IPB

Welcome Guest ( Log In | Register )

6 Pages V  « < 3 4 5 6 >  
Reply to this topicStart new topic
Viking '75 Mars Lander Construction, Looking for Viking lander design/construction information
climber
post Apr 2 2020, 08:49 PM
Post #61


Senior Member
****

Group: Members
Posts: 2917
Joined: 14-February 06
From: Very close to the Pyrénées Mountains (France)
Member No.: 682



QUOTE (mcaplinger @ Apr 2 2020, 08:46 PM) *
Over on nasawatch it's being claimed that the NASA worm logo appeared on the Viking lander, but I couldn't find any evidence of this. Bicentennial logo, yes, Viking patch logo, yes, American flag, yes, but no obvious worm. Maybe there's a small one on the patch? I couldn't find any high-res images of the patch as it appeared on the lander. Anyone know?

What about a PM message to Olivier? I mean Vikingmars


--------------------
Go to the top of the page
 
+Quote Post
atomoid
post Apr 2 2020, 10:13 PM
Post #62


Member
***

Group: Members
Posts: 866
Joined: 15-March 05
From: Santa Cruz, CA
Member No.: 196



its already April 2nd, so what the heck is the NASA "worm" logo? so i found this arstechnica article. This NASA article says it was used from 1975 to 1992, so guessing everything on the lander would have been finalized before then, so no probably not on Viking hardware.

Go to the top of the page
 
+Quote Post
Tom Dahl
post Apr 2 2020, 10:57 PM
Post #63


Member
***

Group: Members
Posts: 101
Joined: 3-May 12
From: Massachusetts, USA
Member No.: 6392



As far as I know, the NASA "worm" logo did not appear on the Viking landers. As mentioned, the wind covers for the two Radioisotope Thermoelectric Generators on each lander sported an American flag, the US Bicentennial logo, and the patch designed by Peter Purol. The Proof Test Capsule lander at the Smithsonian National Air and Space Museum has a good representation of the Flight wind cover decorations:
Attached Image

Here is better view of Peter's patch (which reveals no worm logo):
Attached Image
Go to the top of the page
 
+Quote Post
Tom Dahl
post Jul 8 2020, 12:02 PM
Post #64


Member
***

Group: Members
Posts: 101
Joined: 3-May 12
From: Massachusetts, USA
Member No.: 6392



I have completed a 22-minute video that describes the Viking lander's three communications antennas in detail (UHF relay antenna for transmitting to either Viking orbiter, S-Band Low Gain Antenna for direct reception from Earth, S-Band High Gain Antenna for direct transmission and reception to/from Earth). I hope that people find it interesting.
Go to the top of the page
 
+Quote Post
Tom Dahl
post Apr 18 2021, 02:42 AM
Post #65


Member
***

Group: Members
Posts: 101
Joined: 3-May 12
From: Massachusetts, USA
Member No.: 6392



The latest addition to my work-in-progress Viking '75 Mars lander 3D digital model is the propellant- or fuel-system tanks, valves, piping, and the MR-50F roll-control thrusters that are mounted on the fuel tanks. The digital model is freely available via DropBox as a SketchUp SKP model file.
Attached Image

Attached Image

Attached Image

The following montage compares the 3D model with the test lander at the Virginia Air and Space Science Center. That unit has slightly different piping compared to the two Flight landers, and it is missing the 1/4-inch serpentine line that connects the two roll-control thrusters on each fuel tank.
Attached Image
Go to the top of the page
 
+Quote Post
Tom Dahl
post Apr 18 2021, 02:53 AM
Post #66


Member
***

Group: Members
Posts: 101
Joined: 3-May 12
From: Massachusetts, USA
Member No.: 6392



Here are detailed views of the MR-50F roll-control thrusters, made by Rocket Research Company (now part of Aerojet Rocketdyne), with solenoid valves by Parker Hannifin. The thrusters were used during the final minute of landing on Mars to orient the lander such that it would point in a desired azimuth in its landed location to optimize mid-day solar illumination in "front" of the lander where the two cameras had best coverage of the Mars surface.
Attached Image

Attached Image

Attached Image

Attached Image
Go to the top of the page
 
+Quote Post
Tom Dahl
post Apr 18 2021, 03:08 AM
Post #67


Member
***

Group: Members
Posts: 101
Joined: 3-May 12
From: Massachusetts, USA
Member No.: 6392



