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Unmanned Spaceflight.com _ New Horizons _ A New Horizons Clone To 2003 Ub313?

Posted by: SFJCody Dec 22 2005, 01:07 PM

Pluto's current distance from the Sun: ~31AU
2003 UB313's current distance from the Sun ~97AU

Is an all chemical (no electric propulsion, solar sails, etc) mission to 2003 UB313 possible? I'm thinking of a travel time and spacecraft mass similar to New Horizons. Perhaps NASA's new http://www.nasa.gov/images/content/125170main_comparison_full.jpg (payload capacity 125 metric tonnes to LEO) will be up to the task and could do this on a test flight.

Posted by: ugordan Dec 22 2005, 01:45 PM

A quick and dirty calculation shows that even with a heliocentric average speed of 20 km/s you'd need over 20 years to reach that distance.
That's comparable to the Voyager 1 spacecraft, currently at 97 AU from the sun and it took 2 gravity assists and over 25 years to reach that distance. And it's the fastest escaping probe out there.

I doubt anyone would ever launch a mission that would have to wait more than 20 years before any scientific return would be made. IMHO, chemical propulsion is totally out of the picture, nuclear powered ion propulsion or perhaps efficient solar sails would be possible alternatives.

EDIT: A very large cryogenic upper stage might do the job, but really, lifting a hundred tons of propellant into low earth orbit just to kick-start a few hundred kilograms on a very fast trajectory seems like a huge waste of resources. Not to mention that the faster you launch the probe, the faster you whizz by the target (in a matter of few minutes). Ideally, you'd want to slow down (possibly even braking into orbit) to have more time to get the highest resolution measurements available, again fission powered ion engines seem like the only alternative.

Posted by: JRehling Dec 22 2005, 02:51 PM

QUOTE (ugordan @ Dec 22 2005, 05:45 AM)
A quick and dirty calculation shows that even with a heliocentric average speed of 20 km/s you'd need over 20 years to reach that distance.
That's comparable to the Voyager 1 spacecraft, currently at 97 AU from the sun and it took 2 gravity assists and over 25 years to reach that distance. And it's the fastest escaping probe out there.
*


Are all gravity assists made equal? I'm sure they're not. The Voyager path was chosen to hit the needed planets, not for superspeed. It's another matter how fast a spacecraft would go if it were intended to get maximum heliocentric speed and Jupiter-Saturn gravity assists were timed accordingly. I doubt that the Voyagers hit those marks, and the difference could be considerable. Someone capable of simulating that?

Posted by: djellison Dec 22 2005, 03:00 PM

But, Maximum possible speed from a flyby, and the course required for your intended target are almost certain to not be the same thing as well smile.gif

I'd have thought, if you were intent on doing a misssion out to near 100AU then you're going to have to go with Ion or even more interesting propulsion ( A solar powered Ion 'stage' to the spacecraft, ejected once prop is exhausted after perhaps 12 months of thrusting adding a few km/s to the velocity of the RTG powered spacecraft )

Doug

Posted by: ugordan Dec 22 2005, 03:05 PM

QUOTE (JRehling @ Dec 22 2005, 03:51 PM)
The Voyager path was chosen to hit the needed planets, not for superspeed.
*

Wasn't Voyager 1's flight path targetted for passage through the Io flux tube? If so, it would mean it passed quite close to Jupiter already. I suppose even closer flybys are feasible, but it brings the question on additional radiation hardening of the electronics. In any case, I wouldn't go closer than 200 000 km from Jupiter, about half of Voyager 1 C/A distance (OTOH).
Also, there's only so much a gravity assist can boost, it's a function of the planet's tangential velocity. In any case, I don't believe reasonable (10 years) flight paths are feasible with a Jupiter slingshot. Arranging the geometry for a Saturn flyby as well would be even more difficult.

Posted by: ugordan Dec 22 2005, 03:20 PM

QUOTE (djellison @ Dec 22 2005, 04:00 PM)
I'd have thought, if you were intent on doing a misssion out to near 100AU then you're going to have to go with Ion or even more interesting propulsion ( A solar powered Ion 'stage' to the spacecraft, ejected once prop is exhausted after perhaps 12 months of thrusting adding a few km/s to the velocity of the RTG powered spacecraft )

I was wondering about the feasibility of a weak ion engine that would be powered off the surplus energy from an RTG during most of the cruise. How feasible would it have been for NH to have included a 100 watt ion engine that would slowly accelerate during 8 years or so of (otherwise dormant) interplanetary cruise? What cumulative delta-Vee could we expect from that on a 500 kilogram probe? A fast kick-start would still be needed during Jupiter injection, but if the long thrusting period shaved a year off the trip time, it might just have been worthwhile. Have any studies been done on that?

