41
votes
Accepted
Does the International Space Station get TV?
More or less.
While the ISS is below the satellites use for TV transmissions, it is passing by so fast that the coverage will be highly intermittent, meaning that you would be able to watch a ...
- 12.6k
33
votes
Accepted
What would be the first noticeable consequences to the general public of widespread satellite destruction?
What would you notice first?
Satellite navigation: immediately (depending on how often you use satnav)
TV: immediately (depending on how often you use TV). Even if you don't use satellite TV ...
- 125k
28
votes
Accepted
SpaceX's 4,425 satellite constellation - what's the method to the madness?
Nodal precession doesn't matter for a plane of satellites like this, they will rotate around in unison, so the coverage will remain the same.
Okay. So, why the unusual dual inclination constellation? ...
- 121k
27
votes
Accepted
What is carrier lock and bit lock?
First you lock on to energy at (or near) the expected frequency. That’s carrier lock.
Then you start to look for patterns in how the phase changes. The transmitter is coding groups of bits as phase-...
- 12.6k
25
votes
Accepted
Why are obsolete geostationary satellites re-orbited above the geostationary belt?
Orbits at the altitude of GEO are stable for very long times (millions of years). There is no significant decay of the orbital height due to some kind of drag, so the risk of these satellites ...
- 14.9k
24
votes
Quantum technology for starship communications and landing on Mars
No, quantum mechanics cannot be used to transmit information faster than light. This is a common misconception based on misunderstanding how quantum mechanics works. Go here to read more about it. ...
- 1,700
22
votes
Accepted
Would adding satellites between Earth and Mars improve communications latency?
No. Communication latency (the time between sending a bit and receiving it on the other end) between Earth and Mars probes is limited almost entirely by the speed of light, as they are radio waves on ...
- 4,548
22
votes
Will Curiosity and the Mars 2020 rover be able to communicate with each other via a Mars orbiter?
Yes, they could theoretically communicate with each other over the DSN, however in practice this will not happen (as it has no current uses).
The amount of functions that Curiosity can perform ...
- 17.9k
22
votes
Accepted
Is it normal for the US Space Force to warn companies about a possible collision (conjunction)?
Space Fence is what our current tracking system is called. This article claims that some companies and countries have an arrangement to receive tracking data, but few details. It appears that this in ...
- 348
22
votes
Accepted
Why do Teledesic satellites look so weird? What are these structures and where's the satellite bus?
After a great deal of searching, I found a PDF here, by Mark A Sturza of Teledesic. There's a basic diagram of the satellite on page 8
(Image credit: Teledesic Coporation)
There is also the ...
- 2,451
20
votes
Why are obsolete geostationary satellites re-orbited above the geostationary belt?
Actually, it makes a lot of sense to raise the orbit of end-of-life geostationary satellites: Coming from Earth you have to cross through a lower orbit to transfer from low earth orbit to a ...
- 7,216
19
votes
Quantum technology for starship communications and landing on Mars
There's already two good answers that say a lot of what I wanted to say, and I will refrain from repeating any of their content here. I do think it is useful to add one more item of insight though. ...
- 420
18
votes
Accepted
Are commercial communications satellites in GEO being constantly monitored by telescopes?
It seems that the company ExoAnalytic Solutions regularly observes high- orbiting satellites (MEO, HEO, and GEO), using the data to provide tracking, ensure they are at the right spot, and provide ...
- 121k
17
votes
Accepted
What (actually) makes Iridium "the world's only truly global mobile satellite communications company"?
As of today (October 2016), Iridium is the only public satcomm provider using a constellation of low earth orbit satellites with high inclination orbits to provide a service with global coverage. You ...
- 1,375
17
votes
Accepted
How do communication satellites remain positioned above a particular region?
Such satellites are in a geosynchronous orbit (GSO), orbiting at an orbital altitude where orbital period matches Earth's rotation on its axis. Their orbital speed is roughly 3 km/s at mean orbital ...
- 76.5k
16
votes
Accepted
Do antennae on the ISS have to constantly move to maintain data links?
