NASA : objectif Uranus & Neptune
http://lft.jpl.nasa.gov/courier/web/1000@/wmDownload.html ou
http://twitter.com/jjfplanet/status/874366189622796288 Voila qui vend du rêve !
La NASA vient de mettre en ligne un rapport, « Ice giants- Pre-decadal Survey mission study report »
Objet du document : servir de base pour étudier la faisabilité dune mission vers Uranus, ou Neptune, voir les deux ! Diverses options sont proposées : simples fly-by ou orbiter, avec ou sans lander, SLS ou fusée classique, propulsion, ect
Ce nest hélas pas pour demain ; Les auteurs évoquent des lancements vers 2030 pour une arrivée 10 à 13 ans plus tard En ce qui me concerne je doute fort dêtre encore de ce monde, mais quimporte, the show must go on !
Le rapport complet fait 529 pages, faut du temps pour se faire une idée sur lensemble des options évoquées. (il y a une version courte)
Je note que dans les conclusions un appel aux autres agences spatiales, en particulier lESA, est recommandé pour diminuer les coûts Extraits : The study finds that launches to an ice giant are possible any year within the study timeframe, but there are significant variations in performance and available science targets. The availability of Jupiter gravity assist maximizes delivered mass to an ice giant resulting in preferential launch windows for Uranus missions in the 20302034 timeframe and a corresponding window of 20292030 for Neptune. In these favorable periods chemical trajectoires could deliver ample mass for the Uranus missions studied in an 11-year flight time, using a launch performance capability similar to the Atlas V 551. Neptune trajectories utilizing solar electric propulsion (SEP) can deliver a similar mass to Neptune orbit in 13 years using launch performance capability similar to the Delta IVH. There are no all-chemical trajectories to Neptune, even using a Delta IVH, that yield a mission duration less than 15 years, a design target chosen to be consistent with Radioisotope Power System (RPS) design life and mission reliability. Significant science can be done during gravity assists at a gas giant, particularly if a Doppler Imager-type instrument is on board. If a Saturn flyby is preferred over the Jupiter gravity assist, only trajectories to Uranus are available in the time period studied, and launch must occur before mid-2028.
The use of SEP for inner solar system thrusting has the potential to significantly reduce flight times to Uranus and/or increase delivered mass. A variety of trajectories to Uranus and Neptune were evaluated considering a range of SEP power levels, assuming inclusion of an additional SEP flight element (referred to as a SEP stage). The SEP stage would carry solar arrays and ion thrusters and would be used in the inner solar system as far out as 6 AU, at which point solar power is insufficient to provide additional thrusting and the SEP stage would be jettisoned. SEPenhanced mission concept designs also see a slight preference in launch dates corresponding to availability of Jupiter gravity assists, but well-performing trajectories are possible in any year of the period studied. Early A-Team studies suggested low-mass SEP stages are possible which would provide significant performance enhancements at both Uranus and Neptune. The more detailed Team X design suggested much higher masses, negating the usefulness of SEP to Uranus. It may be valuable to perform a detailed assessment of an optimized SEP stage design for outer planet missions to confirm the optimal uses of SEP.
There are no trajectories that allow a single spacecraft to encounter both Uranus and Neptune.
A single SLS launch vehicle could, however, launch two spacecraft, one to each ice giant [Ce message a été modifié par jackbauer 2 (Édité le 13-06-2017).] [Ce message a été modifié par jackbauer 2 (Édité le 13-06-2017).] [Ce message a été modifié par jackbauer 2 (Édité le 13-06-2017).] [Ce message a été modifié par jackbauer 2 (Édité le 13-06-2017).]
http://twitter.com/jjfplanet/status/874366189622796288 Voila qui vend du rêve !
La NASA vient de mettre en ligne un rapport, « Ice giants- Pre-decadal Survey mission study report »
Objet du document : servir de base pour étudier la faisabilité dune mission vers Uranus, ou Neptune, voir les deux ! Diverses options sont proposées : simples fly-by ou orbiter, avec ou sans lander, SLS ou fusée classique, propulsion, ect
Ce nest hélas pas pour demain ; Les auteurs évoquent des lancements vers 2030 pour une arrivée 10 à 13 ans plus tard En ce qui me concerne je doute fort dêtre encore de ce monde, mais quimporte, the show must go on !
Le rapport complet fait 529 pages, faut du temps pour se faire une idée sur lensemble des options évoquées. (il y a une version courte)
Je note que dans les conclusions un appel aux autres agences spatiales, en particulier lESA, est recommandé pour diminuer les coûts Extraits : The study finds that launches to an ice giant are possible any year within the study timeframe, but there are significant variations in performance and available science targets. The availability of Jupiter gravity assist maximizes delivered mass to an ice giant resulting in preferential launch windows for Uranus missions in the 20302034 timeframe and a corresponding window of 20292030 for Neptune. In these favorable periods chemical trajectoires could deliver ample mass for the Uranus missions studied in an 11-year flight time, using a launch performance capability similar to the Atlas V 551. Neptune trajectories utilizing solar electric propulsion (SEP) can deliver a similar mass to Neptune orbit in 13 years using launch performance capability similar to the Delta IVH. There are no all-chemical trajectories to Neptune, even using a Delta IVH, that yield a mission duration less than 15 years, a design target chosen to be consistent with Radioisotope Power System (RPS) design life and mission reliability. Significant science can be done during gravity assists at a gas giant, particularly if a Doppler Imager-type instrument is on board. If a Saturn flyby is preferred over the Jupiter gravity assist, only trajectories to Uranus are available in the time period studied, and launch must occur before mid-2028.
The use of SEP for inner solar system thrusting has the potential to significantly reduce flight times to Uranus and/or increase delivered mass. A variety of trajectories to Uranus and Neptune were evaluated considering a range of SEP power levels, assuming inclusion of an additional SEP flight element (referred to as a SEP stage). The SEP stage would carry solar arrays and ion thrusters and would be used in the inner solar system as far out as 6 AU, at which point solar power is insufficient to provide additional thrusting and the SEP stage would be jettisoned. SEPenhanced mission concept designs also see a slight preference in launch dates corresponding to availability of Jupiter gravity assists, but well-performing trajectories are possible in any year of the period studied. Early A-Team studies suggested low-mass SEP stages are possible which would provide significant performance enhancements at both Uranus and Neptune. The more detailed Team X design suggested much higher masses, negating the usefulness of SEP to Uranus. It may be valuable to perform a detailed assessment of an optimized SEP stage design for outer planet missions to confirm the optimal uses of SEP.
There are no trajectories that allow a single spacecraft to encounter both Uranus and Neptune.
A single SLS launch vehicle could, however, launch two spacecraft, one to each ice giant [Ce message a été modifié par jackbauer 2 (Édité le 13-06-2017).] [Ce message a été modifié par jackbauer 2 (Édité le 13-06-2017).] [Ce message a été modifié par jackbauer 2 (Édité le 13-06-2017).] [Ce message a été modifié par jackbauer 2 (Édité le 13-06-2017).]