Which are the top albums? Any idea?

ver no google.

Hope the chutes on Phoenix Mars lander remain intact upon deployment. Best wishes for the girl to land safely in a prime spot and best of luck for everything with the mission to go well. Those will be ten hour-long minutes while waiting for communication from the lander to say it’s down and everything is A-OK.

On one level, it may be fine and dandy to jack up the metabolism to a ludicrous pace suited to marketing preconceptions on the attention-deficit of a generation jaded by whip-fast stimuli, and justifiable on another level to try to cram in as much as possible within a limited duration such breakneck back-and-forth between the talking heads and the fairly well-done cgi sequences in an editing tour de force…but for crying out loud already, this is getting ridiculous!

Worse, the PR departments at NASA and JPL are obviously buying into precisely the same sensationalist (clap)trap that Hollywood is famous for which you, Phil – and so many others – have worked so hard to try to rectify.

Phil, please, we can usually rely on your laser-like sharp eye to point out misrepresentations – especially gross ones – to keep us all straight, no matter what the source. Your mention of the inaccurate use of the word “friction” by one of the commentators is proper and a good point…just that ONE POINT.

But you leave an awful lot hanging there! For example, in the cgi sequence when the lander is released from the backshell the action is so ridiculously speeded up that it looks like it’s falling in a gravitational field of maybe 50 g’s! It looks as if it was shot out of a cannon toward the surface!

Come ON already!!! Doesn’t anyone ever notice this sort of shameless hyper-exaggeration anymore? What are kids to bring away from this video? That they have been given an accurate and informative sense of the actual events that will transpire during that “SE7EN MINUTES OF TERROR”???

Gimme a friggin’ break already. This trend of padding the material up for public consumption is grotesque beyond belief. The actuality is spectacular enough as it is. WHY are these lousy wrongheaded gimmicks being utilized? For improvement???

And what about all the many cool things that will actually have to happen that we are NOT seeing in this “very cool video”?

We don’t see how the lander is programmed to begin firing it’s thrusters a second after release.*

We don’t see how it’s programmed to maneuver “upwind” AWAY from the backshell/parachute in order to minimize the chance of recontact.

We don’t see MANY cool things that ACTUALLY will happen (hopefully, of course, along the lines of the desired plan).

What do we see instead in the moments before landing? Some peculiar guesswork gyrations that look like a major departure from the nominal – so much so that it looks like the lander is in major stability trouble or fighting an invisible dust devil.

As for the quality of the cgi parts in this video in general? The real-time paced sequences are fairly well accomplished. Maas Digital does superb work. But IMHO their work on the MER landing was BY FAR better done.

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*Oh yeah, dropping the lander out of the backshell at a mere 3.72 m/s^2 or 0.38 g’s would have RUINED the “drama” of the preferred cannon-shot – “sciencefix”, pay attention now: one trusts that you don’t “teach motion” by referring to another similarly wildly imbecilic sequence that rarely icites a rolling of the eyes – in the film Apollo 13, when the LEM’s main engine is employed for a course-correction maneuver, we see the whole stack take off as if it was under the impulse of ALL FIVE of the F5 engines of the first stage. The word “ridiculous” doesn’t seem to have any meaningful impact when such a stupendous stupidity appears in a POPULAR film that did extremely well at the BOX OFFICE. (“OBVIOUSLY” it made MONEY which MEANS that it had the RIGHT RECIPE for SUCCESS, and INCIDENTALLTY it’s ONLY a MOVIE, ad nauseam). Meanwhile, we are all teaching the general public pure crap because we treat them like consumers rather than thinking, curious beings invested with something that resembles intelligence.

Ok. I’ve said it. SOMEBODY has to.

With tonight’s TCM (trajectory correction maneuver) coming up, you may want to watch this video which explains navigation: http://www.jpl.nasa.gov/videos/phoenix/phx20080124/

That didn’t occur to me about the captioning, but it makes sense. Thanks.

Tom – possibly they were referring to the heated air outside the heat shield and not to the heat shield itself. Unless the heat shield is immersed in the gas long enough to achieve thermodynamic equilibrium (and clearly it isn’t), it will be cooler than the gas. Whether several thousand degrees cooler, I doubt, but maybe. You could tell by observing the color of the fireball, if you were suitably positioned on the martian surface

I’m looking forward to the landing.