The US side of the ISS has a number of antennas to support its rather complicated comm system. Most visible are the two Ku-band High Gain Antennas which are 6 foot diameter azimuth/elevation gimbaled ...
- 178k
16
votes
Accepted
Difference between Tundra and Molniya orbits?
They are definitely not identical.
Tundra is geosynchronous; period = 1 day. The eccentricity allows it to spend most of the time over a region of Earth off the equator, something not possible for ...
- 54.9k
16
votes
What would be the first noticeable consequences to the general public of widespread satellite destruction?
The experiment has been done, with a single, geosynchronous, satellite, Galaxy IV, in 1998. The immediate effect I noticed in the San Francisco Bay Area was loss of the live NPR feed. I did not check ...
- 281
16
votes
Does the International Space Station get TV?
@Antzi's answer is right, but I'll add some context as a supplement.
While Doppler (mentioned there) might or might not be an issue for an off-the-shelf commercial satellite TV box (I don't know) it ...
- 149k
15
votes
What is the most popular programming language in space?
I wrote code that flew on 3 spacecraft that went to Mars, one to the Moon, one to a comet and back, and a few Earth-orbiting satellites, the last of which was about 10 yrs ago. All of them used C.
It'...
- 546
15
votes
Accepted
Main differences between 5G and Starlink?
Starlink and 5G don't have that much to do with each other--they compete for different customers.
Starlink systems currently require a large receiver the size of a pizza box to uplink to satellites. ...
- 17.9k
14
votes
Accepted
Do satellite uplink/downlink signals spread or leak into space?
They have to spread their signal. Also, it requires a really big dish to not spread your signal at all.
Imagine that there was no spreading at all. The dish would have to be pointed exactly at the ...
- 121k
14
votes
Does SpaceX expect 1 collision involving one of their Starlink satellites every 2 years?
I think you've made a bit of a logical/statistical misstep.
Primarily, the "1 in 100,000" figure is a bit misleading because it's not a statistic. It's an operational risk level threshold ...
- 17.9k
13
votes
Is it normal for the US Space Force to warn companies about a possible collision (conjunction)?
It's routine, and done as a service for the space community at large. Companies doing official business with the U.S. Government can get access to a variety of additional services, but the basic ...
- 7,778
12
votes
Accepted
What will be "unique" about upcoming SES-9 GTO transfer profile by SpaceX?
SpaceX has stated a goal that every launch going forward will attempt to land. The expectation initially is not 100% success, but an attempt at the very least.
Large GTO payloads do not leave enough ...
- 79.3k
12
votes
How much will SpaceX's constellation of Internet satellites cost?
First of all, let's figure out how many satellites per launch vehicle. The estimate of the mass of these satellites is 386 kg. The mass for a launch of a Falcon 9 is 5500 kg. That means one could ...
- 121k
11
votes
Could a smartphone really transmit to satellites in a space based internet system?
While power requirements are higher than for regular GSM service, they are not as high as one might think.
Current satellite telephones use handsets of the size of 2000-era mobile phones and are able ...
- 14.9k
11
votes
Accepted
What does "clearing of C-band spectrum" mean and why will it cost Intelsat a billion dollars?
There is currently a push in the United States to expand mobile phone and data service. In particular, 5th generation (5G) uses part of the telecommunications C band. However, Intelsat already has a ...
- 47.7k
11
votes
How were Intelsat 1 “Early Bird” and Telstar 1's "hundreds" of simultaneous telephone conversations multiplexed/demultiplexed?
It was done on the ground, and frequency-multiplexed.
In this arrangement,
12 individual telephone channels are frequency-multiplexed into the 60 to
108 kc band as shown.
Source: Results of the ...
- 178k
10
votes
How much time does it take to circularize a GTO orbit using ion propulsion?
I'm taking Eutelsat 117 W B as an example.
The simple, obvious answer is "about half a year" — this satellite was launched in March and entered service in October 2015.
But I wanted to figure out ...
- 1,632
Only top scored, non community-wiki answers of a minimum length are eligible