Balloon Landing System from Phobos to Mars

SpaceNut · 2020-05-22 20:28:09

valid image file extensions of png, gif, jpeg, bmp all work

The first is a search results page of yours that displays images for the key words.
http://www.bing.com/images/search?q=ima … ORM=IQFRBA

The second link was a web page showing the how to get a volume
https://www.chegg.com/homework-help/que … -q19029896

tahanson43206 · 2020-05-23 06:52:47

For SpaceNut re #76

Thanks for the clarification about how to set up images in FlubBB ...

Just FYI ... I have found the documentation for FluxBB to be difficult to use at best, and nearly impossible to use to find something specific like this.

I'll try to remedy the problem in ** this ** forum by making your post above easy to find:

SearchTerm:ImagePosting
SearchTerm:HowToPostImage

I've been thinking about the design of the shape for a metal cushion to fit between links of Kevlar thread for the tether from Phobos.

Overnight, I realized that the square cross section of the base of the two halves of the shape must be 2 meters square, instead of 1.

The objective is to provide 1 meter of space for the ribbon coming into the intersection from 90 degrees with respect to each other.

With a 2 meter diameter for the cylinder, the resulting shape would have the following characteristics:

Diameter: 2 meters
Length: 2 meters
Flange width: 1/2 meter
Ribbon track width: 1 meter
Flange height: 1/2 meter
Flange diameter: 3 meters

SearchTerm:RibbonCushionGuide
SearchTerm:RibbonGuideCushion

I'll try to work up a 3D image in the next week or two.

A contribution by another forum reader would be welcome.

As a suggestion for anyone thinking of registering for the forum to help with this project (or any discussion) ...

Please consider making a straight forward comment or suggestion about a topic you are interested in.

The great (vast) majority of applications for participation in this forum are spam artists, or just work-a-day spammers out to place advertisements.

In order for your application for membership to stand out, please make it relevant to whatever discussion you join.

We have need of additional assistance with (just about) every branch of engineering, science and the practical arts, such as agriculture, construction and hundreds if not thousands of other disciplines.

(th)

Last edited by tahanson43206 (2020-05-23 06:54:29)

tahanson43206 · 2020-05-25 11:36:26

Today I'm hoping to be able to show preliminary images of the design of a Cushion Guide to sit between links in a tether.

While the design is intended for the specific case of a Phobos tether, it could (presumably) be used anywhere a tether is needed.

If Lockbox displays an advertisement, please just dismiss it. They need to make a return on their free services, so an advertisement is part of the deal.

Above is a jpg version of a first draft of a Cushion Guide shape.

Since the image did not display, here is the url to the image: https://www.dropbox.com/s/17ok0h8kok961 … g.jpg?dl=0

Below is a png version of the shape, from a slightly different perspective.

Since the image did not display, here is the url to the image: https://www.dropbox.com/s/1d81a8pp0glgb … n.png?dl=0

The design shows empty space inside the form. That is an artifact of the method I used to create the object.

A future version should appear solid, as would be required for the tether application.

For purposes of the current study, the ribbon width is planned to be 1 meter, and the thickness will be dependent upon the number of threads needed to hold the tether and its load below that point. A program to compute the required thickness is in development.

Edit#1: Here is a version with a bit of texture added:

In case the image does not work, here is the url: https://www.dropbox.com/s/zp2gwu52bpjz7 … g.jpg?dl=0

Edit#1: SpaceNut has kindly provided the "secret" that allows FluxBB to display original content:

The ** secret ** is NOT to try to use the link provided by Dropbox, but instead, to follow the Dropbox link to their site, and right click on the image.

Then, ** save ** the url they provide, and post ** that ** inside the BBCODE [ i m g ] and [ / i m g ]

(th)

Last edited by tahanson43206 (2020-05-27 07:54:05)

SpaceNut · 2020-05-25 13:12:10

right click each image to get the properties of the image and select that for making them visible.

tahanson43206 · 2020-05-25 15:25:04

For SpaceNut re Demonstration in Post #79

Thanks for posting the command you used (in the Housekeeping topic)

I'll attempt to find a better site for storing images for display in the NewMars forum.

