Saturn Ring Sample Return Mission?
Craig Fink
and analysis it and/or return a sample to Earth. The relative velocity
between the probe and ring material would be almost zero if the probe is
in-plane near circular.
Has anyone proposed or is working on a Saturn Ring Sample mission?
--
Craig Fink
Courtesy E-Mail Welcome @ WeBe...@GMail.Com
hal...@aol.com
nope all the money goes to shuttle and shuttle replacement, science
has little priority and even less money
Matt
That's an interesting thought. It's hard to believe no one has ever
considered it, but I try to be well-read on space science, and I've
never heard of a proposal to do that. Possibly it's felt that fly-bys
have analyzed it sufficiently.
Matt Bille
Herman Rubin
Craig Fink <WeBe...@GMail.Com> wrote:
>A planetary probe should be able to fly in and sample Saturn's ring material
>and analysis it and/or return a sample to Earth. The relative velocity
>between the probe and ring material would be almost zero if the probe is
>in-plane near circular.
>Has anyone proposed or is working on a Saturn Ring Sample mission?
Assuming you had a big enough and complex enough vehicle
you could get to the neighborhood of Saturn and get the
vehicle into the same orbit as ring particles, getting the
piece of the ring particle might not be too difficult.
But it would have to be analyzed there. Returning it
to Earth in usable shape might be difficult for many
reasons, one of them being that the current estimate
of what the ring particles are come up with some sort
of water-ammonia ice, and even returning an empty
probe requires more energy than will be available.
--
This address is for information only. I do not claim that these views
are those of the Statistics Department or of Purdue University.
Herman Rubin, Department of Statistics, Purdue University
hru...@stat.purdue.edu Phone: (765)494-6054 FAX: (765)494-0558
il...@rcn.com
> A planetary probe should be able to fly in and sample Saturn's ring material
> and analysis it and/or return a sample to Earth. The relative velocity
> between the probe and ring material would be almost zero if the probe is
> in-plane near circular.
Yes -- it's getting the probe into this circular orbit which is the
problem. Escape velocity at the outer edge of the rings (120,000 km
above Saturn's equator) is about 20 km/sec. Circular orbital velocity
is 14 km/sec. So a return probe needs 6 km/sec delta-v to escape
Saturn, at least the same amount to transfer from an interplanetary
trajectory to circular Saturn orbit in the first place (repeated Titan
flybys could help a little with either), then AT LEAST 5.5 km/sec
delta-v to get back to Earth. Flat-out impossible with chemical
rockets, and doable but very expensive with nuclear-powered ion
propulsion.
> Has anyone proposed or is working on a Saturn Ring Sample mission?
To the best of my knowledge no -- at least not seriously.
Alain Fournier
> A planetary probe should be able to fly in and sample Saturn's ring material
> and analysis it and/or return a sample to Earth. The relative velocity
> between the probe and ring material would be almost zero if the probe is
> in-plane near circular.
>
> Has anyone proposed or is working on a Saturn Ring Sample mission?
If the probe is in-plane near circular at 180 Mm from Saturn centre
(the top of Saturn rings) it needs a delta v of about 6 km/s to get
out of the Saturn system. That is a rather large delta v. And then
you knead some more delta v to get to Earth.
You can get some help by using gravity assists from Saturnian moons and
you can use some fancy high ISP propulsion (ion drives or what not). But
still we aren't talking about an easy mission here.
Alain Fournier
Alain Fournier
> On Apr 9, 12:21 am, Craig Fink <WeBeG...@GMail.Com> wrote:
>
>>A planetary probe should be able to fly in and sample Saturn's ring material
>>and analysis it and/or return a sample to Earth. The relative velocity
>>between the probe and ring material would be almost zero if the probe is
>>in-plane near circular.
>
>
> Yes -- it's getting the probe into this circular orbit which is the
> problem. Escape velocity at the outer edge of the rings (120,000 km
> above Saturn's equator) is about 20 km/sec. Circular orbital velocity
> is 14 km/sec. So a return probe needs 6 km/sec delta-v to escape
> Saturn, at least the same amount to transfer from an interplanetary
> trajectory to circular Saturn orbit in the first place (repeated Titan
> flybys could help a little with either), then AT LEAST 5.5 km/sec
> delta-v to get back to Earth. Flat-out impossible with chemical
> rockets, and doable but very expensive with nuclear-powered ion
> propulsion.
