Discussion Uranus and Neptune mission concepts

[Nicholander]

For me at least, It's pretty late in the day, so are you still setting up the thread or something?

 

[TMac3000]

You have to get some screenshots from inside Neptune. I bet it's mega-creepy down there:shifty:

 

[ISProgram]

For me at least, It's pretty late in the day, so are you still setting up the thread or something?

Yes. I'll suppose I'll just make it a general purpose thread where anyone can discuss their mission concepts to Venus/Mars.

---------- Post added at 02:32 AM ---------- Previous post was at 02:21 AM ----------

Sorry for the long delay, but here it is.

 

[Nicholander]

So I've been thinking about remaking my Neptune Flyby And Atmospheric Probe after I sort of abandoned it, but I wasn't really happy with It's design now that I think about it, so I've made a quick little illustration in MS Paint, though it looks sort of bad:

I think this is better because it allows a much bigger antenna and thus a decent bandwith, which is a pretty big improvement, but I'm worried about how much the center of mass would change once the atmo. probe has separated.

K_Jameson, what do you think about this redesign? And would the center of mass shift be an issue?

 

[ISProgram]

I saw that design and felt the need to kitbash(?) stuff from a few of my old models. Seems similar enough.

 

[Nicholander]

Seems pretty similar, if you increased the size of the probe it'd be almost the same. How big is that thing, by the way? And what did you originally make it for? (Or did you take a bunch of stuff from other models and put them together just now?)

And K_Jameson, please remember to answer my questions in my previous post. (Not trying to be rude! Just a little reminder)

---------- Post added 03-05-15 at 06:40 AM ---------- Previous post was 03-04-15 at 08:34 PM ----------

I hate to bump, but I really need you to answer my questions about my redesign, K_Jameson. I need to know if It will work. (Again, not trying to be rude or anything, just a reminder)

 

[ISProgram]

Seems pretty similar, if you increased the size of the probe it'd be almost the same. How big is that thing, by the way? And what did you originally make it for? (Or did you take a bunch of stuff from other models and put them together just now?)

And K_Jameson, please remember to answer my questions in my previous post. (Not trying to be rude! Just a little reminder)

Um, the HGA is roughly 7 meters in diameter, the hexagonal bus is 3.03 m across. The full height of the craft is 6.41 m from top to bottom. I didn't have a good understanding of the limitation of size for a spacecraft, so it's far too big, especially considering that this thing was supposed to flyby Pluto.

It's basically IPSA's version of New Horizon. It's also wildly inaccurate. :lol:

The only thing that I just stuck on this model was the atmospheric problem that was rescaled from VESPA.

 

[K_Jameson]

@Nicholander:
For me, your redesign can work. If the "cruise stage" part is only intended as a flyby spacecraft, no need of that big engine, typically mounted aboard spacecrafts that must perform orbital insertions. But the RCS are still needed.
The RTG must be shielded.

Remember that, if the orbiter acts as relay for the atmospheric probe, you has two alternatives: 1) install aboard your orbiter a second antenna for receiving data from the probe; 2) rotate the entire spacecraft in order to utilize the main HGA as receiver (from the probe) and, later, as transmitter (at Earth). As reference, #1 approach is the first Galileo orbiter (the real one), Galileo II and Efesto; #2 is Cassini and Shakespeare.

The center of mass, IMHO, is not a big issue unless you don't have to make lateral translation maneuvres, and this isn't the case...

---------- Post added at 01:46 PM ---------- Previous post was at 01:45 PM ----------

Um, the HGA is roughly 7 meters in diameter, the hexagonal bus is 3.03 m across. The full height of the craft is 6.41 m from top to bottom. I didn't have a good understanding of the limitation of size for a spacecraft, so it's far too big, especially considering that this thing was supposed to flyby Pluto.

It's basically IPSA's version of New Horizon. It's also wildly inaccurate. :lol:

The only thing that I just stuck on this model was the atmospheric problem that was rescaled from VESPA.

Seems larger than Galileo II!

 

[ISProgram]

Seems larger than Galileo II!

