look at a star. We know it works.

So… would any of you care to share your observations or feelings about Lucasfilm’s creations? Or wax lyrical about your own?

A little bit of moonshine in the night

A lunar eclipse happened in my part of the world on 28th November, hard on the cosmic heels of a solar eclipse earlier in the month. As it turned out, the penumbral eclipse was a huge disappointment. No shadow across the moon’s disc, not even a reddening of the light. So the cirrus cloud partially obscuring the view didn’t matter much. We had moonshine as we always do and the photos were a fizz.

However, it got me to wondering about moons; ours, and other moons in general. To start with, let’s mention the eclipse – the truly spectacular solar eclipse that happened earlier this month. It was a partial eclipse in my part of the world, but even so it is a special event. But why is it so? The moon is tiny compared to the sun.

An extraordinary cosmic coincidence

The sun is about 400 times the moon’s diameter and about 400 times as far way from the Earth and that ratio means that when the moon comes between the sun and the Earth, that shadow is just about a perfect fit.  That relationship is a coincidence. Evidence indicates that the Moon was once closer to the Earth and is gradually moving away, so enjoy your cosmic moment, knowing that in the distant future, there will be no total solar eclipse.

That factoid is not the only extraordinary thing about our moon. Not at all.

It’s not the largest moon in the solar system. In fact, going by this list it comes a creditable fifth after Ganymede (Jupiter iii), Titan (Saturn vi), Callisto (Jupiter iv) and IO (Jupiter i). Indeed, Ganymede and Titan are both larger than Mercury and let’s not talk about poor Pluto. Really, when you think about it, it makes perfect sense that the largest planets have collected the largest moons.

Except ours.

Why is this so?

I have in my possession a tattered little paperback, a collection of essays on astronomy by Isaac Asimov (Asimov on Astronomy, Coronet, 1974). One of the things I loved about Asimov, who had a PhD in chemistry and an interest in everything scientific, was that he could explain complex physics in a way that an interested amateur with absolutely zippo mathematical ability could understand. He wrote papers regularly for magazines and the like and subsequently, they were published in book form. This little volume is a treasure trove of scientific fact and some intriguing speculations. True, some of it is now dated, since it was published before the epic discoveries of Voyagers I and II. Pluto had not yet been demoted. And yet before it could be proved he predicted that many planets other than Saturn would have rings.

To get back to the point, one of these essays is entitled “Just Mooning Around” in which Asimov talks about the gravitational effects of the sun, the planets and the moons in the solar system have on each other. Without going into all the details of the paper, he talks about the ‘tug of war’  ratio, which argues that in most cases, the gravitational attraction of a planet on its moons is vastly greater than the pull of the sun on those same moons. There is also a kind of ‘goldilocks’ zone around a planet in which a true moon would exist (as opposed to loosely captured satellites like Neptune’s Nereid). A moon must be between a minimum Roche limit and a maximum ‘tug of war’ distance. For the mind-bending number-crunching, go read it yourself – I told you I can’t do maths. However, I can appreciate logic. And you will see it is so.

According to his theory, of the four innermost rocky planets, Mercury could not have a moon because it has no ‘goldilocks’ zone. The other three are highly unlikely to have moons because of the narrowness of the ‘goldilocks’ zone. And indeed, Mercury and Venus do not have satellites, and Mars’s Phobos and Demos are overlarge potatoes which are expected to disintegrate.

I see you jumping up and down. What about us? Earth and that thing up there?

Ah, Asimov argues that the Earth/Moon pair is not a true planet/moon relationship because the Moon is so much larger in comparison with its primary than any other such relationship in the solar system. By a long way. He suggests that the Earth/Moon combo is really a binary planet, waltzing its way around the sun. Of course, all planets with moons have a wobble in their orbit but the Earth/Moon shimmy must be quite pronounced. Certainly I don’t think there’s much disagreement these days that our Moon was derived from the same stuff as the Earth. This article suggests accepted theory is that a Mars-sized object collided with the Earth, aggregating the material and spewing off a portion which later formed the Moon.

The next thing you have to wonder is – how important is that massive moon to life on Earth? But that’s another topic, isn’t it?

Isn’t science wonderful?

What would you weigh on an exoplanet?

picture of an exoplanetI was reading an article from somebody, all enthusiastic about the exo-planets the Kepler probe keeps finding. They’re all many times larger than planet Earth even if they’re in the ‘Goldilocks’ zone. You know the one – not too close, not too far, just right. That is, a planet neither too close to its primary nor too far away, where liquid water could exist. My immediate reaction was ‘sure, but we’d weigh too much’.

Then I began to wonder how much more. I’m not a mathematician – never have been. In truth, I can’t add up to save my life. So I’m counting on you (ha ha) to correct me if I get this wrong.