Here are details of the pair of main valves on each of the lander's two fuel tanks. First the valves and lines for fuel tank 1:
Attached Image

The valves and lines for fuel tank 2:
Attached Image

And details with exploded view of the main valve pair on fuel tank 1 (the main valves on fuel tank 2 are inverted from this arrangement). The valve on the right (upright T) is Normally-Open (NO), allowing fuel to flow through the 0.75 inch fuel line (tube) leading from the bottom of the fuel tank. When pyrotechnically triggered, the NO valve will permanently close, blocking the flow of fuel upon landing. The valve on the left (inverted T) is Normally-Closed (NC), preventing fuel from flowing from the tank toward the lander's three Terminal Descent Engines (TDEs). When pyrotechnically triggered, the NC valve will permanently open, allowing the flow of fuel to reach the TDEs during descent to Mars. During the mission the NC valve triggers first, opening to allow fuel to flow (through the already-open NO valve and then the now-open NC valve). At landing, the NO valve triggers second, closing to ensure the TDEs shut down.
Attached Image
Go to the top of the page
 
+Quote Post
Tom Dahl
post Oct 23 2021, 12:38 AM
Post #68


Member
***

Group: Members
Posts: 101
Joined: 3-May 12
From: Massachusetts, USA
Member No.: 6392



I have been adding some major internal components to the Viking '75 Mars lander 3D digital model, including the large Equipment Plate that spans most of the upper interior of the lander. The Equipment Plate is a one-piece aluminum machined unit which is supported by nine titanium fittings attached to the sides of the lander body. Most of the lander's interior equipment (batteries, power control, tape recorder, science instruments, computer, communications assemblies) are bolted to the bottom surface of the Equipment Plate and hang down below it within the volume of the lander body. Here is an overall view of the lander body and equipment plate, without the lander's top dust cover.
Attached Image

Here is an above view of the equipment plate and attached components, including those nine titanium support fittings arranged around the plate's perimeter. The little red cylinders are standoffs to support the lander body top dust cover.
Attached Image

Here is a below view of the equipment plate, which is relatively plain. It does show the portion of the serpentine coolant loop which was attached to the underside of the plate. The coolant loop was used prior to launch to circulate chilled water around the lander's two Radioisotope Thermoelectric Generators (RTGs), which produced more excess heat under Earth seal-level conditions than the lander was designed to sustain. As seen here, the loop also traveled around the equipment plate to reduce internal lander temperatures.
Attached Image

Here is a detail view of one of the two camera mount adapters bolted to the top of the equipment plate, to which a camera was attached on top of the lander (this is the mount for camera #1). The little red fasteners are Hi-Lok collars, a specialized type of nut that was used extensively in assembling the lander. The collars work with Hi-Lok pins, a type of bolt. Along with a special installation tool, the Hi-Lok pins and collars can be installed in situations with limited access to the bolt-side of the fastener. The tip of the pin has a hex recess; the installation tool uses this to prevent the pin from rotating when the collar is tightened.
Attached Image

This detail view shows a small tripod and bipod attached to the equipment plate's upper surface. These supported the inboard side of RTG #2; the outboard side was supported by the upper edge of the adjacent lander body side beam (not shown in this image, but visible in the first image above). A similar tripod-bipod pair for supporting RTG #1 is located across the equipment plate.

Attached Image
Go to the top of the page
 
+Quote Post
vikingmars
post Oct 25 2021, 10:02 PM
Post #69


Senior Member
****

Group: Members
Posts: 1078
Joined: 19-February 05
From: Close to Meudon Observatory in France
Member No.: 172



QUOTE (Tom Dahl @ Oct 23 2021, 02:38 AM) *
I have been adding some major internal components to the Viking '75 Mars lander 3D digital model, including the large Equipment Plate that spans most of the upper interior of the lander. The Equipment Plate is a one-piece aluminum machined unit which is supported by nine titanium fittings attached to the sides of the lander body. Most of the lander's interior equipment (batteries, power control, tape recorder, science instruments, computer, communications assemblies) are bolted to the bottom surface of the Equipment Plate and hang down below it within the volume of the lander body. Here is an overall view of the lander body and equipment plate, without the lander's top dust cover.

Here is an above view of the equipment plate and attached components, including those nine titanium support fittings arranged around the plate's perimeter. The little red cylinders are standoffs to support the lander body top dust cover.

