Author Archives: jetradjames

What is a uSv?

It’s a micro-Sievert. Micro means one millionth. It’s abbreviated the Greek letter “mu”, which I don’t have on my keyboard, so I use a “u” which is sort of close.

A Sievert is a unit of radiation that has to do with the absorption rate of radiation in human flesh. Some guy with the last name Sievert named it.

I talk about it more at the bottom of the page in my first couple of posts.

On the ground in Aspen

This is the first opportunity that I’ve had to get a radiation reading on the ground, in the mountains. I had heard that the levels were elevated in places, such as Denver, where you’re quite a bit above sea level. For a comparison, let me show you the levels of radiation at various cities around the US.

Raleigh, NC – .11 uSv/hr
Tampa, FL – .10 uSv/hr
Dallas, TX – .07 uSv/hr
Los Angeles, CA – .13 uSV/hr
Phoenix, AZ – .11 uSv/hr

At 8500 feet above sea level, here in Aspen:

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I would have guessed the level to be higher. So this is definitely a number I could live with if I were to spend my whole life up here (I wish!).

Cheers

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New job, new data

Hello all! Some of you may have been wondering where I went to. I haven’t posted anything for quite some time. Well, without an airplane to fly, it became hard to get high altitude data!

So I got a new job in a new plane in a new place. I’m flying the Hawker 800xp now from a base in Tampa, FL. This aircraft can fly at 41,000′ so the data I collect should be good to go!Hawker

I just flew a trip from Tampa to Boston and thought I’d let you know that NOTHING HAS CHANGED in the upper atmosphere.  This trip was flown at 39,000 feet.  Other than forgetting to turn off the detector after we landed, the graph looked pretty boring.  Here it is…

PIE-BOS

Radiation in Space

Many people have asked me what the dangerous radiation levels are.  The answer that I’ve found is 100,000uSv in a year.  Cancer has been directly linked to this exposure value.  Jet pilots and Flight Attendants can expect to get around 6000uSv per year if they fly 800 hours.  That’s not to say radiation can’t make you sick at lower levels.  It can.  But it’s really hard to link things like the common cold to a couple days of flying at high altitude.  This is what has caused so much confusion about it and why it’s so hard to find concrete data on what radiation can do.  The best advice I can give to aircrew and frequent flyers is to maintain a healthy lifestyle.  Any detrimental affects to the mild doses we receive are probably magnified by poor eating and other health habits.

So what’s the radiation level at the International Space Station?

I’ve been getting measurements at a maximum altitude of 8.5 miles.  The International Space Station orbits at about 280 miles up.  The average astronaut on the ISS, during their 6 month stay, gets a whopping 70,000 uSv!  So you can see why they don’t, normally do more than 6 months.

In fact, man will never conquer space travel without handling the radiation problem.  Low Earth Orbit is about the best we can do for extended periods of time, right now.  The Van Allen belts extend from roughly 600 miles to 22,000 miles above the Earth.  These are belts of high levels of radiation that men can’t stay in for long.  Above this, the effects of the Earth’s magnetosphere are so diminished, that solar activity is uninhibited.

Throughout the years of the Apollo moon landings, there were regular solar flares.  A couple of them would have cooked the astronauts going to the moon.  The success of these missions was mostly luck of timing.  The future of space travel depends entirely on finding the best ways to shield against radiation.

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Around the world in 8 days

I’ve flown half way round the world and back during the past week and a half.  I’ve crisscrossed the Arabian Sea and the Atlantic Ocean.  I’ve been within spitting distance of the equator and seen the snow-covered landscape of Greenland!

All my raw results are posted below.  You be the scientist.  Can you make any conclusions of your own?  Does changing altitude make much of a difference at the equator?  Does it make a difference over Greenland?  What’s the average dose at 41,000′ down south?  How about up north?  What’s the dosage rate over Europe?

