View Full Version : Satellites

2006-Mar-26, 06:25 AM
Hey all! I'm new to the site, though not overly new to the whole concept of the Universe, and "what's out there"...

I just wanted to ask a question, cos I'm having heaps of difficulty writing a paper and I wanted to ask some people that seem very "in the know" when it comes to space-related issues! ^_^

Can anyone tell me some of the positives and negatives of different satellites? In particular (if possible):
- Weather satellites (survsats and meteosats)
- Reconnaissance/Spy satellites
- Communications satellites (in particular telephones and televisions)

If some people could answer my question, I'd be eternally grateful, as I'm having a real hard time finding any information anywhere on the postives/negatives!

Manchurian Taikonaut
2006-Mar-26, 10:47 AM
I'll try and sum it up as bluntly as possible

Negatives: They cost a fortune and some religious loonies or anti-space people will want money spent on something else

Positives : Thanks to them and other inventions we are no longer living in medieval era and satellites can be used to help monitor floods, forecast storms, help in search and rescuse, for defence, GPS, there are huge economic benefits where technological spin-off often filter down into the airline industry or cars or even simple household objects, satellites improve communication providing mobile cell phone coverage, better internet linkage, improve trade with financial transactions, they can be used to study climate change or global warming.

'Everything we do in space benefits us down here' By: Justin Trottier
Space spin-offs
Experiments done by the Columbia astronauts will lead to improved earthquake safety, cleaner air, better human health and will save lives.
Check the ESA projects they have a bit of info

2006-Mar-26, 01:37 PM
Manchurian Taikonaut, this is a warning. I recognise that you don't respect people who have religious reasons for disliking satellites, but you can't call them bad names.

Manchurian Taikonaut
2006-Mar-26, 04:03 PM
you're right I'm sorry to offend anyone

2006-Mar-26, 08:42 PM
Sattelites are important

Larry Jacks
2006-Mar-26, 08:43 PM
- Weather satellites (survsats and meteosats)

Positives: It has been a long time since a hurricane hit without warning - essentially before weather satellites. Advanced warning allows for earlier evacuation, saving countless lives. Weather affects everyone in countless ways, from airline flight delays to the price of food.

Negatives: there aren't any that I can think of

- Reconnaissance/Spy satellites

Positives: Back in the 1960s, President Johnson once commented that all of the money spent on reconnaissance satellites had justified the entire space program (both military and civilian). Before those satellites, the US believed that the Soviet Union had thousands of bombers and missiles aimed at us. The satellites reveiled that the number was only a tiny fraction of that. As a result, we greatly reduced the number of bombers and missiles we bought.

You have to remember that at least two generations of military and civilian leaders lived in fear of a "nuclear Pearl Harbor" attack. Reconnaissance capabilities reduced the level of tension and probably helped prevent WWIII.

Negatives: This technology can cut both ways. It can be and is used against the US military just as the US military uses it against others.
- Communications satellites (in particular telephones and televisions)

Positives: Communications satellites no longer play as important a role for telephone calls as they once did due to the widespread use of fibre optics. They're still used for communications to really remote areas, to ships and planes, and for special purposes. However, communications satellites play a tremendous role for television. Not only do we have satellite systems like Dish Network and DirectTV directly broadcasting to millions of homes, but almost all of the non-local channel programming carried on cable TV outlets around the country are delivered to the cable TV companies via satellite.

Communications satellites are also used in many areas that people don't realize. For example, a significant percentage of credit card machines at gas station pumps and ATM machines use communications satellites to carry the information. We realized this when one day, several years ago, the failure of a single satellite affected something like 40% of the ATMs, pagers, and credit card machines.

Negatives: Geosynchronous communications satellites have a propagation delay due to the distance involved and the speed of light. This is one of the reasons why they aren't used as much for phone calls anymore. The delay is just long enough to be both noticeable and annoying.