Oh dear. :blink:

The model is REALLY old; I was really naive back then. :lol:

 

[Nicholander]

Ah, thanks for the advice! :thumbup:

I'll (Try to) add an RTG shield and (Try to) add some little RCS thrusters. And I'll choose to do what you put for #2, since I really don't see any reason it'd need to communicate large amounts of data to Earth during the brief period that the atmo. probe is in the Neptunian atmosphere.

---------- Post added at 05:27 PM ---------- Previous post was at 03:36 PM ----------

By the way, this is how my model looks so far:

That little "Cone" on that bar on that's across the antenna is a smaller low-gain antenna, by the way. I haven't made the RTG yet.

K_Jameson, what do you think?

---------- Post added at 08:05 PM ---------- Previous post was at 05:27 PM ----------

I've just finished the RTG, and I've done some hardness/softness stuff:

I'm happy with the RTG, but I'm not quite sure about the hardness/softness of the RTG panels, and in this screenshot I have them have all there edges be hard. So, K_Jameson (Or anyone, really), what should I have for the hardness of the RTG panels?

 

[ISProgram]

I like the hardness of the RTG as is. Just a little interested by the fact that it only has 4 panels, not 6. That's just me though.

 

[Nicholander]

I added just 4 panels so it was easier to model. (And later, UV map)

 

[Nicholander]

Yes, DONE! I've finished the model and the UV map!

That little cube by the way is supposed to be some RCS thrusters. (It was simple to make an UV map).

Now I just have to texture it!

---------- Post added at 04:47 PM ---------- Previous post was at 01:48 PM ----------

Textures are complete!

So, now all I have to do is finish the Spacecraft3 cfg, and I'll be done with the cruise stage! (Which I've named Poseidon, by the way)

---------- Post added at 05:11 PM ---------- Previous post was at 04:47 PM ----------

Just finished the Spacecraft3 cfg, and the engines look quite nice now:

Hmm... So now what should I do? Perhaps I should do the atmospheric probe, but I really have no idea how to do 2 things:

1. The animation for the atmo. probe's parachute
2. The Spacecraft3 atmospheric characteristics config

Does anyone here have any advice on how to do these? Because I'm really stumped and confused here.

 

[K_Jameson]

In the last days I have reprised my thoughts about the Neptune/Triton concepts. One underestimated effect of an aerocapture maneuver is that can allow a NOI even trough a very high relative velocity, de facto reducing drastically the transfer time. Some launch windows can allows a transfer of only 7.9 years (with Jupiter gravity assist). This is really promising...

Hypothesis for the launch window. As you can see, the configuration is for a "flyby" mission rather than a "rendez vous" mission, thus the transfer time is small and the approach velocity is very high. Aerocapture is the only maneuvre that allows an orbit insertion under these conditions without consuming a prohibitive quantitative of propellant. In order to properly explore Triton, the capture must be in a retrograde orbit. I wonder if such an high approach velocity can be manageable by an entry aeroshell.



Comparison with the flight plan approved for the Shakespeare/Pope space probe. Note the far longer transfer time even with a shorter path:

 

[K_Jameson]

Resumed some work on the Neptune aerocapture mesh. Here, another possible layout for the orbiter, reworked heavily for reducing the envelope and thus the aeroshell dimensions (showed in transparency). I don't like particularily the umbrella-like HGA, having Galileo troubles in mind, but it is the only way to reduce the dimensions of the spacecraft. Anyway, the probe will be equipped with at least another medium or high gain antenna, for backup.
Also, I was forced to install the RTGs very close to the spacecraft body, altough well away from the instrument package. The proximity to the folded antenna bothers me... can be a source of problem? Suggestions and comments are welcome.



About naming of the spacecraft. The current name is set to "Le Verrier", in honour of the mathematician that has predicted the existence of Neptune. Another name can be "Trieste", after the [ame="http://en.wikipedia.org/wiki/Bathyscaphe_Trieste"]famous bathyscaphe[/ame], the first manned vessel to have reached the bottom of the Mariana Trench. Neptune is the god of sea, and this spacecraft would dive deep in it... so the name sounds solid.

