Tag Archives: NOAA

Proof that some things don’t change…

DIDT

Here are some fun stories for you, courtesy of The Space Review. Perry Mason, shotguns, bombs, and Thor–all of these have a common element–the human.  Just click on this link: The weird ones. And of course the whole thing wouldn’t be complete without mentioning NOAA-19.

Can this happen today during space operations and in the space industry? If you’ve worked with people in any sort of way, then you know the answer to this. While Murphy may have cheered all of them on, the characters in these stories certainly didn’t need much encouragement. Remember, one of the steps in completing human condition therapy is acceptance…

Just one question, really, resulting from these stories: If a government satellite falls over in a high bay, do taxpayers still foot the bill even though they didn’t hear it? I think the answer, no matter what sort of PR is posted around that story, is sadly, yes. But happy reading!

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1980: Mt. Saint Helens from Space

Imagine being this close while the mountain is doing that. Image from http://svtmarcq.e-monsite.com/.

I was only 10 years old when Mt. Saint Helens erupted in 1980.  I remember the newspapers with pictures of the volcano spewing ash and smoke.  I remember seeing pictures of cars in Spokane covered in the ash from that angry mountain.  I remember the little cylinders of ash enterprising business-people sold to people who wanted a little piece of that natural history.  And this was while I was living with my family in the High Desert in Southern California.

But I don’t recall ever seeing any pictures of the active volcano from space.  Wired.com posted this article, which shows not just pictures, but two videos (kind of) of Mt. Saint Helens as it’s blowing its top.  The first one shows the impressive ash cloud, but the ash cloud is somewhat obscured by regular clouds (clouds in the Pacific Northwest?  Go figure.)–the bane of all regular imagery.  The second video, however, the one using infrared, shows just how far the ash cloud spread and how quickly.

The satellite that took these images was the National Oceanic and Atmospheric Administration’s (NOAA’s) GOES-1 weather satellite.  It was a fairly old satellite already, launched in 1975 when computers were probably still the size of continents.  It continued to collect environmental data until it was deactivated in 1985.  While the images of Mt. Saint Helens’ eruption are pretty nifty, the analysts and scientists who worked on analyzing the data probably took some time to put the images together (if anyone knows different, please let me know), so they weren’t available in real-time or near-real-time.

Literally a blast from the past, coming from space.  Wired’s article is definitely interesting, if only to watch the videos.

 

The UN “Disaster Charter”–what is it and who uses it?

Satellite image of 2013 Colorado flooding (town of Lyons). Image from Digitalglobe, and hosted by Digitalglobe.

Because it’s been a year, I’m taking a little break, but don’t worry, more original content is coming starting tomorrow again.  So you’re currently looking at some of the Clearancejobs.com articles about space I’ve written.  I’ll be interspersing these throughout for a little bit (not long).  This particular article was posted on Clearancejobs.com on 22 January, 2014.

Quick quiz:  What nation has invoked the United Nations International Charter for Space & Major Disasters twice in the past two months?  What, you didn’t know there was a UN “Disaster Charter?”  You don’t even know what the Charter means?  Well the Charter does exist, and you can fully get up to speed on it at the official Disastercharter.org website, right here.

But back to the question and possible answers. Did you answer Vietnam?  Malaysia?  The Philippines?  No fair using the internet for your answer.  But if you did try those particular answers, you’d be incorrect.  The answer is:  the United Kingdom.  That’s right, the UK activated the Charter on 4 December, and then again on 6 January.  There’s been extreme amounts of flooding in the land of jelly babies, tea, and crumpets during these past two months.

What does activating the UN “Disaster Charter” do?  It allows countries facing disasters to request image data collection immediately.  The imagery collection depends on who is immediately available in the satellite pool.  The satellite operator pool consists of many different organizations and companies, including DigitalGlobe, the National Oceanic and Atmospheric Administration (NOAA), the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), and about twenty other charter members.  Each of them brings a complement of satellites to help image the disaster area.

Why is the UN “Disaster Charter” important?  Simple—the activation and subsequent actions get images to the affected countries quickly.  This is theoretically a faster process than having to rely on a single national or commercial entity and waiting for their specific satellites to fly overhead at the right time.  The Charter activation allows the affected countries to see where the impact of the disaster and then “rack and stack” emergency resource responses based on the imagery.  To request activation of the Charter, you don’t even need to be a member–the Charter promotes universal access to the satellite resources.  Neat idea, eh?

It’s going to be more exciting and interesting to see how involved with the UN “Disaster Charter” companies like Skybox, Planet Labs, and Urthecast will be.  Such small and relatively inexpensive satellites and their operators might actually be more responsive than the bigger satellite operators.  Skybox wants to stream HD video from their birds—so imagine seeing the disaster area in real-time and how handy that might be.

