Index Home About Blog
From: Henry Spencer <>
Subject: Ranger landing capsules (was Re: FAQ Part II)
Date: Tue, 28 Jan 1997 16:31:02 GMT

In article <>,
Thomas J. Frieling <> wrote:
>>and although Surveyors 3-5 did
>>carry hard-landing capsules with retrorockets, the facts that (a) none
>>of them succeeded and (b) the main bus was still intended to impact
>>do argue for classifying it as an impactor.
>What??  More details on these Surveyor "hard-landing capsules", please Henry.
>I sure don't remember these.

First, I must correct a slip of the fingers:  for "Surveyor", read "Ranger".
Ranger was the topic under discussion.

Second, the history...  Ranger was actually three programs in one.  Maybe
four if you allow for the fact that it was supposed to develop technology
for deep-space missions (which is why a lunar-impact probe with a useful
lifetime of only a few days had solar arrays instead of batteries).  This
attempt to do several things at once contributed to its woes.

Rangers 1 and 2, "Block I", were never intended to come near the Moon.
They were "sky science" missions, meant to explore fields and particles at
large (by the standards of the day) distances from Earth.  Both, by the
way, suffered launch failures.

Rangers 3-5, "Block II", were lunar-impact missions.  They carried several
instruments, and a little hard-landing capsule.  The spherical capsule
would be released at low altitude, spun up by small solid rockets, and
then decelerated by a large one, after which it would simply fall.  The
outer layer of the capsule was balsawood, intended to cushion the impact.
Within was a spherical liquid-filled payload chamber with a bottom-heavy
spherical payload, the idea being that it didn't matter what attitude the
capsule ended up in because the payload would simply rotate within the
liquid to be right-side up.  The payload -- a single-axis seismometer --
would radio data back with a battery-powered transmitter sending through
the shell.  Quite a clever idea, and there were concepts for landing a
camera (which would push its way out through the shell) the same way.
Unfortunately, Rangers 3-5 all had major electronics failures en route
and the landing capsule never got its chance.

(Between Rangers 4 and 5, there was one small ray of hope in all this
gloom:  Mariner 2.  Mariners 1 and 2 had been hastily built -- in 11
months -- as Ranger derivatives, after original plans for larger Venus
probes were stalled by the development problems of Centaur.  Mariner 1
was lost in a launch failure, but Mariner 2 worked and reached Venus.)

That was actually where the original Ranger program ended.  The advent
of Apollo extended it somewhat.

Rangers 6-9, "Block III", were impact missions dedicated to close-up
TV imaging of the lunar surface.  Early plans to fly some secondary
sky-science instruments (to placate the unhappy Block I scientists) were
scrapped in the stink that followed five consecutive failures.  Also
scrapped was heat sterilization, which was probably the biggest reason
for the electronics problems, and the attempt to use Ranger to develop
planetary-mission technology.  There were also some serious management
shakeups.  The mass released by the demise of the secondary payloads
was used to add redundancy in major subsystems.  Ranger 6's camera
system failed (both sides of a redundant system) due to a design error.
Rangers 7-9 functioned perfectly, which was just as well because JPL's
survival as a NASA facility was at stake by this time.

Rangers 10-12, "Block IV", were intended to be improved versions of the
Block III spacecraft with some of the Block II instruments added.  This
idea never generated much enthusiasm and Block IV died early.

Rangers 13-18, "Block V", renumbered 10-15 after Block IV died, were meant
as another try at Block II, including the landing capsule.  They hung on a
bit longer, but died around the time Block III started flying.  This was
partly because upper management was angry with all the failures, partly
because the increased redundancy of the spacecraft bus made the heavier
payload hard to accommodate, and partly because better missions were in
the pipeline by that time.  The landing capsule had been a great idea in
1960, but flying Ranger 10 just a few months before Surveyor 1 did not
look like a particularly sensible way to spend money.

The best reference on all this is "Lunar Impact", the NASA History book
about Ranger.  Oran Nicks's "Far Travellers" also sheds useful light on
the program, from the viewpoint of NASA HQ.
"We don't care.  We don't have to.  You'll buy     |       Henry Spencer
whatever we ship, so why bother?  We're Microsoft."|

From: Henry Spencer <>
Subject: Re: Ranger landing capsules (was Re: FAQ Part II)
Date: Wed, 29 Jan 1997 16:37:03 GMT

In article <>, David Lesher <> wrote:
>...The technicians all went to "high-tech soldering
>school" and said it was no laughing matter.
>The reason for this was early failures such as Ranger were at least
>in part attributed to soldering failures.

After Ranger 5 -- the third major electronics failure in a row -- both JPL
and NASA HQ ran inquiries.  Even JPL's inquiry said that the workmanship
on the Rangers was inferior to that on Mariners 1 and 2, and the Kelley
inquiry (the one done for NASA HQ) made scathing observations about poor
workmanship and casual attitudes toward quality.  I don't recall seeing
mention of soldering in particular, but I haven't seen the actual reports,
just historical accounts based on them.

After that, a major effort was mounted to improve the quality of
spacecraft hardware, and I can well believe that the fussy NASA attitude
toward soldering (which is well known) came out of this.  Some of it may
have been an over-reaction in the long term, but in the short term NASA
couldn't afford any more conspicuous failures.
"We don't care.  We don't have to.  You'll buy     |       Henry Spencer
whatever we ship, so why bother?  We're Microsoft."|

Index Home About Blog