I wouldn't go so far as saying flat-out impossible with chemical
rockets. You can use multiple gravity assists with multiple
Saturnian moons. But it would be a very complex mission.
With chemical rockets and without using gravity assists it would be
a ridiculously monstrous mission. But with careful planing you can
lose and gain almost all the delta v needed to get in and out of
the Saturnian system with multiple gravity assists. Still it would
be a very complex mission. Using, Venus, Earth, Mars, Jupiter,
Titan, Rhea, Tethys and Mimas, you can do the trip with little
more energy than that needed to reach Venus. Unless you are lucky
with the planetary alignment it would take a lot of time, but it
could be done.
Alain Fournier
Pat Flannery
>
> But it would have to be analyzed there. Returning it
> to Earth in usable shape might be difficult for many
> reasons, one of them being that the current estimate
> of what the ring particles are come up with some sort
> of water-ammonia ice, and even returning an empty
> probe requires more energy than will be available.
>
Ideally, once the probe was in Saturn orbit near the rings, it would
start from the outer edge and slowly work inwards to the inner edge,
sampling and analyzing the ring material in multiple places as it moved,
so that a detailed model of ring composition could be built up.
Photography from inside the rings would really be something to see.
Pat
Pat Flannery
>
> You can get some help by using gravity assists from Saturnian moons and
> you can use some fancy high ISP propulsion (ion drives or what not). But
> still we aren't talking about an easy mission here.
Which brings up a interesting possibility; the gravity of the tiny moons
located near and in the rings is very low, and the probe would be
traveling in their orbital plane...so why not land the probe on one of
them and sample its surface?
Pat
Pat Flannery
>
>
> With chemical rockets and without using gravity assists it would be
> a ridiculously monstrous mission. But with careful planing you can
> lose and gain almost all the delta v needed to get in and out of
> the Saturnian system with multiple gravity assists. Still it would
> be a very complex mission. Using, Venus, Earth, Mars, Jupiter,
> Titan, Rhea, Tethys and Mimas, you can do the trip with little
> more energy than that needed to reach Venus. Unless you are lucky
> with the planetary alignment it would take a lot of time, but it
> could be done.
This still sounds like something ion engines would be helpful for once
you get near Saturn.
The key for a successful sample return would be a very small and
lightweight return capsule, but frankly I think it makes more sense to
examine the samples in-situ from a overall spacecraft mass point of view.
One thing the ion engines would allow you to do is maneuver to different
areas of the rings at different orbital heights over the planet in a
reasonable amount of time.
Pat
Pat Flannery
>
> This still sounds like something ion engines would be helpful for once
> you get near Saturn.
> The key for a successful sample return would be a very small and
> lightweight return capsule, but frankly I think it makes more sense to
> examine the samples in-situ from a overall spacecraft mass point of view.
> One thing the ion engines would allow you to do is maneuver to
> different areas of the rings at different orbital heights over the
> planet in a reasonable amount of time.
Continuing along this line of thought, why not put the ring sampling
probe into a orbit at a slight angle to the rings themselves, so that it
rises or falls below them by say 100 miles in each orbit, and cuts
through them twice in each orbit, so that it is able to transmit its
data back to Earth while above or below the rings, while avoiding
possible damage while within the rings themselves?
Using ion engines the probe can steadily lower its orbital altitude
above Saturn as it travels from the outside to the inside of the ring
system, and can continue right down to atmospheric entry after releasing
a slightly decelerated atmospheric entry probe...that by this means
needs nowhere near the heat-shielding of the Galileo Jupiter probe's
entry velocity.
The main probe needs only a extra orbit or two to transmit the entry
probe's data back to Earth before it too enters the atmosphere via
atmospheric drag.
Pat
Jeff Findley
news:3af536a8-d64f-4309...@q10g2000prf.googlegroups.com...
