A multiple planet ARM/SEP derived mission design architecture
Okutsu designed a Cassini end of mission disposal orbit to satisfy quarantine rules; interestingly Okutsu designed Titan/Saturn escape flybys to Jupiter and Uranus and Neptune with TOF of 8 to 9 years to Jupiter and 2 to 4 decades for Uranus and Neptune.
My take is a SEP powered spacecraft that does a Jupiter flyby followed by Saturn orbit insertion with a mission to Enceladus and the rings followed by a Titan gravity assist to Uranus,The SMD has announced at OPAG meeting a study of building two spacecraft one each for Uranus and Neptune
This creates possibilities!
(A)(1) Enceladus flyby and sample return via a Titan/Saturn escape to a Jupiter Trojan and subsequent Earth return (Discovery class)This is a modified LIFE proposal Enceladus sample return with Jupiter Trojan flyby ( we added in the trojan flyby on the return trip)
(A)(2) Enceladus flyby sample capture(not returned) in route to Uranus and/or Neptune with Saturn gravity assist (Flagship class) Titan and Enceladus Feasibility Study Report (JPL 2006) This report informs us as to what the science goals are and the costs for various mission designs.None of the ideas in this report include Titan gravity assist/SEP/return to L2 for astronaut retrieval of sample return
(A)(3) Close Saturn ring flyby and Saturn orbital mission /Titan Gravity assist en route to Uranus or Neptune.(Flagship class)This is the secondary preferred option
Difficult but possible with SEP
(B)(1) Two spacecraft to Uranus and Neptune after leaving Saturn orbit and gravity assist from Titan combined with SEP,These two missions would look like (A)(2) and (A)(3) with the exception that these two spacecraft are doing a Saturn orbiter mission first with a subsequent Titan escape trajectory to the ice giants.With Enceladus sample collection(not return) and Uranus orbital mission this is clearly a flagship $2.5 Billion mission and this is the primary preferred option.Building a second spacecraft would add how much to this figure?
Saturn/Titan gravitational escape to a Jupiter gravitational assist to Uranus? So S/J/U . So Saturn/Titan to Jupiter with SEP could be less than 9 years? As compared to Saturn/Titan to Uranus of 26 to 30 years minus SEP? perhaps the Saturn/Titan to Jupiter to Neptune make more sense? SEP would reduce the Titan to Uranus 26 year time to something less so the 45 year TOF from Titan
EDIT 27 Aug 2015
The preferred mission is the Saturn Enceladus plume sample collection with an onboard microscope and instruments to detect complex biological compounds such as DNA/amino acids/proteins;This is not a sample return mission! Spacecraft then departs Saturn via Titan to Uranus.We need RTG and SEP to shorten the 26 year flight time.We need a method to get the Enceladus samples to the instruments.
This spacecraft should have the Uranus /Neptune portion of the mission in common
(A)build three atmosphere probes, one each for Saturn/Uranus/Neptune
(B) a common spacecraft bus X 2
(C) SLS allows for dual manifest so Enceladus is a third spacecraft ? and is an international contribution?
(D) ARM derived SEP is a stage in the inner solar system and out to Jupiter(solar array) SEP stages from spacecraft and returns to Earth L2( Using a SEP that stages a RTG spacecraft has been proposed for a Jupiter Trojan tour) An ARM derived SEP could stage for a flagship mission.
(E)(1) consider placing solar array for SEP on the spacecraft so after separation some residual solar power augments RTG, spacecraft has it own SEP/NEP on a smaller scale OR The SEP stage has its own modest science payload that travels to a secondary target (weight penalty)The SEP stage for example could be our atmosphere probe deployers and/or communications relay spacecraft.While the Uranus bound probe is smaller than we first imagined it to be.
(E)(2)) The SEP stage could have one solar array while the Saturn orbiter/Uranus probe contains the other;both power the SEP stage in the inner solar system while the probe keeps 1 solar array after spacecraft separation.(E)(3) This outer solar system solar array could double on its back side an aerogel sample collector ! (E)(4)Saturn would be a difficult mission for a solar powered SEP stage but perhaps it could return the Enceladus sample return to Earth while the Uranus probe continues on after doing extensive Titan science***
*** The JPL 2006 report suggests low science results for a orbiter that does both Enceladus and Titan science in part do to the time it takes to perform Titan flybys.SEP stage return to earth puts the sample return back into play but also might allow ARM SEP stage reuse after refurbishment at L2. Titan gravity assist back to Jupiter and Earth with SEP might allow for Jupiter Trojan flyby.
(F)SLS plus SEP/RTG is a must for Neptune!
(G) NEP with RTG alone is a challenge
(H) An Arm Derived SEP vehicle could easily carry two spacecraft to Saturn and perhaps carry back the Enceladus sample return,The SEP itself would have already had its R&D paid for with the existing three way partnership.The SEP would be in production serially for human space flight missions such as prepositioning of human space flight cargo.Building and flying 4 or more atmospheric entry probes for Jupiter/Saturn/Titan/Uranus and Neptune places these in serial production and the NASA HQ idea of building two spacecraft for Uranus and Neptune combined with our idea of using ARM derived SEP might save money in the long run by adding SBAG decadal survey requirements with the OPAG requirements! SEP combined with RTG make this possible.If each probe requires an SEP and the human spaceflight directorate requires three over a decade, then this is a buy of 5 such vehicles
This paper describes SEP/NEP Uranus missions for the decadal survey Earth with a Saturn flyby provides for very high Uranus arrival speeds making it impossible to enter orbit.Uranus orbit insertion missions
In contrast we have this idea Saturn Uranus atmosphere probes 6-UranusTrajStudy_Hughes_et_al (1)