What is the current status of Voyager 1's attitude and control system?

[Alltimegreat1]

From what I can gather, Voyager 1 is headed in the direction of Sagittarius and the center of the Milky Way. Will Voyager 1 eventually get sucked into the black hole at the center?

Furthermore, where is the Earth within the Milky Way in terms of up/down? The galaxy is 1,000 LY thick, but how close are we to the top?

 

[davenn]

From what I can gather, Voyager 1 is headed in the direction of Sagittarius and the center of the Milky Way. Will Voyager 1 eventually get sucked into the black hole at the center?

no

from wiki

Future of the probe[edit]

Image of Voyager 1's radio signal on February 21, 2013[76]
Voyager 1 will reach the Oort cloud in about 300 years[77][78] and take about 30,000 years to pass through it.[60][71] Though it is not heading towards any particular star, in about 40,000 years, it will pass within 1.6 light-years of the star Gliese 445, which is at present in the constellation Camelopardalis.[79] That star is generally moving towards the Solar System at about 119 km/s (430,000 km/h; 270,000 mph).[79] NASA says that "The Voyagers are destined—perhaps eternally—to wander the Milky Way."[80]

Provided Voyager 1 does not collide with anything and is not retrieved, the New Horizons space probe will never pass it, despite being launched from Earth at a faster speed than either Voyager spacecraft . New Horizons is traveling at about 15 km/s, 2 km/s slower than Voyager 1, and is still slowing down. When New Horizons reaches the same distance from the Sun as Voyager 1 is now, its speed will be about 13 km/s (8 mi/s).[81]

Furthermore, where is the Earth within the Milky Way in terms of up/down? The galaxy is 1,000 LY thick, but how close are we to the top?

http://www.nasa.gov/mission_pages/sunearth/news/gallery/galaxy-location.htmlDave

 

[Alltimegreat1]

Thanks, now what about the golden record? Is Voyager spewing out radio signals to alert any potential aliens of its existence? How would intelligent aliens even notice and get ahold of the golden record? Wouldn't they have to slow it down and capture it? I wonder if a similar alien probe was flying by the Earth at 30 miles per second whether we humans would be able to and prepared to retrieve it.

 

[davenn]

The galaxy is 1,000 LY thick, but how close are we to the top?

Ohhh and I forgot to comment ...

that statement is basically incorrect
Like the majority, the galaxy, is not a constant thickness throughout
most spiral galaxies have a central bulge and are more or less similar to this pic, ...

Dave

 

[Drakkith]

Thanks, now what about the golden record? Is Voyager spewing out radio signals to alert any potential aliens of its existence?

It is not. The main dish is pointed back towards Earth and its transmissions are purely devoted to returning scientific data. In addition, the RTG's powering Voyager 1 have already dropped to just over half of their original power output. Somewhere around 2025 the power output will drop below minimum acceptable levels and the spacecraft will essentially be "dead", incapable of transmitting anything.

How would intelligent aliens even notice and get ahold of the golden record?

They'd have to somehow detect the spacecraft and then physically capture it.

I wonder if a similar alien probe was flying by the Earth at 30 miles per second whether we humans would be able to and prepared to retrieve it.

If we had good reason to suspect it was an alien probe I'm almost certain we'd devote every possible resource to capturing it. It would be one of the greatest discoveries in history.

 

[Alltimegreat1]

If we had good reason to suspect it was an alien probe I'm almost certain we'd devote every possible resource to capturing it. It would be one of the greatest discoveries in history.

Sure, of course we would try, but detecting and capturing a probe traveling 11 miles per second would likely not be easy. How would we slow it down? Also, it would be interesting to see what the government would do if we detected it passing by but were not prepared to capture it. Would it be feasible to then launch some sort of spacecraft to chase after it and send it back to Earth?

 

[Drakkith]

I suppose we could send out a probe of our own to catch up to it (or wait for it to carch up with oyr probe) and catch it with a clamp or net or something.