> On Apr 8, 10:21 pm, Craig Fink <WeBeG...@GMail.Com> wrote:
>> Has anyone proposed or is working on a Saturn Ring Sample mission?
>
> considered it, but I try to be well-read on space science, and I've
> never heard of a proposal to do that. Possibly it's felt that fly-bys
> have analyzed it sufficiently.
My guess is that the delta-V and mass requirements necessary for such a
mission are a bit beyond the state of the art for a single launch.
Jeff
--
A clever person solves a problem.
A wise person avoids it. -- Einstein
.
Totorkon
Apparently it has been determined that the rings are nearly pure water
ice with a slight dusting of...dust. Because of collisions and
reconfigurations it might be impossible to determine the age of the
rings from its constituants.
It would be interesting to drop a few small satellites into the ring
plane to assess the gravitational forces that maintain stability and
get an inside view instead of ringside.
Craig Fink
>> A planetary probe should be able to fly in and sample Saturn's ring
>> material and analysis it and/or return a sample to Earth. The relative
>> velocity between the probe and ring material would be almost zero if the
>> probe is in-plane near circular.
>>
>> Has anyone proposed or is working on a Saturn Ring Sample mission?
Matt wrote:
> That's an interesting thought. It's hard to believe no one has ever
> considered it, but I try to be well-read on space science, and I've
> never heard of a proposal to do that. Possibly it's felt that fly-bys
> have analyzed it sufficiently.
I haven't heard of it either.
It's tough to focus a microscope as the probe flys by. I imagine the Rings
would collect a lot of interesting stuff in them.
--
Craig Fink
Courtesy E-Mail Welcome @ WeBe...@GMail.Com
Craig Fink
> Craig Fink <WeBe...@GMail.Com> wrote:
>>A planetary probe should be able to fly in and sample Saturn's ring
>>material and analysis it and/or return a sample to Earth. The relative
>>velocity between the probe and ring material would be almost zero if the
>>probe is in-plane near circular.
>
>>Has anyone proposed or is working on a Saturn Ring Sample mission?
>
Herman Rubin wrote:
> Assuming you had a big enough and complex enough vehicle
> you could get to the neighborhood of Saturn and get the
> vehicle into the same orbit as ring particles, getting the
> piece of the ring particle might not be too difficult.
>
> But it would have to be analyzed there. Returning it
> to Earth in usable shape might be difficult for many
> reasons, one of them being that the current estimate
> of what the ring particles are come up with some sort
> of water-ammonia ice, and even returning an empty
> probe requires more energy than will be available.
An Aerobrake using Saturn's atmosphere to start the journey at the bottom
ring, a reasonable L/D could supply the plane change. And it could be used
at Earth with the returning samples...
Water-ammonia is an acceptable in-situ propellent for the return trip...
I would think the list of cool Objects in the Rings would be quite large,
not to mention the possibility to Orbit and study all the in-plane Moons
while the return vehicle climbs out of Saturn's gravity well. Energy
wouldn't be a problem with nuclear power, and Solar Cells would not be a
bright idea...
Craig Fink
Shuttle? what money?
I was talking about returning part of Saturn's rings to Earth to study and
sell. Cosmic SnowFlakes, StarDust, very small asteroids, that type of
thing. All the interesting things that collect in the rings.
--
Craig Fink
Courtesy E-Mail Welcome @ WeBe...@GMail.Com
Craig Fink
> On Apr 9, 12:21 am, Craig Fink <WeBeG...@GMail.Com> wrote:
>> A planetary probe should be able to fly in and sample Saturn's ring
>> material and analysis it and/or return a sample to Earth. The relative
>> velocity between the probe and ring material would be almost zero if the
>> probe is in-plane near circular.
>
> Yes -- it's getting the probe into this circular orbit which is the
> problem. Escape velocity at the outer edge of the rings (120,000 km
> above Saturn's equator) is about 20 km/sec. Circular orbital velocity
> is 14 km/sec. So a return probe needs 6 km/sec delta-v to escape
> Saturn, at least the same amount to transfer from an interplanetary
> trajectory to circular Saturn orbit in the first place (repeated Titan
> flybys could help a little with either), then AT LEAST 5.5 km/sec
> delta-v to get back to Earth. Flat-out impossible with chemical
> rockets, and doable but very expensive with nuclear-powered ion
> propulsion.
