A detached object mission for New Frontiers 4

[_Augustus_]

A while ago, I came up with a proposal for a Sedna mission which could run on MMRTGs and use the SLS rocket. Now, with the discovery of 2014 FE72, a Sednoid that is currently far closer than Sedna, this mission could be a real possibility for a New Horizons-type direct mission, with no Oberth assist. Furthermore, it could use a much cheaper Falcon Heavy or Vulcan Heavy.

Does anyone want to work together with me to find the nearest launch window using a Jupiter or Saturn gravity assist to FE72 around 2024, then seriously propose it to NASA? For the first time, we have a detached object within reach of current technology. FE72 is slowly leaving the Solar System, and it is just past perihelion. Why don't we take advantage of it to study this bizarre new class of objects we barely know about?

[Streetwind]

Hmmm... I don't think that will work out, I'm afraid.

You're suggesting a mission to an object that is at 61.5 AU today, and fairly rapidly moving away from the sun. New Horizons took 10 years to bridge ~31 AU, and it was the fastest spacecraft to ever leave the Earth. Let's say you allow 20 years of travel time for this one because you can use a way oversized rocket to give it a push that makes New Horizons look like a quaint British older gentleman. If the proposed mission launches in 2024, that means it will arrive in 2044, which is 28 years from now.

2014 FE72 reached perihelion at 36.3 AU in 1965; so it gained about... let's call it 25 AU in 50 years. Because of how orbital mechanics works, the rate of gaining altitude above the gravity well increases as you travel away from periapsis - up to a certain point, at which it decreases again as you fall towards apoapsis. With FE72's apoapsis being at 4,000 AU, we can say with confidence that the rate of gaining altitude is still increasing right now, and will increase for the decades to come. So it is not too much to expect that within the 28 years until a hypothetical flyby, the object will gain another 25 AU.

Thus, at the time of encounter, 2014 FE72 may be anywhere between 85 and 90 AU away from the sun (further away that if you just went directly to Sedna, even). This is a problem, as New Horizons illustrates.

When New Horizons intercepted Pluto at somewhere around 32 AU (not perihelion but shortly after it, just beyond Neptune's orbit), it managed a data transmission rate of 2 kBit/s (not bytes, bits). Despite the fact that it carried an antenna the size of the entire spacecraft. There just wasn't enough power to produce a stronger signal... and that is the salient point. In extreme deep space exploration missions, getting out there is never the problem. Having enough power to be useful out there is! In an AMA shortly before the Pluto flyby, the New Horizons team was questioned about the comparatively low resolution of some of the science experiments onboard. Okay, the spacecraft was 10 years old, but surely there was something better available even at that time? Yes there was, they replied, but they specifically chose not to include the highest fidelity instruments. They knew they wouldn't be able to transmit all that data with their limited bandwidth.

So your mission would need to cover three times the distance with communications. The only power sources we have available in the near term that functions in deep space are radioisotope generators, which run on plutonium. Unfortunately, NASA is currently quite short on plutonium, because they didn't make any of it for decades (it's a long story involving politics). They've recently restarted production, but it will produce yields measured in grams, not kilograms, until it slowly ramps up over the course of who knows how long, maybe a decade. Until then, NASA has enough for three MMRTGs, and could maybe, possibly, barely make a fourth by infusing stockpiles of too-old plutnoium with some new stuff if they can make enough of it soon enough (questionable). So let's stick with three. A MMRTG takes between 4 and 5 kg of plutonium, and puts out 125 Watts new and 100 Watts after 12-14 years.