Possibly there’s a weight problem, as IIRC it is claimed that the next lander, Mars Science Laboratory is too heavy to land on (current technology) bags. It could also be a dress rehearsal for that.

I understand that the Mars Exploration Rovers (complete with landing platforms) were at the hairy edge of what the airbag system could tolerate — and as it is, they had to add a bunch of extra stuff to make it workable, including descent rockets to slow them down a bit more and a sophisticated landing guidance system to avoid rocks, since the airbags were highly vulnerable to punctures with all that mass behind them.

So yes, MSL will be much too massive for the airbag system. It will have to land using the old-fashioned retrorocket method.

Oooo, nice take-down of the BA there, Robin.

I do have one nitpick with the video. The geeky dude with the brown shirt and glasses makes this statement:

“The outside can get almost as hot as the surface of the sun”

The very next statement is “the temperature of the heat shield can reach 2,600 degrees Fahrenheit”

According to Wikipedia the surface temperature of the sun is 5,778 degrees Kelvin = 5,505 degrees Celsius = 9,941 degrees Fahrenheit. So they are off by a factor of 3.8 unless the other parts of the exterior of the spacecraft become hotter than the heat shield which I somehow doubt.

The heating during entry (or reentry if’n you’ve already been there) is due to aerodynamic drag. Aerodynamic drag can be broken into two components: induced drag and parasite drag. Induced drag is a byproduct of lift. Parasite drag can further be broken into two components: pressure drag (due to difference in pressure between the forward and aft sides of the vehicle) and, wait for it, skin friction! Skin friction is also called viscous drag and is due to the shearing force in the boundary layer between the gas and the surface of the vehicle. So, the word “friction” is used correctly by the folks at JPL. Although friction isn’t the only thing that slows the vehicle down.

The equation for total heat input to a reentry vehicle (assumes a few simplifications of course, I’m an engineer, what are you gonna do?) is:

Q=m/4*(Cf’*S/Cd*A)*(Ve^2-Vo^2)

m=mass of the vehicle
Cd=drag coefficient
S=surface area
A=aerodynamic area
Ve=entry velocity
Vo=impact velocity (hopefully small!)
Cf’=equivalent friction coefficient (based on local skin friction coefficient and gas properties)

So, two things: 1) the word ‘friction’ can definitely be use when speaking about drag (and therefore atmospheric entry) and 2) heating during entry is only partially due to compression of the gas to which the vehicle is entering.

For example, at one point there’s narrative text which says, “Mission: Dig into the icy soil. Search for chemical building blocks of life. Study the history of water.” So the captioning says, “(Text on screen) Mission: Dig into the icy soil. Search for chemical building blocks of life. Study the history of water.”

But…

I dunno, maybe I’m becoming a crank in my old age, but I really hated the video-game graphics, the super-dramatic text and fonts, the constant “swooshes” – heck, if I want to see that stuff, I could just watch the 6 o’clock news. And the jerky camera work, with all its unnecessary pushes on the interviewees, is exactly the sort of thing that makes me have a hard time watching Battlestar Galactica (the premiere, anyway) or 24 – if I want to see that stuff, I could just watch home videos I made with my camcorder. Of course, the popularity of those shows means that most people are able to get past those video peculiarities – or maybe even enjoy them.

I kinda felt like I felt when I watched the movie Spawn, that this something created for an audience with a 5-second attention span. People who would find a more straightforward presentation boring. So, hey, if it works, it works. I hope it works.

And I hope all goes well with the landing – on Towel Day, no less!

So I disagree that the word friction is being used incorrectly. It’s just yet another word in English like “bat, bat, bat” or “theory, theory” or “heat, heat” (or any of a thousand other such words) that has multiple meanings, and you were wrongly assuming that the speaker meant one particular meaning over the other due to the ambiguous context of the statement.

I actually got a chuckle out of what I thought was a pretty good pun!

Honestly, I love such videos and collect them and demonstrate them to others. On my iPhone I have an earlier video made for the same mission – without any dialogue – as well as a video for the Mars Science Laboratory mission.