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Monday, May 30, 2011

NASA to Launch New Science Mission to Asteroid in 2016

NASA-- NASA will launch a spacecraft to an asteroid in 2016 and use a robotic arm to pluck samples that could better explain our solar system's formation and how life began. The mission, called Origins-Spectral Interpretation-Resource Identification-Security-Regolith Explorer, or OSIRIS-REx, will be the first U.S. mission to carry samples from an asteroid back to Earth.

After traveling four years, OSIRIS-REx will approach the primitive, near Earth asteroid designated 1999 RQ36 in 2020. Once within three miles of the asteroid, the spacecraft will begin six months of comprehensive surface mapping. The science team then will pick a location from where the spacecraft's arm will take a sample. The spacecraft gradually will move closer to the site, and the arm will extend to collect more than two ounces of material for return to Earth in 2023. The mission, excluding the launch vehicle, is expected to cost approximately $800 million.

The sample will be stored in a capsule that will land at Utah's Test and Training Range in 2023. The capsule's design will be similar to that used by NASA's Stardust spacecraft, which returned the world's first comet particles from comet Wild 2 in 2006. The OSIRIS-REx sample capsule will be taken to NASA's Johnson Space Center in Houston. The material will be removed and delivered to a dedicated research facility following stringent planetary protection protocol. Precise analysis will be performed that cannot be duplicated by spacecraft-based instruments.

RQ36 is approximately 1,900 feet in diameter or roughly the size of five football fields. The asteroid, little altered over time, is likely to represent a snapshot of our solar system's infancy. The asteroid also is likely rich in carbon, a key element in the organic molecules necessary for life. Organic molecules have been found in meteorite and comet samples, indicating some of life's ingredients can be created in space. Scientists want to see if they also are present on RQ36.

"This asteroid is a time capsule from the birth of our solar system and ushers in a new era of planetary exploration," said Jim Green, director, NASA's Planetary Science Division in Washington. "The knowledge from the mission also will help us to develop methods to better track the orbits of asteroids."

The mission will accurately measure the "Yarkovsky effect" for the first time. The effect is a small push caused by the sun on an asteroid, as it absorbs sunlight and re-emits that energy as heat. The small push adds up over time, but it is uneven due to an asteroid's shape, wobble, surface composition and rotation. For scientists to predict an Earth-approaching asteroid's path, they must understand how the effect will change its orbit. OSIRIS-REx will help refine RQ36's orbit to ascertain its trajectory and devise future strategies to mitigate possible Earth impacts from celestial objects.

The entire article is here:
http://www.nasa.gov/topics/solarsystem/features/osiris-rex.html

Thursday, May 26, 2011

Heavy Lifting

I've been looking at NASA's proposal for a heavy-lift manned spacecraft for missions to the moon and Mars. Here is the pdf for those interested in such, my (completely underinformed) assessment follows.

http://www.nasa.gov/pdf/510449main_SLS_MPCV_90-day_Report.pdf

Okay, so. The gist of it is basically that Congress has given NASA a mandate and a $7-billion budget to create a space program capable of routinely carrying a crew and 70-100 ton payload to the moon and Mars (and if necessary the International Space Station, although this is a very secondary function), to be operational by 2016. It is not clear how many actual rockets Congress is envisioning, or if they are reusable or expendable, etc.

First off, for perspective, a single B-2 bomber costs about $1-billion, and adjusted for inflation a single Saturn V Apollo rocket would also cost about $1-billion.

Congress and the Obama administration gave NASA the green light to cannibalize as much of the space shuttle hardware and existing Constellation/Ares V hardware as possible. In many cases this is the same hardware; Constellation/Ares V was basically rebuilding Apollo out of spare space shuttle parts.

Respectfully to those far more knowledgeable than myself, building a moon or Mars vehicle out of spare parts from Low Earth Orbital vehicles seems like a fairly inefficient way to design a rocket.

I happen to own a 50cc 3hp scooter, which I enjoy a great deal on those rare occasions when it actually runs. It gets me around Seattle residential streets at about 30mph, and can do that at about 70mpg. If I wanted to build a 300hp truck to haul shipping containers from Seattle to New York, one way I could do that would be to use 100 scooter engines on a single cam shaft. And if all I had to build a truck with was old scooter parts, that's how I'd build a truck.

This is kind of what the Soviets did with N1, which was their answer to the Saturn V. They built four of them, and all four of them failed catastrophically. Which is kind of what you would expect from a truck built out of old scooter parts.


But then the Soviets built Proton, which was originally designed as an ICBM but was actually far too large for that task. After a bumpy start to the program, Proton proved (and continues to prove) to be one of the most successful heavy lift rockets ever built.