Continuing with discussion of the Cushion Guide design ...

I am planning to add solid attachment hardware to the shapes. Right now I'm thinking of symmetrical distribution of attachment hardware at the four corners where the flanges intersect. The attachment points would be used to secure light rail tracks which could be used by descending vehicles to maintain a steady rate of descent instead of plunging uncontrollably as would be the case if they were in free fall.

(th)

Last edited by tahanson43206 (2020-05-25 20:50:07)

tahanson43206 · 2020-05-26 08:29:25

This post is reserved for a report on progress planned for this Earth day:

1) Upload the Version 1.0 of the Cushion Guide shape to Shapeways and provide a link

This will pass the design through the strict software review at Shapeways, and provide a way to see the image by rotating it using their display tools.

2) Return to the tether design program, which has been waiting patiently for other higher priority tasks

The immediate objective is to complete a first version of the link builder, which will (if achieved) produce:

a) Length of thread needed to hold the burden below this link
b) Cumulative length of thread needed, starting with bottom most link
c) Mass of thread for this link
d) Cumulative mass of thread to this point

Detail: The computation of thread length is planned to be based upon a layer width of 1 meter, and thread diameter of 290 micrometers (Type #92 thread)

The radius of the wrap hub will be increased by 290 micrometers for each layer, to insure the length computation is correct.

The height of the flange is currently planned as 1/2 meter, so it will hold 1 meter / 290 micrometers or 3448 threads / 2 or 1724 layers

Each layer will hold 3448 * 2 * 13 kilograms or 89648 kilograms per layer using #92 Kevlar thread.

The mass of the payload needed by NASA is 40 Metric Tons.

A vehicle capable of delivering that mass safely to the surface of Mars is estimated to total 190 MT (using retro-propulsion) (see GW Johnson/Phobos topic)

Therefore the bottom most layer should be able to hold 190 MT plus its own mass plus a margin for safety.

The gravity pull of Mars is (about) 38% so the actual force exerted on the payload will be 72 MT and change

A single layer of Kevlar #92 thread can hold 89+ MT.

I think that two layers should provide a sufficient level of safety. The tether must not only hold the dead mass of the descent vehicle while the operator waits for a suitable release time, but also allow for transient extra tension due to braking loads imposed as the descent vehicle slows after rapid (controlled) descent.

Critical review of this set of computations is not only welcome but most definitely encouraged.

***
Here is a design detail that I need help to understand ...

My first concept for the material of the Cushion Guide was to make the entire structure of Aluminum (Atomic Weight ~27).

However, the atomic weight of Carbon (~12) is attractive, and the mass of the cushions is going to add up.

Carbon can be crushed down to the density of carbon, but I doubt that will happen in this application.

What form of Carbon would be suitable for a filling of an Aluminum shape as shown in earlier posts for the Cushion Guide?

Edit#1: As of the morning of 2020/05/27, attempts to merge a mounting slab with the existing Cushion Guide shape have not succeeded.

Work on the program has remained in pending status.

Edit#2: A pesky problem with how boolean logic works was (apparently) solved today, by breaking the problem into parts.

Two of four planned corner bumpers are now installed in the 3D model. I expect to finish later today.

(th)

Last edited by tahanson43206 (2020-05-27 09:05:55)

tahanson43206 · 2020-05-27 14:53:41

For SpaceNut (and anyone else who may be interested) ...

Update 2020/05/28 ... the links which worked (for me) yesterday are not working today.
Update later the same day ... now the links are working. Perhaps there was something going on at Dropbox.

Design of the Cushion Guide for the Phobos Tether is coming along. The design is not 3D printable at this point. However, the visual image comes close to showing what I have in mind.

Using the technique shown by SpaceNut, these three views of the model should show up:

CushionGuideVersion25 only appeared for a day.