Here's two reasons why this is a dealbreaker for your mission. Reason one: of those three MMRTGs, one is already spoken for. It goes on the Mars 2020 rover. That leaves just two. You'd literally have to tell NASA "please throw every last scrap of plutonium you have left onto this one-shot flyby space probe". Very unlikely for you to succeed in that. Reason two: even if you convinced NASA to do just that, it wouldn't be enough. Remember New Horizon's data transmission rate over 33 AUs? New Horizons doesn't carry a 4 kg MMRTG. It carries a 9.75 kg Cassini-class GPHS-RTG (literally, the casing was a spare from the Cassini mission). It provided 245 W at launch and 200 W during its encounter at Pluto. In other words, that's two MMRTGs worth. Which is all NASA has left. But your spacecraft would need to transmit over triple the distance that New Horizons did, and the RTGs would have 10 extra years to degrade during the trip, further lowering the power output - to maybe as low as 160 W. In order to properly communicate in any sensible way, you'd probably need to throw at least 500 W at an antenna of comparable size to new Horizons. So, six MMRTGs minimum, four of which cannot be built...

NASA has said that they will accept proposals for New Frontiers 4 that request one MMRTG, but between "accept proposal" and "approve proposal" lies a great big ocean... and it wouldn't be enough power anyway.

 

It should also be noticed that NASA has published rough guidelines about what they want to hear in a New Frontiers 4 proposal. None of the desired goals goes further out than Saturn. It will definitely be difficult to get something approved that doesn't fall into those guidelines, even if it was technically possible.

And "technically possible" still doesn't mean it could be made affordable. A 20-year trip to an object 85 AU away would probably require SLS. And New Frontiers missions are budget limited to below $1 billion. If the launcher alone costs half of that or more...

Edited September 13, 2016 by Streetwind

[PB666]

6 hours ago, Streetwind said:

Hmmm... I don't think that will work out, I'm afraid.

You're suggesting a mission to an object that is at 61.5 AU today, and fairly rapidly moving away from the sun. New Horizons took 10 years to bridge ~31 AU, and it was the fastest spacecraft to ever leave the Earth. Let's say you allow 20 years of travel time for this one because you can use a way oversized rocket to give it a push that makes New Horizons look like a quaint British older gentleman. If the proposed mission launches in 2024, that means it will arrive in 2044, which is 28 years from now.

2014 FE72 reached perihelion at 36.3 AU in 1965; so it gained about... let's call it 25 AU in 50 years. Because of how orbital mechanics works, the rate of gaining altitude above the gravity well increases as you travel away from periapsis - up to a certain point, at which it decreases again as you fall towards apoapsis. With FE72's apoapsis being at 4,000 AU, we can say with confidence that the rate of gaining altitude is still increasing right now, and will increase for the decades to come. So it is not too much to expect that within the 28 years until a hypothetical flyby, the object will gain another 25 AU.

Thus, at the time of encounter, 2014 FE72 may be anywhere between 85 and 90 AU away from the sun (further away that if you just went directly to Sedna, even). This is a problem, as New Horizons illustrates.

When New Horizons intercepted Pluto at somewhere around 32 AU (not perihelion but shortly after it, just beyond Neptune's orbit), it managed a data transmission rate of 2 kBit/s (not bytes, bits). Despite the fact that it carried an antenna the size of the entire spacecraft. There just wasn't enough power to produce a stronger signal... and that is the salient point. In extreme deep space exploration missions, getting out there is never the problem. Having enough power to be useful out there is! In an AMA shortly before the Pluto flyby, the New Horizons team was questioned about the comparatively low resolution of some of the science experiments onboard. Okay, the spacecraft was 10 years old, but surely there was something better available even at that time? Yes there was, they replied, but they specifically chose not to include the highest fidelity instruments. They knew they wouldn't be able to transmit all that data with their limited bandwidth.

So your mission would need to cover three times the distance with communications. The only power sources we have available in the near term that functions in deep space are radioisotope generators, which run on plutonium. Unfortunately, NASA is currently quite short on plutonium, because they didn't make any of it for decades (it's a long story involving politics). They've recently restarted production, but it will produce yields measured in grams, not kilograms, until it slowly ramps up over the course of who knows how long, maybe a decade. Until then, NASA has enough for three MMRTGs, and could maybe, possibly, barely make a fourth by infusing stockpiles of too-old plutnoium with some new stuff if they can make enough of it soon enough (questionable). So let's stick with three. A MMRTG takes between 4 and 5 kg of plutonium, and puts out 125 Watts new and 100 Watts after 12-14 years.