The American equivalents were and are the Atlas and Delta programs, with the Atlas V HLV and Delta IV Heavy being the current best heavy-lift rockets the US possesses, other than the remaining Atlantis space shuttle. Proton, Delta and Atlas have the advantage, like the Apollo rockets, of actually being designed from the ground up for long distance heavy lift.


It seems that Charlie Bolden is pushing to use the congressional mandate to create heavy-lift on-the-cheap as a means to restart the Constellation program under a different name. One salient point he makes in his report is that NASA had already looked at some 2000 different heavy-lift designs prior to Congress becoming involved in the discussion. With the implication that Constellation actually was the best and least expensive solution for heavy-lift, and if that's what Congress wants they need to get out of the way and actually fund it. Which is not entirely unreasonable, and a reasonable Congress might even be inclined to accommodate that. But the Congress we have right now, which does not want to fund disaster relief in Missouri and elsewhere because they have become so psychotically obsessed with the budget, isn't one which is going to hear that argument.

I happen to agree with Congress that learning from the Soviet "big dumb booster" concept is valuable, and can help NASA rethink its process of developing heavy-lift long distance space craft. But in doing so one needs to have a realistic understanding of what the Soviet program actually was able to accomplish, and how different the successful Soviet programs actually were from the US programs. Vostok, which epitomizes the BDB concept, was excellent but never intended for more than Low Earth Orbit. N1 was the biggest of the dumb boosters, but it didn't work. Proton worked splendidly, but could as well have been a US design.

What Bolden is basically saying is that to build a heavy-lift surfaced launched vehicle to reach the moon and Mars we need another Apollo, with Apollo funding. There is no time or money built into the congressional mandate for new R&D, so everything has to be accomplished with off-the-shelf parts. The Constellation/Orion MPCV capsule is already completed, so it's a no-brainer to use that. If we're insisting on leaving for Mars or the moon from earth's surface (as opposed to building and launching from the ISS) then duct-taping as many PBAN solid rocket boosters as needed to the outside of the main engines makes sense. The only remaining question is whether to use space shuttle main engines, Delta IV main engines or Atlas V main engines.

Either way, what you end up with is Constellation. By any other name.

Which, if it had simply been allowed to continue, over-budget and behind schedule as it was, still would have been completed earlier and cheaper than it will now, with all of this start/stop/start mess.

Because, at the end of the day, NASA has a much better understanding of what it takes to build a rocket than Congress does. Because being a politician isn't exactly rocket science.

Saturday, May 21, 2011

Bad Judgment Day

Shockingly, it turns out that Harold Camping is a false prophet. Still.

But, no worries. Only 19 months left of the current Mayan Long Count, and then we can play this stupid charade all over again!

One good thing has come of this day. A whole new generation of music listeners have been exposed to Blondie.

Friday, May 20, 2011

Apocalypse Now

As I write this, it is a little less than one hour before 6pm in New Zealand, which will be the first major population center to experience the Rapture. The Rapture has already been happening in Kiritimati and the other Line Islands for about an hour now, no reports yet of a massive earthquake, angelic trumpets, airborne horsemen or 2000 year old rabbis. But then, the news out of Kiritimati always comes slowly, and the British nuked Kiritimati so many times the folk there may just be inured to it. But we're expecting live streaming footage of the festivities from Aukland news agency NZTV starting in just a little more than an hour, so stay tuned!

LATE BREAKING NEWS:

Undisclosed sources say that the archangel Gabriel has been replaced by the great Dizzy Gillespie!

Flowers for Algernon

6 men on the current space shuttle Endeavor crew.
5 men and 1 woman on the International Space Station Expedition 27 crew.

This is the best NASA could do to preserve and repopulate our species after the imminent Rapture tomorrow? What ever was Charlie Bolden thinking?

How will they know when it's 6:00pm up there? Is Universal Time really "universal"?

Will the ISS be in any danger from the faithful rocketing up to heaven?

So many questions.

So little time.

Thursday, May 19, 2011

CDC protocols for Zombie Apocalypse

Just in time for the Rapture this weekend!

No, really, they did. Because people are entertained by zombies, and it happens that most of the protocols for zombie apocalypse preparedness would serve you pretty well in a hurricane, earthquake or other natural disaster. Awesomeness.

The link is here:

http://blogs.cdc.gov/publichealthmatters/

Tagging

At the request of several of my readers I'm beginning the process of tagging different categories of posts here. It was originally my intention to NOT do this, because part of the point of the blog was to expose people from different fields to other interrelated fields. But it is helpful to be able to find other related posts. One reader related the difficulty she had finding my space exploration posts while "wading through page after page of Seattle weather reports". Which is a fair critique.

So, I'm working on it. Some categories are easy, like "Navigation" and "Weather". The ongoing series on human outmigration to other worlds is "Outmigration", and I've given "Project Orion" its own tag because I'm shamelessly wanting to attract more Project Orion folk to this blog. More categories are to come.

