Japan Launches "Super-Speed" Internet Satellite 159
A number of readers wrote in about the launch this morning of a Japanese H-2A rocket carrying a Kizuna ("Winds") satellite into orbit. Kizuna is intended to provide "super high-speed data transmission" for Japan and Southeast Asia. The news stories on the launch, such as the AP's linked here, are short on technical detail. For example they say the satellite successfully achieved orbit 175 miles above the earth — hardly suitable for Internet communications to a specific area on the surface (remember Teledesic?). Reader nebulus4 provided a link to the Japan Aerospace Exploration Agency site with an illustration and a little more detail. Such as the fact that Kizuna is destined for geosync orbit, and that a 45-cm antenna will equip eventual users for 155 Mbps down / 6 Mbps up, whereas a 5-m antenna will allow enterprises and ISPs to tap into 1.2 Gbps down. Given the latency to geosync orbit, you probably wouldn't want to use Kizuna to play an online shooter.
Now featuring... (Score:1, Insightful)
Re:Now featuring... (Score:4, Insightful)
I believe geosync orbit has a MINIMUM lightspeed latency of 119.4ms.
Not a fun starting point BEFORE collisions and noise.
Re:In other news... (Score:4, Insightful)
You cannot be serious (Score:3, Insightful)
Geosynchronous Latency (Score:4, Insightful)
round trip = times 4 = 88,932 miles
speed of light (wave propagation) = 186,282 mi/sec
latency = 88,932 / 186,282 = 0.477 seconds (on top of regular network latency)
Curse you speed of light. You win again!
Molniya orbits (Score:3, Insightful)
Problem is, a Molniya orbit requires three satellites for coverage at the apogee, which is at about the same altitude as the geosynchronous orbit. At the perigee the satellites move faster, so you need more of them to keep one always on sight.
Re:You cannot be serious (Score:3, Insightful)
Re:Now featuring... (Score:5, Insightful)
You have to multiply times four to get a useful figure. Latency is normally measured round trip. Hop up, hop down, return hop up, return hop down. Latency to geostationary orbit is half a second.
However, 175 miles up is NOT geostationary. Geostationary is 35,786 km up, give or take. The orbit is geosynchronous. That just means the orbital period is the same as the earth's rotation, so it returns to the same spot at the same time every day. It will NOT stay in the same place, however. They'll have to have several of these things in a similar orbit flying over periodically like we do for GPS satellites. It also means the round trip latency is about 3.76 msec (just less than a millisecond per hop), a heck of a lot shorter than half a second.
Re:You cannot be serious (Score:2, Insightful)
Re:Latency? What latency? (Score:5, Insightful)
175 miles? Try more like 22,230 miles. That's pretty much the only place you can put it unless you want your internet connection to only work 3 minutes out of every 90 minutes...
The reasons are simple physics. Gravity causes everything to want to fall towards the center of the Earth. Satellites manage to stay in orbit because they are constantly "falling" ahead of the Earth. That's why things in "low earth orbit" are referred to as being "in freefall" and not REALLY in zero gravity. Gravity is still there, only the velocity of the satellite is so high that all gravity manages to do is curve the trajectory of the satellite, not cause it to lose height. This means your satellite is going to be moving VERY fast with respect to the ground.
It's only at 22,230 miles out where the circle is so big that your satellite now appears fixed with respect to the ground. It's still moving. It's still "free-falling". But it appears to be hovering over a fixed spot over the equator - very useful for communication satellites since now you know where to aim your antenna and you don't have to bother moving it.
What happens when (not if) ... (Score:3, Insightful)
With all this reliance on satellite technology for GPS, communications, and weather prediction what happens when (not if) the sun hits a more active solar cycle eliminating all of these satellites in one fell swoop? We have become terribly dependent on satellite technology (that I agree is cool). However, there have been solar storms that would knock out all of our satellites in recent memory -- only we did not have any satellites up yet. Now the satellites are up and the next large solar storm is just lurking out there getting ready to strike.
As usual, beware any significant reliance on any one technology.
Comment removed (Score:3, Insightful)
Speed? How about slow but free global access? (Score:2, Insightful)
But. Why can't we use the already existing technology to provide (initially) slow but "pervasive" internet access everywhere? The developed world could easily afford to build a network of satellites that provides both "super-speed" data capabilities for their own wealthy subscribers while offering slower but free access to anyone else interested. Free internet access (ie. communications), independent of the policies of local regimes, could easily be considered a modern human right.
Instead of the token complaints of lack of media and communication freedoms in countries like China and their vassal dictatorships in North Korea and Burma, the West could give these oppressed people access to the outside world, and the ability to communicate within their local "firewalls" without pervasive state monitoring. Of course the possession of unauthorized (ie. fully monitored) communication devices is criminalized in such countries, so the devices would have to be not only affordable but also compact, perhaps identical to existing smartphones or PDAs. In places where satellite dishes are allowed or somewhat tolerated, there should be a way of converting existing dish/decoder combos into simple internet terminals.
I've no doubt that this could be done, but thanks to Dubuya's misguided quasi-religious "war of terror" and "partnering" with the likes of Putin and Hi Jintao (aka the Butcher of Tibet) and the resulting labelling of occupied Tibetans as "terrorists", the USA in particular seems to be in no mood for creating freedom of communications in such "partnering" countries, not when their dominant corporations would see no financial incentives in creating such network and in any case they tend to be extremely friendly with the ruling Chinese regime already. And god forbid if those dangerous prayer and freedom(!)-chanting Tibetan "terrorists" would be able to use their own language to communicate freely and even "terrorize" the occupying Chinese army with details of their oh-so-liberating policies in Tibet!
Where's the union of peace- and freedom-loving democracies when we'd need it?