 

[newjerseyrunner]

I wonder if a similar alien probe was flying by the Earth at 30 miles per second whether we humans would be able to and prepared to retrieve it.

It's aimed at species that are far far more advanced than we are, you'd have to be able to patrol interstellar space. It has a shelf life of it is something like a billion years.

 

[Alltimegreat1]

With that in mind, it is a shame that civilizations slightly less advanced than ours would have very little chance or capturing or detecting Voyager even if it made a close approach to their planet.

 

[Janus]

It's aimed at species that are far far more advanced than we are, you'd have to be able to patrol interstellar space. It has a shelf life of it is something like a billion years.

We'll just have to hope that someone with the right attitude finds it:

 

[newjerseyrunner]

Human's wouldn't see it either. There could be hundreds of alien probes in our solar system for all we know. We only really scan the space immediately around the Earth, and that's most tracking already known objects or looking for things like ballistic missiles. If Voyager's antenna was turned off, it could fly right between Earth and the Moon, and we'd never see it; and that's less than a light second away. Voyager's message is aimed at the type of civilization that can detect a small, cold object in a cubic light year.

A few months ago humans lost a 747 on the surface of our own planet. Voyager is a thousand times smaller.

 

[mfb]

From what I can gather, Voyager 1 is headed in the direction of Sagittarius and the center of the Milky Way. Will Voyager 1 eventually get sucked into the black hole at the center?

It is not heading towards the center of the galaxy. It is only heading in a direction where we also see the center of the galaxy. Both the sun and Voyager (and everything else in the solar system) orbits the central part of the galaxy with roughly 200 km/s. The speed of voyager is tiny compared to that, so it is still in a wide orbit around the central part.
Even if we could have something actually heading for the galactic center: the black hole there is an incredibly tiny target. It would be really difficult to hit it.

Apart from the directed emission of radio waves and the heat from its radioactive power source, we have no way to find a probe like Voyager unless it comes very close to Earth by pure chance (space is HUGE). And then we probably would not have enough time to prepare a capturing mission.
We do not even know all the 100m-sized objects that cross our Earth's orbit - much larger than the Voyager probes, conveniently located in the inner solar system, and potentially dangerous.

 

[micromass]

Fun related reading https://what-if.xkcd.com/38/

 

[Ophiolite]

Voyager's message is aimed at the type of civilization that can detect a small, cold object in a cubic light year..

I suggest the message was aimed at ourselves, to make us appreciate our humanity, recognise our achievements as a species, and give us a sense of our place in the cosmos. It was a symbol, not a conventional communication.

 

[davenn]

I suggest the message was aimed at ourselves, to make us appreciate our humanity, recognise our achievements as a species,

no, definitely not, it was definitely aimed at those who may find it ...

no point in starting the audio recording with "Greetings from Earth ( variations thereof in the different languages) ... " if it was aimed at us

The Voyager Golden Records are phonograph records that were included aboard both Voyager spacecraft launched in 1977. They contain sounds and images selected to portray the diversity of life and culture on Earth, and are intended for any intelligent extraterrestrial life form, or for future humans, who may find them.

http://www.theatlantic.com/technolo...ger-1-carries-for-alien-civilizations/279662/

http://voyager.jpl.nasa.gov/ spacecraft /greetings.html
Dave

 

[Alltimegreat1]

"We could launch a probe (like this one), send it out to Voyager, latch on, turn everything around, and let it spend a few decades slowing Voyager down."

A few decades just to slow it down? The latching on part is what fascinates me the most. Unfortunately I haven't come across an explanation of this containing any detail. I wonder if NASA has published any information about how specifically they would envision aliens capturing Voyager (latching, clamping, lassoing, netting, etc.).

 

[newjerseyrunner]

"We could launch a probe (like this one), send it out to Voyager, latch on, turn everything around, and let it spend a few decades slowing Voyager down."

