Somewhere, something incredible is waiting to be known. – Sagan


Wednesday, November 30, 2011

Taking an ion drive to Mars

Over at Scientific American they have a brilliant article that traces the steps of a think tank formed in October of 2009, prompted by the Augustine commission, that consists of dozens of space geeks that wanted to provide direction to the next great leap in space exploration. Their aim is to land astronauts on Mars.

With the intent of finding practical solutions to NASA’s biggest technical and budgetary concerns, they went out to come up with a solid plan that could provide fast and financially sound solutions.

A Hall thruster is a type of ion thruster in which the propellant is accelerated by an electric field in a plasma discharge with a radial magnetic field. Also known simply as plasma thrusters, Hall thrusters use the Hall effect to trap electrons and then use the electrons to ionize propellant, efficiently accelerate the ions to produce thrust, and neutralize the ions in the plume.

When all was said and done, their plan started to form around one central idea: using an ion drive to propel the craft. They’ve combined “the most promising proposals with tried-and-true strategies” and have come up with a plan to send a human presence to the near-Earth asteroid 2008 EV5 as soon as 2024 with the eventual goal of landing people on Mars.

I have to admit I’m a little disappointed that they are proposing to use Hall effect thrusters powered by solar panels instead of nuclear reactors. Reactors used in submarines and other sea craft have been tried and tested, and have proven to be very solid. In all the years of using nuclear in subs and ships, they have been no accidents. Also, solar will not cut it beyond the inner planets and the farther out you go, the less power you will get out of it. Any damage to the relatively fragile solar panels will mean certain death to anyone out there between Earth and Mars, while a reactor, properly shielded, would fare much better. The reliance on solar seems a bit myopic, and I’m concerned that irrational fear of nuclear, in the light of recent events in Japan are clouding peoples perceptions of its safety track record.

Pods Instead of Suits

The idea of donning pods, like those deep-sea submersible pods, instead of space suits would allow the use of more sophisticated instruments, advanced maneuvers, particularly in the context of ship repairs and inspections. Consider that in a pod, an astronaut would have room to rest and eat in case they needed to stay in it for days at a time. Attach the pod to a wheeled base and you have a Mars rover that would keep people safe and allow for more advanced exploratory excursions.

Problems that still need to be overcome

Shielding travelers against radiation from the sun and other sources will always be a problem. The reality is that a 2 to 4 foot thick shield of water, in the form of ice, would be sufficient, but it means you have to propel this massive amount of water around meaning more fuel. Luckily, NASA has discovered that variants of polyethylene could provide this necessary shield. Called RXF1, it is stronger and lighter than aluminum, and compared to aluminum, polyethylene is 50% better at shielding solar flares and 15% better for cosmic rays, all the while producing less damaging secondary radiation than aluminum. RXF1 is remarkably strong and light, 3 times the tensile strength of aluminum and is 2.6 times lighter.

Another issue is the harmful effects of micro-gravity on the human body. This becomes an engineering problem. Artificial solutions like centripetal habitation modules have always been thrown around. It’s unclear if a solution like this can be engineered to work out in space yet.

Ion propelled craft

Concerns to This Approach

My main concern is the power source. Using nuclear, even multiple RTGs, seems like the better way to go. NASA has a great amount of experience with nuclear power sources in probes while the military has as much or more experience with it in a heavily manned contained environment with an excellent track record.

China no doubt is working on the same goals we are and I don’t think they have the same aversion to nuclear technology that some people here in the states seem to. But I have no doubt that once progress gets made on the other side of the globe, that will be our kick in the pants to cast aside our idealogical notions and beat China to Mars. It worked in the 60s.


Wednesday, October 26, 2011

Green Apples

It’s no secret I am a big Apple fan, and any big Apple fan has done business with a company called Other World Computing, an Apple focused accessory maker and reseller, at some point or another. So I was pleasantly surprised to hear two bits of good, green news from both of those companies.

The Charlotte Observer is running a story about a 171 acre solar farm installation Apple is trying to get approved to power their new billion dollar data center in Maiden, North Carolina. Which is a good thing since they will be sucking up the power at a huge rate and Duke energy, the local power company, is mainly powered by coal.

Apple data center. Click to enlarge a map of the initial 70 acre plot.

It’s said that Apple is clearing 100 acres of wooded area to make room for the farm. It’s still unclear if the clearing of trees and installing a solar farm in it’s place is better for the environment in the long run, however. The data center is where Apple houses most of it’s servers that contain the iCloud service that was recently announced.

Other World Computing, or OWC as it’s well known by, in Woodstock, Illinois is actually making one of the best corporate efforts at being green that I have every witnessed. Consider what their business is based on: getting the most out of your current computer before dumping it in the trash in the form of upgrades and self-repair kits.

ArsTechnica has an article showing OWC’s commitment to environmentally friendly building and products.

“Conservation is really at the core of our business,” O’Connor told Ars. “The average Mac is used maybe three years, and the average PC even less, about a year. But with a little help and the right upgrades and tools, those machines could be put to good use for much longer. Recycling is great—we do a lot of that here in our facility. In fact, I can count on one hand how many times we’ve had our regular ‘trash’ picked up since our new facility opened three years ago. But what’s even better than recycling is not throwing things away in the first place.”

OWC built their 10,000 ft2 facility in 2006, and right from the start, they integrated ideas that would be environmentally sound and cost effective. They use geothermal energy to heat and cool their building which saves energy and eliminates emissions. A wind turbine out front is able to power their whole facility, with the excess being sold back to the local power company. There is fiber-optic solar lighting through out the building and sensors that turn off the supplementary florescent lights when the outside light is adequate indoors. And there are plenty of skylights installed to allow that light to come in.

OWC Headquarters

Other ideas in place are less whizz-bang, but just as effective. For example, they recycle everything they possibly can. Refuse and recyclables are accumulated in the warehouse until there is a full load that can be carted away in order to save on fuel costs. Old computers are still used for suitable tasks like tracking inventory. They even have waterless urinals installed.

Radical eco-friendly thinking isn’t the norm in the tech industry, but with some companies leading by example, I hope this is a lasting trend that others pick up on.


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