UNITAR’s Operational Satellite Applications Program (UNOSAT), a sub-branch of the United Nations Institute for Training and Research (UNITAR) is the coordinating agency for all the images collected from the satellites responding to Charter activation.  It also insures the images get to the correct organizations and people (they are acting as collection managers).

For more information about the Charter’s purpose, in a presentation format, just go to this site.

Why Space Matters: GEO Satellite operations, Part 7–Curves and Angles

Geosynchronous (GEO) satellites are wonderful.  They can see a lot of the Earth from 22,236 miles in space.  It’s why they make great observation and communications satellites.  Previous chapters explained some of the problems facing GEO satellites, too, such as solar influence and eclipses.  But now’s the time for a few lesser known problems GEO satellites deal with have to do with:  angles and curves.

When talking about points on the Earth’s surface, I’ll be referencing latitude (the points north or south of the Equator), and longitude (the points east or west of the Prime Meridian).  If you aren’t acquainted with those topics, please go ahead and read my Zulu lesson series, here.

Not quite accurate, but you get the idea, right?  The 70 latitudes are represented by the red lines.

Not quite accurate, but you get the idea, right? The 70 degree latitudes are represented by the red lines.

Pole Position

If you live anywhere above the Antarctic or below the Arctic circles, specifically past 70 degrees South or North latitude, you’ve probably not had to deal with one particular angular issue.  Theoretically, a GEO satellite can see most anything on the Earth’s surface—to a point.  That point is the 70 degree latitude mark.  Remember how the Earth is shaped like a squashed pumpkin and therefore curved?  The Earth curves away from the satellite the further north or south from the equator you get.  Same deal with longitude.  The further away east or west from the area of longitude the satellite is stationed over the more the Earth curves.

This is a two-way problem, since a GEO satellite not seeing a spot on the Earth means that particular spot probably can’t get line-of-sight of the GEO satellite.  Once past 70 degrees latitude, you can’t see the satellite anymore from the Earth.  If you attempted to do so, the Earth would be getting in the way (your antenna would be aimed at the ground).  If you can’t see a satellite, you can’t communicate with it (unless you’re relaying communications–another story).  There is currently no “radiowave-passing-through-the-ground-through-the-atmosphere-into-space” communications technology, yet.  So anyone wanting a DISHTV or DirecTV receiver in those latitudes is out of luck.  If you don’t believe me, you can just use this convenient Geostationary Satellite Azimuth and Elevation Calculator to see what numbers you get past 70 degrees.

Polar Gap

High latitudes are a problem for the NOAA/NASA GEO imaging satellites, too.  It’s just one of the reasons why those organizations use Low Earth Orbiting (LEO) satellites for their imagery to augment their capability to get imagery of the poles.  There is another particular orbit, which will be discussed later, that also helps cover the polar region of the Earth.

For East and West longitudes, the answer is simpler—just place another satellite in GEO further east or west and continue in that manner until you get global coverage.  It only takes about three GEO satellites to get rudimentary global coverage.  The reason why the poles can’t be covered in the same way is because satellites are moving, orbiting the Earth–it’s just that in GEO the satellites are moving with the Earth’s spin.  There are orbits that do help compensate, but those aren’t GEO.  Again, that’s a topic to be discussed later.

But why do we care about communications at the poles?  Why do we want pictures of the poles?  Well, believe it or not, aircraft do tend to fly over, or pretty close to, the North Pole.  It can be the shortest way to get from one side of the planet to the other.  Wouldn’t it be good if a passenger aircraft had good communications with a satellite?  Coast Guard cutters breaking up the ice probably wouldn’t mind consistent satellite communications, either (although they might be using the Iridium satellites to help compensate for that).  And climatewise, there’s always something interesting happening at the poles.

Snell!! Snell!!

It’s a simple problem, then.  The Earth gets in the way of GEO satellites and the Polar Regions are difficult, if not impossible, to see from GEO.  But, the curving Earth is causing another, more complicated issue for the GEO satellites, too.  Remember that air that you breathe?  Yup, that is part of the Earth’s atmosphere, which, thankfully, hugs the Earth and creates that nice environment conducive to life.  The Earth’s atmosphere, while wonderful, is denser than the vacuum of space.

The atmosphere is not just uniformly dense, but changes density the closer to the Earth’s surface the atmosphere is.  This is where Snell’s Law comes in.  I won’t get into the specifics of Snell’s Law in this post—the wonderful folks at the Khan Academy have a great lesson series, with one particular lesson explaining Snell’s Law below.

The Bends

The upshot is that satellites deal with refraction, the bending of light as it passes from one medium, the vacuum of space, to another medium, the Earth’s atmosphere.  GEO satellites deal with refraction.  At the point above the Equator, the refraction isn’t obvious, because there’s barely any bending.  But the further away from that point, North, South, East, or West, the light bends more and more.