Of course, a very reliable ion engine would be needed, possibly similar in design to Hayabusa's microwave driven one? As I gather there is no weardown of the electrodes in that case which would make it very convenient. Then there's the problem of the drive failing and the achieved final trajectory would probably not reach Pluto but fell short.
I wonder if a thrust angle profile could be set up so that at any point if the engine was cut-off the Pluto fly-by geometry would be set up, yet only the arrival date varied by continuing thrusting onward? In other words, the engine would continually move the aimpoint to earlier arrival times, keeping the C/A distance pretty much constant. Orbital dynamics probably don't allow for that, though.

Posted by: tasp Dec 22 2005, 03:30 PM

Pioneer 11 passed Jupiter at less than 30,000 KM.

High angle across Jovian equator drastically cut radiation exposure.

Sending craft out of the ecliptic with maximum gravitational assistance form Jupiter seems entirely within our capablitites.

High speed at the target object remains a problem, though.

Posted by: djellison Dec 22 2005, 03:32 PM

I doubt you could run any sort of Ion engine off normal RTGs - certainly not one worth investing the time, money and particularly mass and volume in.

You need something like a kw or 2 to make it worth while

Doug

Posted by: um3k Dec 22 2005, 03:49 PM

One thing I would like to point out is that a mission to 2003 UB313 would need an extremely sensitive camera. The brightness of sunlight at 97 AU is .01 percent of the brightness at 1 AU! That means either a very large light-collecting mirror, an extremely sensitive CCD, or a combination of both! Another option, of course, is to skip imaging altogether, but... *cringes*

Posted by: ugordan Dec 22 2005, 04:14 PM

QUOTE (tasp @ Dec 22 2005, 04:30 PM)
Sending craft out of the ecliptic with maximum gravitational assistance form Jupiter seems entirely within our capablitites.
*

Yeah, but sending the probe sharply above or below the ecliptic plane inherently diminishes the Jovian gravity assist, does it not? I'd think the biggest speed gain is when your outbound velocity is directed along Jupiter's orbital velocity, not upwards or below. That means the greates speeds achievable using gravity assists will be more or less in the ecliptic plane.
I guess... unsure.gif

um3k: That problem could be partly alleviated simply by using longer integration/exposure times. This again prefers slower flyby speeds as motion blur would be smaller. Motion blur would probably be a big problem with the highest resolution imagery around C/A even when using target motion compensation as the target area viewing vantage point is changing in addition to doing a simple translation (which motion compensation takes care of) when viewed from the spacecraft point.

All points show ordinary chemical propulsion would pretty much suck at the task.

Posted by: SFJCody Dec 22 2005, 06:04 PM

QUOTE (um3k @ Dec 22 2005, 03:49 PM)
One thing I would like to point out is that a mission to 2003 UB313 would need an extremely sensitive camera. The brightness of sunlight at 97 AU is .01 percent of the brightness at 1 AU!
*



Ah, but the sunlight at Neptune (30 AU) was about 0.11 percent of the brightness at 1 AU. And Voyager 2 successfully imaged Proteus (with a 6% albedo) at that distance. With vidicon tube technology! If 2003 UB313 has an albedo of ~70% (which seems to be the case given the difficulty in seeing it with Spitzer), it will have a surface slightly *brighter* than Proteus, even at 100AU. In that case, all we're left with is the increase in velocity. If New Horizons to UB313 carries a CCD with just 5 times the efficiency of Voyager's mid 70s vidicon tube technology (not asking much), it will be able to image 2003 UB313 as successfully as Voyager 2 was able to image Proteus even if it moves 5 times faster.