Yeah, I agree nuclear-powered ion propulsion is the way to go. It would be
20 km/sec plus to climb out from the inner ring. The ion engine allow the
vehicle to visit Titan up close and personal if the planes are close
enough...
Herman Rubin mentioned that most of the in-situ propellent is water-ammonia,
so the candidate ions for the engine would be H, O and Nitrogen...
>
>> Has anyone proposed or is working on a Saturn Ring Sample mission?
>
> To the best of my knowledge no -- at least not seriously.
Seriously, I think it's doable...
Craig Fink
A chemical rocket would complement a nuclear/ion engine quite well for a
Saturn Ring Sample return. If the third stage of the Earth ascent vehicle
is the Aerobrake Sample Return vehicle, a much larger sample of Ring
material could be returned to Earth. Probable larger than the payload taken
to Saturn.
After orbit insertion at Earth, the Return vehicle would have almost empty
tanks. The Nuclear/Ion Engine could be used to climb out of the Earth's
Gravity well. At the edge of the Earth's gravity well, very little delta-V
is required to lower perigee back down to within several hundred km above
the Earth. The rest of the fuel in the Third Stage/Return Vehicle/Aerobrake
vehicle could be used to send it on it's way to Saturn, or the gravity
assists.
Chemical rocket burns deep in gravity well are very efficient and a much
larger delta-V above Earth escape can be attained by a small burn deep in
the gravity well. Essentially, this is why the injection burns at Saturn or
Jupiter are reasonable.
Another way to think of it, is the that the Ion engine vastly increases the
potential energy of the Chemical propellant. This potential energy isn't
lost, but is converted to kinetic energy by the burn deep in the gravity
well. Gravity is a time function, the time to fall from apogee to perigee
is much longer than the time to escape Saturn's (or Earth's) influence
after the perigee burn.
In-situ propellent for both the Nuclear/Ion Engine and the Return Vehicle
can be used at Saturn. Aerobraking to the inner ring of Saturn eliminates
the need for propellant at Saturn for the injection burn and the huge burn
to get down to the bottom of Saturns gravity well.
Using the nuclear/Ion Engine to maneuver around, collect samples, refill the
Return Vehicle tanks, refill the Ion Engine's tanks, and slowly climb out
of Saturns gravity well. Even visit and orbit each Saturnian Moon. Once at
the upper edge of Saturns gravity well, very little delta-V is required to
lower perigee back down to Saturn.
During the plunge back down Saturn's gravity well, the large Sample return
vehicle would be separated from the nuclear/ion powered Orbiter vehicle
that contains all the science packages. Both going there separate ways. The
Orbital probe could spend decades visiting interesting things, until the
nuclear power plant is depleted.
A Chemical rocket burn from this highly eccentric orbit at perigee is
reasonably small to send the Return Vehicle on it's way directly back to
Earth, or use some gravity assists (more payload).
I would think only one launch would be required for the mission, and the
Returned Sample would probably be larger than the Saturn Orbital Probe, as
the Return vehicle would have tanks that were sized for the third stage of
Earth ascent. Several thousand kilograms of Saturn's rings, maybe even some
small asteroids if some can be found in the rings.
Craig Fink
> On Apr 8, 9:21 pm, Craig Fink <WeBeG...@GMail.Com> wrote:
>> A planetary probe should be able to fly in and sample Saturn's ring
>> material and analysis it and/or return a sample to Earth. The relative
>> velocity between the probe and ring material would be almost zero if the
>> probe is in-plane near circular.
>>
>> Has anyone proposed or is working on a Saturn Ring Sample mission?
>
>
> Apparently it has been determined that the rings are nearly pure water
> ice with a slight dusting of...dust. Because of collisions and
> reconfigurations it might be impossible to determine the age of the
> rings from its constituants.
>
> It would be interesting to drop a few small satellites into the ring
> plane to assess the gravitational forces that maintain stability and
> get an inside view instead of ringside.