Notes 1:
This view shows the guideway for the ribbon coming up from below. The width of the guideway is 1 meter. The height of the flange is 1/2 meter. The blocks at the corners are intended for mounting of auxilliary equipment, such as aluminum track for slowing the descending landing vehicle to prevent unwanted acceleration toward Mars.

CushionGuideVersion25 only appeared for one day.

Notes 2:
This overhead side view shows the guideway for the ribbon coming up from below, as well as the vertical rise for the ribbon descending from above. The blocks at the corners are intended for mounting of auxilliary equipment, such as aluminum track for slowing the descending landing vehicle to prevent unwanted acceleration toward Mars.

CushionGuideVersion25 only appeared for one day

Notes 3:
This view shows the guideway for the ribbon coming down from above, as well as the outer flange for the ribbon descending from above. The blocks at the corners are intended for mounting of auxilliary equipment, such as aluminum track for slowing the descending landing vehicle to prevent unwanted acceleration toward Mars.

(th)

Last edited by tahanson43206 (2020-05-31 07:26:16)

tahanson43206 · 2020-05-28 09:47:57

This post is an experiment to see if something happened at imgur.com

The path to the image included a subdirectory /a/ in the first use.

Today the path looks "normal"

Version 12 of CushionGuide

Perhaps imgur.com moved the image from a temporary directory to a permanent one.

Note for SpaceNut ... I also had to add .jpg to the link provided by imgur.com

Note#2 for SpaceNut ... I used the technique you suggested, of right clicking on the image as provided by imgur.com, and noticed .jpg was included.

For someone wanting to learn how to post images ... hang in there!

Edit#1: This post was included in an update on Luf.Org, about the Phobos Tether.

https://luf.org/2020/05/28/kevlar-tether-for-phobos/

(th)

Last edited by tahanson43206 (2020-05-28 10:16:29)

tahanson43206 · 2020-05-31 11:18:36

The image shown in post #83 was a first attempt. It is viewable but not 3D Printable.

I've started over, and made sure to pass the partial components through Shapeways before proceeding to the next step in assembly.

The stl of the model is available for free download to anyone with a 3D Printer who would like to participate in development of the Cushion Guide.

20200531CushionGuide11Half is the product you will find at the bottom of the shop.

https://www.shapeways.com/shops/tahanson43206

If you do not have a 3D printer, but would like to test the concept, you can order the part from Shapeways. Please note that shipping cost is greater than the cost of the part, which is only 2 centimeters in size (1:50 scale).

Edit#1: The model on view at Shapeways is NOT able to interlock as shown in the image in Post #83.

I'm working on a replacement. The image shown in Post #83 was/is unprintable because of complications caused by the use of boolean logic to join the two halves of the structure. The 2020/05/31 model passed muster with Shapeways confirmation software, but it did not start out with the right dimensions. A corrected version is in progress.

Edit#2: (2020/06/15) Two half sections of the CushionGuide arrived from Shapeways. They ** do ** interlock correctly!

I used a spot of glue to fuse the two halves. The resulting model can be used to show the concept for the cushion guide to an audience.

This model does NOT include the cubical corner elements which are intended to be incorporated in the complete design.

The complete design itself has been moved from Blender to Fusion 360 for addition of mounting holes for structural hardware.

(th)

Last edited by tahanson43206 (2020-06-15 07:14:51)

tahanson43206 · 2020-06-03 11:54:58

This is an update for #84

The challenge of creating 3D printer instructions for what would seem a simple shape turns out to be more significant than (I at least) had imagined.

There are only two shapes involved ... cylinders and cubes. There are only 7 pieces that need to be assembled.

The smaller parts are to be assembled to the Core Cylinder. Unfortunately, Blender runs into (or in my case, ran into) problems depending upon the sequence of boolean operations.

Today I succeeded in persuading the super critical software at Shapeways to accept a preliminary stage in development of the CushionGuide which has been the recent focus of this topic.