A few decades just to slow it down? The latching on part is what fascinates me the most. Unfortunately I haven't come across an explanation of this containing any detail. I wonder if NASA has published any information about how specifically they would envision aliens capturing Voyager (latching, clamping, lassoing, netting, etc.).

Considering the vast delta in technology between Voyager and the type of species expected to find it, I imagine Voyager being like a wooden canoe and the aliens riding around in nuclear submarines. Humans capture much larger objects traveling at 18,000 mph (such as Hubble.) Once you match the object's speed, grabbing it is fairly easy and an interstellar species should certainly be able to match Voyager's speed, it'd be like a nuclear submarine trying to catch a canoe.

 

[EU2AA]

If we had good reason to suspect it was an alien probe I'm almost certain we'd devote every possible resource to capturing it. It would be one of the greatest discoveries in history.

Moreover, there is a precedent: the comet Churyumov-Gerasimenko and chase her Probe Rosetta.

 

[mfb]

The comet has a known orbit in the solar system, and Rosetta had 10 years of time to get aligned with that orbit.

 

[EU2AA]

The comet has a known orbit in the solar system, and Rosetta had 10 years of time to get aligned with that orbit.

Therefore, you need to solve two problems:
- Learn to count orbit;
- Learn how to maneuver the machine in space.

 

[Janus]

Therefore, you need to solve two problems:
- Learn to count orbit;
- Learn how to maneuver the machine in space.

But a space probe from another system would not be in closed orbit like comet Churyumov-Gerasimenko, which has a period of 6.45 years and where we have the luxury of letting it complete as many orbits as we like while we prepare the mission, launch it, and make the needed orbital maneuvers to meet up with up with the comet.
A space probe would enter an leave the system on a hyperbolic trajectory in one pass. It would also be moving a lot faster than the above comet at a given distance from the Sun. Also, being much smaller than a comet, it would be even harder to detect and would traveled a lot further into the Solar system before we even had a chance of spotting it. This would give us even less time to mount a mission to capture it before it left forever.

 

[EU2AA]

But a space probe from another system would not be in closed orbit like comet Churyumov-Gerasimenko, which has a period of 6.45 years and where we have the luxury of letting it complete as many orbits as we like while we prepare the mission, launch it, and make the needed orbital maneuvers to meet up with up with the comet.
A space probe would enter an leave the system on a hyperbolic trajectory in one pass. It would also be moving a lot faster than the above comet at a given distance from the Sun. Also, being much smaller than a comet, it would be even harder to detect and would traveled a lot further into the Solar system before we even had a chance of spotting it. This would give us even less time to mount a mission to capture it before it left forever.

Big difference there.
By measuring the parameters of the orbit, it is possible to calculate the parameters of the future and launch a probe for a meeting.
Repeating these calculations we will obtain more accurate calculations and more accurately guide the probe.
It is quite obvious algorithm.

 

[mfb]

Qualitatively, it is easy. The numbers make it hard. With the E-ELT telescope (under construction, more mirror surface than the current 20 largest telescopes together), we can detect things that lead to ~10^-23 W/m^2 visible light on Earth. If we look right in the direction at the right time, and long enough to see such extremely dim objects. That is, under very optimistic assumptions, a Voyager-like probe in ~8 AU distance, a bit closer than Saturn. It travels through the inner solar system in about 1-2 years, with a typical speed in excess of 20 km/s. Which gets even worse if you consider the speed relative to Earth.

Rosetta needed 10 years to change its speed much less than that. Forget it.

