Tag Archives: Communications satellite

The Mission Readiness Review–Episode 5: NOAA Means NO!!

This site contains my opinions and ideas only, not the opinions or ideas of any organization I work for. It’s my idea playground, and I’m inviting you in. Welcome!

Click on the link below to get the latest TMRR episode. There will be no TMRR next week–I’m gonna be really, REALLY busy.

https://tmrr.podbean.com/e/episode-5-noaa-means-no/ .

On this episode we talk about: A space nation takes us to its leader; SpaceX and NOAA point fingers at each other; and India’s communications satellite just won’t speak up.

We are also on Google Play Music.

Intro background music POD Dreams by Stefan Kartenberg (c) copyright 2017 Licensed under a Creative Commons Attribution Noncommercial (3.0) license. dig.ccmixter.org/files/JeffSpeed68/56307 Ft: Debbizo, Michael Bacich.

Show links

Launch schedule: https://spaceflightnow.com/launch-schedule/

NOAA licensing: http://spacenews.com/noaa-speeds-up-remote-sensing-license-reviews-amid-broader-regulatory-changes/

SpaceX/NOAA: http://spacenews.com/noaa-explains-restriction-on-spacex-launch-webcast/

Asgardia: https://gizmodo.com/the-mostly-online-space-kingdom-of-asgardia-attempts-de-1824310853

Cult analysis: https://carm.org/cults-outline-analysis

Asgardia-1: https://asgardia.space/en/satellite/

Beer in Space: https://www.smithsonianmag.com/science-nature/how-to-make-beer-in-space-180968404/


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 4–Moley, Moley, Moley, Molniya!

During the last lesson, you might have been enlightened with the information that even though the Soviets have used, and Russians do use, geosynchronous (GEO) orbits for satellites, they seem to have a special place in their vodka-filled hearts for the highly elliptical orbit (HEO).  And that last lesson enumerates the reasons why they like it.  For one particular instance and for one particular HEO, they liked it so much, they gave the orbit a name.

Soviet satellite scientists were very clever when they first started using the HEO.  They already knew the Earth’s squashed pumpkin shape (its oblateness) normally “spins” (or perturbs) a satellite’s orbit slowly about the Earth’s axis.  But, they somehow figured out that a HEO satellite with a 12-hour orbital period using a specific inclination of 63.4 degrees nearly nullified that perturbation.  That particular period and inclination is a special kind of HEO the Soviets named “Molniya.”  By the way, they named their communications satellites in this orbit AND a rocket (a modified R-7), Molniya, too (so no potential for confusion there, I guess).

The Molniya orbit. Image from Wikipedia–click on it–you know you want to…

Let’s translate all that scientific “hoo-haw” into English a little bit.  The angle between the path of the satellite’s orbit, as it passes from south to north over the Earth’s equator, and the Earth’s equator itself is 63.4 degrees.  The satellite’s particular HEO is a 12-hour long trip around the Earth, which means the Molniya satellite orbits the Earth twice a day.  And the inclination was specifically chosen by Soviet scientists because it’s a very stable orbit.  The satellite seems to be rising, flying over the Earth, and setting at about the same spots over the globe every single orbit (there’s a slight shift backwards around the Earth of about -.07 degrees per orbit).  These characteristics are very specific to a Molniya orbit.

But the best thing about the Molniya is when a satellite in that orbit is near and at the Molniya’s apogee.  The satellite appears to “hover” over the Earth (no mystery why—read this lesson for a refresher).  Of a 12-hour period, there’s nearly 8-9 hours of time when the satellite can “see” most of a particular part of the northern hemisphere.  This characteristic means that for about 8-9 hours, the HEO/Molniya satellite can maintain contact with a ground station, broadcasting messages from that ground station to all receivers within that satellite’s Field Of Regard (FOR), which includes areas above 70 degrees north latitude.  Below are a few Wikipedia-cribbed pictures showing a satellite’s FOR in a Molniya orbit four hours before apogee, at apogee, and four hours after apogee.  As you can see, there’s a lot of the Earth in view during all that time (Russia, China, India, Koreas, etc.).

View of Earth four hours before apogee in a Molniya orbit. Image from Wikipedia–click to embiggen.

View at apogee in a Molniya orbt. Image from Wikipedia–click to embiggen.

View of Earth four hours after apogee in Molniya orbit. Image from Wikipedia–click to embiggen.

There’s one obvious problem for people wanting to broadcast 24 hours a day with a Molniya satellite:  communications only lasts about 8-9 hours from a Molniya satellite’s “rise” to its “set” on the opposite side of the Earth.  This means there is “dead air” for their broadcast area for nearly 15-16 hours each day.  Yes, 15-16 hours—a broadcaster’s nightmare (unless they’re union).  The gap is because the Earth has continued rotating, and by the time the Molniya satellite rises again for the second orbit of the day, the other side of the planet is now in the satellite’s FOR.

There is an answer to this problem, though.  If 1 or 2 more satellites are put into different Molniya orbits, ones in opposing orbits (so the orbits create an “open scissors” if you traced their paths—see below), then the broadcast coverage is 24 hours.  And this is what the Soviets did, successfully starting the Molniya constellation by launching the Molniya-1 satellite in 1965 (after two satellites had been destroyed in previous launch attempts).  And even as the Soviet empire fell, the Russians used and continue to use the Molniya orbit today.

Moley 1

The upshot of the Molniya orbit is that it’s an orbit perfectly suited to help a communications satellite (or satellites with other missions) keep sight of countries at very high latitudes.  Using multiple satellites in a Molniya orbit provides a very good, very big, FOR and can be extremely useful for communications, especially with stations and vehicles working within the Arctic Circle.

But what are some of the other things being done with satellites in HEO?  Maybe Part 5 of this HEO Series will answer that question.


Why Space Matters: 2014 FIFA World Cup–30,000 Hours of It


This is more of a **yawn** for me, as I’m not the biggest sports fan in the world.  Maybe not even the millionth biggest.  But there are a lot of people who inexplicably are–especially those soccer (“football” for everyone not in the US) fans.

Good news then, for those fans:  satellites and frequencies have been allotted to ensure Fédération Internationale de Football Association (FIFA) goals are seen and met.  According to this SatNews.com post, 30,000 hours of coverage delivery by broadcasters to SES, a communications satellite operator, will occur during FIFA’s World Cup in Brazil.  At least seven of SES’ satellites will be used to broadcast World Cup globally, with some regional focus.

These broadcasts will be covering all FIFA World Cup venues and are focused on Europe, Latin America, and North America (where the one soccer fan will appreciate it, I’m sure).  But, other country regions will also get the FIFA broadcasts.

Ultimately, SES believe nearly 3 BILLION people will be watching FIFA around the world.  And that probably doesn’t count the ones who will watch the internet streaming of the event.  So yes, this is important for the soccer fans of the world.

DIY Space week project today–take some motion capture pictures with your camera.  This post tells you how to do that:  http://makezine.com/projects/how-to-capture-breathtaking-time-lapses-of-the-night-sky/


You might remember in another aside I posted, I noted the Chinese may not be just targeting the United States with their space activities, but their Indian neighbors, too.  Well, according to this article, the Indians just had one of … Continue reading