A view of the interim model is available here:
https://www.shapeways.com/product/C5XUU … 1&li=shops

The model can be downloaded in stl format if anyone is interested in tackling the next stage of the project as I attempt to do so.

Edit#1: If someone ** does ** look at the model, they will note that one end of the cylinder is sunken. This is another example of the (to me for sure) unpredictable consequences of attempting boolean logic with Blender.

The next stage of development is to bisect the model.

As part of the bisect operation, the defective section will be cut in half. It is possible repair may be possible at that point.

The ** trick ** will then be to join the two halves back to each other, after the duplicate is rotated on two axis to arrive at the needed form.

Meanwhile I have Fusion 360 running on a desktop, where performance is acceptable, but the learning curve for this Autodesk software is steep.

At a minimum, I've learned how to import the Blender output into Fusion 360 where I can look at it, but it will be some time before I understand how to do the simplest change.

(th)

Last edited by tahanson43206 (2020-06-03 12:05:48)

tahanson43206 · 2020-06-04 13:34:19

This is a brief report on an experiment with OpenSCAD.

To my surprise, the stl file from Blender, which was refused by Shapeways, was loaded into OpenSCAD using the Import command in the Editor window

I would like to thank Kevin McCormack for his helpful YouTube video on how to import an stl file into OpenSCAD.

2020/06/04 Screenshot of CushionGuide version 25 loaded into OpenSCAD

Edit#1: See Post 51 to put the CushionGuide in context. It fits between the links to protect the Kevlar thread by distributing forces as evenly as possible.

http://newmars.com/forums/viewtopic.php?id=9475&p=3

(th)

Last edited by tahanson43206 (2020-06-05 04:29:44)

Calliban · 2020-06-06 10:38:36

Given that Phobos is tidally locked and orbits only 5000km above the Martian equator, it should be possible to lower a high strength polymer cable all the way to the top of the Martian atmosphere. This would reduce the braking that the balloon would need to provide. Otherwise, a straight drop from 5000km would result in the balloon hitting the top of the Martian atmosphere at 5km/s. That is a lot of atmospheric heating for a thin balloon.

Mars has an ionosphere. One way of reducing the final velocity before hitting the sensible atmosphere, would be to use a superconducting loop to trap atmospheric ions in a magnetic field. Not sure how practical that would be compared to a conventional parachute.

Last edited by Calliban (2020-06-06 10:40:09)

tahanson43206 · 2020-06-06 11:05:35

For Calliban re #87

Thank you ** very ** much for your contribution to this topic.

By any chance, could you evaluate the use of aluminum as the material from which to make the CushionGuide as shown in post #86?

The initial load on the cushion guide will be 60 metric tons of mass at the 38% gravity of Mars, but the crushing burden will increase as the guides are installed every 10 meters from the lowest to the ones at Phobos. I am holding a program/calculator in readiness for further development, after I finish modeling the cushion guide. I have ** just ** succeeded in adding the fourth corner cube to the model, and am about to test the model to see if the solution is robust.

My concern is that aluminum may not have the strength to resist the forces which can be anticipated in the proposed design for a Phobos tether.

The reasons for the design have been given earlier in this topic, so i will not repeat them.

Thank you again for your helpful contribution!

(th)

Calliban · 2020-06-06 11:37:09

Previously, I can remember the idea being 'floated' :-) of a tethered hydrogen filled balloon on Mars with thin film solar cells on its upper surface. The idea was to tether it via a power cable to a ground vehicle and use the power from the solar cells to power an electric ground vehicle. Suitable for a vehicle that needs to shift a lot of mass at low speed. If a dust storm were to occur, the balloon could be deflated and would drop to the ground.

