Project Long Duration Deep Space Vessel

[T.Neo]

The navigator works very well for low-thrust trajectories...

The navigator? I'm not sure what you're referring to... as a navigator, I don't work well on high thrust trajectories, let alone low thrust ones...

For a low-thrust vessel, no. Hitting the moon is very difficult, hitting Jupiter or Saturn is relatively easy. I made a low thrust flight there once with IMFD, you can make do. But how he managed to hit the moon is beyond me... unless he extended the orbit and just waited for the moon to come by.

I would imagine the opposite would hold true for flying to other planets, considering the other variables involved. Flying to the Moon is relatively easy, it is simply a case of extending your orbit at the right time and place.

Literally hitting the Moon is easy if you're aiming for it but forget to raise your periapsis. I've managed to do it a couple of times...

 

[jedidia]

The navigator? I'm not sure what you're referring to... as a navigator, I don't work well on high thrust trajectories, let alone low thrust ones...

:lol: Sorry, I was refering to the upcomming Orbiter Navigator add-on, which I'm currently beta-testing.

I would imagine the opposite would hold true for flying to other planets, considering the other variables involved.

No. They move much slower, so it's alot easier to hit them. Plus, the longer the distance, the better you can plan the trajectory. For the moon, you have to start at the exact right time to get there when it gets there. For Saturn, you can do an earth eject in any direction, since the difference you induce into your solar orbit with a low energy eject are negligible, and then use your superior delta-v push your trajectory in the right direction, all in one burn. The real difficulty is to start breaking at the right time, but IMF managed that one surprisingly well. I still had a much higher excentricity than planed when I got to Saturn, but at least I managed capture...

 

[T.Neo]

Well... I was referring primarily to TransX, which cannot be used for such trajectories. I suspect the same of IMFD, but since I've never used it and I have no clue how it works I wouldn't be sure.

 

[Slice N Splice]

(actual living volume would be less because hab also houses laboratory facilities for various research)

You reasearch toilets in space???
You could do that on earth. :lol:





XD

 

[T.Neo]

Actually various missions have sampled astronauts waste for analysis back on Earth.

 

[Polaris]

Is this going to have onboard "cryo" modules?

 

[Sky Captain]

I just made it to Jupiter in ~6 months with half of the propellant remaining. I used IMFD, IEAT, Attitude hold and stock orbit mfd's. Main problem with IMFD is that it don't allow higher than 10 time acceleration when in autoburn mode so at high time accelerations you have to do the burn manually and manage attitude with IEAT or attitude mfds. Otherwise IMFD worked fine for my 1,5 month long ejection burn.

And what if something goes wrong with the reactors?
I would think that a problem with one of the nuclear reactors would be a much more urgent issue than a problem with one of the engines. If one engine goes kaput, the other engines can compensate (you have 5.) If one of the reactors undergoes meltdown, you lose the ship.

A competently engineered reactor would have multiple layers of protection to prevent meltdown and even if it somehow suffers meltdown it shouldn't cause serious damage to nearby reactors or other systems.

No... to point the z+ translation thrusters backward requires no extra propellant.

How? If you want to do pitch or yaw maneuver you have to fire pitch or yaw thrusters and also linear ones in the same time to put the structure under tension.

---------- Post added at 02:26 AM ---------- Previous post was at 02:25 AM ----------

Is this going to have onboard "cryo" modules?

Currently it's basic spacecraft3 vessel so there is no simulation of various systems.

 

[Izack]

You reasearch toilets in space???
You could do that on earth. :lol:

I believe you're thinking of lavatories, not laboratories. :rofl:

...Unless you routinely pee in a beaker. :uhh:

 

[Slice N Splice]

Actually various missions have sampled astronauts waste for analysis back on Earth.

Holy crap?

Really?

I mean why?

Crap is crap and nothing but.

Crap in space is no different from crap in a toilet...

 

[francisdrake]

Years ago NASA had a concept of an unmanned exploration vessel with the reactor up front, then a long truss with a lot of radiators, the science payload and the engines in the rear:

I think this arrangement makes sense, as it moves the radiaton source far away from the payload or crew. I am quite happy Sky Captain choose this arrangement for his addon :thumbup:

Just a few comments:
If shadow shields are used for the reactors, everything extending outside of the shadow tends to scatter the gamma radiation, so part of it is scattered back into the shadowed area.

The rotating crew section looks cool, but is a complex engineering task. If the vessel does not thrust during long cruise periods, it could alternatively go into a "tumbling pigeon" mode, rotating head over heels, to give the crew a continous aft acceleration.

 

[Sky Captain]

Sure, but without any math on the subject it's impossible to tell how far it would spread, really.

In this video of VASIMR engine testing it seems that exhaust spreads fairly quickly after it exits the nozzle.

[ame="http://www.youtube.com/watch?v=4zSou_r-W9Q&feature=channel"]YouTube- Record Power Level For The VASIMR VX-200i, HD[/ame]

But then again, one must ask how often the engines would break down...

