End of Mission Planning
| Colour | Meaning |
|---|---|
| Red | Poor |
| Yellow | Fair |
| Light Green | Good |
| Green | Excellent |
During planning for its extended missions, various future plans for Cassini were evaluated especially on the basis of science return, cost, and time. Some of the options examined include collision with Saturn atmosphere, icy satellite, or rings; another is departure from Saturn orbit to Jupiter, Uranus, Neptune, or a Centaur. Other options include leaving it in certain stable orbits around Saturn, or departure to a heliocentric orbit. Each plan requires certain amounts of time and changes in velocity. Another possibility was aerobraking into orbit around Titan.
This table is based on page 19 of Cassini Extended Missions (NASA), from 2008.
| Option | Set Up Requirements | Execution Time | Operability +
Assurance of EOL |
Velocity change (Delta-V)
required |
Science Evaluation circa 2008 |
|---|---|---|---|---|---|
| Saturn Impact – Short Period Orbits | High inclination achievable via any XXM design | 2–10 months total | Short time between last encounter and impact | 5–30 m/s | D-ring option satisfies unachieved AO goals; cheap and easily achievable |
| Saturn Impact – Long Period Orbits | Specific orientation and inclination required | 4–22 months to set up long period orbit + 3 years for final orbit | 3 years between last encounter and impact | 5–35 m/s | Operations costs required for 3 years with no science could be applied elsewhere |
| Impact Icy Satellite | Can be implemented from any geometry | 0.5–3 months total | Short time between last encounter and impact | 5–15 m/s | Cheap and achievable anywhere/time |
| Impact Main Rings | Can be implemented from any geometry | 0.5–3 months total | Short time between last encounter and impact but difficult to prove spacecraft destruction | 5–15 m/s | Cheap and achievable anywhere/time; close-in science before impact |
| Escape to Gas Giant | Specific orbit period, orientation and inclination required + specific departure dates | 1.4-2.4 years to escape + long transfer time (Jupiter 12 years, Uranus 20 years, Neptune 40 years) | Planetary impact can only be guaranteed shortly after escape for Jupiter | 5–35 m/s | Gas giant science unlikely |
| Escape to Heliocentric orbit | Can be implemented from any geometry | 9–18 months to escape, open-ended Solar orbit | Last encounter goes to escape | 5–30 m/s | Solar wind data only |
| Escape to Centaur | Large target set offers wide range of departures | 1–2 years to escape + 3+ year transfer | Last encounter goes to escape; must maintain teams for 3+ years for Centaur science | 5–30 m/s | Multi-year lifetime and funding seems better spent in target-rich Saturnian environment |
| Stable Orbit Outside Titan | Specific orientation and orbit period required | 13–24 months + open-ended time in stable orbit | 200 days between last encounter and final orbit | 50 m/s | Limited Saturn / magnetospheric science, but for long period of time |
| Stable Orbit Outside Phoebe | Specific orientation and orbit period required | 8+ years + open-ended time in stable orbit | Many months between last encounter and final
orbit |
120 m/s | Solar wind data; very
rare passages through magnetotail |
The choice was XXM (Cassini Solstice Mission), starting in 2010, several years of flybys culminating in proximal orbits and Saturn impact in 2017. See Planetary Science Decadal Survey for other Solar System mission concepts.
Read more about this topic: Cassini–Huygens
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