Tag Archives: geosynchronous orbit

Profits in Space

Moneysats

Do you know there are not many markets in the space business that are profitable?  At least that’s the spin of this Space Daily article.  It gives a few examples of areas in space business  and operations that can continue to grow and/or have potential to grow.

The area of space business which is growing like gangbusters, at least according to the post, is the communications sector.  This sector includes the continued use of communications satellites orbiting the Earth in geosynchronous orbit (GEO).  While the post doesn’t define exactly what the communications sector is, let’s assume it’s one full of internet relay, television broadcast, and telephone services.  There are quite a few commercial players in this particular field such as Dish, Arabsat, InMarsat, etc., so this kind of information shouldn’t be too shocking.

The growth part is in something we’ve already heard so much about:  space debris.  The post writer admits there really hasn’t been much done to fix the debris issue.  Sure, there are plenty of plans and announcements, but the writer believes there currently is no marketplace incentive to remove debris orbiting the Earth.

While I’ve always wanted some attention and eventual solution to the space debris problem, I do think that a solution won’t be built until something truly terrible happens.  That’s when there’s suddenly a market, because nations will be desperate to remove any other potential disasters.  Or, that a solution will come forth, but it will be a “dual-role” satellite.  This satellite would be able to not only clean up space debris, but it could also be used to take out satellites from other countries in time of war.

But back to the post–sure, if there’s nothing happening in the space debris market right now, then any growth will be a positive in business, right?  There’s an obviousness to that kind of prediction.  That’s kind of like mobile phone analyst “predictions” that the new iPhone will have a better screen, faster processor, etc.  Of course, these analysts still get paid for that kind of thing…

The writer of the post also mentions, almost curtly, the space tourism market.  Companies like Virgin Galactic and XCOR are working hard to get the millionaires into a sub-orbital flight.  I say millionaires because there are few “real” people who can afford the $75,000 to $250,000 price tag per seat on those spacecraft.  Perhaps the writer recognizes there’s a limited market for such space tourism–at least until prices begin to tumble.

Curiously, there’s not much focus on the launch market.  Someone has to get all of these satellites into orbit, and companies like SpaceX and Orbital are aggressively moving into it.  Ms. Gwynne Shotwell of SpaceX is saying the company is aiming to at least build two rockets per month by the end of the year to help it cope with a backlog of launches it needs to do.

There’s also the smallsat market, which is innovating at such a speed, it’s very difficult to keep up.  And these satellites will also need a way to get up into space.  So, yes, there is a chance to make profits in space.  But why limit it to just the obvious space communications and debris market?  There are definitely more opportunities out there in these other markets, too.

 

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Jam On It!–Arabsat’s Ethiopian Space Jam Problem

You knew this was the picture I was going to use. It’s only right, right? Image linked from Gifsoup, but Mel Brooks and his Spaceballs crew created it.

What does a satellite operator do if someone jams its broadcast signal?  Specifically, what does Arabsat do when someone jams its TV signals in Africa and the Middle East?  According to this Satellite Today post, the company first finds out where this “intentional uplink interference” is coming from.  Then it takes its case to the International Telecommunication Union (ITU) and, in this case, the Arab League.

Arabsat provides telecommunications and television broadcasting through its geosynchronous (GEO) satellites throughout the Middle East and North Africa.  According to Arabsat’s research, the jamming seems to be originating from Ethiopia.  That’s right–someone in Ethiopa has been jamming particular satellite TV signals last week.  RFI, France 24, Deutsche Welle, Al-Jazeera Arabic, Voice of America, and BBC are some of the jammed channels.

Why is Arabsat going to the ITU?  An arm of the ITU is the cooperative organization responsible for allocating “global radio spectrum and satellite orbits.”  It is the organization that is concerned about coordinating radio spectrum use globally.  Nations and private organizations coordinate the satellite radio frequencies they use through the ITU.  This is to help minimize the number of radio frequency conflicts between those organizations.

The ITU also  coordinates and allocates orbital “slots” for nations and private organizations to use.  For Arabsat, the GEO slot is 26 degrees east of the Prime Meridian.  Because the jamming seems to be affecting not just Arabsat communications, but the satellites around the 26 degrees east slot, the ITU is the natural place for anyone with a grievance and problem related to satellite communications.

Coverage of Arabsat. Image linked from CDN Satellite Today. Click on link to embiggen.

What happens if they actually catch the Ethiopian jammer?  According to this BroadbandTVNews.com story, Arabsat will:

“…follow up the matter and take all appropriate actions to prosecute the culprit at the judicial authorities and the international organisation of frequencies and any legal means that may deem appropriate to ensure that any damage already incurred or to be incurred by the noise, will not go without legal action, regardless of whether this damage is direct or indirect.”

Maybe a more civilized option than using a cruise missile or drone to solve the problem?  After all, a jammer being used in wartime just becomes a priority target on a list.  But this isn’t wartime, and making something expensive to do, such as operating a jammer and then being fined and/or put in jail, is probably an excellent deterrent.

