Linked Questions

12 votes
4 answers
2k views

Why are uncertainties of orbital state vectors provided as covariance matrixes?

I have recently become interested in testing a numerical orbital propagator with ISS ephemerides, following @RyanC's suggestion in this answer. Ephemerides for the ISS seem to be publicly available in ...
Rafa's user avatar
  • 1,750
8 votes
3 answers
1k views

Arecibo: Advantages of Giant Dish?

I'm sure all of you have heard about the recent events at the Arecibo observatory, and the controversial decision to close the facility. I've also heard that Arecibo is the second largest single ...
Zhaochen He's user avatar
5 votes
2 answers
1k views

Is there a way (working or in development) to track satellites in lunar orbit like we track objects in Earth Orbit?

I understand that Earth orbiting satellites are tracked using technologies such as radar, but due to the distance between the Earth and the Moon, they aren't really useful for Moon sats. Is the ...
Bensas's user avatar
  • 193
8 votes
2 answers
1k views

What is the current record for the farthest detection of a "dead" spacecraft?

In order to better defend my position that trying to track Juno from Earth once it can no longer transmit would be Quixotic, I'd like to ask what the current record is for the farthest detection from ...
uhoh's user avatar
  • 149k
19 votes
1 answer
2k views

Has DSS-43 ever been used in high power mode (>>20 kW) for an emergency situation?

This answer notes that while most Deep Space Network transmitters are 20 kW of power or less, one dish (DSS-43 in Canberra) is equipped with a transmitter capable of 400 kW. As described in 101, 70-m ...
uhoh's user avatar
  • 149k
11 votes
2 answers
612 views

Why do the LRO's orbital elements appear to constantly oscillate - except recently?

I plotted some of the orbital elements of the Lunar Reconnaissance Orbiter from JPL's Horizons database, and I see that there are constant oscillations. The period of the semi-major axis and ...
uhoh's user avatar
  • 149k
6 votes
2 answers
1k views

Why does DSN sometimes uses two dishes at the same time to receive Voyager-1?

I just looked at the Deep Space Network site DSN Now at https://eyes.nasa.gov/dsn/dsn.html and I saw that both dish numbers 25 and 26 are receiving a 8.42 GHz downlink signal from Voyager 1. Both ...
uhoh's user avatar
  • 149k
6 votes
1 answer
787 views

How does a three-way doppler shift measurement work?

I was looking at this document who's name I can only speculate. Its title and designation includes: 810-005, Rev. E, 201, Rev. B, DSN Telecommunications Link, Design Handbook, 201, Rev. B, Frequency ...
uhoh's user avatar
  • 149k
6 votes
2 answers
584 views

From whence (what ground stations) do the world's major space agencies receive signals from their missions?

The ISRO web page Ground Segment says: SRO Telemetry Tracking and Command Network (ISTRAC) will be providing support of the TTC ground stations, communications network between ground stations and ...
uhoh's user avatar
  • 149k
4 votes
2 answers
238 views

For how many total hours had Arecibo transmitted a signal?

Update: Sadly, parts of the dish have collapsed, several cables have snapped, and the Arecibo radio telescope is now decommissioned and demolition has been recommended because it is now too unsafe to ...
DrSheldon's user avatar
  • 48k
4 votes
1 answer
203 views

Can ion propulsion system be used to maintain lunar orbit?

I am doing research on propulsion systems and it was suggested that I use an ion propulsion system for a theoretical satellite I am tasked with designing, I need to maintain orbit for three years ...
Sam's user avatar
  • 73
3 votes
2 answers
150 views

Longest duration of a Moon orbiter?

From all the spacecraft that orbit or orbited the Moon, which one lasted the longest in lunar orbit? By defunct spacecraft includes.
Joe Jobs's user avatar
  • 2,650
2 votes
1 answer
153 views

Was Chandrayaan-1 recovered (tracked) only that one time in 2016, or is someone still keeping an eye on it from time to time?

Has there ever been probability of conjunction between spacecrafts in Lunar orbit? describes a recent maneuver of two spacecraft in orbit around the moon to avoid a potential collision: Apparently ...
uhoh's user avatar
  • 149k
3 votes
0 answers
208 views

What was the most intense beam ever sent from Earth?

By a freak coincidence sensors on a passing alien ship a hundred light years away had picked up a faint artificial blip from Earth, thereby discovering our inhabited planet. But which blip was it? ...
uhoh's user avatar
  • 149k
2 votes
1 answer
104 views

What will happen to Chang’e 5 orbiter?

What will happen to the Chang’e 5 orbiter which will return the collected samples to earth? Will it burn up in the atmosphere like Hayabusa, or is an extented mission planned?
RAD6000's user avatar
  • 1,168

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