Posted by: ugordan Dec 22 2005, 06:17 PM

QUOTE (SFJCody @ Dec 22 2005, 07:04 PM)
If New Horizons to UB313 carries a CCD with just 5 times the efficiency of Voyager's mid 70s vidicon tube technology (not asking much), it will be able to image 2003 UB313 as successfully as Voyager 2 was able to image Proteus even if it moves 5 times faster.
*

But if we were to send a probe across such an immense distance, we wouldn't be settling for a C/A distance of 150 000 km or so. We'd like at least a 10 times closer approach distance which will make any motion blur problems 10 times worse. So, if you wanted highest resolution observations during closest approach, you'd need 10 times more sensitivity in the cameras apart from your 5x. That's 50 times more sensitive than a vidicon.

Posted by: SFJCody Dec 22 2005, 06:25 PM

QUOTE (ugordan @ Dec 22 2005, 06:17 PM)
...you'd need 10 times more sensitivity in the cameras apart from your 5x. That's 50 times more sensitive than a vidicon.
*


50x might not be out of the question, esp. given that the launch vehicle under discussion wont become available for a decade or so. That's about 40 years after the Voyagers were built. Does anyone have the photosensitivity specs on the Voyager vidicons and the latest in cutting edge CCDs?

Posted by: ugordan Dec 22 2005, 06:35 PM

Then again, newer propulsion methods will probably be available by that time also so all bets are off.

I'm no expert on CCD technology, but it's based on semiconductors. The lower the temperature of the detector, the better the signal/noise ratio is. However, at very low temperatures the semiconducting properties of the detector start to degrade.
IIRC, sillicon based elements have a low threshold around 80 deg Celsius, I might be wrong, my electronics are a bit rusty. All this would imply there's a lower limit to how sensitive a CCD can get.

Posted by: SFJCody Dec 22 2005, 06:40 PM

QUOTE (ugordan @ Dec 22 2005, 01:45 PM)
EDIT: A very large cryogenic upper stage might do the job, but really, lifting a hundred tons of propellant into low earth orbit just to kick-start a few hundred kilograms on a very fast trajectory seems like a huge waste of resources.
*


Normally, yes, but it might make an interesting 'dummy' payload for a test launch of the SDLV. IIRC large cryogenic upper stages for the new heavy lifter are needed for the Earth to Mars transfer if they go with in orbit assembly of a Mars 'stack'.

Posted by: Jyril Dec 22 2005, 06:42 PM

QUOTE (SFJCody @ Dec 22 2005, 09:04 PM)
If 2003 UB313 has an albedo of ~70% (which seems to be the case given the difficulty in seeing it with Spitzer), it will have a surface slightly *brighter* than Proteus, even at 100AU.


At first try, Spitzer didn't detect 2003 UB313 because of a pointing error. Later observations haven't been published yet. But as the object is expected to have a Pluto-like or brighter surface, an albedo of 70% sounds reasonable.

Posted by: tasp Dec 22 2005, 06:47 PM

QUOTE (ugordan @ Dec 22 2005, 10:14 AM)
Yeah, but sending the probe sharply above or below the ecliptic plane inherently diminishes the Jovian gravity assist, does it not? I'd think the biggest speed gain is when your outbound velocity is directed along Jupiter's orbital velocity, not upwards or below. That means the greates speeds achievable using gravity assists will be more or less in the ecliptic plane.
I guess...  unsure.gif
*


Not sure I've worked this out in my head correctly, but at a 45 degree angle to Jupiter equator, maximum grav assist would be around 71% of nominal.

And the angle allows a closer approach per a given radiation exposure. Angled to reach Pluto, (17 degree maximum) the grav assist would be almost maximum possible if timed properly.

Once a craft is on the trajectory to Jupiter, mass of the craft becomes irrelevant in regards to grav assist, btw.

Dramatic photo op!

Posted by: ugordan Dec 22 2005, 07:02 PM

QUOTE (tasp @ Dec 22 2005, 07:47 PM)
Not sure I've worked this out in my head correctly, but at a 45 degree angle to Jupiter equator, maximum grav assist would be around 71% of nominal.

Isn't Jupiter's equator more or less edge on to the ecliptic? A 45 degree approach is bound to slinghot you way above/below the ecliptic.

QUOTE (tasp @ Dec 22 2005, 07:47 PM)
Once a craft is on the trajectory to Jupiter, mass of the craft becomes irrelevant in regards to grav assist, btw.

True, but the additional mass certainly counts when you're injecting the spacecraft to Jupiter in the first place. The fact Jupiter doesn't care how massive you are doesn't help your escape from an Earth parking orbit at all.