Here's two reasons why this is a dealbreaker for your mission. Reason one: of those three MMRTGs, one is already spoken for. It goes on the Mars 2020 rover. That leaves just two. You'd literally have to tell NASA "please throw every last scrap of plutonium you have left onto this one-shot flyby space probe". Very unlikely for you to succeed in that. Reason two: even if you convinced NASA to do just that, it wouldn't be enough. Remember New Horizon's data transmission rate over 33 AUs? New Horizons doesn't carry a 4 kg MMRTG. It carries a 9.75 kg Cassini-class GPHS-RTG (literally, the casing was a spare from the Cassini mission). It provided 245 W at launch and 200 W during its encounter at Pluto. In other words, that's two MMRTGs worth. Which is all NASA has left. But your spacecraft would need to transmit over triple the distance that New Horizons did, and the RTGs would have 10 extra years to degrade during the trip, further lowering the power output - to maybe as low as 160 W. In order to properly communicate in any sensible way, you'd probably need to throw at least 500 W at an antenna of comparable size to new Horizons. So, six MMRTGs minimum, four of which cannot be built...

NASA has said that they will accept proposals for New Frontiers 4 that request one MMRTG, but between "accept proposal" and "approve proposal" lies a great big ocean... and it wouldn't be enough power anyway.

 

It should also be noticed that NASA has published rough guidelines about what they want to hear in a New Frontiers 4 proposal. None of the desired goals goes further out than Saturn. It will definitely be difficult to get something approved that doesn't fall into those guidelines, even if it was technically possible.

And "technically possible" still doesn't mean it could be made affordable. A 20-year trip to an object 85 AU away would probably require SLS. And New Frontiers missions are budget limited to below $1 billion. If the launcher alone costs half of that or more...

Lots of dead fuel rods at nuclear reactors around the country in which plutonium can be extracted from.

You would not need 3 times the power, you would need 9 times the power, so you would need 9 MMRTGs, or 9 times the antenna. This weight gain is the deal breaker. I suspect that most of these distal kuiper belt objects are pretty much the same thing, liquified and frozen gases covering unknown. There is no real utility in studying these unless you intend to exploit them and I can hardly see the justification for that. IMO, in very deep outer solar system have a low-gravity body is a much better choice, because you do not need to invest dV to land or get off. At plutos orbit it takes about 4000 dV to enter a circular orbit about the sun, If you had a great (unrealistic) ion drive system with fusion power with something like 60,000 dV you could invest in the 8000 need to break orbit and the 10,000s needed to decelerate at Earth, thats pushing it. Really its on the boundary of what it theoretically possible with today's technologies. 

A much, much, much better and more practical idea is to find a >jovian orbit periapsis short period comet or trojan object to attempt a landing on. Very difficult because of the horizontal dV required to gain orbit and the vertical dV required to stop descent (Or take forever to get there). Land on the object collects samples and return to say mars and await a fly-by mission that could be piggy backed to earth. With jovian trojans there is a much more practical benifit, the objects are just beyond the conditional sublimation line which means volatiles are relatively stable for long periods, and there are a mixture of dust balls and comets, providing the diversity. If these are not sufficient then missions could be planned to the saturn trojans. 

1. Light sufficient to due passive spectrography.
2. A means of mapping landing sites and studying rotations
3. Many objects in relatively close proximity and in the same gravity well meaning not to much dV required to select best roids for landing.
4, Both rocky objects (covered with ice) and slush-balls are expected.
5. Close enough for newer solar panels to work, close enough for antenna to work.
 

 

 

There is no reason at this point other than vanity to go chasing planetoids into interstellar space, we already have vojagers on that mission.

[Streetwind]

7 minutes ago, PB666 said:

Lots of dead fuel rods at nuclear reactors around the country in which plutonium can be extracted from.

