Discussion Uranus and Neptune mission concepts

[boogabooga]

Well, here is my Uranus orbit scenario with a polar orbit. It has constant Earth LOS for the time being. I needed NO plane change to get this orbit, just a slight MCC in interplanetary space.

BEGIN_DESC
Contains the latest simulation state.
END_DESC

BEGIN_ENVIRONMENT
  System Sol
  Date MJD 69474.0212237036
END_ENVIRONMENT

BEGIN_FOCUS
  Ship ChapmanOuter
END_FOCUS

BEGIN_CAMERA
  TARGET ChapmanOuter
  MODE Extern
  POS 3.68 -8.42 -6.01
  TRACKMODE AbsoluteDirection
  FOV 24.22
END_CAMERA

BEGIN_HUD
  TYPE Surface
END_HUD

BEGIN_MFD Left
  TYPE User
  MODE Interplanetary
  Scenario Old2
  MapMFD V5
  Reference uranus
  Target uranus
  Center uranus
  Data 0 1 2.690216559767465e-008 0 1 1 1 2 1 1 0 0
  MassLimit 1e+020
  CMode 0
  Config 1 1 1 1 0 0
  ExtMode 0
  Periapis Uranus
  END 
  CorMFD V4
  Reference Uranus
  Target Titania
  Source ChapmanOuter
  ActiveProg 1 1
  DataA 0 3 2 0 0 0
  DataB 1 100 69474.0198882681 0 600000000 5.163790307526563 -1.570796326794897 69474.99978845489 0
  DVProg 5425.615904785619 0 0 1
  AdvConf 4.71238898038469 5.340707511102659 2420000000 0 0
  Guidance 0
  END 
  EjectMFD V5
  Reference Auto
  Data 0 1 3 0 1 64131.9236773348 10
  Guidance 0
  END 
  BaseAprMFD V2
  Reference Auto
  Target none
  Source none
  DataA 0 0 120000 0.10821 0.366519 1 1 64131.9236773348 64131.9236773348 0
  DataB 0 3 0 1 0 1
  END 
  SlingMFD V4
  Reference Auto
  Source none
  Data 0 1 1 3 0 1 64131.9236773348 0
  END 
  LaunchMFD V4
  Target None
  Data 0 1 1 3 0 1 0
  END 
  CF1_DataA 0 0
  CF1_DataB 0 10 120000 2 20 150000
  CF1_SecTgt 
  mfdShare -1
  mfdProgram 2
END_MFD

BEGIN_MFD Right
  TYPE Orbit
  PROJ Frame
  FRAME Ecliptic
  ALT
  REF Uranus
END_MFD

BEGIN_SHIPS
Jarvis_E:JARVIS/Jarvis_E
  STATUS Orbiting Sun
  RPOS -2796369554494.79 45627740437.47 955371098958.20
  RVEL -4045.927 91.083 -2782.154
  AROT 95.62 7.32 -45.16
  AFCMODE 7
  PRPLEVEL 0:0.072907
  NAVFREQ 0 0 0 0
  XPDR 0
  FAIRINGON 0
  STAGE 2
  PRPLEVEL 2:0.072907
  PLNUM 1
  GLIMIT 5.000000
  GTVACC 6.000000
  TGT_APOGEE 300000.000000
  TGT_PERIGEE 300000.000000
  TGT_INC 28.541900
  AP 100
  MET 410.938357
  PAYLOAD_FILE Jarvis_E\Chapman.ini
END
PadJa:JARVIS\PadJa
  STATUS Landed Earth
  POS -80.6312150 28.5419000
  HEADING 90.00
  AFCMODE 7
  PRPLEVEL 0:1.000000
  NAVFREQ 0 0 0 0
  XPDR 0
  ANIM_0 2 1.0000
  ANIM_1 2 1.0000
  ANIM_2 -2 0.0000
  ANIM_3 2 1.0000
END
Js2:JARVIS\Jarvis_s2
  STATUS Orbiting Sun
  RPOS 7039276775411696600.00 2530470610826138600.00 13167872163072250000.00
  RVEL 16263513773.755 5846388055.339 30422993336.100
  AROT 177.90 28.75 -101.47
  AFCMODE 7
  NAVFREQ 0 0 0 0
  XPDR 0
END
ChapmanOuter:ChapmanModules\ChapmanOuter
  STATUS Orbiting Uranus
  RPOS 415154676.44 -137432319.51 258140268.13
  RVEL 2443.298 -540.251 -1919.595
  AROT 153.04 54.59 154.37
  AFCMODE 7
  PRPLEVEL 0:0.167599 1:0.936060 2:0.186529
  NAVFREQ 0 0 0
  XPDR 379
  RTG_DEPLOYMENT 1 1.00000
  MAGNETOMETER 1 1.00000
END
END_SHIPS

