I'm back from the Europa Focus Group meeting... |
I'm back from the Europa Focus Group meeting... |
Guest_BruceMoomaw_* |
Mar 1 2006, 07:33 AM
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#1
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Guests |
...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. |
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Mar 7 2006, 08:17 AM
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#2
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Senior Member Group: Members Posts: 1870 Joined: 20-February 05 Member No.: 174 |
Actually, Ranger A or I think more accurately the Block 1 series were Rangers 1 and 2, engineering test missions with a full load of science instrumentation to be placed in a highly eccentric orbit with apogee beyond lunar orbit. Both were stranded in low parking orbit due to Agena re-ignition failures, could not maintain proper attitude control or communications due to 90 min day-night orbits, and re-entered rather promptly.
Ranger Block 2 was Rangers 3 -5, with a payload including the balsawood cushioned capsule. Yes, the seismometer instrument package was cushioned in fluid, was to right itself inside the impact capsule after impact, then fire "bullets" to drain the fluid and let the seismometer to settle with "down" down. Block 3 was the 6-TV camera Rangers, while a block 4 or D series were to have been an improved version of the Block 2 missions, but was cancelled early in development. Point of Terminology: Impact missions are un-braked or insufficiently braked and are destroyed on impact. Descent probes are atmosphere descent probes that may or may not survive to reach a planetary surface. They are not required, expected, or instrumented to survive impact. If they do, like the Pioneer Venus Day probe, they are defacto hard landers. Early Soviet Venera missions were instrumented for atmosphere descent with the hope/expectation they'd reach the surface and survive, but they were crushed by the atmosphere before impact. Hard landers are landing vehicles that are protected against impact damage on all sides and are not required or expected to maintain attitude control or stable contact with a surface after impact. Ranger Block 2 impact capsules, early Luna landers (9 and 13 succeeded), early Venera landers (7 and 8), Pathfinder and MER rovers are hard landers. Soft landers are required to maintain controlled attitude during landing. They may simply impact at low speed in a controled orientation, like Huygens, on a landing ring like the large Venera and Vega landers, or on legs like the Surveyors, Viking, Luna heavy landers, and Phoenix. Penetrators are required to maintain attitude control after impact as they penetrate the surface and embed themselves below the surface, usually leaving an afterbody (very hard lander) on the surface. |
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