13 votes

Why was the 100m Green Bank dish needed together with DSN's 70m Goldstone dish to detect Chandrayaan-1 in lunar orbit?

The explanation has to do with the operation of the radar transmitters and the round trip light travel time. It takes about 3 seconds for a radar pulse to travel from the Earth to the Moon and back. ...
Joseph Lazio's user avatar
7 votes
Accepted

When NASA spacecraft arrive at Mars, is Mars always always above the horizon in the US?

Easy enough to verify by computing the Alt/Az of Mars on the descent date/time of NASA spacecraft. I picked a few, got the descent times from Wikipedia, and generated the Alt from Cape Canaveral ...
Greg Miller's user avatar
4 votes

Why was the 100m Green Bank dish needed together with DSN's 70m Goldstone dish to detect Chandrayaan-1 in lunar orbit?

I know nothing of the activity you're asking about, but I do know something about radar. All the radar systems I've worked with used a single antenna to both transmit and receive. The power of the ...
Steve's user avatar
  • 1,174
4 votes

Why was the 100m Green Bank dish needed together with DSN's 70m Goldstone dish to detect Chandrayaan-1 in lunar orbit?

Since the deep space network can perform ranging on spacecraft much farther away (tens of thousands of times farther than the moon) by itself, why was it necessary to use a non-colocated, non-DSN dish ...
Hobbes's user avatar
  • 127k
3 votes
Accepted

How long did the plasma blackouts of Perseverance's signals to MRO and direct-to-Earth last during its seven minutes of terror?

There are some misunderstandings here (similar to this question) that make the question(s) a little malformed. Roughly what frequency was used in the link(s) between Perseverance and MRO? From ...
BrendanLuke15's user avatar
2 votes
Accepted

Why will radioastronomy telescopes be used to listen to InSight's entry into Mars' atmosphere instead of DSN?

InSight used an UHF transmitter to transmit a tone beacon during EDL: At the top of each of InSight’s legs is a trigger sensor; when the surface pushes up the leg and hits the trigger, it shuts off ...
Hobbes's user avatar
  • 127k
1 vote
Accepted

What are monostatic radar observations, and how will Deep Space Network's DSS-13 be used to observe asteroid 1999 WK4's flyby of Earth?

Monostatic just means the transmitter and receiver are in the same place (DSS-14), as opposed to bistatic radar where they are separate (DSS-13 transmitter, Green Bank receiver). No klystron means ...
Hobbes's user avatar
  • 127k
1 vote

Why was the 100m Green Bank dish needed together with DSN's 70m Goldstone dish to detect Chandrayaan-1 in lunar orbit?

This started out as a comment on one of the answers already provided, but it grew much too big to stay that way. There is good reason to collect and process bistatic ranging data even when there is no ...
Ryan C's user avatar
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