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Comment: Re: Such potential (Score 3, Insightful) 520

by cjameshuff (#49061315) Attached to: Nim Programming Language Gaining Traction

In Python, that could easily have been one or more statements that were unintentionally made conditional or removed from the conditional, perhaps while adjusting the indentation of adjacent just-moved code so the interpreter would put it in the right block. Python's indentation significance doesn't improve things one bit. If you want a fix for this problem, make the end delimiter non-optional, which would make it much more difficult to accidentally put a statement in the wrong block.

And of course, the presence of delimiters does nothing to prevent a language from requiring indentation or producing warnings when it finds inconsistencies between indentation and delimiters.

Comment: Re:Such potential (Score 5, Insightful) 520

by cjameshuff (#49059673) Attached to: Nim Programming Language Gaining Traction

Thank you. The "why don't you like indentation?" argument is nothing but a ridiculous straw man...the issue is not the use of indentation to reflect structure (which, as you point out, Python actually interferes with in some gets worse with higher dimensional cases such as voxel maps), it's with the lack of properly delimited blocks. With blocks being implied by indentation, you lose an important visual anchor and cross-check of intent with the compiler, and what do you gain? Potential problems with tab characters, code truncation errors that are undetectable until you attempt to execute the code, huge headaches if you have to use code that has had its indentation broken...there are no positives here, unless the proponents are seriously objecting to the onerous burden of typing a few } characters or "end" keywords.

Indentation significance is a design flaw, and it's disappointing to see it repeated yet again...

Comment: Re:Nice! (Score 2) 75

A solar storm causes problems by producing shifts in Earth's magnetic field. It's many orders of magnitude away from being anything like a MRI, and wouldn't scramble hard drives directly, it would disrupt power grids and copper communication lines. The only impact on hard drives or other electronic devices on Earth would be from power surges, while satellites would have increased ionizing radiation to deal with.

Comment: Re:Why not the spaceplane already built ~15 yrs ag (Score 1) 91

by cjameshuff (#49011183) Attached to: DARPA's ALASA Could Pave Way For Cheaper, Faster Satellite Launches

Aerospike systems are heavier and have more demanding cooling requirements, due to the central plug surrounded on all sides by hot exhaust, with radiative cooling being largely ineffective, and the increase in plumbing to all the injectors. Their advantage is in being less optimized for a particular atmospheric pressure, increased complexity and weight are tradeoffs. This is mainly a large advantage if you're using the same engines for liftoff and for the burn to orbital velocity once outside the atmosphere, which is why aerospikes are common features of SSTO schemes, but it's much less of a benefit if you have a separate booster stage and upper orbital stage or stages. They're not being held up by patents, there simply hasn't been a great deal of interest in developing them for real-world systems (the launch industry as a whole has had little incentive to do anything new for quite a while).

Comment: Re:seems a bit shy... (Score 1) 91

by cjameshuff (#49011097) Attached to: DARPA's ALASA Could Pave Way For Cheaper, Faster Satellite Launches

You get the same with a couple geographically separated launch sites. SpaceX launches to equatorial orbits from Florida and polar orbits from California, and they do so far more cheaply than an air-launch system could, without having to make sacrifices in payload, adding risks due to loss of on-pad test fires and abort capabilities, etc.

Sea launch does look much better than air launch, but it still makes the logistics and operations more difficult. SpaceX doesn't even want to land rockets at sea when they can bring them down on land, and is talking about future plans of refueling the first stages for a short flight back rather than shipping them back on the landing platform. Political issues with launch and landing locations might make it simpler to do things at sea, though...

Comment: Re:seems a bit shy... (Score 1) 91

by cjameshuff (#49010221) Attached to: DARPA's ALASA Could Pave Way For Cheaper, Faster Satellite Launches

Which is why they can manage to only be 5x the cost per kg of a Falcon 9 launch, right? Perhaps 10x when SpaceX starts reusing first stages...

Aerodynamic drag losses are only important for the tiniest of rockets. For most launchers, it's only in the area of 100 m/s. Additionally, propellant is a fraction of a percent of launch costs, and the cost of rocket hardware is not simply proportional to its size.

Comment: Re:seems a bit shy... (Score 2) 91

by cjameshuff (#49010203) Attached to: DARPA's ALASA Could Pave Way For Cheaper, Faster Satellite Launches

The failure rate of Pegasus has dropped a fair bit. The big problem is the extremely high cost (around $30 million for 400 kg to orbit these days) and the inflexibility and lack of scalability of air launch systems in general. The Stratolaunch system is building the largest aircraft by wingspan to ever fly to launch rockets with less payload than a Falcon 9...and they won't be able to attempt anything larger without building an even bigger aircraft, while SpaceX is already building the Falcon Heavy (with about 8.7 times the payload capacity of Stratolaunch) based on Falcon 9 hardware.

There really is little to gain. Air launch doesn't get you meaningfully closer to orbit to start with. You don't operate heavily loaded aircraft in bad weather, especially not aircraft loaded with multimillion dollar payloads and tens to hundreds of metric tons of hazardous rocket propellant. Especially when loss of the aircraft removes your ability to perform launches until a new custom-built/modified replacement is ready. You don't simply operate aircraft carrying such payloads out of whatever airport you like, you need special ground infrastructure and flight plans. The altitude and speed are more simply, cheaply, and effectively achieved with a rocket stage...see Orbital's own Taurus, which is essentially a Pegasus launched on top of a rocket first stage instead of dropped from an aircraft, and has a 1320 kg payload compared to the Pegasus' 400 kg.

Comment: Re:Lift? (Score 1) 83

Didn't forget them, they're just not very good for ballooning. With their hydrogen-helium atmospheres, the only way to get a reasonable amount of buoyant lift is by heating your lift gas, and the low density of those gases means even that gives little lift at a given pressure. Better than Mars, but worse than Earth.

Comment: Re:Lift? (Score 1) 83

Titan's atmosphere has about 1.5 times the surface pressure of Earth, and the atmosphere is even denser due to the cryogenic temperatures (about 20 K lower, less than the difference between your freezer and room temperature, and it'd start raining nitrogen). The only place in the solar system better for balloons is Venus, they're barely possible on Mars.

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