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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
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Following up on Post #1:
A direct link to the discussion in Void's topic is: http://newmars.com/forums/viewtopic.php … 69#p167469
Edit#1: 2020/05/09
An attractive option for launching balloon landing packages from Phobos is EML (ElectroMagnetic Launch)
This idea goes back decades, and it has been developed into a working system by General Atomics under contract to the US Navy.
A working system is installed on the Gerald R. Ford, where it launches aircraft in a distance of (about) 150 feet at (about) 2.5 G's.
The Orbital velocity of Phobos is given (See Google) as 2.138 km/second.
Physics 101 (a utility physics calculator program) gives a distance of 93,500 meters for a 2.5 G launch to 2,140 meters per second.
Phobos itself is much smaller than that distance, so the launcher would have to be constructed and positioned so that it sends its payloads directly aft of Phobos in its path around Mars. A detail to be resolved is whether Phobos holds steady in its motion about Mars. The moon is tidally locked, but it might rotate about the axis that passes through the moon and through the center of Mars.
A benefit of this system is that Phobos would receive an impulse in the direction of its motion, which would act to counteract the steady loss of momentum which is causing the moon to fall toward Mars.
The duration of an acceleration along a track of 93,500 meters (58 miles) would be 87 seconds, at 2.5 G.
SearchTerm:EMLPhobos
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Last edited by tahanson43206 (2020-05-09 20:09:56)
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I think that for mars we did determine that a vacuum was the means to floating on mars. Of course that means increasing mass to make the balloon land.
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For SpaceNut re #3, and other items ...
Thank you for your support of this new initiative. I am hoping this topic can develop into an article that gets published in a print medium.
Thank you (again) for weed removal in the Other Space Organizations topic! It really looks good now!
To your observation about vacuum ... I confess to having missed the discussion you're thinking of. I'd appreciate if you could provide a link.
What I have in mind for this topic is building up a step-by-step outline of a business that could provide soft landing services for Mars bound passengers and cargo. In order for the concept to receive serious consideration, it needs to receive sufficient funding to carry out a test on Earth.
The methodology I have in mind is (certainly) open to adjustment, but the opening bid is to drop off a standard weather balloon at an altitude well above the point at which the Earth's atmosphere matches in density and pressure the atmosphere of Mars at its lowest point on the surface.
The intent of the demonstration is to establish that the balloon will not only survive the drop, but will achieve a state of equilibrium between the buoyancy of the balloon and the pull of gravity on the package, well above the surface.
A successful test should lead to increased funding to establish that the concept can be extended to deliver significant mass to a stable equilibrium at 53 kilometers above the surface of the Earth.
At that point, unless I've missed something (which is certainly possible) the concept should have demonstrated the ability to work reliably at Mars.
As a reminder, this topic is a branch from a topic managed by Void, whose creative thinking about bubbles landing on Mars is direct inspiration for this topic.
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Last edited by tahanson43206 (2020-05-08 13:05:12)
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If it's a one way, one time descent, then have a leak in vacuum for descent.
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It was in this page http://newmars.com/forums/viewtopic.php … 27#p163727
My post contains the use of it as a lifting agent.
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For SpaceNut re #6
Thank you for the link to the vacuum discussion.
I was surprised to see my ID in the list of posters. Thanks for the memory refresh!
The idea of creating a vacuum chamber using fabric is bold. Perhaps its time has come !!!
SpaceNut, would you be willing to pursue that a bit further. The vacuum would be readily available at Phobos' orbit.
The only question I would have is whether the fabric enclosure would weigh less than the buoyancy of the Mars atmosphere would provide.
That is the direction I'm hoping you might be willing to look.
In the mean time, I'm hoping the suggestion of a tough material as suggested by RobertDyck (in another topic) will turn out to be capable of both service as a balloon envelope, and after landing, as the pressure bearing member of a habitat/greenhouse/storage facility.
In order to win funding, (it seems to me) the proposal needs to show that there is a reasonable chance the method chosen will (a) work at Mars and (b) permit delivery of substantial mass (including passengers and all their support equipment).
Edit#1: It was proposed in the vacuum discussion, that helium be used to fill the outer (load bearing) shell of the dirigible. I am curious about why the designer chose Helium, which is likely to be rare at Mars, when Hydrogen would perform better, and can be extracted from water, which is abundant in (selected) locations in space.
Edit#2: The web site at the link below appears to contain guidelines for design of vacuum chambers on Earth. The text discusses various metals, glass and ceramic. The concern of the authors appears to be outgassing from the materials chosen for the application. There is specific mention of high levels of outgassing from plastics that might be used for seals, for example.
http://www.normandale.edu/departments/s … -materials
A vacuum chamber to be made of fabric, in the manner shown in the link provided by SpaceNut, would need to be strong enough to withstand the pressure of the gas used to maintain the shape of the chamber wall despite the pressure exerted by the external environment while at the same time holding the inner wall of the chamber from being pulled away from the threads holding the inner wall to the outer wall.
As a first reaction to the proposal, I can imagine that material fabricated of nanoscale threads (such as proposed for the Space Elevator) might have the needed strength. However, it may turn out that the math has been done, and existing materials may be able to withstand the load.
Whatever material is chosen must mass less than the mass of the atmosphere displaced by the device, in order for it to establish buoyancy.
During operation, the chamber will be under constant threat of disruption, due to the enormous pressure exerted by the external atmosphere.
