Question about the extent of the solar system....

[sao123]

We are claiming that Voyager 1 has crossed the termination shock into the heliosheath.
That took about 28 years, and now voyager is slowing down, about out of fuel, and instruments are breaking. If we want to continnue exploration of the outer solar system to the bow shock and further into interstellar space...

Here is my question... Long range comets... Like Halleys who has a orbit of 75 years... how far out do they go? Do they cross the termination shock, or just end their orbit in the Oort cloud?

My idea... to save fuel and energy. Could we not land a craft like voyager on a comet like halleys, and then re-activate the probe at the farthest point of the comets orbit...

Or do we have better propulsion technology that we can get there faster than voyager did without runing out of fuel?

 

[DrPizza]

I believe that if our intentions were to get farther out quicker, we would spend the first few years doing more gravitational slingshotting around the inner solar system to increase the velocity. But, I think the goal so far (for most? all?) of the probes has been to hang out long enough to take a nice look at the other planets, rather than whiz right by (or whiz right past where their orbit is, while that planet is on the other side of the sun) AFAIK, and I may be mistaken on this, we haven't sent a probe specifically to examine the Oort cloud.

If we did want to, your idea of just parking it on a comet almost sounds like a decent idea, however, (and this is the hard part without drawing a diagram), landing on the comet pretty much means you're going to be moving in almost the same direction at the same speed as the comet. If God waved his hand and the comet just vanished from existence 1 second before your probe landed, your probe would still end up at the same place at the same time as it would have had the comet continued to exist. From your previous posts, I think you'll understand what I mean.

Weird analogy: Suppose you're on top of a 2 mile high cliff. You see a rock that was dropped from a helicopter hovering 3 miles above you. (ignoring air resistance, because this is an analogy to space, although someone can argue that the solar wind.. yadda yadda...)
Now, you decide that you want your rock to reach the ground. Rather than dropping it, you want it to hitch a ride on the rock dropped from the helicopter. At the moment the helicopter's rock passes the cliff, you have to fire your rock at the same speed it's moving so that some state of the art device aboard your rock can cause it to attach to the helicopter's rock. (Obviously, if they're going at much different speeds, you're going to end up with pebbles when they collide) Now, your rock has hitched a ride to the ground below. Note: if your attaching device failed to work, since it was going at the same speed along side the other rock as it passed the top of the cliff, it's going to still hit the ground at the same time.

 

[sao123]

good thoughts... and i understand what your saying about if the comet vanished.

However, I was guessing, (possibly incorrectly) that if we caught a comet on its way toward the sun, it would be easier to land on it and ride it back out... (all accelleration heads toward a natural pull - less energy spent.)

 

[imported_Dimicron]

Keep in mind also that comets have a tendancy to evaporate while they are near the sun. It just wouldn't do for your probe to get smashed off the comet because the area you landed on broke off the comet because it was too close to the sun.

 

[Soccerman06]

Originally posted by: Dimicron
Keep in mind also that comets have a tendancy to evaporate while they are near the sun. It just wouldn't do for your probe to get smashed off the comet because the area you landed on broke off the comet because it was too close to the sun.

Your missing a big point, sao123 wants to get outside the solar system, that meens the comet has to be going away from the sun. So chunks of ice (rock whatever) might fall off, but you could ancor the craft by using multiple locations for each ancor, ie one on the top one of the bottom and so on.

Another problem arises when you want to hitch a ride on a comet, the tail. If you want the probe to land on the comet from the back side you have to create some kind of shielding because of the debree that is in the tail. If you were to land on the front side, the side away from the sun, you would have to be very very careful to not slow down too much because you might hit the comet at the wrong speed and crash. Another problem arises if the comet is spinning, how would you ancor a probe onto something that is spinning.

I remember reading that NASA has made leaps and bounds in their propulsion tech compared to the one used in Voyager. The article said that NASA has created Ion Drives that could pass Voyager in 10 years. Then theres the idea of using solar wind to speed up the probe up to 1/4 the speed of light by using the slingshot effect from the sun's gravity and massive amount of solar wind (photons?).

 

[egkenny]

Originally posted by: sao123
We are claiming that Voyager 1 has crossed the termination shock into the heliosheath.
That took about 28 years, and now voyager is slowing down, about out of fuel, and instruments are breaking. If we want to continnue exploration of the outer solar system to the bow shock and further into interstellar space...