On a something like 5 year mission to Kuiper belt a lot of unforseen stuff can happen so I think it would be better to have as little critical components as possible in inaccssible areas even if it comes at slight weight penality. After all if othervise 5 year mission becomes 5 years an 1 month because of added weight it's not a big deal.

Just a few comments:
If shadow shields are used for the reactors, everything extending outside of the shadow tends to scatter the gamma radiation, so part of it is scattered back into the shadowed area.

Didn't think of that. At current layout the truss that supports radiators and part of radiators would be exposed to radiation from reactors. To solve that it would recquire to increase the length of central truss and redesign the layout of radiator panels to have them all in a shadowed area. I also don't want to move main radiators too close to cargo and crew section because there would be multiple gigawats of heat coming from them which might cause some unwanted heating.

The rotating crew section looks cool, but is a complex engineering task. If the vessel does not thrust during long cruise periods, it could alternatively go into a "tumbling pigeon" mode, rotating head over heels, to give the crew a continous aft acceleration.

The tumbling wouldn't work because it is envisioned that this vessel would spend most of the cruise time under continous thrust so some sort of centrufuge section is recquired.

 

[T.Neo]

In this video of VASIMR engine testing it seems that exhaust spreads fairly quickly after it exits the nozzle.

Sure... I'm still looking for the video of the testing of a 25 meganewton thrust fusion engine. Until then, math will have to do... :lol:

If shadow shields are used for the reactors, everything extending outside of the shadow tends to scatter the gamma radiation, so part of it is scattered back into the shadowed area.

You sure you don't mean the neutron radiation? Gamma rays tend to go through pretty much anything.

The tumbling wouldn't work because it is envisioned that this vessel would spend most of the cruise time under continous thrust so some sort of centrufuge section is recquired.

Or the ship could spin on the Z axis rather than the X or Y axes.

 

[RisingFury]

In this video of VASIMR engine testing it seems that exhaust spreads fairly quickly after it exits the nozzle.

The spread of the plasma from VASIMR is probably not from the static pressure, but because the ion follow the magnetic field lines of the engine...

 

[Polaris]

I think it would be best to launch from Lunar orbit...

 

[francisdrake]

"You sure you don't mean the neutron radiation? Gamma rays tend to go through pretty much anything."

Ah, yes. Mainly neutron radiation. Although gamma rays also scatter, they only lead to straying electrons, which have little penetration effect. Scattered neutrons have much more energy.

 

[Sky Captain]

I changed the placement of reactors and shape of the shadow shield to have all rear structure including radiators in a shadow. Also placed the radiators on main truss and removed the now unneccesary horizontal truss.

Or the ship could spin on the Z axis rather than the X or Y axes.

That's certainly possible although every time when ship has to change attitude or when a lander is docking or undocking rotation would have to be stopped and restarted again which vould consume propellant.

---------- Post added at 01:31 AM ---------- Previous post was at 12:06 AM ----------

I have calculated the thrust at various ISP with constant thrust power of 85 GW

 ISP m/s   THR kN       
15000       11350       
30000        5660       
50000        3400       
100000      1700       
150000      1130       
200000      850       
300000      565       
400000      425       
500000      340       
600000      285       
700000      240       
800000      215       
900000     190       
1000000   170

 

[francisdrake]

Cool! One thing that comes to my mind is any docking / undocking procedure should be from the rear, staying in the radiation shadow cone. I assume that even on low power settings the reactors will emitt radiation. The landing parties will want to avoid the unshielded, unhealthy zone.

 

[Sky Captain]

Started to model a heavy cargo lander. It's main purpose will be to gather water for refueling LDDSV and to deploy heavy equipment like base modules to the surface of various moons.
Cargo will be attached in the empty space inside the frame. On a propellant gathering mission there will be placed large tank.










---------- Post added at 01:36 AM ---------- Previous post was at 01:29 AM ----------

Cool! One thing that comes to my mind is any docking / undocking procedure should be from the rear, staying in the radiation shadow cone. I assume that even on low power settings the reactors will emitt radiation. The landing parties will want to avoid the unshielded, unhealthy zone.

That's sure, manned landers would undock and then fly to the rear paralel to the ship to stay in shadow until large enough distance is reached. At least one reactor would always be on even if in orbit around planet to generate power and to crack water so there would always be radiation in unshielded area. A completely shut down reactor also would emit some radiation because of residual radioactive decay.

 

[jedidia]

170 kn at 1,000,000 meters per second is still quite a lot, but I kinda like the figures. It seems like the radiators are a bit on the small side for 85 GW, but I have no sense of scale of the model, so I might be quite wrong.

 

[PeterRoss]

Started to model a heavy cargo lander. It's main purpose will be to gather water for refueling LDDSV and to deploy heavy equipment like base modules to the surface of various moons.
Cargo will be attached in the empty space inside the frame. On a propellant gathering mission there will be placed large tank.

Ever thought about cargo lander able to deliver cargo to and from Mars? There is serious lack of cargo landers able to land on Mars on the OrbitHangar. It will make your vessel even more versatile.