Arte : A la conquête de Mars

Aspic a écrit:Merci Shuttlegirl, mais là il s'agissait d'un autre documentaire.

astroyoyo a écrit:il y a un dessin annimé de 1957 sur les projets
martien de Von Braun, quelqu' un a t'il des infos la dessus ?

yoann a écrit:pour faire plus simple, c'est CA:
https://www.youtube.com/watch?v=FRCQ2Cu3bSE&feature=PlayList&p=BAF97368F77C60F3&index=5

"Race to Mars" is a reasonable attempt to tell the story of the first human mission to Mars (comprising two Americans, a Russian, a Canadian, a Frenchman and a Japanese scientist), backed by the "International Space Development Agency". The story is initially told in terms of a "race" between the human crew of the space vessel Terra Nova and its various unmanned support vehicles, and an automated Chinese probe as both attempt to reach water and analyse it for possible Martian life. Against a background of the usual mix of human intrigue - crew tensions, corporate cost-cutting putting the mission at risk, triumph in adversity, etc., - the story gradually unfolds. Sometime trite, sometimes engrossing, the series arcs across four 40-minute segments in a somewhat bumpy narrative and style, with all of the cast at times appearing ill-at-ease with either the subject matter or (more likely) the clumsy script. Race To Mars is certainly a brave attempt to tell what is likely to be the greatest human adventure of the 21st century, and it comes as something of a breath of fresh air after all the speculative documentaries on the subject that have bombarded the likes of the Discovery Channel over the last 10 years. However, it is an attempt that is deeply flawed. The mission itself, requiring no fewer than 4 vessels (the Mars hab where the crew will live on Mars, a logistical support vehicle, a Mars Ascent / Decent Vehicle and the vessel used to get the crew to / from Mars (the "Terra Nova") is hardly reflective of current mission planning, in which it has been identified that an optimum mission plan requires the use of TWO vehicles (or at most three). The show also opts for an opposition-style mission, rather than a conjunction-class mission. Without getting all technical, this also flies in the face of current thinking, because an opposition-class mission maximises the transit time in space (9-11 months each way) while limiting the time on the surface of Mars to just 60 days. In a conjunction-class mission, the reverse holds true: transit time to / from Mars is limited to around 6-8 months, but the crew get to spend 18 months on the surface of Mars, thus maximising the science returns they can gain. Of course, a conjunction-class mission does massively increase the consumables and supplies a crew needs to take to Mars - but reliance on on-board supplies can be reduced through the use of local Martian resources, something that is not explored in the show at all. More importantly, a conjunction-class mission enormously reduces the risk of radiation exposure (solar and particularly cosmic) for the crew. On an opposition-class mission, the crew is exposed to some 22 months of cosmic radiation while in interplanetary space; in a conjunction-class mission this is reduced to some 12-14 months. The opposition-class mission makes event less sense when one considers the window for conjunction-class missions opens once every 26 months or so. And indeed, in the time-frame of the mission (2030) such a window is available. So why is it ignored? Drama seems to be the only reason. It's easier to tell a story of people cooped up in a malfunctioning space ship than it is to actually tell the story of the first Martian explorers. Another negative on the show is the use of nuclear propulsion. I don't say this for any environmental reasons (on the contrary, I very much support the use of nuclear power in space, away from any risk of polluting our atmosphere). No, my objection is on the grounds that show fails to demonstrate the sheer value in using nuclear propulsion on human Mars missions: the further reduction of flight-time between Earth and Mars. Again, the reason for the 6-8 month flight time required of a conjunction-class mission is down to the limitations of chemical propulsion. With "ordinary" rocket motors, we have a limited amount of fuel that can be carried by the launch vehicle. This needs to be balanced between the initial launch / acceleration away from Earth and the need to slow down at Mars and achieve orbit (even when using aero-braking). So we launch with limit fuel, burn some of that fuel to push us on the way to Mars, then effective "coast" there, before slowing down and entering orbit - similarly because the amount of fuel we'd need for our rockets to run for any longer would massively increase the mass of our vehicle to a point where it is impractical.

Nuclear propulsion, on he other hand, requires much less fuel - and can run for much, much longer, both accelerating the vehicle gently away from Earth, then slowing it gently into Mars orbit. In the process, such a propulsion system could shave weeks - if not months - off the 6-8 months transit time of a conjunction-class mission. Yet in Race for Mars, no distinction is drawn on the benefits of nuclear propulsion, with the engines used pretty much as one might expect chemical motors to be used. Indeed, it is (wrongly) suggested in the blurb supporting the series that in order to reach Mars, the ship must first fly to Venus (going towards the sun and thus increasing the crew's radiation exposure risk), in order to make a "gravity-assist" flyby (using the gravity of Venus to "sling" the ship out towards Mars, accelerating it along the way). This is again somewhat nonsensical, and such flybys haven't featured in mission planning since around the early 1980s.

But all these flaws are there to serve the basic need for human drama of the mission; which is unfortunate; as nearly all of this drama is artificially developed around a flawed vehicle design (the Terra Nova suffers more systems crashes than a PC running Windows Millennium). This is a shame, as with a little more effort, the show could have shown up significant drama and tension as our lonely band of explorers are faced with the awesome magnificence of Mars and their attempts to explore and understand their surroundings. Instead, we're left with a 3-episode story arc largely devoted to 6 people battling a recalcitrant space, with an middle intermission showing them working (and dying) on Mars. That said, Race To Mars still provides an interesting alternative to the portrayal of the first human mission to Mars that stands in difference to the usual talking heads we see on Discovery. On the whole, the acting is fine (allowing for the aforementioned script grinds), and Michael Riley in particular carries off the role of the mission commander with particular aplomb, revealing his character to be a complicated, humane leader in need of close company, but necessarily isolated from his team by the burden of command. Had more work been put into actually developing a fictional representation of the first human mission to Mars, rather than using Mars as the backdrop to explore a long-duration space mission in which just about everything goes wrong for the sake of maintaining viewer interest, then the series could have been outstanding, rather than merely "good".

Steph a écrit:il y avait un sujet dédié qui date du moment de la diffusion du reportage sur Arte, je fusionne les deux.

Un Loup survient à jeun qui cherchait aventure,
…………..
Tu seras châtié de ta témérité.
- Sire, répond l'Agneau, que votre Majesté
Ne se mette pas en colère;
Mais plutôt qu'elle considère
Que je me vas (*) désaltérant
Dans le courant,
Plus de vingt pas au-dessous d'Elle,
Et que par conséquent, en aucune façon,
Je ne puis troubler sa boisson.
……………
Et je sais que de moi tu médis l'an passé.
- Comment l'aurais-je fait si je n'étais pas né?
Reprit l'Agneau, je tette encor ma mère.
- Si ce n'est toi, c'est donc ton frère.

(*) provincial
J. de La Fontaine, Fables, Livre Premier, 10

Firnas2 a écrit:1) Un équipage composé de 5 nationalités, n’est ce pas trop?

Eissero a écrit:Je me permet de lancer le fil de discussion sur le sujet des deux documentaires "A la conquête de Mars".