Last edited by Calliban (2020-06-06 11:38:13)

Calliban · 2020-06-06 11:39:20

tahanson43206 wrote:

For Calliban re #87
Thank you ** very ** much for your contribution to this topic.
By any chance, could you evaluate the use of aluminum as the material from which to make the CushionGuide as shown in post #86?
The initial load on the cushion guide will be 60 metric tons of mass at the 38% gravity of Mars, but the crushing burden will increase as the guides are installed every 10 meters from the lowest to the ones at Phobos. I am holding a program/calculator in readiness for further development, after I finish modeling the cushion guide. I have ** just ** succeeded in adding the fourth corner cube to the model, and am about to test the model to see if the solution is robust.
My concern is that aluminum may not have the strength to resist the forces which can be anticipated in the proposed design for a Phobos tether.
The reasons for the design have been given earlier in this topic, so i will not repeat them.
Thank you again for your helpful contribution!
(th)

Will look into this. I don't understand the concept at present, but will read through the past posts.

tahanson43206 · 2020-06-06 17:32:34

After a bit of experimenting, I've succeeded in persuading Blender to accept a request for four corners for the CushionGuide model.

The software appeared to hit a wall when I added three corners using boolean logic. The solution that eventually worked was to export the model from Version 2.79, and import it into version 2.58. Version 2.58 accepted the request to add a cube to the empty corner. However, as I study the model, I can see subtle differences in the locations of the cubes, but for purposes of showing the model, those differences are not significant. A model developed for implementation in a real tether would not be allowed to have such idiosyncrasies.

The images below were generated from inside Fusion 360:

Top view - looking at surface for ascending ribbon
The reason for those sturdy corner structures is they will be fitted with mounting holes for hardware (pipe, most likely) that will comprise the framework for mounting of track for vehicles, conduit for communications and communications, and protective sheathing to surround the tether to reduce damage caused by ultraviolet light and micrometeors, as well as lower grades of radiation.

End view of surface for ascending ribbon
The strength of Kevlar thread is such that a single layer of #92 thread, wound tightly across the 1 meter width of a CushionGuide, will support 89 metric tons or so. See earlier posts in this topic for details. However, at this stage of planning, it seems reasonable to provide a minimum of two layers for the lowest level link, and then to add layers as the safety margin is approached as links are added to the chain.

End view of surface for descending ribbon - slight asymmetry of corner cubes is visible

Opposite end of surface for descending ribbon - symmetry of corner cubes is visible.

(th)

Last edited by tahanson43206 (2020-06-07 08:30:37)

Void · 2020-06-13 11:43:49

(th), perhaps you could look at Titan, for your various balloon methods.

Deeper atmosphere, cold Nitrogen dominant, lower gravity.

Maybe something on your methods could prove useful.

Perhaps the heat of entry could warm the contents, and provide buoyancy. And of course you could use a lifting gas as well.

Last edited by Void (2020-06-13 11:45:17)

tahanson43206 · 2020-06-13 12:05:47

For Void re #92

Thank you for your interest in balloons!

Thank you for your encouragement of exploration of Titan! I agree that is a worthy goal, and hopefully your encouragement will reach other forum members.

However, ** this ** topic is about ONLY landing on Mars after departure from Phobos.

Perhaps SpaceNut can find a suitable already-existing-topic for development of your new interest?

For those who may be finding the forum, and this topic in particular for the first time, here is a re-statement of the focus of ** this ** topic:

tahanson43206 wrote:
This new topic is a branch from the work done by Void and friends in the Alternate Transportation topic.
The intention of this new topic is to provide a tight focus on design of a practical soft landing system for passengers and cargo at Mars.
The origins of the idea can be found in a series of posts which begin at the point where the following search string is stored:
SearchTerm:VoidsConjecture
SearchTerm:ConjectureofVoid

(th)

Last edited by tahanson43206 (2020-06-13 12:07:38)

tahanson43206 · 2020-07-10 13:35:48

A preliminary version of the Cushion Guide is available for study at Shapeways.com.

This version is the result of a large number of try/fail cycles.

