I'm back from the Europa Focus Group meeting... Options

[Guest_BruceMoomaw_*]

...which I decided to attend literally at the last possible minute, which is why I didn't alert you guys in advance. Very interesting -- both the discussions about the likely design of the mission (and how to retrieve it from cancellation), and many of the actual science presentations (which aren't on the Web yet, although they probably soon will be). I'll give you some more information tomorrow -- although I can't resist telling Alex that Tom Spilker's subgroup took my ideas about a Europa penetrator, and the printed information I gave them on the subject, seriously enough to recommend making further inquiries to NASA HQ on it. (And without my browbeating them, either. Nyaah.) The case for it, however, is still extremely far from certain.

As I say, more tomorrow.

[Guest_BruceMoomaw_*]

The article is extremely explicit that there WERE inflatable airbags, and that they were the cause of the Luna 8 failure. (The craft began tumbling at 2 rpm 13 seconds after the inflation began.) The precise cause of the leak was discovered 5 days later. One letter from a co-worker describes Korolev -- who valued this program very highly -- as seemingly teetering on the verge of slitting his own throat after the failure.

Quoting the description: "During flight to the Moon, the Automatic Landing Station [aka the lander capsule] was covered in a thermal blanket. Within the blanket, there was a second covering, this one comprising an expandable rubber chamber with a a protective Kapton shell. Compressed gas from a spherical bottle mounted on the separable Compartment #1 [one of the two side equipment pods jettisoned from the main craft during retrofire] would inflate this second covering into two independent cushioning airbags which would protect the actual lander cocoon moments before impact....

"After the Luna 8 accident... Babakin's engineers introduced changes primarily related to the sequence of operations before landing. In the Ye-6 [previous design], inflation of the shock absorbers was carried out before main engine ignition. But as two senior engineers from the Lavochkin Design Bureau later noted, the sequence was changed for the 'Babakin variant': 'It was established that it was essential to carry out the inflation of the shock absorbers after ignition of the braking engine, to prevent harmful rotating moments that arose when the shock absorbers were inflated before braking engine ignition.' This reasoning seems to be supported by at least two contemporary accounts of the Luna 9 mission from 1966 in which the authors note that the airbags 'were prepared for landing while the engine was working.' Because the compressed-gas bottle for the shock absorbers was in a container attached to Compartment #1 which separated before engine ignition, Babakin's engineers moved this bottle to the side of the I-100 control system compartment on the main bus. One source notes that another difference on Luna 9 was that the attitude control thrusters were used in a continuous mode rather than intermittently to stabilize the spacecraft after airbag inflation."

There is an accompanying diagram of the Luna 9 design from a Soviet technical magazine showing Luna 9, complete with the new position for the airbag gas bottle, and there are very extensive bibliographic notes for all of this -- including the 1966 articles that mention the airbags. The thermal cover over the entire capsule-airbag assembly was jettisoned at the very start of the landing sequence. (The I-100, by the way, was also the spacecraft control system that was the bane of the whole program from Jan. 1963 through May 1965.)