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 ...
  • 12.2k
34 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 ...
  • 122k
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? ...
  • 119k
26 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-...
  • 12.4k
25 votes
Accepted

Is it possible to replace Internet with LEO satellites?

You can't replace the Internet like that since Internet is also a collection of protocols for routing and addressing, and transmitting users' data. You can try swapping fiber optic links for LEO sat ...
  • 11.4k
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 ...
  • 13.5k
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. ...
23 votes

Can a satellite orbit Earth so that it always has the Moon in line of sight?

http://en.wikipedia.org/wiki/Lagrangian_point A satellite orbiting at the L1 point or L2 point would be in constant contact with the moon. Unfortunately, neither of these are particularly useful for ...
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 ...
  • 4,526
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 ...
  • 15.1k
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 ...
  • 347
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 ...
  • 2,204
20 votes
Accepted

Can a satellite orbit Earth so that it always has the Moon in line of sight?

If I understand your edited question, then no. While the Earth's J2 (oblateness) produces enough torque to rotate a Sun-synchronous orbit once a year, it does not produce enough torque to rotate a "...
  • 57.9k
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 ...
  • 7,116
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. ...
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 ...
  • 75.7k
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 ...
  • 1,355
17 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 ...
  • 271
17 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 ...
  • 119k
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 ...
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 ...
  • 148k
15 votes

Can a satellite orbit Earth so that it always has the Moon in line of sight?

It is possible in several ways. Let's get the dumb ones out the way first. As I commented, you can orbit the moon itself. Technically correct, since anything orbiting the moon is also orbiting the ...
  • 1,767
15 votes

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 ...
  • 52.9k
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. ...
  • 15.1k
14 votes
Accepted

How do polar satellites disrupt communications between GEO satellites and ground control?

Satellites in LEO travel at around 7000 m/s. This means that a 1 m sized LEO satellite will take around 150 us (microseconds) to cross a given line between a GEO satellite and a ground antenna. So it ...
  • 741
14 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'...
  • 526
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 ...
  • 119k
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 ...
  • 6,022
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 ...
  • 76.9k
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 ...
  • 119k

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