[X] My Assistant

[Tesheiner]

I do have one question about the image showing the horizon: given that Phoenix is tilted at a quarter degree, doesn't that mean it's sitting on a hill? The horizon looks to be tilted by several degrees there.

Not "several degrees" but 1.5º if I did my math correctly. In any case, it's not a quarter of a degree so I have the same question.

[centsworth_II]

Thanks all for your kind words and for sticking with me through the various attacks on the website and ustream channel!

Were those really attacks and not just the result of heavy traffic? I can't understand attacks. It does not compute.

[elakdawalla]

Thanks Doug -- that one went straight into the blog

And yes, there were attacks. Our site handles high traffic just fine; it's managed by a company whose clients are mostly major motion picture studios whose websites have to stream movie trailers, so bandwidth is the least of our problems (though not always the least of our expenses ) Fortunately the team was on duty last night and was really able to recover from the attacks very quickly -- it just seemed to take forever from my perspective, as it happened, of course, right during the landing!

We seem to be all better this morning though.

--Emily

[ElkGroveDan]

Emily are the press conferences still going to be coming from JPL today? Or has it all moved out to Arizona now that science has taken over?

[nprev]

Attacks during the landing...incredible. I don't think a swear jar large enough to absorb the financial penalties incurred by me describing the fully accurate obscene attributes and activities of such alleged people could ever be built...

Thanks for persevering, Emily; you were beyond great!

[elakdawalla]

Emily are the press conferences still going to be coming from JPL today? Or has it all moved out to Arizona now that science has taken over?

I am certain that at least Monday and Tuesday there will be briefings at JPL. I'm a bit confused as to the rest of the week -- one pre-landing schedule I saw had them returning to UA on Wednesday, but JPL had press briefings all week on their calendar. I'll get clarification when I go there today. I believe Peter Smith has already returned to Tucson.

--Emily

[Leither]

Does anyone know the actual diameter of those landing pads? Does something near 30 centimeters sound correct? Sounds big to me.

30cm is a bit big. A caption on Phoenix image gallery says -
"Each footpad is about the size of a large dinner plate, measuring 11.5 inches from rim to rim. The base of the footpad is shaped like the bottom of a shallow bowl to provide stability."

[Stu]

My idle, sleep-deprived speculation continues...

Still wondering about this "rock"... feel free to jump in, anyone... I've even found a way to line up the lander's POV with the "sharp rock" and two vague mounds/humps on the horizon and features on the HiRISE image.



Probably nothing, but I'd appreciate input from more informed members.

[ugordan]

Nick, it's not the altitude that triggers the parachute (and really it shouldn't even be, as Ralph pointed out), it's parachute dynamic pressure margin (don't go too fast!) on one side and not too slow a speed on the other side. Both of these can be perfectly well accomodated by a good IMU that integrates from a known initial velocity. All you need to do is make sure there's plenty of altitude left for the parachute to do its job and Phoenix did this. IIRC, the chute was opened at around 12 km and the majority of remaining velocity was lost soon thereafter. It was a more gentle descent after that.

To cope with varying atmospheric density, an active entry of some kind might be envisioned that adjusts lift/drag effects on the heatshield to compensate for modeled/measured deceleration profile. That's just arm-waving on my side, though.

[ElkGroveDan]

I'd appreciate input from more informed members.

Paging Phil Stooke... Mr. Stooke please pick up the white courtesy phone.

[glennwsmith]

I am still stunned by the correspondence between the planned mission objectives and the first views of the landing site -- looks (to my fevered imagination!) exactly like the type of heaving terrain beneath which one would expect to find ice!

[imipak]

Infestations of trolls, etc, in the chat channel were unfortunate but not too surprising, alas. But an attack against TPS really boggles me, both as a TPS member and professionally speaking, as someone who works in security. It wasn't a normal "DoS" attack where a site's swamped with spurious, but otherwise normal, requests, because Emily referred to rebooting the server to bring the site back. I don't know of any public "crash your server" exploits in the wild that work against Apache 2.0.59 as used on planetary.org . There's no money to be made from such an attack, which suggest sociopathic types ("script kiddies") with too much time on their hands... Although come to think of it, there's a thriving industry in DoS for blackmail purposes, especially around one-off events with high traffic peaks (hitting betting sites on the day of a huge sporting event was a favourite tactic a year or two back.)

Well, anyway, last night saw some of the absolute best the Internet can offer, as well as a couple of glimpses of the worst. (The Internet, plus dedicated, unbelievably knowledgeable people like Emily and Doug of course!) It bears repetition: enormous kudos to Emily, Doug and the Selsey crew, and all the UMSFers out there, as well as of course to the project team. So many memorable moments... and what a fabulous atmosphere, from Sir Patrick Moore's shirt and monocle, to the banter in the chat rooms (especially as the beers went down!) I'd love to see some traffic stats from umsf as well - did you pick up many new user registrations?

PS Next press briefing is 7pm BST / 1800 UTC on NASA TV I think?

PPS 11.5 inches == 29.21 cm

[fredk]

Not "several degrees" but 1.5º if I did my math correctly. In any case, it's not a quarter of a degree so I have the same question.

I noticed that as well - I also get 1.5 degrees. Could it be the SSI mast is tilted a degree or so from vertical?

[nprev]

Nick, it's not the altitude that triggers the parachute.

Gotcha; thanks, man! I'm overthinking this; too used to INS as applied to military airdrop systems, I guess.

[DEChengst]

That was quite a night. I actually decided to sleep through the event as I had to hack some application into submission at work this morning so I couldn't take the day off and needed to be focussed. Somehow my internal timer managed to boot my brain exactly 10 minutes before touchdown ERT. After taking a look at the clock it dawned on me what time it was. I quickly rolled out of bed, put on some clothes, ran to the living room and turned on the TV. Just in time to hear that atmospheric entry was confirmed. Back in bed 5 minutes after touch down. Deep sleep failed but mission accomplished