One category I've created is called "Best of Blog". I'm tagging this post with that label just so you can easily find which posts are tagged there from here, because I have not yet figured out how to make a hotlink to the tags. I'd really appreciate feedback on my selection of posts in that category, and hope to modify the list based on that feedback.

SS Dix found off Alki Point


SEATTLE (AP) — Divers believe they have found the steamer Dix, which for more than 100 years has rested at the bottom of Puget Sound off Alki Point.

The Mosquito Fleet ferry collided with an Alaska freighter and sank in 500 feet of water in November 1906, killing as many as 45 people, "their bodies, in all probability, being imprisoned within the cabins of the steamer, 100 fathoms below the surface of the Sound," according to a Seattle Daily Times report the next day.

There are no plans to bring up the wreckage, or to explore the interior. Finding it was enough for diver Laura James, who had been searching for two decades.

"This was the wreck I wanted to find in Puget Sound as long as I've been diving," she said.

-------------------
The full story is here:
http://www.seattlepi.com/news/article/Ferry-that-sank-in-1906-found-in-Puget-Sound-1385026.php#ixzz1MmNAZFxc

Wednesday, May 18, 2011

Mount Saint Helens, 31 years ago today


I didn't live in the Pacific Northwest when Mt St Helens erupted. My wife did. She was camping with her family at Dry Falls when the eruption happened. They heard the initial explosion, and assumed it was ordnance testing at the Yakima Firing Range. Later that afternoon they were driving back toward Seattle when the ash-fall started. Civil Defense broadcasts on the car radio were giving instructions but not information as to the cause of the ash-fall; being 1980 and the height of the Cold War, she reasonably wondered if what they were experiencing was radioactive fallout from a nuclear attack on the Puget Sound region.

Later, my wife's father, an editor for the Seattle Times, was one of the two first people inside the caldera after the blast.

I on the other hand was living in North Carolina, and all we experienced were really amazing sunsets.

After I moved from the Carolinas to Seattle (courtesy of the US Navy) I went to St Helens, a decade after the eruption. I was most struck by the millions of fallen trees, spreading for miles around the volcano. And the fact that, at that time, still nothing was growing in the ground which had been scorched by the blast.

Life is slowly returning to the slopes of St Helens, but it will be centuries before the young cedars, firs and hemlocks reach the maturity of the forests which once blanketed the mountainside.

Wreck of SS Dix found!

The steamer Dix has been located by diver Laura James. The Dix was lost in a collision with the SS Jeanie off of Duwamish Head Seattle in 1903. Will post more when I'm in front of a real computer tonight.

Sunday, May 15, 2011

Three self-contained methods for celestial navigation

In keeping with our budget-rate celestial navigation discussion, here are three different publications, each $30 or less, which are self-contained methods of deriving a three-body celestial fix, and the pros and cons of each.

Nautical Almanac with NAO Tables


Price: $30

Objects useable: Sun, moon, planets, stars

Duration: 1 year

Ease of use: Almanac moderately easy, NAO tables moderately easy with good workform. Included instructions barely usable.

Pros: Can use essentially every body visible in sky. Designed for marine navigation.

Cons: Requires 2102d Starfinder or equivalent for sight planning. NAO tables make necessary sacrifice of simplicity for significantly smaller size, by turning each navigational triangle into two right triangles. Elegant solution, but not very transparent for user.

Kolbe Long Term Almanac


Price: $30

Objects useable: Sun and stars

Duration: 50 years

Ease of use: Usable with good workforms. Sight reduction method is same NAO/Davies tables used in Nautical Almanac.

Pros: Physically smallest of all three methods. Can be used for as long as an individual would likely need to use it.

Cons: Requires 2102d Starfinder or equivalent for sight planning. Most difficult of the three methods discussed here.

Pub 249 vol 1


Price: $20

Objects useable: Stars only.

Duration: 10 years

Ease of use: Extremely easy to use. Sight reduction integral to method and not an additional step.

Pros: Utter simplicity and allows easy precomputation of sights, yet yields a good three-body fix.

Cons: Does not allow you to use brightest objects in sky (sun, moon, Venus and Jupiter). Designed for air navigation, so some information needs to be copied and pasted into book from Nautical Almanac or other source, such as Dip, Altitude Correction and times of twilight. Weird use of precession and nutation rather than simply correcting GHA of Aries for each year, there is some advantage to using GHA Aries from Nautical Almanac as well, but this is not strictly necessary.

I'm going to use 249 volume 1 for my test because it is cheapest and easiest. But if I were going across an ocean and was limited to only one publication for celestial navigation I would use the Nautical Almanac, because I prefer to be able to use the moon and planets when they're available.