Not only is there bending, but the more the atmosphere curves away from the satellite, the more atmosphere there is for the light to have to go through when looking at it from GEO.  This can affect accuracy for determining where clouds are with weather satellites.  It might make a lake appear further north or south than it actually is.  It can wreak havoc with radio signals.  It’s one of the reasons why multiple satellites are better for looking at the Earth—two or three satellites looking at the same cloud can give a better “geo-location” coordinate for that cloud.

Now you know of some of the major problems of, as well as the great reasons for, using GEO satellites.  I did say there was another orbital solution to pick up the slack of coverage in the Polar Regions of the Earth, right?  I wonder if there’s anyone with a good inclination to read about that ;-)?

http://www.ashburysatcom.co.za/coverage/inmarsat-network-coverage/

LATE ADDITION:  I found the above link on Ashbury Satcom’s site.  It leads to a picture that shows the footprint of the three GEO INMARSAT satellites.  Note how the poles are not covered? 

Why Space Matters: GEO Satellite operations, Part 3–Revolution Earth

“Endless Distance, Wildlife and Stars, Blanket the Night…”

The last lesson was about Field of View (FOV) and Field of Regard (FOR).  It was intended to help with understanding the next few lessons regarding satellites in geosynchronous orbit (GEO).  All mentions of GEO on this blog, unless otherwise stated, refer to a particular type of orbit:  it is an orbit above the Earth’s equator matching the revolution, or rotation, of the Earth.

Just in case there are people reading this blog poised with a “well, actually”—yes, yes—there are other orbits associated with GEO.  You can go here to read all about those—the article is mercifully short, so if you’re curious, go ahead and read it.  But we’re not going to cover those other geosynchronous orbit types in these particular lessons.  The geosynchronous orbit type we will be focusing on is the geostationary orbit.  As stated before, we will use GEO as the term for that orbit type.

“…You lying beside me darling, Eyes open wide…”

Hopefully the concept of a GEO weather satellite being able to see more with its “eyes” in its FOR than a Low Earth Orbiting (LEO) satellite is an easy concept to grasp.  This main FOR distinction means a few things:  with GEO satellites, you can see the patterns of the clouds, instead of just cloud cover, which LEO satellites will give you.  With GEO weather satellites, you can see where a weather pattern is trending towards—so they are important for hurricane warnings and such.  The GEO satellite’s “eyes” cover a wider area.  The resulting images from such a vantage point are like the next image:

Image from “ThisIsMoney.uk” but they got it from NASA.

But one of the most important advantages is associated with the GEO’s orbital period (how fast it goes around the Earth).

While the wide arc of the globe is turning, We feel it moving through the dark…”

In the LEO satellite lessons, you found there were some variations in the orbital period of LEO satellites.  This has to do with the variations in altitude of the different satellites and you can just go to these posts to read more about them.  A GEO satellite is, obviously, at a much higher altitude and directly “above” the Earth’s equator:  35,786 km (22,236 mi) from Earth’s surface—or 26,199 miles if you go to the Earth’s core.  This altitude, and its position above the Earth’s equator, means the GEO satellite’s orbital period will match the Earth’s rotation.  Below is a decent animation of what’s happening:

GEO animation from Wikimedia

The satellite will arc through the sky, matching the globe as it turns.  So, what is the benefit of this orbital characteristic?

It means a weather satellite (or any kind of satellite, really) in a GEO position will observe the part of the Earth the satellite is orbiting above 24 hours a day.  This one aspect describes the concept of “persistence” in satellite operations.  Persistence is how weather satellites in GEO can “track” a weather system.  Instead of seeing small, swiftly passing “weather trees” that a LEO weather satellite can see, a GEO satellite sees the entire “weather forest.”

“…On a voyage between dusk and dawn, Space and time…”

And the GEO satellite can observe that “forest” for 24 hours a day, seven days a week, etc.  A LEO satellite, because it’s moving so quickly, and the Earth is rotating as much as 2,200 km (1,367 miles) per 90-minute low earth orbit, doesn’t have this kind of persistence.  Is it possible for a LEO satellite to have persistent observation of a single point of the Earth?  Well, kind of—you have to have more than one LEO satellite to accomplish persistence.  But, as discussed in previous lessons, this kind of LEO satellite constellation introduces complicated ground system requirements, communications interlinks, etc., which is why using only one GEO satellite is the option selected by many organizations to do the job.

There is another advantage regarding this orbit, though, and we’ll get into that next week.

The interspersed lyrics are from the B-52’s song, “Revolution Earth.”  Disappointing video, but great song from their album “Good Stuff.”