The limiting factor is not the resources. Much rather, the machines themselves which were used to extract, purify and package the Plutonium were allowed to fall into disrepair and eventually broke. Resuming production took like 4-5 years and yielded 1.8 ounces across all of 2015. And even now they're using the same old machines, barely patched up into working conditions, while the same circular political arguments that have been going on for decades about this still hold up any real progress or innovation... you know, the usual

[DerekL1963]

34 minutes ago, PB666 said:

Lots of dead fuel rods at nuclear reactors around the country in which plutonium can be extracted from.

Mostly (as in 98-99%) of the wrong kind of plutonium.   Reactors produce mostly Pu-239 (which is used in nuclear bombs), along with a good proportion of -240 (which is a messy contaminant useless to everyone).  Only a very small proportion is the -238 that's wanted for RTG's.   It's much cheaper and easier to produce -238 directly than it is to haul those fuel rods around and process them.

[_Augustus_]

15 hours ago, Streetwind said:

Hmmm... I don't think that will work out, I'm afraid.

You're suggesting a mission to an object that is at 61.5 AU today, and fairly rapidly moving away from the sun. New Horizons took 10 years to bridge ~31 AU, and it was the fastest spacecraft to ever leave the Earth. Let's say you allow 20 years of travel time for this one because you can use a way oversized rocket to give it a push that makes New Horizons look like a quaint British older gentleman. If the proposed mission launches in 2024, that means it will arrive in 2044, which is 28 years from now.

2014 FE72 reached perihelion at 36.3 AU in 1965; so it gained about... let's call it 25 AU in 50 years. Because of how orbital mechanics works, the rate of gaining altitude above the gravity well increases as you travel away from periapsis - up to a certain point, at which it decreases again as you fall towards apoapsis. With FE72's apoapsis being at 4,000 AU, we can say with confidence that the rate of gaining altitude is still increasing right now, and will increase for the decades to come. So it is not too much to expect that within the 28 years until a hypothetical flyby, the object will gain another 25 AU.

Thus, at the time of encounter, 2014 FE72 may be anywhere between 85 and 90 AU away from the sun (further away that if you just went directly to Sedna, even). This is a problem, as New Horizons illustrates.

When New Horizons intercepted Pluto at somewhere around 32 AU (not perihelion but shortly after it, just beyond Neptune's orbit), it managed a data transmission rate of 2 kBit/s (not bytes, bits). Despite the fact that it carried an antenna the size of the entire spacecraft. There just wasn't enough power to produce a stronger signal... and that is the salient point. In extreme deep space exploration missions, getting out there is never the problem. Having enough power to be useful out there is! In an AMA shortly before the Pluto flyby, the New Horizons team was questioned about the comparatively low resolution of some of the science experiments onboard. Okay, the spacecraft was 10 years old, but surely there was something better available even at that time? Yes there was, they replied, but they specifically chose not to include the highest fidelity instruments. They knew they wouldn't be able to transmit all that data with their limited bandwidth.

So your mission would need to cover three times the distance with communications. The only power sources we have available in the near term that functions in deep space are radioisotope generators, which run on plutonium. Unfortunately, NASA is currently quite short on plutonium, because they didn't make any of it for decades (it's a long story involving politics). They've recently restarted production, but it will produce yields measured in grams, not kilograms, until it slowly ramps up over the course of who knows how long, maybe a decade. Until then, NASA has enough for three MMRTGs, and could maybe, possibly, barely make a fourth by infusing stockpiles of too-old plutnoium with some new stuff if they can make enough of it soon enough (questionable). So let's stick with three. A MMRTG takes between 4 and 5 kg of plutonium, and puts out 125 Watts new and 100 Watts after 12-14 years.

