[FPSPACE] Waddling across Mars, and other notes on the Soviet program

Larry Klaes lklaes@bbn.com
Wed, 16 Aug 2000 15:17:17 -0400


Posted with permission by Jennifer Green:


From: "Bruce Moomaw" <moomaw@jps.net>
To: "Europa Icepick Group" <europa@klx.com>
Subject: Waddling across Mars, and other notes on the Soviet program
Date: Sat, 12 Aug 2000 00:04:59 -0700
Sender: owner-europa@klx.com
Reply-To: europa@klx.com


-----Original Message-----
From: Larry Klaes <lklaes@bbn.com>
To: europa@klx.com <europa@klx.com>; Europa Icepick Group <europa@klx.com>
Date: Friday, August 11, 2000 12:26 PM
Subject: Re: Soviet rovers to Mars?


>
>Bruce, what is the name and author of this document on
>Soviet space probes and how did you acquire it?
>
>As for Mars 2, I was of the impression that the landers
>were released automatically by preprogramming and that
>the Soviet controllers on Earth could do nothing to
>change the program, thus the reason Mars 2 and 3 could
>not wait out the global dust storm like Mariner 9 did,
>though of course the US probe was "only" an orbiter.
>
>As for the Mars 3 lander's early silence, I read that
>it was due to a communication problem between the lander
>and relay orbiter, but that also was speculation.
>
>Larry
>
>
>At 01:38 AM 08/11/2000 -0700, Bruce Moomaw wrote:
>
>>-----Original Message-----
>>From: Larry Klaes <lklaes@bbn.com>
>>To: europa@klx.com <europa@klx.com>; europa <europa@klx.com>
>>Date: Thursday, August 10, 2000 3:29 PM
>>Subject: Re: OT: Two rovers to Mars
>>
>>
>>>
>>>Note they say that this is the first time NASA has sent
>>>two rovers to another planet.  The USSR did it thirty
>>>years earlier with Mars 2 and 3, but seeing as both
>>>landers failed, the news of these rovers were not
>>>released until 1990.
>>>Larry
>>
>>
>>
>>Actually, those two "rovers" were tiny little tethered crawlers about the
>>size of a matchbox -- and their only instrument was a penetrometer to
>>measure soil hardness.  As a basis for claiming a space first, this is
>>pushing things a bit even for the Soviet Union.
>>
>>By the way, I've recently gotten hold of a history of some concealed parts
>>of the Soviet Mars program by a former participant.  There was
>>disappointingly less than I had hoped -- but he does reveal the fact that
>>the failure of the Mars 2 lander, the very first human object to hit Mars,
>>was due to exactly the same thing that wrecked Mars Climate Orbiter!  The
>>Soviets bungled the last midcourse maneuver, and knew several hours before
>>entry that it would enter the atmosphere at too steep an angle.  (He also
>>speculates that the loss of contact with the Mars 3 lander less than a
>>minute after landing was probably due to the fact that the powerful dust
>>storm raging over Mars' surface at the time built up a disastrous
electrical
>>charge in the lander.)
>>
>>Bruce Moomaw



First, a more complete description of the tethered micro-rovers on the
Soviet Mars-2 and 3 landers, from the July-Aug. 1990 "Planetary Report":

"Their range was to be 15 meters from the lander.  They moved by using skis
set on either side [for a waddling motion].  Two thin bars at the front of
the lander were sensors to detect obstacles in the vehicle's path.  It could
determine on which side the obstacle lay, step back,change direction and try
to go around it... They each carried two instruments: a dynamic penetrometer
and a [gamma-ray]densitometer, to measure the bearing strength and density
of the soil. [but not its composition]."

