14 x 10^9 miles OT but too interesting to let go by


Liam Perkins
 

NASA's Voyager 1, the farthest spacecraft from Earth, said farewell to the
solar system almost a decade ago, passing through an invisible door some 11
billion miles from Earth and crossing into interstellar space. Since then,
it's tacked on another 3 billion miles and it's still sending home data,
allowing scientists to probe the space between stars. In a paper published
in the journal Nature Astronomy on Monday, researchers examined data beamed
back by Voyager 1's Plasma Wave System over its journey, but particularly
after it passed through over the solar system's border.

The border is a messy "edge" where the sun's influence disappears and the
interstellar medium begins. The medium is typically characterized as empty,
desolate and dark, but the PWS on Voyager 1 has detected a low, constant
pattering against its detector, space raindrops gently falling on a window.
Those drops signify plasma waves -- or interstellar gas -- is constant
company for the spacecraft.

"We're detecting the faint, persistent hum of interstellar gas," said
Stella Koch Ocker, a doctoral student at Cornell University who led the
research. "It's very faint and monotone, because it is in a narrow
frequency bandwidth."
==============
And there's this:
https://www.theregister.com/2020/09/18/voyager_1_14_billion_miles/
where we read that:

"NASA's extraordinarily long-lived Voyager 1 probe this week passed 14
billion miles from Earth.
It takes light nearly 21 hours to reach the spacecraft, making commanding
it increasingly tricky."

I'd love to know how they lock onto that signal.

Liam


Roger Evans
 

If you google for "voyager 1 telecommunications" you should find a link to a PDF file on NASA.gsfc.gov which gives a lot of information on the telecoms systems. The spacecraft transmitter is phase locked to the carrier from the ground station, there is of course a Doppler shift which will be known from the 'range and range rate data'. You do get all of 22 bps but that may be raw data including the error correcting code.

Interesting post, many thanks.

Roger


Tim Phillips
 

Sorry, everyone - I was trying to forward the original to someone not on
this list.
Tim



On Fri, 21 May 2021 at 12:40, Roger Evans via groups.io <very_fuzzy_logic=
yahoo.com@groups.io> wrote:

If you google for "voyager 1 telecommunications" you should find a link to
a PDF file on NASA.gsfc.gov which gives a lot of information on the
telecoms systems. The spacecraft transmitter is phase locked to the
carrier from the ground station, there is of course a Doppler shift which
will be known from the 'range and range rate data'. You do get all of 22
bps but that may be raw data including the error correcting code.

Interesting post, many thanks.

Roger