Posted by: SFJCody Dec 22 2005, 07:33 PM

QUOTE (tasp @ Dec 22 2005, 06:47 PM)
Not sure I've worked this out in my head correctly, but at a 45 degree angle to Jupiter equator, maximum grav assist would be around 71% of nominal.

*


Why 45 degrees (except as a 'worst case')? 2003 UB313 isn't all that far from the ecliptic, and it's getting closer (it should pass through it before this century is out).

Edit: A thought about data transfer: At 100AU, the New Horizons clone would take years to downlink a 'Pluto encounter's worth' of data. A larger high-gain or optical communication may be needed.

Posted by: SFJCody Dec 23 2005, 11:28 AM

This is beginning to resemble the TAU (thousand astronomical unit) mission conceived in the mid 80s.


Bulletin of the American Astronomical Society, Vol. 18, p.1012 (09/1986)


Edit: Scientifically, a mission to 2003 UB313 (or 2005 FY9, which might be more Pluto-like) would be a useful counterpart to New Horizons. New Horizons will pass Pluto a few decades past perihelion, complete with atmosphere/outgassing/geysers/etc. But unless we are still around in a century's time we won't get to see it in its more quiescent aphelion state. Luckily, Pluto's cousin TNOs are close to aphelion (which is probably why they escaped detection for so long).


Posted by: BruceMoomaw Dec 24 2005, 01:45 AM

This seems to be the type of mission that can ONLY be done either by a solar sail or by nuclear-electric propulsion. (I know which one I'd prefer.)

http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/16979/1/99-0394.pdf
http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/17917/1/99-1367.pdf
http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/18379/1/99-1857.pdf
http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/12194/1/01-0122.pdf
http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/15590/1/00-1293.pdf
http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/13644/1/00-0010.pdf

Posted by: Comga Dec 24 2005, 06:09 AM

QUOTE (SFJCody @ Dec 23 2005, 05:28 AM)
This is beginning to resemble the TAU (thousand astronomical unit) mission conceived in the mid 80s.
*


Wow. Thanks for dredging up the TAU document. What a blast from the past! It is hard to think how ideas so far out were being discussed in those days. This topic is about as close as we come these days.

Posted by: edstrick Dec 24 2005, 10:02 AM

The "Purple Pigeons of Planetology" Wish List. Don't remember them all, but things like Rosetta and Cassini are in that category.

Posted by: ilbasso Dec 24 2005, 10:44 PM

At what angle and distance did Ulysses encounter Jupiter to be shot into an 80-dgree inclided orbit?

Posted by: Planet X Jan 9 2006, 11:59 AM

I was looking at the planetary orbits (as viewed from 90 degrees above the ecliptic) the other day and noticed it might be possible to fly a Uranus-2003 UB313 mission. Just wondering, is the NH2 concept dead? If not, would it be possible to fly that mission to Uranus and 2003 UB313? That, IMO, would be one cool mission. Has anyone yet pondered this idea? Later!

J P

Posted by: abalone Jan 9 2006, 01:54 PM

QUOTE (ugordan @ Dec 23 2005, 06:02 AM)
Isn't Jupiter's equator more or less edge on to the ecliptic?
*

It is not Jupiter's equator or the ecliptic that matter it is the plane of the planets orbit. It just so happens that for Jupiter they are almost the same. For Uranus it matters of course if it is to be used for grav assist

QUOTE
Planet X Posted Yesterday, 10:59 PM
At what angle and distance did Ulysses encounter Jupiter to be shot into an 80-dgree inclided orbit?


If a gravity assist is an increase in velocity then this may not qualify as if was simply using Jupiter to change the inclination of the orbit, but then again that is a deltaV so it may. unsure.gif unsure.gif unsure.gif

Posted by: ugordan Jan 9 2006, 02:09 PM

QUOTE (abalone @ Jan 9 2006, 02:54 PM)
It is not Jupiter's equator or the ecliptic that matter it is the plane of the planets orbit. It just so happens that for Jupiter they are almost the same. For Uranus it matters of course if it is to be used for grav assist
*

I think you misunderstood me. What I was getting at is that most planets (well, all when you exclude Pluto tongue.gif) orbit in practically the same plane. Jupiter's equatorial plane is also similar to that plane meaning the most intense radiation area around Jupiter is "conveniently" placed so most spacecraft that want to reach one of those planets need to fly through the densest part of the radiation belt IF they want to maximize the slingshot effectiveness, that is fly as close to Jupiter as possible.