As for that document on the Soviet Mars program, Larry himself put me onto
it over a year ago.  It's "The Difficult Road to Mars", by V.G. Perminov --
NASA's "Monographs in Aerospace History", Number 15 (NAS
1.83:1999-06-251-HQ).  You can order a copy of it for $9 ($11.25 outside the
U.S.) at http://bookstore.gpo.gov/market/00-12.html .  You can also get it
as one of the many government documents included in "Mars" the NASA Mission
Reports" -- a book-CD combination from CG Publishing -- for $28.95 (U.S.):
http://www.cgpublishing.com/mars/htm

Key news in it is:

(1)  Perminov confirms an earlier report that the 1962 probe "Mars 1" failed
because it immediately suffered a leak in one of its nitrogen attitude jets
and ran out of attitude-control gas after a few days.  By then, its
controllers had put it into a slow roll around its Sun-pointing axis so it
could at least retain low-rate radio contact with Earth -- but it failed
completely for other reasons after 5 months.  For this reason, the 1964 Mars
probe Zond-2 was fitted instead with plasma attitude-control jets -- but one
of its two solar panels failed to unfold, and so it failed due to inadequate
power 5 months into the flight as it moved farther from the Sun.

(2)  The first two "advanced" Soviet planetary spacecraft (like Mars 2
through 7, Venera 9 through 14, and Vega 1 and 2) were indeed launched to
Mars in spring 1969.  They were identical to the Mars 2 and 3 orbiters, but
without landers -- the original intention was to provide parachute-equipped
crash-landing capsules to measure atmospheric composition and gain
engineering data for the 1971 landing attempts, but even these proved too
heavy at the time.  Both boosters failed -- although a separate article on
this project in the aerospace history magazine "Quest" quotes the engineers
as saying that this project was so hurried by Soviet government orders that
the orbiters would probably have malfunctioned even if their launches had
succeeded.

(3)  Mars-2 failed because it was equipped with an completely autonomous
onboard optical guidance system (shades of Deep Space 1!) to carry out a
final midcourse correction 7 hours before Mars orbit insertion -- but the
computer malfunctioned and commanded that the orbiter veer too close to
Mars, so that the ejected lander hit the atmosphere too steeply and crashed
before it could open its parachute.  Ironically, if the automatic guidance
system had not been turned on at all, the craft's preexisting Mars flyby
trajectory was good.  (The only reasons that the automatic system was turned
on were that a third Mars craft -- an orbiter without a lander -- had failed
at launch because a ground controller sent its last-stage restart command in
reverse order; that orbiter had been intended to reach Mars first and allow
more precise radio-tracking location of Mars' precise ephemeris.  Perminov
points out that they could also have gotten this data from the U.S. if the
1972 U.S.-Soviet exchange of data from their Mars and Venus probes had
occurred a year earlier.)  Mars-3's autonomous guidance system put it onto
the right trajectory for the lander ejection, but then shut off the engine
much too early during orbit insertion -- leaving it in a very elongated Mars
orbit with a period of almost 13 days.

(4)  The hell with Mars Pathfinder being innovative -- the Soviet Mars
hard-landers used an absolutely identical system, except that they used a
20-cm layer of foam plastic rather than airbags for shock absorption.  (I
knew this for decades -- but I didn't know that the Soviet Moon hard-landing
capsules Luna-9 and 13 did use rubber airbags, and they were cancelled on
the Mars landers only because the final solid rocket motor that yanked the
capsule to a halt 16-30 meters above the Martian surface kept burning
through the airbags during tests.)

(5)  One free-lance Russian space analyst has earlier suggested that Mars-3
also crashed, and the Soviets announced that it worked briefly on the
surface before failing only so that they could get the official credit for
the first soft landing on Mars.  But Perminov insists that the official
story is true -- it did work for a few minutes, and that both facsimile
cameras transmitted brief slivers of photos that were completely blank gray,
presumably because of the gigantic global Mars dust storm at the time.  He
speculates that coronal discharges from that dust storm knocked out the
lander.

