orbital mechanics

9 Articles

Hitchhiking To The Moon For Fun And Profit

March 18, 2019 by 43 Comments

On February 22nd, a Falcon rocket lifted off from Cape Canaveral carrying the Indonesian communications satellite Nusantara Satu. While the satellite was the primary payload for the mission, as is common on the Falcon 9, the rocket had a couple of stowaways. These secondary payloads are generally experiments or spacecraft which are too small or light to warrant a rocket of their own such as CubeSats. But despite flying in the economy seats, one of the secondary payloads on this particular launch has a date with destiny: Israel’s Beresheet, the first privately-funded mission to attempt landing on the Moon.

But unlike the Apollo missions, which took only three days to reach our nearest celestial neighbor, Beresheet is taking a considerably more leisurely course. It will take over a month for the spacecraft to reach the Moon, and it will be a few weeks after that before it finally makes a powered descent towards the Sea of Serenity, not far from where Apollo 17 landed 47 years ago. That assumes everything goes perfectly; tack a few extra weeks onto that estimate if the vehicle runs into any hiccups on the way.

At first glance, this might seem odd. If the trip only took a few days with 1960’s technology, it seems a modern rocket like the Falcon 9 should be able to make better time. But in reality, the pace is dictated by budgetary constraints on both the vehicle itself and the booster that carried it into space. While one could argue that the orbital maneuvers involved in this “scenic route” towards the Moon are more complicated than the direct trajectory employed by the manned Apollo missions, it does hold promise for a whole new class of lunar spacecraft. If you’re not in any particular hurry, and you’re trying to save some cash, your Moon mission might be better off taking the long way around.

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Orbital Mechanics On A Vintage Kaypro

April 8, 2018 by 18 Comments

These days, a good proxy for hacking prowess is getting Doom playable on the oldest piece of hardware imaginable. While we respect and applaud these efforts, perhaps the bar should be set a bit higher. Like orbital mechanics on an early 80s Kaypro, perhaps?

At least that’s the hurdle [Chris Fenton] set for himself as a fun project for his spare time with his Kaypro 2/84, a vintage Z80 clocking in at a screaming 4 MHz and 64-kB of RAM. With its built-in 80×25, 9″ green phosphor CRT monitor and flip-top keyboard, the Kaypro fit into that loveable luggable category of machines and predated IBM’s and Apple’s market dominance by a few years. The CP/M operating system has actually aged pretty well — but well enough to port [Chris]’ Deep Dish Nine, a graphical game written for the Arduboy that uses Kerbal-like orbital mechanics skills to deliver interplanetary pizzas? In the first instance, no — the game, ported to Turbo Pascal, only managed fractional frames per second, rendering it unplayable. But with some very clever coding, [Chris] was able to improve refresh rates 10-fold. The optimization road not taken includes hardware hacks, like overclocking the Z80 or even replacing it with an FPGA and emulator, but that’s hardly keeping with the spirit of the thing.

It’s always great to see vintage machines pushing the envelope. A great place to see them is one of the Vintage Computer Fairs, like the upcoming VCF Southeast in Georgia. We were at the one diagonally across the country a few weeks back, and they’re well worth the trip.