Crazy idea: giving the particularity of the spacecraft, I started to think that could be very cool to launch it with a non conventional launcher: the Eridanus orbiter, instead of an unmanned launcher. The spacecraft well fit into the cargo bay. Further thoughts and calculations are needed...

 

[ISProgram]

Suggestions and comments are welcome.

The chief concern I have with the design *as seen* is the lack of any heat shield for the RTGs; compare with the New Horizons diagram below.

I also wonder how, even with fins, the RTGs will manage to stay at acceptable temperatures, with the main body of the spacecraft so close to them.

Just my thoughts..

 

[K_Jameson]

Actually, heat shields for the stowed antenna are present (not showed in the previous image). In red:



Rear shielding are not installed because the lower part of the spacecraft body is intended to be mostly empty space and act as shield itself - all the sensible areas are in the upper part. In fact, the reverse problem (RTG temperature) is the worst. Take in account that the entire thing must be encapsulated in an aeroshell for the entire voyage of 7 years and 9 months... how we can manage the heat? Maybe the ASRG, that has less heat dispersion, can be a solution, but is another menacing variable (classical RTG are more reliable, having no moving parts).
Solar panels? At Neptune, the required surface is at least 1000 square meters, only for mantain the spacecraft barely alive...

EDIT:
I know that we have examples of RTGs enclosed in aeroshells (MSL, Vikings), but those have a lower power output (125 W for Curiosity) and thus a lower heat output. Even my Europa minilander of Galileo II has a mini RTG enclosed, but is only 65 W. The RTGs for Le Verrier / Trieste spacecraft (at this point the second name is the more likely) are scaled-down versions of the Galileo II / Shakespeare RTGs, with a power output of about 230 W each. Maybe must be drastically reduced...

---------- Post added 03-30-15 at 09:11 AM ---------- Previous post was 03-29-15 at 10:05 AM ----------

Another layout modification is coming. Analysis of the trajectory shows very little delta-V requirements for the basic maneuvres needed at Neptune (periapsis raising and apoapsis adjusting for insertion in the Triton-resonant science orbit indicated here, pag. 2 ), thus very little fuel tanks are needed, possibly hydrazine instead bipropellant for an even more compact design.
I want to reduce the RTGs and relocate it more far away from the spacecraft body. Comparison with New Horizons shows that a reduced science payload can be powered by a supply of 250, 300 W or so. A single RTG of the same model of Galileo II (that has four) and Shakespeare (that has two) in my fiction can provide 330 W, so appears adequate.
Even the HGA should be rescaled in order to reduce the stowed dimensions; I think to reduce it from 4 to 3.5 meters. At Neptune, the corrispondant downlink rate is about half of Shakespeare at Uranus.

The base payload comprises these instruments, with some focus on Triton instead Neptune:

- wide and narrow angle cameras
- near IR spectrometer
- far IR radiometer
- gamma ray and neutron spectrometer
- magnetometer
- fields and particles package (high energy particles, plasma)

Highly desired, if possible, the addition of a radio and plasma wave package.

The science package is smaller than the one embarked on the Shakespeare spacecraft (that has twice of the power). The reduced power output has forced me to remove the expected subsurface radar for Triton; instead, some subsurface investigations can be accomplished with HGA tracking and magnetometers.

For the launcher: once again, Jarvis C is the favourite launcher, providing exactly the required performance.
The Quasar 220 / Eridanus option is difficult to realize because we haven't a kick stage that can provide the necessary 7.34 km/sec escape delta V and reenter in the payload capability of the orbiter.

 

[barrygolden]

You really have some great Ideas for planetary missions to come. Can't wait to fy them

 

[K_Jameson]

I'll try to rescale the entire spacecraft for remaining under 1500 kg of total weight, enabling the possibility of the spectacular Eridanus launch! An adequate kick stage will be required, probably a modified version of the JS-4, the third and last stage of the Jarvis C.

 

[barrygolden]

I had a chance to see Galileo, Magellan, and a little of Cassini not only in orbit but Deployed from the shuttle with both the IUS and Centaur.I'm a shuttle guy and could hook you up with a shuttle scenario. Really would like to see the other two outer planets up close. I was able to take Magellan and turn off the cloud layers and the made for a great view of the landscape