BEGIN_SpaceNetwork
END

BEGIN_ExtMFD
END

 

[K_Jameson]

Will the atm probe be separated after or before UOI?

Some weeks before. The probe has no thrusters and is spin-stabilized. The main spacecraft must be placed in a collision course with Uranus, release the probe and then perform a course correction. As Galileo did.

---------- Post added at 07:50 PM ---------- Previous post was at 07:23 PM ----------

I have chosen a profile aero-braking, as Neptune Orbiter: http://www.orbiter-forum.com/showthread.php?t=34860

Interesting spacecraft. I have already read some documentation. I want to use the concept too, for Neptune or maybe for Titan.

But ... is mandatory Jovian direct transfer? EVJU a flight would take a year or two more but could allow increased payload.

The probe is designed to be relatively small and cheap: the main spacecraft is a derivation of another FOI probe (Efesto); the atmospheric capsule is very minimal, etc.
With the resulting weight, the probe can be comfortably launched towards the external solar system with existing FOI medium rockets and without Venus-Earth gravity assists.

 

[Urwumpe]

Some weeks before. The probe has no thrusters and is spin-stabilized. The main spacecraft must be placed in a collision course with Uranus, release the probe and then perform a course correction. As Galileo did.

And the main spacecraft is 3DOF stabilized or also spin stabilized?

 

[K_Jameson]

Have a close approach at Jupiter and a low capture Delta-V at Uranus are mutually exclusive. The closer you get to Jupiter, the faster you will be flung out to Uranus, and the higher the capture velocity will be. IRC, the double Hohman transfer has a Jupiter pass radius at about the distance of Callisto. Any closer, you will need more delta-V somewhere.

You're right. In addition, Shakespeare hasn't a heavy radiation protection (no "radiation vault" as Galileo II for example), and a very close flyby can be dangerous for the electronics.

An additional consideration is the plane alignment of the moons upon your arrival. Remember, Uranus is tilted on its "side". There will be one point in its orbit where you can arrive at Uranus in the plane of the moons' orbits. While this doesn't occur from the 2034 launch, you get the second best situation IMHO, a polar orbit. I described in the mission description how to set up for perpendicular encounters and I was able to get several.

BTW, Uranus' moons are puny, don't expect constructive trajectory changes from them.

I have, somewhere, a report which shows how a Uranus moon tour can be profitable as a Jupiter moon tour. Anyway i don't want to program the moon tour in detail at this point. An arrival at northern emisphere solstice is the more likely and allows a coperture of the side in darkness in the Voyager 2 flyby, although the Uranus atmosphere tends to be much more active in proximity of the equinxes rather than at the solstices.

---------- Post added at 08:02 PM ---------- Previous post was at 08:02 PM ----------

And the main spacecraft is 3DOF stabilized or also spin stabilized?

3DOF during the science phase; spin stabilized during the cruise.

 

[Urwumpe]

3DOF during the science phase; spin stabilized during the cruise.

OK

The launch site is Capo Passero?

 

[K_Jameson]

Depends to the launch trajectory and the launch vehicle: for some launches, Capo Passero is not optimal because the first stage can fall on terra firma in Greece. I want to use KSC that allows more freedom.

 

[K_Jameson]

Well, the May-02-2021 EJU window showed by Urwumpe is my favorite choice, for now. If someone can provide better alternatives, these are welcome. Thanks to all for the help!

Returning in the probe development, here a list of the scientific instruments.

