Uranus beyond Voyager 2, Meudon 9/2013 Sini Merikallio, Mark Paton, - - PowerPoint PPT Presentation

Uranus and Neptune: ice giants one launch away

Uranus beyond Voyager 2, Meudon 9/2013

Sini Merikallio¹, Mark Paton¹, Pekka Janhunen¹, Jean-Pierre Lebreton², Petri Toivanen¹, Jouni Envall¹

¹Finnish Meteorological Institute ²CNRS/LPC2E, Orléans, and LESIA, Observatoire de Paris

Traditional approach

Electric Solar Wind Sail (E-sail)

100 - 200 kg 1 N, 700 W @ 1 au Thrust ~1/r Power consumption ~1/r²

Flexible launches:

• No need for gravity assists
• Any escape orbit is good

 piggyback opportunities

www.electric-sailing.fi

Uranus

(19 au)

Total mass Total minus E-sail Travel time Entry Speed

300 kg 200 kg 3.1 yr. 36 km/s 550 kg 450 kg 5.3 yr. 25 km/s 800 kg 700 kg 9.6 yr. 20 km/s

Assumed E-sail:

• 0.5 N thrust at 1 au,
• mass 100 kg

www.electric-sailing.fi

Neptune

(30 au)

Total mass Total minus Travel time Entry E-sail Speed

300 kg 200 kg 4.6 yr. 38 km/s 550 kg 450 kg 8.0 yr. 28 km/s 800 kg 700 kg 14.9 yr. 23 km/s

E-sail: 0.5 N @ 1 au, 100 kg

www.electric-sailing.fi

JPL Space Science Board Summer Study (1974)

Mariner Jupiter/Uranus 1979 mission with Uranus Entry Probe

Trajectory model

2-DoF version: Paton, M. and Schmidt, W. (2007): Atmospheric modelling for realistic EDL scenarios, 5th International Planetary Probe Workshop, 23-29 June, Bordeaux, France

• 3 degrees-of-freedom

numerical trajectory simulation

• Rotation of the

atmosphere and winds

• Polytropic atmosphere

model for Uranus

• Includes guidance

routines for lifting bodies

Heat loads

Galileo 40 km/s retrograde 40 km/s prograde 30 km/s retrograde 30 km/s prograde

g > Galileo

Entry probe mission,

5.3 years travel time

Total in escape orbit 550 kg:

• 0.5 N E-sail 100 kg
• Carrier & Relay S/C 150 kg wet:
• Orbit corrections fuel 35 kg (0.2 km/s ∆v)
• Dry mass 115 kg
• Entry probe 300 kg, 27.5 km/s prograde:
• Heat shield 90 kg
• Bus 175 kg
• Instruments 35 kg

Instrument fraction assumed same as in Galileo probe

Orbiter mission,

9.6 years travel time

Total in escape orbit 800 kg:

• 0.5 N E-sail 100 kg
• Orbit insertion fuel 290 kg (1.8 km/s ∆v)
• Manoeuvre fuel 62 kg (0.3 km/s ∆v)
• Dry mass 348 kg:
• Bus 313 kg (90% of orbiter dry)
• Instruments 35 kg (10% of orbiter dry)

Conclusions

Enabled by 0.5 N E-sail:

• 35 kg of entry probe

instruments in 5.3 years

• 350 kg orbiter (dry mass)

in 9.6 years

• Flexible launches

1 N E-sail is goal, 0.5 N is conservative

www.electric-sailing.fi