Since the software at Shapeways is the ultimate judge of fitness of a 3D Printer design, it didn't matter that other software tools might have shown that earlier attempts might have shown the models were (apparently) acceptable.

https://images1.sw-cdn.net/product/pict … 409082.jpg

Boolean logic was the challenge in this case. It turns out there are many ways to make a model incorrectly using boolean logic.

I'm sure I've only seen a tiny fraction of the possible errors.

The successful sequence included use of a slicer called PrusaSlicer, which was able to cut a draft of the model in half, thus removing a great number of the debris left behind by boolean operations.

However, the join operation that appears to have put the model into the winning collection is use of a thick base in the cut.

The half model (with the thick base) was duplicated, inverted, rotated and then set precisely in the workspace so that the bases exactly overlapped.

Boolean Union then delivered a model with only a few loose vertices and edges to clean up, and Shapeways accepted the result.

The next steps are relatively minor in comparison, and I'm hoping to have those completed by the weekend.

(th)

tahanson43206 · 2020-07-12 08:16:13

This post is part of one offered in RobertDyck's Large Scale Colonization Ship topic ...

The discussion of the benefits that flow from the momentum of Phobos started with a post by Terraformer:

For Terraformer re #144 ... thanks for picking up on the (to me obvious) use of Phobos as a momentum bank.
It is good for at least 2 km/s for any imaginable size vehicle seeking to match orbit with Mars.
Recently GW Johnson has provided additional figures to show the potential of that application, but I am still working on a tether system for Phobos and have not had time to look at them.
One complication for a spacecraft navigator is that the momentum benefit is maximized if the navigator can plot a course that brings the ship into the Korolev crater on Phobos ** just ** when Phobos is in maximum retreat in its orbit. Once safely "docked" inside the crater, the ship will be accelerated by Phobos as it swings around Mars. At the end of the several hour acceleration, the ship will be moving at the same velocity as Phobos, which will be 2 km/s faster than when it arrived.
(th)

Another navigation consideration for a ship plotting a course to land on Phobos is the axial tilt of Mars, which is on the order of 25 degrees. While the orbit of Phobos itself is (very close to) equatorial, the plane of the orbit of Phobos (equatorial Mars) will be shifting (with respect to the arriving spacecraft) so the navigator will have to adjust impulse direction and duration to compensate.

The goal in any case will be to achieve the maximum possible momentum benefit from a docking with Phobos at precisely the right time.

(th)

tahanson43206 · 2020-07-16 08:42:56

A model of a Space Tether Cushion Guide is available for study at Shapeways:

https://www.shapeways.com/product/3CEMT … 2&li=shops

The model shown is 1:100 scale. It is offered with the option to download the stl for anyone who has a 3D Printer and would like to make a chain of these for a science fair project. Ordinary thread can be substituted for the Kevlar thread, for purposes of demonstration of the engineering principles involved.

There is a need for development of robotic "spiders" to wind Kevlar thread around the cylindrical guides, and fortunately there are plenty of young Earth humans who are studying robotics with expectation of earning a living by designing them, as well as manufacturing, maintaining, configuring and selling them.

Edit#1: The initial render of the model was free of defects. However, the render for customer viewing shows gaps in the walls which have been a problem all along.

Edit#2: I set the Solidify parameter to .2 instead of .1 and the display at Shapeways is improved but not perfect:

https://www.shapeways.com/product/A7EX7 … 8&li=shops

Edit#3: As a reminder, here is an image of a plastic chain, that is similar in form to the proposed Phobos Tether:
http://newmars.com/forums/viewtopic.php … 85#p168285

Edit#4(2020/07/23) A cushion guide model arrived from a 3D Printer service bureau. The volume of the model (1:100 scale) is 15 cc.

The full scale version of the cushion guide would have a volume of 15 cubic Meters.

For comparison, a sphere with radius 1.5 with have a volume of 14.13717 (per Google).

Again for comparison, a cube with a side of 2.47 meters will have a volume of 15 cubic Meters.

