33
votes
Why are there four RTGs in a row sitting in this room? What are they waiting for? Were they built together and stored for separate launches?
There were seven General Purpose Heat Source - Radioisotope Thermal Generators (GPHS-RTGs) assembled (there were parts for an eighth).
The seven would eventually fly in space on four different ...
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28
votes
Accepted
Why do we use Chebyshev polynomials to predict positions of solar system bodies?
I'm also surprised that JPL uses a numerical model rather than doing a n-body physics simulation of the Solar System.
JPL does use an n-body physics simulation of the solar system. It's a very ...
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18
votes
How are the "lucky JPL peanuts" shared post-pandemic?
People received individual packages of peanuts and could sneak one under their mask.
This page shows people holding individual packages of peanuts.
And this video explains the procedure briefly.
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16
votes
Accepted
What is the numbering system used for the DSN dishes?
I found a sort of explanation in "Uplink-Downlink" the NASA history of the DSN.
The first digit [range of digits, really, see the table] gives the geographical area.
The second digit gives the ...
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12
votes
What is the numbering system used for the DSN dishes?
Looking at the history of DSN on Wikipedia, it appears that the tens-place digit originally was allocated to identify the region or site, and within a region/site the dishes were numbered sequentially ...
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10
votes
Accepted
Why did Curiosity perform TCMs?
We try, but our ability to model reality isn't perfect. In fact, we don't even know the gravitational constant $G$ to more than 4 significant digits. Our data on the masses of the sun and the planets ...
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10
votes
Accepted
What is the history behind having peanuts in mission control during critical missions?
It turns out this goes way back to the 1960s. Landing on a celestial body isn't easy; JPL had suffered a series of failures during the Ranger missions, some during launch and others further on in each ...
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7
votes
Accepted
What did JPL's 1939 lunar lander look like and what practical aspects of landing on the Moon did this engineering design address?
The Jet Propulsion Laboratory didn't exist under the JPL name until 1943-1944. What existed in 1938-1939 was its predecessor, rocketry experiments at the Guggenheim Aeronautical Laboratory at the ...
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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 ...
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6
votes
Accepted
What are those plastic hoses on Perseverance used for?
The original poster on reddit seems to have come to a conclusion to their question only a couple of days after posting it, and I've not found anything that seems to contradict their conclusions.
Here'...
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6
votes
Accepted
What time zone is used for JPL tests?
UTC
This page gives launch local time as
Friday, September 7, at 9:30 a.m
in Virginia, USA.
Virginia is Eastern Time (GMT-5) and September is in Daylight Savings Time which accounts for the ...
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6
votes
Does NASA's Deep Space Network sometimes listen to other space agencies' spacecraft "just for the heck of it" or other non-mission related reasons?
China has done it with NASA
China used signals sent from NASA’s Juno probe orbiting Jupiter to test the capabilities of ground stations vital to its deep space ambitions.
Scientists involved in ...
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6
votes
Access to Chebyshev coefficients from JPL ephemerides
Your question is slightly ambiguous, a file containing the Chebyshev coefficients wouldn't be an ephemeris, but it's something you could use to generate an ephemeris. Regardless, the article Format ...
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5
votes
What will the US government start to label its GPS spacecraft after SVN 99
The numbering of 01-99 you refer to is the one used for the PRN of the satellites. The SVN is numbered using 3 digits in IGS files and is therefore not going to run out anytime soon. PRN's are often ...
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5
votes
How to obtain Chebyshev coefficients directly from the JPL Horizon's interface?
The best and most concise answer is here
The "gold standard" is the SPICE toolkit. You can read more about using spice in this excellent answer.
The JPL Development Ephemerides are lists of the ...
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4
votes
Accepted
When was the idea behind the DESCANSO Book Series first conceived, by whom, and what is its "mission"?
From the foreword of Volume 1:
The Deep Space Communications and Navigation Systems Center of Excellence (DESCANSO) was recently established for the National Aeronautics and Space Administration (...
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4
votes
Why are JPL using this expression to emulate Schwarzschild orbits?
To understand the meaning of the formula, one needs to face its origins in general relativity. GR is not just about corrections to Newtonian expressions for gravitational forces and accelerations. It ...
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4
votes
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Tradeoffs between using two 34 m and one 70 m Deep Space Network dish?
The major downside to using a pair of 34-meter antennas is that they have only half the collecting area of a single 70-meter antenna, and produce only half the signal strength. Beyond that, on the ...
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4
votes
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Are the Perseverance rover's "drivers" working on Martian sols or Earth days right now?
A team of about 350 scientists and engineers are keeping "Mars time" right now !
From Business Insider's article "Now on 'Mars time,' NASA's Perseverance team shifts their work hours 40 ...
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4
votes
Access to Chebyshev coefficients from JPL ephemerides
The best method I've found is to use Brandon Rhodes' Python "jplephem" from here, specifically using the _load() function of an SPK segment. You get a ...
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3
votes
Why did Curiosity perform TCMs?
The first trajectory course maneuver, and oftentimes, the first two TCMs, are absolutely essential given NASA's planetary protection protocols. Trajectories toward Mars are designed so that there is ...
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3
votes
Access to Chebyshev coefficients from JPL ephemerides
Update :
I have found a way to extract Chebyshev coefficients at a requested date for a particular body using CSPICE.
Here the program that allows to do this :
...
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3
votes
Accepted
What information was stolen from JPL during the Raspberry Pi hack?
As an information security professional this makes me cringe, but I'm not in the last surprised. I've read the OIG report, there's not that much information on the data that is lost, but the report ...
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2
votes
How to obtain Chebyshev coefficients directly from the JPL Horizon's interface?
You don't get those from HORIZONS. You download them from here. They are best accessed with the SPICE toolkit, or you can roll your own to extract the Чебышёв coefficients from the SPK files.
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2
votes
Lunar landing module and orbiting space craft personnel transfer
While the modules were launched with the engine in between, the modules docked nose-to-nose. The crew moved between the modules using hatches in the noses of each module.
Image location
Related ...
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1
vote
Accepted
Was the famous SPICE package of programs, utilities and data kernels named after "Melange" found on the planet Arrakis?
According to this, SPICE stands for
Spacecraft ephemeris
Planet (plus moon, comet, asteroid) ephemerides
Instruments (geometric information such as field-of-view, shape, orientation)
C-matrix (...
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