Shuttle Endeavor RSS Rollback Completed, Fueling to Begin Sunday Night

NASA-- The opening of the rotating service structure (RSS) that protected Endeavour on Launch Pad 39A and provided access to the shuttle's systems began its retraction Sunday at 11:44 a.m. EDT and completed at 12:24 p.m. This major milestone paves the way to loading the giant external fuel tank with about 500,000 gallons of propellant.

The STS-134 crew members are sleeping and are scheduled to be awakened at about midnight to gear up for launch. The weather forecast for Endeavour's 8:56 a.m. liftoff to the International Space Station calls for a 70 percent chance of favorable conditions.


Launch Countdown Highlights (All Times Eastern)

11:30 p.m. NASA TV: External Tank Fueling Coverage Begins
11:36 p.m. Countdown resumes at the T-6 hour mark
Midnight Crew wakeup
12:21 a.m. Liquid Hydrogen Low Level Cutoff sensors go "wet"
12:30 a.m. Crew breakfast
12:36 a.m. Liquid Hydrogen "fast fill" begins
1 a.m. Crew final medical exams
1:51 a.m. LH2 "topping" begins
2:36 a.m. Countdown enters a 2 1/2 hour hold at the T-3 hour mark
3:30 a.m. Launch Coverage Begins on NASA TV and the Launch Blog
4:31 a.m. Astronauts receive a weather briefing from the Ascent Team
4:41 a.m. Astronauts suit up for launch
5:06 a.m. Countdown resumes at the T-3 hour mark
5:11 a.m. Crew departs for Launch Pad 39A
5:41 p.m. The astronauts begin to board Endeavour
6:56 a.m. Endeavour's hatch is closed and latched for launch
7:46 a.m. Countdown enters a 10-minute built-in hold at the T-20 minute mark
7:56 a.m. Countdown resumes at the T-20 minute mark
8:07 a.m. Countdown enters a ~40-minute built-in hold at the T-9 minute mark - MMT conducts final poll "Go-No Go" for launch
8:52 a.m. Countdown resumes at the T-9 minute mark
8:56:26 a.m. Launch of Endeavour on the STS-134 Mission
9:04:49 a.m. Main Engine Cut-Off (MECO)
~ 10 a.m. NASA TV: Post launch news conference

Saturday, May 14, 2011

Sailing

On the water next few days, will post as I can. At least the weather is better, at the moment. If you happen to be near downtown Seattle, tugboat races starting soon! Also stitch-and-glue boatbuilding contest at pier 66!

Update: Crowley's tug Hunter won, yet again. Waked the hell out of us while we were boarding passengers, again. Go team Crowley!

Wednesday, May 11, 2011

Only ten more shopping days 'til the Pocky Clips!

The Bible guarantees it!


God hates rich people, so please donate all of your money to me, c/o Strait of Magellan Blog, effective midnight 23 May 2011. Gracias.

Tuesday, May 10, 2011

Martha, I think it's aliens.

For those of you living in the Salish Sea area, the bizarre looking thing coming down the Strait of Juan de Fuca is the offshore X-band radar platform SBX, coming down from its normal station in Alaska for repairs at Todd Shipyard. It will be rounding Point Wilson and heading into Admiralty Inlet and Puget Sound around 1400pdt today, and will be arriving in Seattle early this evening.

Once it arrives at Todd there will be a 100 meter security zone around it; how that will affect vessels fueling at Ranier Petroleum remains to be seen.

You can track the platform here if you're interested, it's being escorted by the Lindsey Foss:
http://www.marinetraffic.com/ais/

Monday, May 9, 2011

TED Talk on Project Orion

George Dyson on TED Talks, interesting new/old footage from original project.

http://www.ted.com/talks/george_dyson_on_project_orion.html

Project Orion series update

It's been nearly a month since my last post on Project Orion (DARPA's proposed "hundred year starship"), so I want to do a quick recap and an explanation of where the series is going.

So, to recap:

We started with the premise that the ultimate survival of the human species requires that humans establish permanent settlements beyond earth's atmosphere.

We explored different possible locations for human settlement within the solar system. Some or all of these will certainly be colonized, but none of them are especially habitable by humans and other terrestrial life.

We explored the nearest star systems, and determined that the Alpha Centauri system is by far the best candidate for having an earth-sized planet with liquid water on the surface.

We explored existing propulsion systems for reaching Alpha Centauri, and found that only one currently existing method could reach Alpha Centauri within a single human lifetime. That method is nuclear pulse propulsion, which is a polite way of saying lighting off a bunch of atomic bombs behind a space craft and blasting it into the next solar system. Intact.