I discovered this site http://www.exploratorium.edu/ronh/weight/ and learned that gravitational pull weakens by the radius squared. So let’s say you weighed 60kg on planet Earth. Planet Gliese 581g is estimated at 2.6 Earth masses and 1.4 Earth radii. So yes, you’re going to weigh more on Gliese 581g, but not 2.6 times as much. If I’ve got this right, the increased diameter of the planet means you’ll weigh about 1.3 times as much – so about 78kg. That’s certainly not a huge imposition. And all of a sudden, I’m bouncing in my chair, going oooh oooh.

Here’s some estimated figures about Gliese 581g, taken from this fascinating website http://phl.upr.edu/projects/habitable-exoplanets-catalog

Mass = 2.6 Earth Radius = 1.4 Earth  Temp = average surface temperature, so this place, at 10, is rather cooler than our 15 degrees (NASA’s figure from 2008), but the estimate of average temperature assumes an Earth-like atmosphere, which is a pretty big assumption. On the face of it the planet zips around its sun in a fraction of the time it takes ours, taking only 32 days as compared to 365. But that might not be the case, since the Gliesean day may be much longer than Earth’s. The figures don’t mention period of rotation, which I find a tad surprising. As a comparison, Venus’s ‘day” (the time it takes to rotate on its axis) is actually longer than its year (the time it takes to orbit the Sun.) (http://www.universetoday.com/14282/how-long-is-a-day-on-venus/)

So there you have it. I found out today that a candidate for Torreno (capital of the Coalition of Worlds in Morgan’s Choice) may be only 20.2 light years away. And with the shift drive of the future, that’ll be a place to add to your holiday plans.

Ain’t science grand?

Humans are such fragile entities

The more I read about the strangeness of our universe, the more I wonder if we, humanity, will ever colonise other planets. There’s not much chance we’ll settle on a diamond planet and I have to wonder how we’d go on many of the ‘earthlike’ planets already pinpointed. We are such fragile entities, we humans.

I’m in the throes of writing a sequel to my space opera Morgan’s Choice, which accepts the existence of political groupings of star systems into coalitions, federations and the like. Hey, I’m not special in that respect. Lots of SF writers have done the same thing, with great success – Elizabeth Moon, Jack McDevitt, Isaac Asimov etc etc and of course, Star Trek, Star Wars and the like. But how likely is it really?

Like all other animals we are closely attuned to our environment, more so than many of us actually realise anymore. In these days of electricity we can heat or cool our homes, spend half the night watching TV, or reading books, source food from all over the world so nothing is ever out of season, cross distances that took years in days. Yet we cannot escape the factors which shaped us.

I think there are five vital factors we will not easily overcome.

The first is our perception of time.

I use the word ‘perception’ advisedly, because time is something we measure for ourselves to put ourselves into context, if you will. But whether we think the sun is rising where we are, or setting, our bodies are built to expect a ‘day’ of twenty-four hours or so, because that’s how long it takes for the planet to revolve on its axis. What’s more, if we are suddenly wrenched from one time of day to another, as happens with long distance air travel, it takes time for our bodies to adjust. (It’s called jet lag)

Next is gravity, what we call weight.

We have evolved to suit the amount of force the planet exerts upon is. The advent of space travel and weightlessness has proved how important gravity is to our ability to function. Without gravity our bones lose density and muscles atrophy.

Then we move on to air.

Most of our atmosphere, what we breathe, is nitrogen, with twenty-three percent oxygen and a bunch of other gases in smaller quantities, including carbon dioxide. It also has a level of density. There’s more of it at lower altitude (see gravity). See what happens to mountain climbers if they climb before becoming acclimatised. Their bodies can’t cope. And if that mixture of gases changes past a certain level of tolerance, then what?

Then there’s temperature.

Humans exist in an apparently wide range of climates, providing they can find protection from the elements. But the range is actually not that wide in the scheme of things. This article in New Scientist speculates that global warming of only about 11° would render many places on our own planet ‘unliveable’.

The last factor is light.

Earth orbits a G class star which emits light towards the red end of the spectrum. We’re used to seeing colours in that light. If we lived on a world orbiting a cooler star with redder light, or a brighter star with more bluish light, we’d see colours differently.

Humans are adaptable. That’s why the species has been so successful. But even so, we’ve only ever had to adapt to the extremes of one planet. If humans are to venture to other planets I believe we will have two choices; terraform the planet into another Earth or modify the settlers to cope with the conditions. That would mean physically very different races of humanity occupying different planets. And here again, SF can offer plenty of examples. One that springs to mind is Moon and McCaffrey’s joint effort, Sassinak, where members of the Star Fleet have different body characteristics, depending on which planet they come from.

I admit I don’t take that route in my own writing. I simply assume all planets are earthlike, with only small variations in light, heat, time and gravity. I reckon I’m in pretty good company. Come on SF fans and writers, what do you do, what do you prefer?