Here is my question... Long range comets... Like Halleys who has a orbit of 75 years... how far out do they go? Do they cross the termination shock, or just end their orbit in the Oort cloud?

My idea... to save fuel and energy. Could we not land a craft like voyager on a comet like halleys, and then re-activate the probe at the farthest point of the comets orbit...

Or do we have better propulsion technology that we can get there faster than voyager did without runing out of fuel?

You seem to imply that Voyager is running out of fuel. Voyager has not had any fuel for propulsion since it was boosted to the solar system escape velocity by the Centaur upper stage of the Titan-Centaur booster rocket. Since then it has been coasting. All fuels onboard the Voyager spacecraft were mostly for coarse correction. The only speed boost possible was using gravitational assist. Voyager 2 used such an assist by using Saturn to propel it toward to Uranus and Neptune. Both spacecraft are slowing down simply because of the continuous pull from the sun. However they are still going fast enough to eventually leave the solar system.

Some other facts:

Pluto's oribit ranges from 30 AU to 50 AU from the sun.
The Termination Shock is located about 90 AU from the Sun.
The Oort Cloud extends out to about 3 light years (63,240 AU).

Voyager 1 is escaping the solar system at a speed of about 3.6 AU per year.
Voyager 2 is escaping the solar system at a speed of about 3.3 Au per year.
Voyager 1 reached the Termination Shock at the end of 2003.

Comets:

Short-period comets: Entire orbits lie within Kuiper Belt which extends to just beyond Neptune. Halley is a short period comet. It has a period of about 76 years. short-period comet orbits are subject to perturbations in their orbits mainly by the Sun, Jupiter and Saturn.

Long-period comets: Entire orbits lie to just with the Kuiper Belt to the Oort cloud. Their periods range from hundreds of years to over 100,000 years. Long-period comets are also subject to perturbations from objects outside the solar system. Five out of six comets observed so far are long-period comets.

Hitching a ride on a short-period comet will only get you out to about Neptune.

To hitch a ride on a long-period comet you would have to meet it at it's closest approach which is at least as far as Neptune. Then you would have a slow ride of hundreds or thousands of years. This seems impractical.

 

[Gibsons]

wow, I had no idea the Oort cloud was so far away...

I think to get there, given current tech, you'd want to build a really really really big rocket and wait a year or three for some really optimal planetary alignment so you could maximize your slinghot(s). Would that get enough velocity to go 3 light years in some "reasonable" amount of time?

 

[DrPizza]

Same idea for hitching a ride on the comet while it was heading toward the sun... it wouldn't make any difference if the comet was actually there to rendezvous with. Once you got to the speed of the comet, where the comet was supposed to be, your probe would experience the same acceleration from the sun as the comet would. Thus, it wouldn't make any significant difference to actually meet the comet.

 

[sao123]

You seem to imply that Voyager is running out of fuel. Voyager has not had any fuel for propulsion since it was boosted to the solar system escape velocity by the Centaur upper stage of the Titan-Centaur booster rocket. Since then it has been coasting. All fuels onboard the Voyager spacecraft were mostly for coarse correction. The only speed boost possible was using gravitational assist. Voyager 2 used such an assist by using Saturn to propel it toward to Uranus and Neptune. Both spacecraft are slowing down simply because of the continuous pull from the sun. However they are still going fast enough to eventually leave the solar system.

When I say running out of fuel, I mean that Voyagers Nuclear batteries will only have enough power to function the unit until about 2020.

Voyager 1 reached the Termination Shock at the end of 2003.

As far as that, there is still some degree of disagreement... see quotes from the nasa page.

NASA
In November 2003, the Voyager team announced it was seeing events unlike any encountered before in the mission's then 26-year history. The team believed the unusual events indicated Voyager 1 was approaching a strange region of space, likely the beginning of this new frontier called the termination shock region. There was controversy at that time over whether Voyager 1 had indeed encountered the termination shock or was just getting close.

We don't know the exact location of the termination shock and changes in the solar wind cause it to expand, contract, and ripple like a plate underwater. Water spreads out over the plate in a relatively smooth flow but has a rough edge where the water slows down abruptly and piles up. The edge is like the termination shock, and as the water flow changes, the shape and size of the rough edge change.