We learned that the US government has had the plans and technology to build a vessel of this type since 1957. Really. It was called Project Orion. It was then canceled due to the Partial Test Ban Treaty of 1963. The Cold War is over, and now DARPA and NASA are looking at it again. But I'm not sure that governmental agencies or corporations have the attention span for a project of this magnitude. This may be something that interested individuals need to start collaborating on independently of governments.


The next parts of the series will explore what life would be like, both on Orion for 88 years and also beginning settlement and terraformation of an earthlike world in the Alpha Centauri system.

I've had some requests to eventually turn this series into a book. I will probably at least consolidate it into an ebook and make that available here. In the mean time, I'm going to go back through the series and tag the posts as "Project Orion" and "Outmigration" to make then easier to find.

Ad astra!

Cheap plastic sextants

Plastic sextants have a bad rep. This is not entirely undeserved, but some of the bad reputation which plastic sextants have is plainly spurious. One of the most frequent complaints I've heard about plastic sextants is that if you leave them out in the sun, the plastic expands and thus degrades your sight. Yes, plastic left in the sun will expand. However, it will tend to expand evenly, so this should not actually effect your sight. Also, no navigator worthy of the name is going to leave any sextant out in the hot sun, so the point is moot. What is not moot is the fact that plastic worm-gears (or even plastic-on-metal worm-gears) are too malleable for the precision desired of a sextant. The good news is, the cheapest plastic sextants don't have worm-gears. If you happen to own a plastic sextant which does have worm gears such as a Davis Mark 15 or 25, it is still possible to get a useful line of position with it, it just takes a lot more work. David Burch's excellent How to Use Plastic Sextants gives superb instructions for how to use these instruments, and if you'll pardon a bit of shameless self-promotion, if you purchase any plastic sextant from Starpath they'll throw in the book for free.


The Davis Mark 3, on the other hand, retails for $50 and is about the very least thing that could ever consider itself to be a functioning marine sextant. It is made out of stamped plastic and held together with model airplane glue, and has only one significant moving part, which is its saving virtue. There is no worm-gear, just a simple pivot point, and instead of a traditional micrometer drum to read minutes of arc it has a very simple vernier scale. The Mark 3 isn't pretty. It doesn't seem to work in the same way as a more traditional sextant (although the basic principles are the same), has no telescope, and instead of a beam-splitter or a traditional split horizon mirror has a simple glass mirror and thin air. In spite of this extreme simplicity (or rather, because of it), if proper sight-averaging techniques are used, the Mark 3 will yield results very comparable to those of an aluminum or brass sextant of $1000 or more. Neither of Davis' more expensive sextants can make this claim. The Mark 3 was originally developed for the US Navy as a lifeboat sextant, but given that the competition for any sextant now is a $100 GPS receiver, the Mark 3 has to be considered a serious first choice of a sextant for routine ocean navigation.


I had intended to include the Ebbco sextant (pictured above) in this discussion as well, but while it is of similar construction to the Mark 3 it does have a traditional micrometer drum, which implies plastic worm gears and springs. My recollection of this instrument is that it performed comparably to the Mark 3, but I don't happen to have one easily available so I'll belay comment on it until I do.

For the dockside and on-the-water tests of the mechanical watch I'll be using a Davis Mark 3 sextant, and I've decided to use the seven-star method of sight reduction using Pub 249 vol 1 since it is the simplest and least expensive means of deriving a 3-body fix anywhere in the world.

Also for the tests I will be using standard Universal Plotting Sheets, and a standard set of dividers and parallel rulers. I am not however including these in the cost of the method, because these would (or should!) be a part of any boat's navigation equipment for an ocean crossing.

Libya refugee boat sank off Tripoli, witnesses say

NEWS.COM.AU -- Refugees from Libya who arrived in Italy today said they saw another boat laden with fellow refugees capsize just off Libyan shores and "many bodies" were in the water, Italian news agency ANSA reported.

"They were in front of us, not far from the shore, when the overcrowded boat capsized," one refugee was quoted as saying of the incident on Friday after landing in Lampedusa, an Italian island where thousands of refugees have been arriving.

"It was terrible. There were a lot of corpses," said the refugee, whose name was not quoted in the report.

ANSA said "dozens of dozens of migrants are believed dead", while others managed to swim to the shore.

Italian newspapers earlier reported that a boat carrying 600 refugees sank near Tripoli, citing a Catholic bishop in Libya and an ANSA report.

A Somali refugee also in Lampedusa whose son was on the boat received a call from relatives telling her that he was one of the victims, ANSA reported.

Italian officials said they had no information about the incident.

Bishop Giovanni Martinelli was quoted by Corriere della Sera daily as saying that he had met some of the boat's Somali passengers before their departure and had received news of the incident from a nun.