Dawn needed 8 years to change it speed by about 10 km/s. Can we build Dawn on drugs? Maybe. It will need a big nuclear reactor to power its ion engines, because it won't stay in the inner solar system. If we are lucky with the trajectory, a speed change of 20 km/s could be sufficient to match its speed. Let's say we need just three years for that, and for some reason we had that spacecraft waiting for a launch already. Three years later the Voyager-like probe is beyond the orbit of Saturn already (while Dawn is still in the inner solar system), invisible to even our best telescopes, so we have to rely on our calculated trajectory and drugged Dawn to find it. But at least the relative speed matches now. Dawn will need a few more years to actually catch up. That happens somewhere outside the orbit of Pluto, assuming the spacecraft finds Voyager in the darkness. It uses some net or whatever to catch the probe. Great! But we probably want to have it on Earth to analyze it? So Dawn has to change its speed plus the speed of the captured probe by another 20 km/s. More years later, it is about as far from the Sun as the Voyager probes now, slowly moving towards Sun. Now we can wait - a few decades later it will make a pass through the inner solar system. Careful trajectory planning will get it caught in the inner solar system, where we can send another spacecraft to it to bring it home.

So with very optimistic assumptions about our telescope measurements, probe luminosity, trajectory calculations, with a spacecraft significantly beyond the capabilities of what we built so far, that works for a few decades, it could be just at the edge of possible.

 

[Alltimegreat1]

Now we can wait - a few decades later it will make a pass through the inner solar system. Careful trajectory planning will get it caught in the inner solar system, where we can send another spacecraft to it to bring it home.

So with very optimistic assumptions about our telescope measurements, probe luminosity, trajectory calculations, with a spacecraft significantly beyond the capabilities of what we built so far, that works for a few decades, it could be just at the edge of possible.

Very insightful response, thank you. What do you mean by the probe "getting caught" in the inner solar system? Also, would it make it easier or more difficult (or no difference) to catch the probe if it was traveling perpendicular to the plane of the solar system instead of on the plane?

 

[mfb]

The probe falls into the inner solar system from very far away, so it is very weakly bound. A gravitational slingshot at a planet (slowing it down) can reduce its energy sufficiently to keep it bound to the inner solar system.
This happens by chance to some comets, which can make them short-periodic.

It is significantly easier if the probe is in the plane of the solar system. To reach a speed of 20 km/s relative to the Sun at large distances, at 1 AU (=launch site) you need a speed of ~47 km/s. If you start in the plane of the solar system, you can use the 30 km/s orbital velocity of Earth (starting at the right time of a year), so you just have to accelerate by 17 km/s. If you have to accelerate out of the plane, you have to get rid of the 30 km/s, and get up to 47 km/s vertical to the plane. A fly-by at Jupiter can help, but only if Jupiter happens to be at the right spot, and you have to get to Jupiter first.

 

[AgentCachat]

From what I can gather, Voyager 1 is headed in the direction of Sagittarius and the center of the Milky Way.
snip
Furthermore, where is the Earth within the Milky Way in terms of up/down? The galaxy is 1,000 LY thick, but how close are we to the top?

Current thinking is the sun, with Earth attached, oscillates up and down in the disk, into and out of the thickest part, in a 25-26 my cycle. Some hypothesize this may correlate with mass extinction events.

 

[Jenab2]

Voyager 1's Keplerian orbital elements.
From JPL Horizons Web-Interface.
a = −3.21347 AU
e = 3.73845
i = 35.7311°
Ω = 178.5878°
ω = 338.6716°
T = JD 2444233.38317

You choose the time of interest, t, in Julian Date format.
Example: t = 2457470.0
= 22 March 2016 @ 12h UT

The hyperbolic mean anomaly, m.
m = 0.01720209895 (t−T) √(−1/a³)
Example: m = 39.527292 radians

When reducing the elements of a hyperbolic trajectory, don't adjust the mean anomaly to the interval [0,2π). With elliptical orbits, this may be done. But the adjustment would result in errors in most of the numerical methods for calculating the hyperbolic eccentric anomaly, e.g., as shown hereafter.