The consensus of the team now is that Voyager 1, at 8.7 billion miles from the Sun, has at last entered the heliosheath, the region beyond the termination shock, said Dr. John Richardson from MIT, Principal Investigator of the Voyager plasma science investigation.

The strongest evidence that Voyager 1 has passed through the termination shock into the slower, denser wind beyond is its measurement of an increase in the strength of the magnetic field carried by the solar wind and the inferred decrease in its speed. Physically, this must happen whenever the solar wind slows down, as it does at the termination shock. Consider a highway with moderate traffic. If something makes the drivers slow down, say a puddle of water, the cars pile up - their density increases. In the same way, the density (intensity) of the magnetic field carried by the solar wind will increase if the solar wind slows down. In December 2004, Voyager 1 observed the magnetic field strength increasing by a factor of two and a half, as expected when the solar wind slows down. The magnetic field has remained at these high levels from December until now.

 

[sao123]

if this figure is correct:

The Oort Cloud extends out to about 3 light years (63,240 AU).

and the Oort cloud must clearly be completely inside of the bow shock barrier(approximately located at 230,000 AU), anything which crosses the bow shock is outside of the suns effective reach and is going to be blown out of our solar system by the Interstellar Winds.

then at 3.6 AU per year... will still take 63,000 years to cross the bow shock.

I doubt that we will see interstellar space anytime soon.

 

[egkenny]

Originally posted by: Gibsons
wow, I had no idea the Oort cloud was so far away...

I think to get there, given current tech, you'd want to build a really really really big rocket and wait a year or three for some really optimal planetary alignment so you could maximize your slinghot(s). Would that get enough velocity to go 3 light years in some "reasonable" amount of time?

I forgot to add that the Oort cloud start at the edge of the solar system and extends out to about 3 light years.

For planets the best boost comes from the closest aproach to the planet but is limited by atmsopheric drag. If you use the sun then it comes to how close you can get before the heat burn you up.

To show long it would take I will calculate how long it will take a spacecraft moving at the solar escape velocity from the earth to distances equal to the distance of the sun to the object. Note this assumes the spacecraft is powered and is moving at a constant velocity of 42.1 km/s. In reality an unpowered spacecraft will be slowing down the farthur it goes becuase of the pull from the sun. The actual times will be even longer the farthur out it goes.
Mercury = 0.04 years
Venus = 0.08 years
Earth = 0.11 years
Mars = 0.17 years
Jupiter = 0.59 years
Saturn = 1.07 years
Uranus = 2.16 years
Neptune = 3.38 years
Pluto = 4.44 years
Oort cloud (farthest point) = 21,361.23 years

 

[The Boston Dangler]

Voyager 1 and 2 took advantage of a planetary alignment that occurs once every 176 years. The only near-term possibility would be an ion drive, powered by ???. Maybe fusion?

 

[Gibsons]

Originally posted by: egkenny

Originally posted by: Gibsons
wow, I had no idea the Oort cloud was so far away...

I think to get there, given current tech, you'd want to build a really really really big rocket and wait a year or three for some really optimal planetary alignment so you could maximize your slinghot(s). Would that get enough velocity to go 3 light years in some "reasonable" amount of time?

I forgot to add that the Oort cloud start at the edge of the solar system and extends out to about 3 light years.

For planets the best boost comes from the closest aproach to the planet but is limited by atmsopheric drag. If you use the sun then it comes to how close you can get before the heat burn you up.

To show long it would take I will calculate how long it will take a spacecraft moving at the solar escape velocity from the earth to distances equal to the distance of the sun to the object. Note this assumes the spacecraft is powered and is moving at a constant velocity of 42.1 km/s. In reality an unpowered spacecraft will be slowing down the farthur it goes becuase of the pull from the sun. The actual times will be even longer the farthur out it goes.
Mercury = 0.04 years
Venus = 0.08 years
Earth = 0.11 years
Mars = 0.17 years
Jupiter = 0.59 years
Saturn = 1.07 years
Uranus = 2.16 years
Neptune = 3.38 years
Pluto = 4.44 years
Oort cloud (farthest point) = 21,361.23 years

Hm, so to get there in a reasonable amount of time, say one human lifetime, we'll need a velocity in the neighborhood of tens of thousands of km/sec? That's an awful lot of rocket fuel.