Here's two reasons why this is a dealbreaker for your mission. Reason one: of those three MMRTGs, one is already spoken for. It goes on the Mars 2020 rover. That leaves just two. You'd literally have to tell NASA "please throw every last scrap of plutonium you have left onto this one-shot flyby space probe". Very unlikely for you to succeed in that. Reason two: even if you convinced NASA to do just that, it wouldn't be enough. Remember New Horizon's data transmission rate over 33 AUs? New Horizons doesn't carry a 4 kg MMRTG. It carries a 9.75 kg Cassini-class GPHS-RTG (literally, the casing was a spare from the Cassini mission). It provided 245 W at launch and 200 W during its encounter at Pluto. In other words, that's two MMRTGs worth. Which is all NASA has left. But your spacecraft would need to transmit over triple the distance that New Horizons did, and the RTGs would have 10 extra years to degrade during the trip, further lowering the power output - to maybe as low as 160 W. In order to properly communicate in any sensible way, you'd probably need to throw at least 500 W at an antenna of comparable size to new Horizons. So, six MMRTGs minimum, four of which cannot be built...

NASA has said that they will accept proposals for New Frontiers 4 that request one MMRTG, but between "accept proposal" and "approve proposal" lies a great big ocean... and it wouldn't be enough power anyway.

 

It should also be noticed that NASA has published rough guidelines about what they want to hear in a New Frontiers 4 proposal. None of the desired goals goes further out than Saturn. It will definitely be difficult to get something approved that doesn't fall into those guidelines, even if it was technically possible.

And "technically possible" still doesn't mean it could be made affordable. A 20-year trip to an object 85 AU away would probably require SLS. And New Frontiers missions are budget limited to below $1 billion. If the launcher alone costs half of that or more...

  MichaelPoole said:

I wholly support this.

Also, Sedna is a lot colder than Pluto and can harbor exotic ices that are gaseous at Pluto temperatures. I honestly very much dislike the "you've seen one you've seen them all" fallacy. Everyone expected Pluto to be either exactly the same as Triton or a cratered dead iceball yet it turned out to be neither of that. Moons of giant planets are all very much different in their geological history and composition and yet they are all similiar sized when it comes to moons for each planet with a few outliers and orbit the same distance from the Sun. The Jupiter system contains both the most active and the least active major solar system body (Io vs Callisto). You might say "but tidal heating..." except none of the moons of Uranus get any appreciable tidal heating at the moment, yet Miranda is a crazy world of chasms and 25 km high cliffs, Ariel has frozen "rivers" of ancient half-melted ice "lava" flows, Titania has a thin CO2 atmosphere and is criss-crossed with chasms, Umbriel is a crater ball - except fully black, yet one crater is bizzarely white, Oberon is a reddish cratered world. Look at Pluto and Charon - drastically different worlds. Sedna is Charon sized, but much colder. At aphelion, it is cold enough to freeze hydrogen. Right now, it might be warm enough for a nitrogen atmosphere. The temperature difference between perihelion and aphelion of Sedna are quite major. Think Pluto has dramatic seasons? Sedna is FAR more extreme.

-----------------------------------------------------------------

See above, buddy.

Edited September 14, 2016 by _Augustus_

[magnemoe]

8 hours ago, DerekL1963 said:

Mostly (as in 98-99%) of the wrong kind of plutonium.   Reactors produce mostly Pu-239 (which is used in nuclear bombs), along with a good proportion of -240 (which is a messy contaminant useless to everyone).  Only a very small proportion is the -238 that's wanted for RTG's.   It's much cheaper and easier to produce -238 directly than it is to haul those fuel rods around and process them.

As I understand the power reactors also makes the wrong mix for bombs. They uses an special reactor where the rods pass trough the reactor in an shorter time and then processed and probably feed again. I guess you do the same for 238 but at another rate. 
The US stopped processing nuclear waste as an political statement. Note it might be cheaper to buy fresh uranium rater than reprocess too as its an fairly expensive process. 
It also had enough plutonium for bombs anyway so no reason to make more. 
RTG is another issue, they also has problems on very long duration trips as others point out. an real nuclear reactor might be better here also as you could run ion engines with it and run it on very low power during the cruise phase however this would make an heavier probe.