Here is a below view of the equipment plate, which is relatively plain. It does show the portion of the serpentine coolant loop which was attached to the underside of the plate. The coolant loop was used prior to launch to circulate chilled water around the lander's two Radioisotope Thermoelectric Generators (RTGs), which produced more excess heat under Earth seal-level conditions than the lander was designed to sustain. As seen here, the loop also traveled around the equipment plate to reduce internal lander temperatures.

Here is a detail view of one of the two camera mount adapters bolted to the top of the equipment plate, to which a camera was attached on top of the lander (this is the mount for camera #1). The little red fasteners are Hi-Lok collars, a specialized type of nut that was used extensively in assembling the lander. The collars work with Hi-Lok pins, a type of bolt. Along with a special installation tool, the Hi-Lok pins and collars can be installed in situations with limited access to the bolt-side of the fastener. The tip of the pin has a hex recess; the installation tool uses this to prevent the pin from rotating when the collar is tightened.

This detail view shows a small tripod and bipod attached to the equipment plate's upper surface. These supported the inboard side of RTG #2; the outboard side was supported by the upper edge of the adjacent lander body side beam (not shown in this image, but visible in the first image above). A similar tripod-bipod pair for supporting RTG #1 is located across the equipment plate.

What a GREAT work ! Thank you so much Tom smile.gif
Go to the top of the page
 
+Quote Post
Tom Dahl
post May 19 2022, 10:39 PM
Post #70


Member
***

Group: Members
Posts: 101
Joined: 3-May 12
From: Massachusetts, USA
Member No.: 6392



The next Viking lander component 3D models to be completed represent the lander's two thermal switches, which were mounted on the upper surface of the lander's Equipment Plate (the subject of my prior post above). The thermal switches are seen here as green-tinted boxy objects (the contactor assembly) connected to horizontal cylinders (the actuator assembly), on the left and right sides of the rendering. The green coloration represents the fact that I don't have exact measurements for these components.
Attached Image

The purpose of each thermal switch was to permit and regulate the transfer of heat from the Radioisotope Thermoelectric Generator (RTG, not shown) mounted directly above the switch contactor assembly, into the lander interior. The near-surface atmospheric temperature of Mars, as measured by the Viking landers, varied from about 1F during a summer day to -178F during a winter night. Most of the lander's components, including electronics and especially its rechargeable batteries, would not survive well-below-freezing temperatures. The RTG's housing exterior was at a fairly steady temperature of about 330F (thanks to the natural radioactive decay of plutonium contained in the RTG's internal fuel capsule), and the lander was designed to utilize that heat to maintain adequate internal temperatures. During cold periods the thermal switch actuator would close the thermal switch, forming a thermally-conductive path between the bottom of the RTG and the lander's internal Equipment Plate. During relatively warm periods, the actuator would open the switch, interrupting the high-conductivity path and allowing relatively little heat to flow into the lander.

When the RTGs were installed onto the landers prior to launch, Earth's relatively dense sea-level atmosphere provided an excess of available heating during the final months prior to launch. Even with the thermal switches open, there was too much heating. Therefore, a coolant loop was incorporated into the lander which circulated chilled water through End Cap Coolers mounted on top of and below each RTG. The top side of the thermal switch contactor assembly was hard-bolted to the underside of the corresponding RTG's lower End Cap Cooler. The bottom of the contactor assembly was hard-bolted to a platform machined into the Equipment Plate.

Here is a cut-away view of a thermal switch with actuator assembly on the left and contactor assembly on the right, connected via a linkage that transmitted the horizontal movement of a piston within the actuator to the contactor.
Attached Image

Here is an exploded view of a thermal switch. The brown objects in two stacks at center are 0.001 inch thick copper foils, 100 per stack. These foils are the core of the conductive path. In the assembled thermal switch, the stacks are interleaved forming a 200-foil group (visible in the middle of the exploded contactor on the right). The foils are bonded together where they overlap at center, and also at their ends, forming a cross with short flexible arms.
Attached Image

Here is a close-up of the cut-away actuator assembly. Freon gas filled the volume surrounding the two bellows chambers. When warmed, the freon expanded and pushed the central piston to the right. The piston pushed the linkage rod which connects the actuator to the contactor via clevises at both linkage ends.
Attached Image