"They said they had finally found a boat to go to Italy... They were all happy and smiling, there were a lot of children among them too. But their boat sank. Their dream sank," Bishop Martinelli was quoted as saying.

"The cemetery of the Mediterranean is continuing to fill up with dead bodies," Corriere della Sera commented.

Some 150 refugees fleeing Libya are believed to have died last month after their boat capsized in stormy weather in the middle of the Mediterranean, with Italian coast guards managing to pluck 53 survivors from the sea.

Italian coast guards earlier today rescued all 528 passengers from a boat that ran aground as it was approaching the port of Lampedusa in the night, forcing panicked refugees to jump into the sea.

Sunday, May 8, 2011

More celestial nav on-the-cheap

I've been assuming the use of the current year's Nautical Almanac, which retails for $30. However, the seven-star method of Pub 249 volume 1 is also a self-contained system which can be used anywhere, and it happens to retail for about $20, eliminates sight-reduction tables entirely and also affords very simple precomputation of your sights without a starfinder. And it is fair to say that the NAO sight reduction tables in the Nautical Almanac are a step above simple celestial techniques.

Personally, I would want to be able to use the bright objects in the sky, specifically the sun, moon and planets, so I would choose the NA. But one could certainly live without these, and 249 vol 1 is actually much easier to use, and good for ten years. So for our purposes, I'm going to knock another $10 off our total cost.

By the way, my ultimate intention with all of this is that once I'm comfortable with the methodology of using very inexpensive tools for celestial navigation, I'm going to actually test it from a small boat somewhere in the Salish Sea, and see how accurate the position I derive is from this. Hopefully by the end of the month I'll have enough data to establish a trend with the watch, and then I'll let it generate out for another 20 days beyond that.

Wednesday, May 4, 2011

May the Fourth be with you

Happy Star Wars Day!!

Corner office with a waterfront view

This week I'm officially back full-time to my perennial summer job, running passengers from Seattle to Victoria BC. Once my schedule stabilizes out a bit I'll have much more time to post, and specifically to continue with the series on Project Orion and possible outmigration to the nearest stars.

Here's my office, the mighty Victoria Clipper IV, in Victoria's inner harbour.

Tuesday, May 3, 2011

Lightning and Sailboats

On the subject of lightning strikes and sailboats, here is a free e-book on the subject from the University of Florida. 4-20% of all sailboats there are struck by lightning each year. Here in western Washington we're lucky to see 4 - 20 lightning flashes each year, due to our propensity for frontal systems to be occluded by the time they reach our shores. In the tropics, it's a whole different situation.

http://edis.ifas.ufl.edu/pdffiles/SG/SG07100.pdf

Sunday, May 1, 2011

Longitude or Entropy

The following is a consolidation into a single post of a recent series of posts, which detailed the testing of an inexpensive mechanical watch for use with celestial navigation.
The posts were consolidated at the request of my wife, whose critique was something like "ten posts about how to wind a watch, really?".



=========================================

Longitude is time, time is longitude. Within the context of navigating on (or above or below) the surface of the earth, time and longitude are one and the same. At the equator four seconds of time equals one mile of distance east or west. At the latitude of Seattle it's close to six seconds equals one mile, but it is still readily apparent why precise timekeeping is so critical. If my chronometer is off by 12 seconds my position on the earth is in error by two or three miles. The larger the chronometer error the larger the position error, the two are inseparable.

In order for my chronometer to actually be a chronometer, it doesn't have to keep accurate time. Every timepiece, including the most sophisticated atomic clocks, gain or lose some amount of time. What makes a chronometer a "chronometer" is the fact that it gains or loses time at a predictable rate.

Tomorrow I will describe in more detail what precisely I am hoping to prove with this inexpensive mechanical watch experiment, and the methodology I'm using to do so. This isn't a trivial consideration; the advent of quartz watches and GPS plus the loss of LORAN has completely changed the balance and importance of marine celestial navigation for routine and emergency applications, and the role (if any) of a non-electronic timepiece which is cost-consistent with a low-end handheld GPS receiver.

For now, the test watch has been rewound and reset at 2300 tonight, ready to roll in the morning.

More to come..

==========================================

So, take-two of the testing of the mechanical non-chronometer.

The manufacturer recommends winding the watch twice daily, but this proved insufficient. Ideally, as with any mechanical chronometer, the watch should be wound at the same time(s) every day, but this is probably not realistic for me this week given my variable work schedule. So instead I'm just going to wind it every several hours or so as I think to do so, understanding that this is less than optimal. Also standard protocol with a mechanical chronometer is to wear the watch constantly, as your wrist provides a better heat-sink than most other things do to prevent the mechanisms from being exposed to temperature extremes. This is reasonable but the very inexpensive watch-band isn't especially comfortable, so I'm just wearing it as much as I can. On the other hand, it's spring (finally!) in Seattle, so the temperatures shouldn't be very extreme in any event. He said.

