Normally Hollywood spaceships are such mindless crap that I have to turn the engineering parts of my brain off in order to enjoy the movie (it still bugs me to watch it). However these Cameron's Mars Design Reference Mission Tour vehicles are good! Somebody who knows a little bit about aeronautical engineering actually provided some input rather than the usual case of some clueless art history major doing everything. These designs are good enough that I'll go to the effort of nit-picking them.

The first picture of interest is a triconic entry vehicle. This design was probably lifted from the Human Exploration Design Studies (HEDS) that were done at JSC a few years ago. Because some politician bitched about it, Goldin canned the HEDS work (one of his worst actions as NASA's worst administrator). A beef I have with this design and the HEDS triconic is the corners are too sharp at the nose (this causes local hot spots due to rapid expansion in hypersonic flow). The little flap in the back is cute. However I doubt that it would have enough control authority because it is in a region of expanded flow. Also it is located too close to some Reaction Control System (RCS) thrusters (there would be plume impignment). The proper place for that control surface is on the vehicle's belly as a split body flap with the flow directly impigning on it.

The second picture shows the triconic with backshell jettisoned. The glaring fault with this picture is: "Where's the hardware driving the flap?" That flap would experience tons of aerodynamic force. Attached to the back end of each flap should be a hydraulic cylinder with plumbing or a big lead screw with a large electric motor driving it.

This picture of a crewed 70 deg. sphere-cone is very cool. Another picture shows this same sphere-cone as part of an interplanetary transfer vehicle. What this implies is the sphere-cone is coming into Mars directly from heliocentric orbit as either an aerocapture entry to a Mars centered orbit or direct entry to the surface. A 70 deg. sphere-cone is the correct way to enter the Martian atmosphere if you're not too worried about G loading. However with a crew, that's a big issue. The only way this design could work would be for the entire transfer vehicle to propulsively enter into a Martian atmosphere (no aerocapture) and then deorbit to the surface. Doing propulsive entry to Mars orbit from deep space for a vehicle this large is too expensive. Besides they don't show a rocket motor on the transfer vehicle so it's not an option.

Finally there's this neat picture of the ascent vehicle. The flaw with this picture just jumps out to an aerospace engineer. The rocket plumes are all wrong. They're shown as these tight cylinders of blue light. For Martian surface pressures, the rocket plumes would expand out at almost ninety degrees from the rocket bells. It still looks cool even though it's wrong!

Again these are nit-picks. James Cameron deserves high praised for creating these artist's conceptions. I hope a movie comes out of this.

Gary