Riyadh to Maldives:

Multi Frame 1

Maldives to Riyadh:

Multi Frame 2

Riyadh to Paris:

Multi Frame 7

London to Detroit:

Multi Frame 3

I’ve flown over Greenland many times, but it’s always either been covered in cloud or too dark to see.  I got lucky on this flight and captured these pictures at high noon.  Notice how long the shadows are, even two months past the winter solstice?  These shots are at 62 degrees North latitude.

Greenland 1-resized

The depth of the snow in the picture above must be thousands of feet deep.  It fills in the valleys completely, leaving the craggy mountain peaks poking out like they were pine trees on an upper mountain slope.

Below is a gigantic glacier, ending in the frozen ocean.

Greenland 2-resized

Detroit to Greenville:

Multi Frame 4

Greenville to London:

Multi Frame 5

How much fuel does it take to fly from South Carolina to London?  About a truck and a half worth!

Fuel-resized

London To Riyadh:

Multi Frame 6

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Northbound to Germany

Here is data from a quick trip from Saudi Arabia to Germany.

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3X The Measured Radiation

There is more up there than what my Gamma detector is picking up.  Judging by the NAIRAS website, my detector is picking up 1/3 of the total ionizing radiation at flight altitude.  This is the case in the northern latitudes north of about the 35 degree parallel.  South of this, my meter seems to pick up most everything.

I’m trying to ascertain what types of radiation are up there so that I can get meters to measure the total spectrum.  For now, though, when I’m up north, I have to simply multiply my reading by 3 to get an estimate of the total dose.  This information is really sobering as I thought 4.0 uSv/hr was quite a high dose rate while flying over the Atlantic.  The actual dose rate was around 12 uSv/hr!

I have also been searching for a dosimeter that pilots, flight attendants and frequent flyers can carry.  I’ve concluded that one dose not exist…at least not one that is affordable.  When I’ve figured out what types of radiation make up the majority of the spectrum, I’ll see what I can do about getting one constructed.

Still, the results I’m getting with my Polismart Gamma detector continue to be fascinating.  And the ability to store the data, graph it and map it is, actually, quite amazing, considering how affordable the device is.  I know, I’m biased because I’m beta testing it.  But really, the Polismart has worked flawlessly and the App has exceeded my expectations.  My hat is off to the Polimaster folks who designed this gadget.  It’s really great.

So, finally, with all the flying I’ve done lately, I’d like to say that I’m getting a very firm grasp on where the radiation is and what you can do about it.  What I’ve discovered, to date, can be summarized like this:

  1. Aircrew get more radiation than nuclear power plant workers.
  2. Aircrew are classified as radiological workers by the NCRP (National Center for Radiation Protection)
  3. On average, north of 35 degrees north-latitude, radiation increases rapidly above about 35,000′.  Pilots who do not need to go higher than that, operationally, might as well stay at a lower altitude if they want to avoid high radiation levels.
  4. Altitude has little affect on the radiation level when flying at latitudes south of about 30 degrees north.  I’ve seen almost zero variation between 35,000′ and 45,000′ when flying from 30 degrees all the way down to the equator.
  5. Flying over the North pole is the most hazardous of all.  Radiation levels will normally be 12-18 micro-Seiverts per hour, at 40,000′.  From 31,000′ upwards, the radiation level will double about every 6500′.  Pilots need to check on solar flare activity because, sometimes, levels can exceed 100 uSv/hr.
  6. An affordable dosimeter, that accurately measures all of the different types of radiation at flight altitude, does not seem to be readily available.  There is 3x more up there than just Gamma.  I think the other main components are radioactive electrons, protons and X-Rays.
  7. Currently, the best prediction center, I’ve found, for flight radiation, is the NAIRAS website.

It’s time to take this to the next level and start including the sun’s solar flares into the equation and see if I can pick up the daily variations of flux.  Because the real danger of upper altitude radiation comes from solar flares directed at Earth.  Levels can exceed 150uSv/hr during the strongest flares.  And that’s dangerous.

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