The hyperbolic eccentric anomaly, u.
u₀ = 0
i = −1
Repeat
i = i+1
E = e sinh uᵢ − uᵢ − m
F = e cosh uᵢ − 1
G = e sinh uᵢ
H = e cosh uᵢ
A = −E / F
B = −E / (F + ½ AG)
C = −E / (F + ½ AG + ⅙ B²H)
uᵢ₊₁ = uᵢ + C
Until |uᵢ₊₁−uᵢ| < 1e-12 (or whatever your computational device's precision is)
u = uᵢ₊₁
Example: u = 3.12957915 radians

The converged value for u from this loop is the eccentric anomaly for the hyperbolic orbit. We don't correct it to the interval [0,2π) either; if it comes out negative, we leave it that way. We will, however, adjust the true anomaly to the interval [0,2π).

The true anomaly, θ, radians.
θ' = Arccos { (e − cosh u) / (e cosh u − 1) }
If u>0 then θ = θ'
If u=0 then θ = 0
If u<0 then θ = 2π−θ'
Example: θ = 1.75635301 radians

The heliocentric distance, r.
r = a(1 − e cosh u)
Example: r = 134.38853 AU

You can get the position (as a vector) of an object in a hyperbolic trajectory from

x''' = r cos θ
y''' = r sin θ
z''' = 0

Rotate the triple-prime position vector about the +z''' axis by the negative argument of the perihelion, −ω.

x'' = x''' cos ω − y''' sin ω
y'' = x''' sin ω + y''' cos ω
z'' = z''' = 0

Rotate the double-prime position vector about the +x'' axis by the negative inclination, −i.

x' = x''
y' = y'' cos i
z' = y'' sin i

Rotate the single-prime position vector about the +z' axis by the negative longitude of the ascending node, −Ω.

x = x' cos Ω − y' sin Ω
y = x' sin Ω + y' cos Ω
z = z'

[x, y, z] is the position of the object in heliocentric ecliptic coordinates.

Example:
x = −27.57834 AU
y = −106.54915 AU
z = +77.11673 AU

The speed in orbit, relative to the sun, v.
v = √[GM(2/r−1/a)]

where
GM = 1.32712440018e20 m³ sec⁻²
1 AU = 1.49597870691e11 meters

v = 29784.6918 m/s √(2/r−1/a)
where r, a are in astronomical units.

Example: v = 17007.8755 m/s

You can get the velocity (as a vector) of an object in a hyperbolic trajectory from

Vx''' = 29784.6918 m/s (a/r) √(−1/a) sinh u
Vy''' = −29784.6918 m/s (a/r) √[(1−e²)/a] cosh u
Vz''' = 0

Rotate the triple-prime velocity vector about the +z''' axis by the negative argument of the perihelion, −ω.

Vx'' = Vx''' cos ω − Vy''' sin ω
Vy'' = Vx''' sin ω + Vy''' cos ω
Vz'' = Vz''' = 0

Rotate the double-prime velocity vector about the +x'' axis by the negative inclination, −i.

Vx' = Vx''
Vy' = Vy'' cos i
Vz' = Vy'' sin i

Rotate the single-prime velocity vector about the +z' axis by the negative longitude of the ascending node, −Ω.

Vx = Vx' cos Ω − Vy' sin Ω
Vy = Vx' sin Ω + Vy' cos Ω
Vz = Vz'

[Vx, Vy, Vz] is the velocity of the object, relative to the sun, in ecliptic coordinates.

Example:
Vx = −2077.3160 m/s
Vy = −13686.9988 m/s
Vz = +9880.2153 m/s

 

[Alltimegreat1]

What point are you making with all those calculations? Are you showing that capturing Voyager is possible?

 

[Jenab2]

What point are you making with all those calculations? Are you showing that capturing Voyager is possible?

No, I was only answering the question in the thread title:
Where is Voyager 1 headed?

Although I used the current date as the time of interest, t, in my example, that time can be changed to any arbitrary instant in the future. The example serves to guide the original poster, should he desire to use the math in my post as the basis of a computer program. By checking his computations against mine, he'll know whether he's on the right track, or whether he's made a programming error somewhere in his code.

After he finishes his program, he can change the time-of-interest to, say, 1 January 9999, or even later, to see where Voyager will be relative to the sun, how fast its moving and in which direction. The calculations will be good enough until Voyager gets curved off its hyperbolic track by the gravity of another object.