(6)  I knew from the start that the science instruments on the Mars-2 and 3
landers included two facsimile cameras, an atmospheric mass spectrometer,
and air temperature, pressure and wind sensors -- but at the time the
Soviets said only that they also carried "other instruments to study the
physical and chemical makeup of the Mars soil", and never said whether these
included life detection experiments.  It turns out that they didn't -- they
consisted of a X-ray spectrometer for soil elemental composition, and that
tiny rover to test soil mechanical consistency for the benefit of future
Soviet Mars rovers.  Perminov in one place seems to say that the rover
didn't include that gamma-ray densitometer -- a device that the Soviets had
taken to the Moon on Luna-13 -- and that instead there was a gamma-ray
spectrometer on one of the lander petals for more surface element data.  But
I think this is wrong; the very good photo of the lander on page 45 clearly
shows a deployable instrument (the X-ray spectrometer) on one petal, but no
instruments on the other three.

(7)  I already knew that the Soviets launched an epic four craft to Mars at
once in 1973 because the launch opportunity was worse and there was no way
to launch an orbiter and lander at the same time -- two flyby craft carried
the landers, and two orbiters would get there first to relay the landers'
signals back to Earth.  These missions and their instruments were very
similar to Mars-2 and 3 -- but the landers now included a second transmitter
to send back air temperature and pressure data and some engineering data
during actual descent.  (This included data on the operations of the
lander's mass spectrometer ion pump during descent -- and since this didn't
work as planned on Mars-6, it misled the Soviets into announcing at the time
that Mars' atmosphere must be extremely rich in argon.)  It turns out that
this second transmitter was Perminov's idea.

(8)  I knew that the 1973 Mars missions failed because of a flaw in the
design of their transistors; this was discovered long before launch, but
there was no time to replace all of them -- and since ground tests indicated
that any individual Mars craft had a 50% chance of succeeding even with this
problem, the government ordered the four craft launched anyway.  It turns
out that this was due to the fact that someone years earlier had the bright
idea of saving money on the transistors by replacing their gold with
aluminum and not testing them afterwards.  It also turns out that all
telemetry from Mars-6 failed only two months after launch for this reason --
but they could still get radio tracking data and send commands, and so the
main Mars-6 craft worked perfectly otherwise and sent its lander just where
it was supposed to be!  (The lander, however, crashed for unknown reasons --
the Soviets said at the time that contact was lost only 3 seconds before
planned touchdown, which leads me to believe that the final solid braking
rocket failed in some way.)  Transistor failures also led Mars-4 to fail to
fire its Mars orbit-insertion engine, and Mars-7's lander to fail to divert
itself onto a Mars impact trajectory after separating from the main
spacecraft.

(9)  Perminov also claims that he personally came up with the plan for the
unmanned Soviet lunar sample-return missions of 1969-76 -- since the lunar
soft-lander needed was already under development for the Lunokhod rovers.

(10)  He also confirms earlier reports that throughout the 1970s, the
Soviets were working on a huge (16 metric tons!) craft to return 200 grams
of Mars samples to Earth, which would have been launched by their N-1 manned
lunar mission rocket.  The return vehicle (in itself a modified version of
the Venera-4 craft!) would be launched into Mars orbit, and later blast
itself back onto an Earth trajectory (without any rendezvous attempt in Mars
orbit).  On earlier test flights, the lander would carry a large Mars rover
instead of the sample-return ascent vehicle.

After the N-1 program failed, the spacecraft was stripped down to weigh only
9.1 tons so it could be launched on two Proton upper stages automatically
docked in Earth orbit --but it soon became clear that the odds of success
were still small, and the behemoth was cancelled in 1978.  According to
earlier Russian documents, though, during its career this thing distracted
enough Soviet resources to seriously delay launch of the last Soviet lunar
sample-return mission (Luna-24), force cancellation of the launch of the
completed third Lunokhod, and reduce testing funds for the 1978 Venera-11
and 12 landers so that both their TV cameras and their X-ray spectrometer
systems for analyzing Venusian soil failed, and that mission had to be
reflown in 1982.

Bruce Moomaw


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