Shakespeare (orbiter):

- Wide angle camera
- Narrow angle camera (17 cm telescope)
- Visual and near infrared imaging spectrometer
- UV imaging spectrometer
- Doppler imager
- Field and particles package (low and high energy MS; plasma)
- Far IR thermal imager
- Microwave radiometer/scatterometer
- RPWS package (electric antennas, magnetic search coils, Langmuir probe)
- Magnetometers
- Dust analyzer
- Neutron and gamma ray detector (not sure)

Pope (atmospheric capsule):

- mass spectrometer
- net-flux radiometer
- temperature and pressure probe

 

[perseus]

With reference to Jupiter gravity assist, there is an annual window to Urano, with a period of approximately one year.
Direct Hohmann trajectories to Uranus, minimum energy
2015
Departure Arrival

16/06/2015 26/07/2031

dV = 42166Km / h (11.7 m / s)

2016
Departure Arrival

22/06/2016 31/07/2032

dV = 42166Km / h (11.7 m / s)

 

[K_Jameson]

Memorabilia:

Hamlet...

...and a portrait of William Herschel, discoverer of Uranus.

 

[Nicholander]

Looking good! When can we expect a release date?

Also, sorry to be off topic, but why has there been no Orbiter Live Missions since November 2013? I just don't know where else to ask.

 

[Paz666]

]Design of Low-Thrust Gravity-Assist Trajectories to the Outer Planets

This is an interesting study that I've often used to make interplanetary flights with the XR fleet. I hope it helps, page 13 should be the one of interest for you.


https://engineering.purdue.edu/peop...avity-AssistTrajectoriestotheOuterPlanets.pdf

 

[K_Jameson]

A logical follow for Shakespeare/Pope can be a sister ship for Neptune (LeVerrier/Galle?). Thus, the same question at the beginning of this thread recurs here...

A potential complication for a such mission can be that, in order to explore Triton, is better to achieve a retrograde orbit around Neptune...

 

[Urwumpe]

..., is better to achieve a retrograde orbit around Neptune...

That's a minor issue if you arrive from interplanetary transfer. The biggest chunk in the DV is matching speed with the planet around the sun - the actual orbit is just a tiny addition in the end.

 

[K_Jameson]

The biggest chunk in the DV is matching speed with the planet around the sun - the actual orbit is just a tiny addition in the end.

A cruise stage with ion engines can be useful for that?
Or use the onboard fuel for that "speed jump" and instead of a propulsive capture perform an aerocapture... but the probe should be totally redesigned.

 

[Urwumpe]

A cruise stage with ion engines can be useful for that?
Or use the onboard fuel for that "speed jump" and instead of a propulsive capture perform an aerocapture... but the probe should be totally redesigned.

Not really, unless you plan for a longer descent. You would need a powerful chemical engine anyway for not just flying past your target - or plan for decades for intercepting an outer planet electrically.

Aerobraking is a (risky) option there, but it still makes it hard with electrical engines only.

 

[K_Jameson]

I asked for aerocapture because the next probe I want develop, after Shakespeare/Pope, could make use of this technique.
I must decide the objective: Neptune-Triton or Titan...

 

[Urwumpe]

I asked for aerocapture because the next probe I want develop, after Shakespeare/Pope, could make use of this technique.
I must decide the objective: Neptune-Triton or Titan...

Well, remember that you need accurate upper athmosphere data of the target body for a safe aerobraking. The data from Earth-based telescopes is usually a good first guess, but not accurate.

 

[K_Jameson]

I know. Moreover, aerocapture is much more critical than a mere aerobraking. In my fictional exploration, informations for Neptune can be derived from the Uranus mission (the two atmospheres can be assumed as similar); for Titan I think that Cassini/Huygens has already provided a very good amount of useful data.

 

[rseferino]

Well, remember that you need accurate upper athmosphere data of the target body for a safe aerobraking. The data from Earth-based telescopes is usually a good first guess, but not accurate.

In this case, an atmospheric probe would measure the characteristics of the upper atmosphere before the arrival of the main probe. Come weeks or months before to give leeway and correct course.

 

[K_Jameson]

I can imagine that the data from the probe can require time to be transmitted, long time to be interpreted and very long time to be utilized for a safe and reliable entry path...
Months (or even years) of distance from the two probes could be needed, IMHO