Here are close-up cut-away views of the contactor assembly, first showing the closed configuration and then as opened. The central area of the stack of copper flexible foils is moved up (when closed) and down (when open) via a bellcrank driven from the actuator assembly by the linkage rod. A layer of highly-conductive tin is cast on top of the foil stack. When the switch is closed, the tin "seat" presses hard against the underside of a very thick block called the platten (at top-center of the images, with a vertical thread hole). The platten is hard bolted to the lower End Cap Cooler, upon which is mounted the hot RTG housing itself. Heat from the RTG flows downward through the lower End Cap Cooler, the platten, the tin seat, and into the center of the stack of copper foils. The heat then flows sideways through the flexible foil arms and into the boxy lower base (tinted green, across the center of the image) of the contactor assembly. Because the base is hard-bolted to the Equipment Plate, heat flows into the plate and spreads throughout the upper part of the lander interior. The lander's internal temperature-sensitive components (computer, batteries etc.) are bolted to the underside of that plate and therefore receive heat.

When the switch is opened the central portion of the stack of copper foils moves downward, causing the tin seat to pull away from the bottom of the platten. While the platten remains permanently warm (as the RTG's plutonium fuel slowly decays over decades), relatively little heat is radiated from the platten to the seat and foils. The switch provides an effective 50:1 heat conductance ratio when closed vs. opened.

Attached Image
Attached Image

Lastly, here is an view of the underside of a thermal switch when mounted on the Equipment Plate.
Attached Image
Go to the top of the page
 
+Quote Post
scalbers
post Jan 2 2023, 07:43 PM
Post #71


Senior Member
****

Group: Members
Posts: 1621
Joined: 5-March 05
From: Boulder, CO
Member No.: 184



Here are a few recent photos of the spare flight qualified lander VL3, being prepared for exhibit at a museum in Oregon:

https://www.facebook.com/VikingMarsMission/...27767297535052/


--------------------
Steve [ my home page and planetary maps page ]
Go to the top of the page
 
+Quote Post
Tom Dahl
post Jan 3 2023, 12:31 AM
Post #72


Member
***

Group: Members
Posts: 101
Joined: 3-May 12
From: Massachusetts, USA
Member No.: 6392



Indeed the Flight Capsule 3 or FC3/VL3 backup lander has moved from The Museum of Flight in Seattle where it was exhibited for many years, now to be exhibited at the Evergreen Aviation and Space Museum in McMinnville, OR. Hopefully the exhibit presentation will be informative and the lander will be as accessible as possible.

For what it's worth, I have visited the FC3 lander a number of times while it was exhibited at The Museum of Flight, including a visit with permission of the unit's owner (the Viking Mars Missions Education and Preservation Project) and supervision by Museum staff that allowed me to capture many detailed measurements of various lander components. I have also taken hundreds of high-resolution detailed photographs of the unit, available in this Google Photos album.
Go to the top of the page
 
+Quote Post
BYEMAN
post Jan 3 2023, 12:48 AM
Post #73


Junior Member
**

Group: Members
Posts: 29
Joined: 7-February 14
Member No.: 7125



Just wondering if anybody has come across a document(s) for the lander equivalent to "Viking 75 Orbiter System and Launch Operations Final Report". With emphasis on the launch operations.
Go to the top of the page
 
+Quote Post
Tom Dahl
post Jan 4 2023, 02:46 AM
Post #74


Member
***

Group: Members
Posts: 101
Joined: 3-May 12
From: Massachusetts, USA
Member No.: 6392



QUOTE (BYEMAN @ Jan 2 2023, 07:48 PM) *
Just wondering if anybody has come across a document(s) for the lander equivalent to "Viking 75 Orbiter System and Launch Operations Final Report". With emphasis on the launch operations.

I'm not sure what kind of document focusing on the lander would be a good equivalent. There is the "Viking Lander System Primary Mission Performance Report" by Martin Marietta. My copy is packed away due to a recent move but the scanned copy linked above on the NASA Technical Reports Server will reveal its full contents. There is also Martin Marietta's "Viking Lander `As Built` Performance Capabilities" which contains details about the actual capabilities of various lander systems (exact ratio transmitter powers, for example) but from memory (my copy is packed away) there is not a lot concerning launch. I have not found a copy on-line, so I'm sorry I can't help much in showing the document's content. I also have a copy of the two-volume document by General Dynamics "Viking AEC Safety Study, Phase I (Launch Vehicle Hardware, Launch Complex and Trajectory Data)" and "Viking AEC Safety Study, Phase II (Range Safety Equipment, Launch Pad Hazards, Launch Vehicle Failure Probabilities, and Reentry Environment)". These contain very detailed technical information for the Atomic Energy Commission (AEC) that addresses safety issues related to the Viking lander's plutonium-powered Radioisotope Thermoelectric Generators (RTGs).