This does show one of the drawbacks of satellites.  Jamming a satellite’s up/downlink and broadcast signal causes all sorts of problems for operators and users.  Operators lose the ability to command a satellite, and of course the broadcast signal from the satellite is overcome with the radio “noise” a jammer creates.  Sometimes it might happen and an operator might not even know about it.  Arabsat notes this occurred to one of their satellites back in 2012 as well.

Why Space Matters: HEO Satellite Operations, Part 2–Those Pesky Overcharges

Charged particles

Satellite highly elliptical orbits (HEOs) are interesting orbits for space operators in any kind of mission, especially considering the challenges inherent in using such orbits.  OK–so that statement’s a little nerdy, but if you’re reading this blog, there’s an inner nerd in you just waiting to be outed.  In the last lesson, you were, perhaps unknowingly, subjected to learning one of Kepler’s Laws of Planetary Motion to help explain the shape of an orbit.  It turns out that even the most circular orbits are ellipses.  But satellites in HEO aren’t following a circular path.  And while Kepler’s Laws were originally applied to the planets, they also apply to man-made satellites.  HEO satellites are an excellent example of Kepler’s laws at work.  But what are the considerations and challenges facing space operators of satellites in HEO?

HEO satellites must face a few challenges geosynchronous (GEO) and low earth orbit (LEO) satellites don’t.  HEO satellites move around the Earth.  So do GEO satellites, but GEOs move at the speed of the Earth’s rotation, so the GEO satellites appear to “hover” over one particular spot of the Earth 24 hours a day.  GEO satellite ground antennas barely have to move in order to communicate with GEO satellites.  But HEO satellite ground terminals are more like LEO satellite ground communication terminals:  in order to communicate effectively with satellites of both HEO and LEO orbits, the ground terminal antennas have to move.

Sometimes they're exposed to the elements...

Example of a satellite ground antenna.

As discussed in this LEO lesson, the antenna on the ground “tracks” the LEO satellite above it to maintain communications contact.  Remember, because LEO satellites are orbiting the Earth so closely, they are also moving fairly quickly over their ground antennas.  This means the time for communications from the satellite’s rise above the antenna’s horizon through its traversing over the antenna and to the satellite’s setting below the horizon, is only about as long as 15 minutes or so.

But this shortcoming in time is one of the advantages of the HEO satellite orbit, depending on a few factors (to be talked about in a future lesson).  A HEO satellite at its orbital apogee (remember—that’s the part of the orbit furthest away from the Earth–pictured below) takes on some GEO characteristics.  It almost appears to hover over particular parts of the Earth.

Football 4

The closer the satellite gets to apogee, the slower it appears to be going.  But the closer the HEO satellite gets to perigee (the part of the orbit closest to the Earth), the faster the satellite is moving.  This “speeding up” and “slowing down” of the satellite is the second of Kepler’s Laws of Planetary Motion (seen in action below).  This post will not go into the law’s details–you can go to the wiki for that.

Kepler’s Second Law of Planetary Motion. Image from Wikimedia.

 

So, the satellite ground antenna moves, always pointing along the satellite’s orbit path at where the satellite should be, tracking the HEO satellite to maintain a constant communications link. The HEO satellite ground antenna can keep in contact with the HEO satellite for hours, vs. the minutes of communications time with a LEO.  This means the HEO satellite, if augmented with two or more other HEO satellites, could be a very good communications satellite—especially if the country interested in communicating has a big land mass in the very northern latitudes of the Earth (this country will be talked about some more in the next post).

The drawback to having more than one HEO satellite is the need for more than one satellite ground antenna–since every single satellite will be in different part of the HEO path (or a different HEO altogether) a different antenna is required to track those satellites as well.  This could also mean that while a HEO’s ground antennas are contact for a long time, there’s also a period when the satellite is not in contact with the ground antenna.  Both lengths of time depend on the orbit’s period.

The other challenge a HEO satellite faces which a GEO satellite normally doesn’t, is the HEO satellite’s orbit transits the Earth’s Van Allen belts four times a day.  The Van Allen belts are layers around the Earth full of charged particles—very energetic electrons and protons—which the Earth’s magnetic field has captured.  The charged particles can do some very bad things to a satellite’s electronics like the solar cells, sensors, and circuits.

This is an older picture. NASA now knows there’s a third, “transitional” belt between the inner and outer belts. Image from Wikimedia.

Satellites anticipated to transit the Van Allen belts are designed with shielding to minimize the odds of a stray electron or proton causing problems.  Like electrical power requirements (talked about here), shielding is also a balance of risk versus cost versus weight.  And weight can equal cost in the amount of fuel a rocket needs to lift the satellite into orbit.  If the satellite is too heavy, the rocket might not be able to lift it into the necessary orbit.  So HEO satellites are playing the odds, with lots of smart people figuring out a balance between risk and reward during the satellite design phase.  While the odds are lowered through design, there’s still the chance of an electrical problem occurring because a very energized particle happens to hit a circuit or sensor “just so,” with odds of such an event happening increasing with every subsequent transit.

