Sunday, July 26, 2015

Pluto a planet?

(This post doesn't concern Nethack).

With NASA being a total winner with its New Horizons mission to Pluto, the debate about whether Pluto should be a planet has emerged yet again.

You can look at wikipedia for more details, but the basic story for how Pluto lost its planet status, or rather, how planet gained its definition is as follows: in 2005, astronomers found a dwarf-planet called Eris with a slightly wackier orbit than Pluto's.

Other, similarly-sized objects had been found, but the kicker in this case was that Eris is more massive than Pluto (still, both are less massive than our own pet rock, the Moon).  This prompted the International Astronomical Union (IAU) to actually come up with a formal definition for the word "planet" in 2006.

So, according to the IAU, in order to be a planet, a celestial body must:
  1. is in orbit around the Sun,
  2. has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and
  3. has "cleared the neighbourhood" around its orbit.
(Incidentally, I assume #1 is why we refer to natural satellites of other stars as "exoplanets" instead of "planets").

Pluto apparently has failed the third test because it shares its orbit with other Kuiper belt objects.  This led to Pluto being deemed a "dwarf-planet", which led to everyone losing their shit because they wanted Pluto to be a full-fledged Planet.

I propose to you a new stance on the topic.  Whether Pluto re-gains its status as a full-fledged planet is irrelevant.  My proposal is that the word "planet" should re-gain its status as not being formally defined by the IAU.

The term "planet" is a cultural term that goes back centuries.  Everyone knows what you mean when you say "planet" and almost no one can recite the formal IAU definition of "planet".  At the same time, if people want to use more technical terms, like "Kuiper belt object", they already exist.  Undefining the word "planet", i.e., making its meaning ambiguous, is a win-win solution.

Tuesday, June 23, 2015

Space Brick

This post has nothing to do with Nethack.  It does, however, have something to with Kerbal Space Program (KSP) 1.0.x.

For those familiar with KSP, you know that prior to the release of version 1.0, there was no atmospheric model.  The amount of atmospheric drag a ship would generate was a function of the mass of its constituent parts.

The folks over at Ferram Aerospace Research (FAR) created a game mod that replaced the stock KSP aerodynamic system with a much more realistic aerodynamic system that took part placement and occlusion into account, along with other things like Mach effects, etc, etc.  It's a brilliant mod.

To give a brief background, the makers of KSP, Squad, released 0.90 Beta a while back, and said their next version would be 1.0 GA (general availability—I assume most are familiar with the term?  At least, that's why my place calls it.  In short, GA is what comes after Beta in the software release life-cycle).

Squad said they would add procedural fairings and an atmospheric model that included aerodynamic heating.  As someone who writes software professionally, I pondered the concept of a single Beta release prior to a GA release and immediately thought, "no fuckin' way."  But, Squad pulled it off and did an amazing job.  It was an extremely impressive feat.

Of course, the folks over at FAR overhauled their aerodynamic model and made it much more hardcore for KSP 1.0.x, taking stuff like cross-sectional area into account when calculating wave-drag at transonic speeds.

Anyway, getting back on topic, one feature that FAR has had for a long time now, and that KSP added as of 1.0.x, is body lift.  In the words of FAR: "All parts lift: a fast enough brick will fly, if not that well."

So, I set out to make a brick.  Rather, a Space Brick.  The rules I gave myself were as follows: no control surfaces of any kind, meaning no wings, winglets, canards, airbrakes, parachutes, flaps, spoilers, etc, etc, etc.  I also opted to not use reaction control systems (RCS), but that wasn't forbidden by my rules.  The Brick had to be able start on the runway at the Kerbal Space Center, achieve orbit, de-orbit, land back on Kerbin, and come to a stop on the runway at the Kerbal Space Center.

(Note the lawyerly wording above.  More on this later.)

Lift is generated entirely by the body, and steering is accomplished entirely by vectored thrusting (and a single reaction wheel that is built into the cockpit by default that I didn't turn off, but it's probably not needed).

The Space Brick is only "capable" in stock KSP 1.0.x.  It does not fly very well with the FAR mod installed.

Also note that I use the MechJeb2 mod so I can plaster a bunch of numbers on the screen that are helpful to me.  The Smart A.S.S. window is open, but it's not needed and I didn't end up using it.

As for the lawyerly wording above, the Brick cannot take off from the runway.  Take-off is accomplished by channelling your inner Jeremy Clarkson, stomping on the throttle, and yelling "POWER!!!"  The Space Brick has to shoot past the end of the runway before it can pull up.

Similarly, since the Brick is only is controllable at around Mach 0.7 or faster, it needs a lot of room to brake after landing, which is why it doesn't have to land on the runway after de-orbiting; it just needs to come to a stop on the runway.

Single Stage to Orbit

This part is actually very easy.  It's a straight shot from the runway to an equatorial orbit.  No commentary needed.

Atmospheric Entry

This was a bit tough.  I had to adjust the center of mass throughout my descent by shifting fuel around.


In short, it's possible:

So, yes, you'll notice that the version in orbit and the version landed are slightly different.  The landed version has many more wheels.  Also, the atmospheric entry and landing (and take off) screenshots were from three different flights.

In short, I have a proof of concept.  In theory, it's possible to take-off, orbit, and land in a single flight, but I'm hoping for someone who's a better pilot than I am to string these feats together into a single flight.

At the moment, I'm trying to figure out how to attach the craft file.


So, I've figured out how to attach the craft file...kind of.

I don't want people following a link to a file that will make people panic (i.e., a flat-text .craft file should be visible as flat text before you decide to download it to your computer).  Since KSP craft files are just flat text files (as all good files are), I copied and pasted the text into a Google word doc.  That's right, I'm copying and pasting the contents of a flat text file into a Google Word Doc (yes, Google, I'm making fun of you for copying Microsoft Word for your docs format).

You can view the Google doc and copy and paste the text into a file and rename it as Space\ Brick.craft, or whatever the hell you want to name it.

In the meantime, I'll just curl up in a corner and cry and pull my hair out for what I had to do to attach the craft file.  Can you spell "KLUDGE"?