 

[Jenab2]

Voyager 1 has a hyperbolic excess speed of 16.617 km/sec, and it will be one-third of a light year from the sun on 15 December 7987. Although you won't be able to see it from Earth, it will be at right ascension 17h31m18s and declination +12°57'04", in about the same direction as the star Rasalhague.

 

[Jenab2]

Big difference there.
By measuring the parameters of the orbit, it is possible to calculate the parameters of the future and launch a probe for a meeting.
Repeating these calculations we will obtain more accurate calculations and more accurately guide the probe.
It is quite obvious algorithm.

Calculating an interception orbit isn't simple. Try it sometime.

The reason it isn't simple is that the solution does not occur in closed form. The solution requires a match in the transit times of two different objects, in two different orbits, with both objects reaching the same position in space at the same time. One of the objects is the thing you're trying to intercept. The other object is the spaceship you are using to intercept that thing with.

In general, the spaceship and the object to be intercepted will require different amounts of time to reach any given point on the path of the object to be intercepted. The job of the celestial mechanic is to find one of those exceptional combinations of departure instant and arrival position for which the two objects' transit times are equal.

Furthermore, when the object to be intercepted is an alien space probe, inbound on one leg of a hyperbolic trajectory and then outbound on the other, undertaking to intercept it is going to require a lot of change-of-velocity by our spaceship. If it can be done at all, it won't be cheap. Or quick, either, since the spaceship's speed along its own outbound hyperbolic path will close on the alien space probe by only the difference in their hyperbolic excess speeds.

It might be more productive to try to find out where the alien space probe came from, by back-tracking its inbound trajectory and by reversing (in simulation) the motions of all nearby stars. If we were lucky enough to identify the likely origin star system, we could point a high-gain radio at it and beam some nifty Star Trek theme music at the aliens.

 

[secur]

It is not heading towards the center of the galaxy. It is only heading in a direction where we also see the center of the galaxy. Both the sun and Voyager (and everything else in the solar system) orbits the central part of the galaxy with roughly 200 km/s. The speed of voyager is tiny compared to that, so it is still in a wide orbit around the central part.

mfb, actually Sol's speed is 253 km/sec according to latest data, but of course you're right: Voyager 1 is much less at 17 and on the galactic scale it's almost meaningless - except, indeed, on a galactic scale of years! Its velocity vector is down towards the galactic plane at an angle of 41 degrees or so, relative to us, so it should cross before us. Since it takes roughly 20,000 years to get a LY away, at that time (galactic plane crossing) it will no longer be in our neighborhood; but it's impossible to know really, since it will experience random alterations in course from stars (even passing within a LY affects it a little), dust collisions, EM radiation pressure, and/or capture by aliens, as the millenia go by. Of course I could be wrong about any of this ...

Bottom line, Sagittarius A doesn't have to worry about being attacked by Earthlings any time soon.

 

[rootone]

Maybe it will accidentally encounter an alien civilization whose preferred choice of clothing is silver miniskirts, and it will become worshipped as a deity.
(jk: star trek movie 1)

 

[Partick]

Ohhh and I forgot to comment ...

that statement is basically incorrect
Like the majority, the galaxy, is not a constant thickness throughout
most spiral galaxies have a central bulge and are more or less similar to this pic, ...

View attachment 97407Dave

Sort of looks like flying saucer!

 

[Oldman too]

Like all high mileage vehicles (approximately 12.1 billion miles) Voyager is needing some attention. https://www.jpl.nasa.gov/news/engineers-investigating-nasas-voyager-1-telemetry-data
"The engineering team with NASA’s Voyager 1 spacecraft is trying to solve a mystery: The interstellar explorer is operating normally, receiving and executing commands from Earth, along with gathering and returning science data. But readouts from the probe’s attitude articulation and control system (AACS) don’t reflect what’s actually happening onboard."