Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!hplabs!hplabsb!dsmith
From: dsmith@hplabsb.HP.COM (David Smith)
Newsgroups: sci.space
Subject: Re: Impossible Space Goals
Message-ID: <5348@hplabsb.HP.COM>
Date: 20 Jul 89 16:48:05 GMT
References: <24b89b35@ralf> <4304@eos.UUCP> <1699@infinet.UUCP> <14475@bfmny0.UUCP>
Reply-To: dsmith@hplabsb.UUCP (David Smith)
Organization: Hewlett-Packard Labs, Palo Alto, CA
Lines: 38

In article <14475@bfmny0.UUCP> tneff@bfmny0.UUCP (Tom Neff) writes:
>>>Was the surface of the moon hard or miles of dust for a lander to sink?
>>
>>There were even two series of Lunar probes launched to specifically
>>answer this and related questions.
>
>Whoa.
>Assuming Zond doesn't count, there were two programs where unmanned
>spacecraft touched the lunar surface: Ranger and Surveyor.  Ranger was a
>hard ballistic impact probe which relayed TV pictures on the way down.
>The final pictures were taken a few thousand feet above the surface;
>nobody really knew what happened when a Ranger hit.  Dust or basalt
>would have extinguished the craft with equal efficiency.

Whoa right back.  Ranger was indeed launched to answer this question.
Rangers 3-5 had seismometers encased in balsa spheres, attached to
retrorockets.  These packages were supposed to separate from the main
spacecraft, brake to a stop 1100 feet altitude, jettison the retros,
then fall from there.  After rolling to a stop, they were to transmit
readings back.  If the balls sank into dust, the signals would reflect
that.

Rangers 1 and 2 were engineering spacecraft, not intended to hit the moon.
Their Agena stages (2nd stage on top of Atlas) failed to fire to get out
of parking orbit.  Ranger 3 was launched 30,000 miles off course by the
Agena, and was only able to to cut the error to 23,000 miles with its
course-correction motor.  As it passed the moon, it failed to aim its
high-gain antenna at the Earth, so its photos weren't received.  Ranger
4's sequencer failed.  Ranger 5's power failed shortly after trans-lunar
injection.  After this, the spacecraft were simplified to be camera-only
probes, and then Ranger 6 failed to turn on its cameras.  Talk about
snake-bitten.  But at any rate, three Rangers had attempted to get an
instrument to survive a moon landing.
-- 

			David R. Smith, HP Labs
			dsmith@hplabs.hp.com
			(415) 857-7898