In my initial test, tracking the watch from one initial winding, it started out losing about a second an hour. Toward the end of the day this had increased to about a second and a half per hour. However, today I've been winding the watch every several hours, and it's keeping remarkably accurate time doing so. 18 hours after resetting the watch, it is only two seconds slow per Android GPS. We'll know in a few days how well this continues to track, but so far it is significantly more accurate than I would have anticipated.

A note on timekeeping; I'm using the GPS on my Android phone as a time reference for this simply because I always have it with me. WWV would probably be a better reference, and I happen to have that on my speed dial as well (cough), but the possibility of routing delays with the phone systems makes direct GPS at least as accurate as a cell phone WWV "radio" time-tick.

What am I trying to learn from this? Specifically for emergency navigation, in the absence of any electronics (such as may result from the electromagnetic pulse from a lightning strike) how would an inexpensive mechanical watch compare to other methods of deriving Universal Time (and hence longitude), such as lunar distances or lunar altitudes. And also to see if, just like the plastic Davis Mark 3 sextant, it is possible to achieve comparable results to far more expensive instruments, simply by taking all of the steps recommended (but rarely done) for the more expensive instruments. So far with this test, I am encouraged.

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Last night around 10pm the watch stopped even though it was still wound. Tapping the face started it again, which is fine for routine use but worse than useless for the sole source of Universal Time in an emergency. Rewound and retesting.

Meanwhile, the $20 Casio quartz watch is tracking like a champ. But it wouldn't survive the EM pulse from a lightning strike. Which brings me to the topic of Faraday Cages.


A Faraday Cage is simply a wire mesh (or just metal, it doesn't matter) enclosure which prevents electromagnetic energy from entering or exiting. Lining a small cabinet with chicken-wire and sticking a spare radio, flashlight, GPS, wristwatch and batteries? Good idea. Sticking the aforementioned into your microwave or conventional oven? Very, very bad idea. They may survive the lightning strike, but won't do so well when your shipmate later preheats the oven, or sticks their coffee into the microwave to warm it.

So, how is the mechanical watch doing now?

Currently 2 seconds fast after 9 1/2 hours. Hopefully I can keep it running long enough to start getting some real data. If I can't, then that's real data too.

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Now well into the second day with the watch running fine. So far losing about 1 second every 2 hours. I'm chalking up the first two failed runs to operator error. I read a number of reviews of this particular watch saying that it didn't work at all; now I'm wondering how much of that was the result of a generation unused to mechanical watches. Will continue to test, but still cautiously optimistic.

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Three and a half days into testing, some interesting preliminary results.

For the first two days the watch was losing about 9 seconds per day, ending up around 20 seconds slow at midnight the night before last. Then yesterday it started gaining time rapidly, and as of right now is about 25 seconds fast.

Will see if this oscillation continues or if it has decided to continue to run fast now. I'm winding it every couple of hours or so when I'm awake, and just before and just after sleeping.

So, for those who are following along with this, the standard of accuracy I'm hoping to obtain is the ability to determine my Universal Time to within 2 minutes after 20 days. These numbers are not arbitrary; 2 minutes of time is about the best accuracy one could expect to obtain from traditional lunar distances from the deck of a small boat at sea (and that may be overly generous), and 2000 nautical miles is realistically the farthest from inhabited land any vessel would likely ever be under even the most extreme circumstances, and a vessel covering only a hundred nautical miles per day (averaging 4.2 knots) would cover that distance in 20 days. Worst case scenario (at the equator) 1 minute of time error is 15 nautical miles, so two minutes is 30 nautical miles, so the land would need to be at least 200 meters high in order to be seen from a small boat at that distance. This is admittedly extreme (the center of all of the overlapping bell-curves here would probably be less than 10 nautical miles inaccuracy), but if your life depended on it you would want to allow for that margin of error.

This is also far more accurate than any means available of determining longitude with the sun alone, with or without an accurate chronometer.

It should be noted that for this to be in any way scientific I'd really need to test dozens of mechanical watches from the same and different manufacturers. But it would only take ten of these watches to equal the cost of a good mechanical chronometer, and if I were going to spend that much money I'd rather just buy a good chronometer. Again, the point of the exercise is to determine whether or not it is possible to have an entirely non-electronic method of routine celestial navigation which costs no more than a cheap hand-held GPS receiver. The other two parts of the equation are the sextant and the almanac and sight reduction tables; will discuss these presently while we're waiting for more watch data.