The above documents plus others in my collection are informally catalogued in this Google Photos album. That catalog is out of date by a couple of years (I got lazy updating it as I acquired more material) but I don't have anything newer relating to the launch phase of the mission.
Go to the top of the page
 
+Quote Post
Tom Dahl
post Jun 7 2023, 12:55 PM
Post #75


Member
***

Group: Members
Posts: 101
Joined: 3-May 12
From: Massachusetts, USA
Member No.: 6392



I have recently completed modeling the Viking lander’s two Radioisotope Thermoelectric Generators (RTGs). Here are some overall views:
Attached Image
Attached Image

Here is an overall cut-away view of the RTG:
Attached Image

The RTGs are a Viking-specific variant of the SNAP-19 type which was used on earlier spacecraft (Nimbus III, Pioneer 10 and 11). SNAP is an acronym for System for Nuclear Auxiliary Power, which is a series of generators stretching back to the 1950s. Odd-numbered SNAP designs convert the heat of natural radioisotopic decay directly into electricity. Even-numbered designs contain a nuclear reactor in which a radioisotope undergoes accelerated nuclear fission; the resulting heat is converted into electricity in a variety of means.

The Viking SNAP-19 RTGs were fueled with Plutonium 238 in the form of Plutonium Dioxide Cermet (rather than the more hazardous pure Plutonium 238 metal), which is 83% PuO2 and 17% Molybdenum. The fuel was shaped into 18 discs or pucks, seen on the far left in the following exploded views:
Attached Image

Attached Image

The RTG has no moving parts and is completely passive with no means of control. It weighs about 34 pounds and is a bit over 15 inches high (including the dome on top). The span of the six cooling fins is 23 inches across opposite pairs. There are 20,600 curies of fuel (equivalent to a few pounds) sufficient to generate 682 thermal watts from the heat of natural radioactive decay at the time of fueling (which was some nine months prior to launch). At the beginning of the mission the RTG produced about 42 watts of electricity at 4.4 volts DC. The conversion is quite inefficient but the generator has extreme reliability and robustness, and the excess heat was critical to the mission (heating the lander’s interior electronic components).

Electricity is generated via the thermoelectric effect, by which a temperature differential across a thermoelectric couple produces electricity. In the SNAP-19 generator there are a total of 90 thermoelectric conversion couples, each consisting of a P-leg and an N-leg:
Attached Image

The P-leg materials are 15% a mix of Tellurium, Antimony, and Silver, and 85% a mix of Germanium and Tellurium, given the designation TAGS-85, plus a Tin-Tellurium segment on the hot side (on the right in the above image). The N-leg materials are a Lead-Tellurium mix designated 3M-TEGS- 2N(M).

The 90 couples are grouped into six thermoelectric conversion modules of 15 couples each. The following image shows two of the modules in exploded views:
Attached Image

The couples are connected by copper straps. Pairs of couples are connected in parallel, and the pairs are connected in series. The couples in adjacent modules are interconnected by #9 gauge wires, forming a partial hex pattern above and below the RTG core that is visible in the overall exploded views. The full hex wire below the core is a magnetic compensation loop. The hot shoe (inboard end) of each couple is up against the graphite heat shield surrounding the fuel capsule (actually separated from the heat shield via a thin mica sheet for electrical insulation). The temperature of the heat shield surface - forming the hot side of the couple - is about 950F (about 510C). To maximize the temperature differential across the thermoelectric couples, a set of “cold end” hardware provides a thermally conductive path from the copper interconnect straps (which are soldered to the outboard ends of the P- and N-legs of the couples) to the relatively cool exterior RTG housing. The temperature of the exterior housing at the root of each of the six large cooling fins - which are directly adjacent to the six aluminum heat sink bars - is typically about 330F (about 160C).