Posted by: abalone Jan 9 2006, 02:29 PM

QUOTE (ugordan @ Jan 10 2006, 01:09 AM)
I think you misunderstood me. What I was getting at is that most planets (well, all when you exclude Pluto tongue.gif) orbit in practically the same plane. Jupiter's equatorial plane is also similar to that plane meaning the most intense radiation area around Jupiter is "conveniently" placed so most spacecraft that want to reach one of those planets need to fly through the densest part of the radiation belt IF they want to maximize the slingshot effectiveness, that is fly as close to Jupiter as possible.
*

Got it, thanks

Posted by: Bob Shaw Jan 9 2006, 09:48 PM

QUOTE (SFJCody @ Dec 22 2005, 08:33 PM)
Why 45 degrees (except as a 'worst case')? 2003 UB313 isn't all that far from the ecliptic, and it's getting closer (it should pass through it before this century is out).

Edit: A thought about data transfer: At 100AU, the New Horizons clone would take years to downlink a 'Pluto encounter's worth' of data. A larger high-gain or optical communication may be needed.
*



I think it was Bruce Moomaw who commented on a related issue, ie the cost per unit of data, and suggested that future spacecraft needed to be examined on an accounting basis as well as in terms of pure science (I wonder how the ISS would come out? NOT!). It does make you think, though, that with spacecraft longevity almost a given, s-l-l-l-o-o-o-w data return might have a range of benefits. Smaller spacecraft sizes, more robust components, and cheaper radio facilities on Earth all spring to mind. Does it *really* matter if the results of a wham-bang-thankyou-ma'am encounter take years to be returned?

Bob Shaw

Posted by: helvick Jan 9 2006, 10:18 PM

QUOTE (Bob Shaw @ Jan 9 2006, 10:48 PM)
Smaller spacecraft sizes, more robust components, and cheaper radio facilities on Earth all spring to mind. Does it *really* matter if the results of a wham-bang-thankyou-ma'am encounter take years to be returned?
*

We're going to need an orbiting deep space receiver to handle all this inbound data fairly soon. The Earth\Moon L4\L5 points seem like a good spot. Are there any plans?

Posted by: Ames Jan 16 2006, 10:30 AM

QUOTE (helvick @ Jan 9 2006, 11:18 PM)
We're going to need an orbiting deep space receiver to handle all this inbound data fairly soon. The Earth\Moon L4\L5 points seem like a good spot. Are there any plans?
*


Until we perfect the technology to create large inflatable structures in space, it's going to be MUCH cheaper to build big DSN receivers here on earth.


Nick

Posted by: ToSeek Jan 16 2006, 07:37 PM

QUOTE (Ames @ Jan 16 2006, 10:30 AM)
Until we perfect the technology to create large inflatable structures in space, it's going to be MUCH cheaper to build big DSN receivers here on earth.
Nick
*


The DSN was upgraded in 2003 to get ready for the MER/Cassini data rush of 2004. I don't think New Horizons is going to be an issue, though I wonder about the Mars Reconnaissance Orbiter, particularly if the MERs are still going come MRO's start of science operations in November. (But wouldn't it be nice to have that problem!)

Posted by: djellison Jan 16 2006, 08:29 PM

Remember - MER rides most of it's DSN time on the back of Odyssey smile.gif Only a brief uplink every day, plus a beep to confirm a sequence hand over

Of course, DSN upgrades are beginning to allow for multiple spacecraft to use a single dish. i.e. Odyssey, MGS, and MER beep off one dish pointed Marsward.

Doug

Posted by: AlexBlackwell Jan 16 2006, 08:35 PM

QUOTE (djellison @ Jan 16 2006, 08:29 PM)
Of course, DSN upgrades are beginning to allow for multiple spacecraft to use a single dish. i.e. Odyssey, MGS, and MER beep off one dish pointed Marsward.
I don't think this is a new capability (i.e., tied to any new upgrades). If I 'm not mistaken, for some time the DSN has had a "multiple spacecraft per aperture" mode, which permits the same antenna to track multiple spacecraft, provided they fall within a particular antenna's beam pattern.

Posted by: djellison Jan 16 2006, 08:44 PM

Ahh right - I just seem to remember them mentioning it quite a bit back with MER landings - they were probably hyping up the issue for something to talk about during the quiet times smile.gif

Doug

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