Voyager Space Probe distance counter

[Harald Kapp]

How about using a RaspberryPi or BeagleboneBlack and some python code to directly read the actual distance of the space probe from NASA's website? Let Nasa do all the math. Then display the numbers on any display of your liking.

 

[KrisBlueNZ]

How about using a RaspberryPi or BeagleboneBlack and some python code to directly read the actual distance of the space probe from NASA's website? Let Nasa do all the math. Then display the numbers on any display of your liking.

I suggested something like that in post #5, third paragraph, and the OP answered in post #6, second paragraph.

 

[Harald Kapp]

Oops, I missed that, sorry.

 

[KrisBlueNZ]

Never mind

 

[BobK]

As of 2013[update], the probe was moving with a relative velocity to the Sun of about 17 km/s.[12] With the velocity the probe is currently maintaining, Voyager 1 is traveling at about 325 million miles per year (520 million kilometres)

you don't even need to worry about 10's or 100's of km of accuracy, its travelling almost 20km every second




you are forgetting that the further out you go, the less the solar gravitational effects will be ( inverse square law = every time the distance is doubled, the field strength is only 1/4 as strong)

EDIT: just read your last sentence properly, Bob, that may be what you were referring to ?
The gravitational effect isn't just reducing a bit, its reducing quite substantially

Dave

I took that into account. That is why the acceleration is 0.79 km / sec / year instead of 9.8 m / sec / sec which is the acceleration here at earth. This latter number would be 309053 km / sec / year. The 0.79 number was actually wrong though. Here is the correct calculation:

The Voyager 1 is 127.5 AU from the sun, i.e. 127.5 times the distance from the earth to the sun. So the acceleration is 1/(127.5 ** 2) times that at earth or:

1 / 127.5 / 127.5 * 9.8 m/sec/sec = 6.02 E -4 m / sec / sec.

That is 6.02 E -4 x 60 x 60 x 24 x 365 = 19011 m sec / year = 19 km / sec / year. In other words, it should start falling back toward the sun within a year.

But, looking at the speeds over the last year, the actual acceleration is 0.007 km / sec / year. I now notice that they are continually burning fuel, so it looks like they are trying to make up for the acceleration back toward the sun, and keep it at nearly constant velocity wrt the sun.

Edited to add: So it looks like there may not be an equation for the speed. It is in the hands of NASA.


Bob

 

[kpatz]

Unfortunately work leaves me with almost no time to pursue anything hobby related, so I wouldn't be able to take on this project, sorry. I can offer suggestions on the forum, that's about the best I can do, without a winning lottery ticket.

A mid-range PIC should work, especially if serial LED drivers are used. That would eliminate the overhead of multiplexing the display. A couple years ago I built a Pinewood Derby timer for my cousin's Boy Scout troop, which had a total of 10 digits of LED display (two 4-digit time displays plus two 1-digit lane counters) and multiplexing this worked fine, even with the added complexity of driving the lane counters at a higher voltage due to the larger displays having series-wired LEDs. It even has a 1/1000 second timing resolution and it polls the sensors 2000 times per second. I used a 20 MHz crystal on a 28-pin mid range PIC and wrote the code in C. I built the whole thing on two perfboards--one for the LED display and drivers and one that contained the PIC, drivers for the IR LEDs/and photodiode lane sensors and the power supply. The whole shebang runs on 6 "AA" batteries.

Probably the most complicated thing for your project in terms of hardware is the LED display and how it'll be driven. The most complicated thing in the software is how to calculate the distance based on speed and time, and (as necessary) adjust for deceleration due to gravity.

How are you planning to construct it? Are you going to have PCBs made? That would make it easier, and the end result will be more reliable. Perfboard and point-to-point gets unwieldy when there are a lot of connections, and on a 11 or 12 digit display there will be a lot! Also, most serial LED driver ICs are only available in surface-mount packages (SOIC etc.), not in DIP.

 

[davenn]

I took that into account. That is why the acceleration is 0.79 km / sec / year instead of 9.8 m / sec / sec which is the acceleration here at earth. This latter number would be 309053 km / sec / year. The 0.79 number was actually wrong though. Here is the correct calculation:

The Voyager 1 is 127.5 AU from the sun, i.e. 127.5 times the distance from the earth to the sun. So the acceleration is 1/(127.5 ** 2) times that at earth or:

1 / 127.5 / 127.5 * 9.8 m/sec/sec = 6.02 E -4 m / sec / sec.

That is 6.02 E -4 x 60 x 60 x 24 x 365 = 19011 m sec / year = 19 km / sec / year. In other words, it should start falling back toward the sun within a year.

But, looking at the speeds over the last year, the actual acceleration is 0.007 km / sec / year. I now notice that they are continually burning fuel, so it looks like they are trying to make up for the acceleration back toward the sun, and keep it at nearly constant velocity wrt the sun.

Edited to add: So it looks like there may not be an equation for the speed. It is in the hands of NASA.


Bob

just one mistake Bob ....

you are using the G for Earth (9.8....) Earth's gravity effects are going to be non existent at that distance. You need to use the acceleration due to gravity produced by the sun


Dave

 

[BobK]

Ach! You are right! Garbage in garbage out.

The gravitational acceleration due to the sun at the position of the earth is 5.9E-3 m/sec/sec, so the calculation becomes:

1 / 127.5 / 127.5 * 4.9e-3 m/sec/sec = 3.63 E-7 m / sec / sec.

Or 3.63E-7 / 1000 * 60 * 60 * 24 * 365 = 0.011 km / sec / year.

Which is much closer to the acceleration we see in the NASA data of 0.007 km / sec over the last year. This makes more sense.

Bob

 

[Senormodeler]

I don't exactly follow the math, but I trust you guys know what you're talking about. Does that equation take into account that the farther away Voyager travels, the less it is affected by the suns gravitational pull?

kpatz, sorry to hear you can't work on this. I really have no clue when it comes to building this thing, so I don't know what PIC's are or any of the other things you mentioned. It all sounds super interesting, but completely incomprehensible.

So the I'm still looking for someone to build this. I will pay for parts and labor.

 

[Senormodeler]

Hello makers.

Just a quick update to say I've started on the voyager model and I'm still interested in finding someone who can build the odometer base for it.

Here's the box:


Let me know if you're at all interested in participating in this project. Thanks.

J

 

[Senormodeler]

I finally finished the model of Voyage 1. Here are some pics:















Still haven't found anyone to help build the odometer. I'll pay for parts and labor. It's a gift for my wife who loves Voyager!

Thanks!
J

 

[Senormodeler]

Hey all,
I'm still hunting around for someone to help me wire up this display. I've been looking at the Arduino and it looks like that might be an easy way to build this. I'm thinking of trying to do it myself, but would be a little in over my head. AND I just had a baby. So free time is at an all time low.

If anyone is interested, please let me know. I could pay for parts and labor!

Thanks.
J