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I've just reached a very critical juncture in this test. Right now, at around 0900pdt five days into the testing, the second hand and minute hand are officially 30 seconds out of synch with each other. At the time GPS read 08:46:00 the watch read either 08:46:52 (which fits well with the existing data trendline) or 08:47:52 (which is an obvious outlier). It is possible that in this situation at sea without an electronic time source that I would be so confident in my record keeping that I would recognize the outlier even without an electronic comparison and then remember to add or subtract a minute for however long is necessary until the second hand became 90 seconds out of synch with the minute hand, and so on. But the room for error here is enormous.

The better practice would be to discard the second hand altogether for this application, and simply read minutes and estimate tenths of minutes on the minute hand. This may even help eliminate some of the oscillating error I've been seeing, will from this point start tracking both.

If this pans out (and based on the very small amount of data I've collected so far, it may) it will be certainly more difficult than using either an electronic or mechanical chronometer. But compared to computing lunar distances, it's making mud pies.

Also if this pans out, it emphatically does NOT eliminate the necessity for a second hand on the watch. You'll need it for many other applications, such as timing lighthouses and estimating speed for dead reckoning. It just won't be used for celestial navigation.

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Continuing to test mechanical watch using only the minute hand. So far the results are looking pretty good, and I've determined the most accurate means of obtaining star sights using it. Instead of estimating the decimal of a minute visually, have one person observe the watch and mark the moment the minute hand passes a minute mark, and have the other person with the sextant standing by with the star properly aligned.

This violates the Starpath protocol of not having two people working together on celestial sights (better for accuracy, worse for relationships!), but in this case you need all of the accuracy you can get.

The other drawback with this method is that it severely limits the number of sights which can be taken within the time that both the star and the horizon are visible, but it is unlikely that you would actually get more than one sight per minute anyway.

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My original plan was to run the watch test for a full 20 days. However, the actual uncorrected inaccuracy is now large enough that it's becoming a minor nuisance to use the watch for my day-to-day timekeeping, and I'm actually pretty satisfied with the data I've collected after 15 days of testing.

My original parameter for "success" for the watch to be a suitable backup to a GPS was to be able to determine Universal Time within two minutes after 20 days. However, using the methods detailed below it appears that you should be able to obtain Universal Time within 18 seconds more or less indefinitely. Which means that if all of the rest of your celestial navigation is done correctly, you should never be more in error than 4.5 nautical miles at the equator, or 3 nautical miles at the latitude of Seattle. So in even the worst possible case, from the cockpit of a small sailboat you could successfully navigate any distance across any ocean and make landfall on any island in the world, however small and however low above sea level. That counts an an unqualified success, and far better than I imagined possible.

The watch consistently gained six tenths of a minute, or 36 seconds, each day; at the end of the experiment the watch was running more than nine minutes fast. For the record and for comparison, the Casio quartz watch gained 4 seconds total over the entire time of the experiment. Which is to say, the Casio completely uncorrected was more than four times more accurate than the mechanical watch with all corrections. But, the Casio is as vulnerable to electromagnetic pulse as any other electronics on board. And the mechanical watch gained time at a consistent and predictable rate, which makes it a chronometer by any reasonable definition.

In practical terms, what this means is that for use as a secondary means of routine ocean navigation, you would of course use a quartz watch as your chronometer, and meanwhile maintain the mechanical watch and log its error daily. Then, if due to a lightning strike or any other reason you should lose electronic means of timekeeping, simply switch to using the mechanical watch and continue with routine celestial navigation and dead reckoning.

The proper method for using the watch to attain this accuracy is as follows:

Wear the watch on your wrist at all times, utilizing your body temperature as a heat-sink and also your flesh to dampen the effects of vibration.

Wind the watch obsessively, with one finger only to avoid over-winding. Really obsessively, every time you think of it, when you wake up, before you go to bed, before dinner, whenever. This undoubtedly introduces some error, but it would be much worse for the watch to stop. And it will.

Use the minute hand only, unless you're really sure you're only going to need to navigate for a couple of days. Use a set-and-wait method, marking the time for the sight at the moment the minute hand aligns with the minute mark on the watch face.

That's really all there is to it.

If anyone is actually interested I'll be happy to email them scans of the raw data. This is obviously not a scientifically rigorous test, but simply a demonstration that, in principle, a modern inexpensive mechanical watch can be used as a functional chronometer for celestial navigation.

Having established that the least expensive plastic sextant and the least expensive mechanical and quartz chronometers are more than adequate for routine and emergency celestial navigation, the third part of the equation is an ephemeris and a method of reducing the celestial data into a fix which can be plotted as a position on a chart. The next post will compare three inexpensive alternatives for this.

Go Navy.

EoM.

'Tis the first of May, 'tis the first of May...

...outdoor boating starts today! At least here in Seattle. Boat safely and soberly, and have fun! It looks like another beautiful day here, finally. Will be on the water myself, so keeping this short.

And for those who celebrate it, happy Beltaine!