But why on Earth should someone even want a satellite to go into HEO?  Why would someone want a satellite that has to transit the Van Allen belts?

That discussion will be in the next lesson.

Oh!  And to answer the question posed to you from this post:  the MMS satellites will be in a HEO.

Why space matters: HEO Satellite Operations, Part 1–You’ve Never Kepled?

In previous lessons you’ve learned about the Low Earth Orbit (LEO) and the Geosynchronous Orbit (GEO).  There are pros and cons in using each orbit.  Generally for satellites in LEO orbit, particularly imagery satellites like those owned by DigitalGlobe and SkyBox, the closer the satellites are to the Earth, the more detail of the objects and activities on the Earth’s surface they’re able to see.

But the con for LEO imagery satellites is that they’re so close, their Field of Regard (FOR) and Field of View (FOV) are very limited (go here for a reminder of what FOV and FOR are).  This means they can see pretty much what is right under them and a little bit around them—but,  and some of this depends on the camera and lens technology, it will be fairly detailed.

The GEO satellites FOR allow for them to see the whole of the Earth’s surface that’s facing them (the Earth’s disk).  And they stay over that particular portion of the Earth because their orbital speed matches the speed of the Earth’s rotation.  But, while weather imagery satellites can give a good understanding of patterns, they can’t see the details.  They’re just too far out.

Perhaps there’s another orbit, one that possibly bridges the capabilities between the other two orbits?  Such an orbit exists, but it’s very eccentric.  It’s an orbit that can be up close to the Earth, but also far away.  It’s called a Highly Elliptical Orbit (HEO).  It’s a very interesting orbit in which many different missions are accomplished.  Also, notice the trend:  LEO, GEO, and HEO.  Space operators try to keep things simple and rhyming acronyms are one way to do it.  Plus we’re not that smart, so if we can memorize this stuff, you can.

The HEO name is a fairly good description of the orbit, but for those who require a visual aid, imagine an orbit that’s shaped like an American football, with the tips more rounded.  This is an ellipse.

Football

Now imagine that football is tilted in in a kicking tee. This represents the orbit’s inclination.  It’s at a particular angle with the Earth’s equator.  And yes, LEO satellites also have inclination.

Football 2

But this demonstrates a HEO property that’s different from a LEO.  Like LEO, a HEO orbits around two fixed points, called foci.  You may be wondering how a LEO has two fixed points—a LEO is typically circular.  And that’s still true, but with two points.  In the case of the LEO circular path, the two fixed points are much closer together.  They are nearly on top of each other.

An elliptical orbit, on the other hand, has two fixed points, but they are much further away from each other.  In our example, the football’s shape wraps around the Earth, with one end of the football (and therefore, one end of the orbital ellipse) closer to the Earth than the other.  The Earth occupies one of the two fixed points within the HEO.  The other fixed point is not occupied by anything.

Football 3

That shape, tilt, and closeness of one end to the Earth is, in essence, the path of a satellite’s Highly Elliptical Orbit.   And now, without the football:

Football 4

The part of the elliptical orbital path that’s closest to the Earth is called perigee.  The part of the orbital path that’s farthest away from the Earth is called apogee.  So congratulations!!  You’ve just learned one of Kepler’s Laws of Planetary motion:  “The orbit of a planet is an ellipse with the Sun at one of the two foci.”  –wikipedia.org, Kepler’s laws of planetary motion.  If the name “Kepler” sounds familiar, it’s also because a satellite was named after him.  You can go the NASA satellite mission website to understand why it’s named Kepler, and what it’s doing.

I wonder what else there is to learn next lesson about HEO?

 

Gravity Check: Thousands of Satellites Orbit Earth

Counting Satellites

Quick–just how many satellites, operational or not, are orbiting Earth?  Pretend you’re trying to impress your fellow engineers.  Even better, pretend you’re trying to impress people in a bar (although that strategy might backfire).  Have you guessed?  Do you really want to know if you’re correct or are you satisfied with impressing the folks in the pool hall?  If it’s the former, then this Talking Points Memo post helpfully gives several numbers regarding satellites orbiting the Earth.  So next time, you’ll be very accurate and the biker in the leather jacket will buy you that beer for your numerical diligence.  Well, it might helpful, at least, for those who love minute details and numbers.  Maybe you should bring it up at an accountants meeting instead?

But before you go over to the post, did you guess a number?  You’d be closer if the number were in the thousands.  Do you know who owns all of them?  What countries do they belong to? Remember, you’re going to have to include cubesats, small sats, GEOs, LEOs, MEOs, and HEOs.  It might help during your counting if you have some excellent optics and a pad and pen.  Or you could just go to Talking Points Memo’s post and find out.  That would certainly be easier, and take less time.  But if you’re like me, maybe you’re not so busy…