I was under the impression that some of the rings are dirty, and there are
lots of small shepherd objects. There should be lots of interesting things
to collect and study.
--
Craig Fink
Courtesy E-Mail Welcome @ WeBe...@GMail.Com
Craig Fink
Some core samples would be interesting, probably the best way to refuel if
it's made of ice. I wonder if the smaller objects are growing with time or
shrinking.
Alain Fournier
>>In article <2OadnXyx8aXEj2Ha...@earthlink.com>,
>>Craig Fink <WeBe...@GMail.Com> wrote:
>>
>>>A planetary probe should be able to fly in and sample Saturn's ring
>>>material and analysis it and/or return a sample to Earth. The relative
>>>velocity between the probe and ring material would be almost zero if the
>>>probe is in-plane near circular.
>>
>>>Has anyone proposed or is working on a Saturn Ring Sample mission?
>>
>
> Herman Rubin wrote:
>
>
>>Assuming you had a big enough and complex enough vehicle
>>you could get to the neighborhood of Saturn and get the
>>vehicle into the same orbit as ring particles, getting the
>>piece of the ring particle might not be too difficult.
>>
>>But it would have to be analyzed there. Returning it
>>to Earth in usable shape might be difficult for many
>>reasons, one of them being that the current estimate
>>of what the ring particles are come up with some sort
>>of water-ammonia ice, and even returning an empty
>>probe requires more energy than will be available.
>
>
> An Aerobrake using Saturn's atmosphere to start the journey at the bottom
> ring, a reasonable L/D could supply the plane change. And it could be used
> at Earth with the returning samples...
Aerobraking at Saturn is a challenge. We are talking speeds greater than
35 km/s here. If you want to complicate this with a plane change using
aerodynamic lift then I think your heat shield is in sci-fi territory.
You might be able to do it with multiple passes where each orbital dip
in the atmosphere only takes away a little velocity and only changes the
plane a little. But that would take a lot of time (years) and would still
be technically challenging.
Alain Fournier
Craig Fink
I agree, Multiple Passes are reasonable to reduce heat loads to within the
physical limits of the heatshield. Or, may not be required. The two largest
passes, Injection into a highly elliptical orbit around Saturn and Apogee
Reduction from the top to the bottom of the rings, are much smaller than
35km/s. The others can be of the same magnitude. A few months, really
dependant on the first aerobrake and the period of the injection orbit.
Although, taking a few years would be ok. Maybe drop off some monitor probes
in a bunch of different orbits.
Lifting surfaces are much cooler than the stagnation point surface. The more
lift, the more the orbital elements can be adjusted. More than just
inclination. The more lift, the lower peak heating loads. All can be
adjusted during Multiple Passes, which really makes it much easier to
target the final orbit.
Flying through the rings may also be possible...just don't run in to
anything solid...
Alain Fournier
> Alain Fournier wrote:
>>Aerobraking at Saturn is a challenge. We are talking speeds greater than
>>35 km/s here. If you want to complicate this with a plane change using
>>aerodynamic lift then I think your heat shield is in sci-fi territory.
>>You might be able to do it with multiple passes where each orbital dip
>>in the atmosphere only takes away a little velocity and only changes the
>>plane a little. But that would take a lot of time (years) and would still
>>be technically challenging.
>
>
> I agree, Multiple Passes are reasonable to reduce heat loads to within the
> physical limits of the heatshield. Or, may not be required. The two largest
> passes, Injection into a highly elliptical orbit around Saturn and Apogee
> Reduction from the top to the bottom of the rings, are much smaller than
> 35km/s. The others can be of the same magnitude. A few months, really
> dependant on the first aerobrake and the period of the injection orbit.
The 35 km/s I mentioned wasn't a delta-V. It is the speed of the probe
relative to Saturn's atmosphere at first encounter. Hitting an atmosphere
at 35 km/s is painful even if you just skim the atmosphere a little and
you only want to have an aero-braking delta-V of a few hundred m/s.
Even if you are hitting a very thin atmosphere, it will be heated to a
plasma, the ions hitting your heat shield at such high speeds will
damage your heat shield no matter what material you use.
I don't think it is impossible to do, but it is very challenging.
Alain Fournier