From Google:

2 699 kilogram
Aluminum weighs 2.699 gram per cubic centimeter or 2 699 kilogram per cubic meter, i.e. density of aluminum is equal to 2 699 kg/m³; at 20°C (68°F or 293.15K) at standard atmospheric pressure.
Aluminum volume to weight conversion - aqua-calc

The mass of Aluminum that can be expected for a full sized Cushion Guide would be 40,485 kilograms.

However, that mass will be attracted to Mars by an amount that depends upon the distance of the Cushion Guide from the center of Mars, but in any case will be less than:

3.711 m/s²

per Google.

SearchTerm:MassOfCushionGuide
SearchTerm:CushionGuideMass

Edit#1 (2020/07/24) The mass of a cushion guide will be fixed, but the pull of gravity of Mars will decrease (slightly) as the distance from the center of Mars increases. This slight decrease in the "weight" of the cushion guide will be included in the computation of strain on a cushion guide at a particular elevation, which will allow computation of the number of Kevlar threads needed to support the tether below that point.

As a reminder, each #92 Kevlar thread can support 13 kilograms. I am looking forward to seeing how a calculation of windings turns out.

(th)

Last edited by tahanson43206 (2020-07-24 05:00:50)

tahanson43206 · 2020-08-03 14:25:57

There is a procedure for software development called "Agile"

It arrived on the scene after I was active in the field, so I'm trying to understand it from the perspective of an audience member at presentations. I ** think ** it involves tackling software development projects in small chunks that last a week or two, and result in a state of the project that the customer can evaluate.

This post is to report on partial progress toward development of a utility program to compute the requirements for the individual links in a Kevlar chain that would make up a tether between Phobos and the location above Mars just above the atmosphere.

In a separate series of activities, the design of a cushion to sit between loops of Kevlar thread was completed. With the completion of the design, the mass of the fixture could be estimated, so development of the software can proceed.

The image above shows tentative default values in input fields.

(th)

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#76 2020-05-22 20:28:09

Re: Balloon Landing System from Phobos to Mars

#77 2020-05-23 06:52:47

Re: Balloon Landing System from Phobos to Mars

#78 2020-05-25 11:36:26

Re: Balloon Landing System from Phobos to Mars

#79 2020-05-25 13:12:10

Re: Balloon Landing System from Phobos to Mars

#80 2020-05-25 15:25:04

Re: Balloon Landing System from Phobos to Mars

#81 2020-05-26 08:29:25

Re: Balloon Landing System from Phobos to Mars

#82 2020-05-27 14:53:41

Re: Balloon Landing System from Phobos to Mars

#83 2020-05-28 09:47:57

Re: Balloon Landing System from Phobos to Mars

#84 2020-05-31 11:18:36

Re: Balloon Landing System from Phobos to Mars

#85 2020-06-03 11:54:58

Re: Balloon Landing System from Phobos to Mars

#86 2020-06-04 13:34:19

Re: Balloon Landing System from Phobos to Mars

#87 2020-06-06 10:38:36

Re: Balloon Landing System from Phobos to Mars

#88 2020-06-06 11:05:35

Re: Balloon Landing System from Phobos to Mars

#89 2020-06-06 11:37:09

Re: Balloon Landing System from Phobos to Mars

#90 2020-06-06 11:39:20

Re: Balloon Landing System from Phobos to Mars

#91 2020-06-06 17:32:34

Re: Balloon Landing System from Phobos to Mars

#92 2020-06-13 11:43:49

Re: Balloon Landing System from Phobos to Mars

#93 2020-06-13 12:05:47

Re: Balloon Landing System from Phobos to Mars

#94 2020-07-10 13:35:48

Re: Balloon Landing System from Phobos to Mars

#95 2020-07-12 08:16:13

Re: Balloon Landing System from Phobos to Mars

#96 2020-07-16 08:42:56

Re: Balloon Landing System from Phobos to Mars

#97 2020-08-03 14:25:57

Re: Balloon Landing System from Phobos to Mars

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