Starting from the moment of assembly, the RTG power output gradually decreased due to a number of factors:
  • Reduction in the RTG core temperature due to decay of the Plutonium fuel, reducing the temperature differential across the thermoelectric couples and thus the efficiency of the thermoelectric conversion process. With a half-life of about 88 years, this was actually not a significant factor during the expected single-digit-years lifetime of the mission.
  • Sublimation loss of material from the thermoelectric conversion components due to continuous exposure to high heat.
  • Increase in Helium gas within the RTG (produced spontaneously by decay of the Plutonium fuel). Helium has a relatively high thermal conductivity, which lessened the temperature difference across the thermoelectric couples and reduced their efficiency.

The effect of the Helium buildup was partly counteracted by a novel solution. The prominent dome on top of the generator, seen in section view in the following image, is a sealed reservoir filled with a 95% Argon / 5% Helium mix at assembly.
Attached Image

The generator’s cylindrical body was filled with a 90% Helium / 10% Argon mix. The initial high Helium fraction within the generator body was deliberately chosen to reduce the beginning-of-life power output. The months-long series of final RTG tests and storage prior to launch in Earth’s warm dense sea-level atmosphere would otherwise have produced RTG temperatures higher than desired. During cruise to Mars (in vacuum) and on the Mars surface (in a very cold low-pressure atmosphere) a higher energy conversion rate - and thus higher temperature differential - was wanted. The interface between the RTG body and reservoir dome was sealed as described earlier, but with an intentionally leaky seal. A dummy electrical receptacle with a Viton O-ring seal was installed between the body and dome. The dummy receptacle is the threaded object at top center of the ribbed RTG upper cover in the above section image. The O-ring permitted an extremely slow but effective gas exchange between RTG body and reservoir, raising the fraction of Argon (which is less thermally conductive than Helium) in the RTG and improving power generation.

A great deal of effort was applied to mitigate risks of Plutonium fuel release that might occur due to launch accidents (explosions) or unintended spacecraft reentry into Earth’s atmosphere (if the booster rocket did not impart sufficient Earth-escape launch velocity). The following cut-away image shows the RTG’s “heat source” (as the encapsulated plutonium fuel assembly was termed) in close-up:

Attached Image

To mitigate the effect of physical shocks and impacts, the fuel stack (olive-drab pucks) was encapsulated in a four-layer metal capsule consisting of the following, from inner to outer:
  1. Inner Liner made of a Molybdenum-46% Rhenium alloy, 0.009 inch thick. This is formed of two slip-fit overlapping shells, in direct contact with the Plutonium fuel. (In order to exactly fill the volume of the capsule, Molybdenum shims were placed as needed between fuel pucks. The fuel capsule I modeled, VF-3, has five such shims, three of which are visible.)
  2. Liner made of a Tantalum-10% Tungsten alloy, 0.020 inch thick. This layer is welded closed and provides the main decontamination and health-physics encapsulation for the fuel.
  3. Strength Member made of T-111, a Tungsten-8% Hafnium-2% Tantalum alloy, 0.090 inch thick. This layer provides the primary impact resistance necessary in case the overall RTG or a separated fuel capsule fell from a great height onto a hard surface.
  4. Capsule Clad made of a Platinum-20% Rhodium alloy 0.018 inch think, providing an oxidation barrier during capsule handling. Handling difficulties were exacerbated by the fact that the capsule’s outer surface was thermally very hot - nearly 1400F (about 760C). (The core of the Plutonium was almost 1900F, 1040C.)

To mitigate the extreme heating that could occur if the RTG were to reenter the Earth’s atmosphere at nearly orbital speeds, the above capsule was first enclosed in three pyrolytic graphite sleeves, and then within a large hexagonal heat shield made of AXF-Ql fine grained isotropic Poco graphite, enclosed on both ends with graphite caps attached via stub Acme threads. The graphite is tolerant of extreme heating. In fact two earlier-version SNAP-19B RTGs were inadvertently subjected to moderate re-entry conditions when the NIMBUS B-1 spacecraft to which they were attached suffered a launch abort about one minute after liftoff in May 1968. The RTG housings were completely destroyed, but the heat sources were found and recovered from the Pacific ocean floor in October 1968 and examined in detail. The graphite heat shields were essentially intact.

The SNAP-19 Viking RTG is marvelously simple in principle but subtly designed for extreme reliability.
Go to the top of the page
 
+Quote Post

6 Pages V  « < 3 4 5 6 >
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 28th March 2024 - 12:53 PM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is funded by the Planetary Society. Please consider supporting our work and many other projects by donating to the Society or becoming a member.