SpaceNut, it should be possible for a home experimenter to make a small (golfball sized) experimental rig to prove the validity of the concept.
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Last edited by tahanson43206 (2020-05-08 17:38:15)
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I would think that any of the ethane groups of gasses would work for mars as hydrogen by its self would tend to get through the containing fabric. The Blatter shell sounds about right for creating shape that we are familiar with but once a vacuum is created would it not fold in on its self....
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For SpaceNut re #6
Thank you for your continued interest in the vacuum dirigible idea. Your closing question gets to the heart of the issue. I'm guessing that the material that would be needed to build a fabric shell as described in the post you showed does not exist.
You are welcome to pursue the idea if you care to do so. I'd be interested in seeing anything you are able to find.
Because the original authors went so far as to create visual images of their concept, and to publish their ideas, they may also have done the math necessary to establish the theoretical feasibility of the idea.
As we consider the image of the outer wall of the proposed "vacuum" dirigible, we can see that the outer wall of fabric is in contact with the external atmosphere (on the outside) and with a layer of helium gas on the inside. That helium gas must be held to a very high pressure indeed, because that layer must bear the full pressure of the external atmosphere.
It is the ** inner ** layer of the fabric shell that is of particular interest to me. It must withstand the full pressure of the helium on the inside, while it experiences vacuum on the outside.
The threads that connect the outer layer to the inner layer are bearing the full force of the helium gas working as hard as it can to push the inner and outer layers apart.
If the math was done by the original authors, or by anyone else, I would be most interested in seeing it.
In the mean time, I propose that the balloon to be considered for this topic should contain hydrogen.
Hydrogen is going to be a valuable commodity on Mars. Dr. Zubrin's original proposal (as I remember it) was to take hydrogen along with the initial fuel manufacturing automated expedition, in order to make methane for the return trip by the crewed expedition to follow.
Nothing has changed (that I have seen) since Dr. Zubrin's original vision. Whoever lands on Mars is very likely to want to make fuel to return to Earth, and while there is plenty of Carbon and Oxygen on hand, Hydrogen is not readily available. While water may be present, and it may be possible to make hydrogen from insitu water, it seems to me unlikely mission planners will take the risk of betting a return mission on that option.
The least risky solution is to take Hydrogen along.
And the premise of ** this ** topic is that the least risky way to deliver that Hydrogen to the surface of Mars is inside a balloon designed for landing cargo and passengers gently on the surface of Mars, after departure from Phobos.
In another topic, RobertDyck suggested a durable fabric that might be suitable for the dual role of landing cargo on Mars, and then serving as the pressure bearing exterior of habitat/greenhouse/storage structures.
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A practical, reasonable objective for this topic is delivery of an article to a print media outlet.
Edited 2020/05/15 after "discovery" of velocity that can be expected for an object falling directly toward the center of Mars, from an elevation equal to the orbit of Phobos. The velocity of such an object appears to be in excess of 6 kilometers per second. A remedy for this situation is the use of a tether, so that feature has been added to the planning for the proposed document.
Whether the Editor accepts the submission is another matter entirely. What ** is ** possible for members of this forum, is to collectively work out what such an article might look like.
A model I've been considering is the Fact article that "usually" appears in an edition of Analog Science Fact and Fiction.
A prolific author who often succeeds in landing publication in the Fact category is Richard A. Lovett.
Wikipedia has an article about Mr. Lovett.
His most recent piece is:
“Space Dust: How an Asteroid Altered Life on Earth Millions of Years before the Dinosaurs”
This article appeared in the May/June 2020 issue of Analog Science Fact and Fiction.
The article is written in an entertaining way, based upon 7 citations which are listed in the Endnotes, along with a paragraph in fine print about Mr. Lovett.
In thinking about what an article might look like:
Possible layout of Balloon Landing System article:
Opening: Overview of how a passenger might experience a landing
This would start with purchase of a ticket on Earth.
Flight to Mars with Docking at Phobos
Boarding landing vehicle
Launch, Descent, Landing
Another version of the sequence is: (revised 2020/05/15)
1)Opening Scenario: Ticket through landing
2)Phobos Station Departure via Tether
3)Balloon/dirigible lander
4)Landing team processing
5)Disposition of components
I just hit a snag in thinking about item 5, and am inviting forum members to pitch in with ideas.
The overall concept is to design the landing system so that ** nothing ** is wasted.
The hydrogen used for buoyancy would be in high demand <check>
The fabric used to make the balloon would be valuable for habitats <check>
The passengers and cargo would be offloaded and delivered to their respective transport vehicles. <check>
I am left wondering about the frame within which the passengers ard cargo are transported during the descent, and the electronics package that would control the vehicle and communicate with controllers on Phobos and on Mars.
Is there some way these essential components could be designed for use on Mars, so that nothing need be discarded or lifted back up to Phobos?
Edit#1
https://www.analogsf.com/contact-us/writers-guidelines/
Fact Articles
Fact articles should be about 4,000 words in length and should deal with subjects of not only current but also future interest, i.e., topics at the present frontiers of research whose likely future developments have implications of wide interest. Necessary images should be provided by the author in camera-ready form.Our readers are very intelligent and technically knowledgeable but represent a very wide diversity of backgrounds. Thus specialized jargon and mathematical detail should be kept to a necessary minimum. Our audience largely reads us for entertainment, and a suitable style for our articles is considerably more informal than many professional journals.
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Last edited by tahanson43206 (2020-05-15 12:05:41)
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This slot is reserved for development of an article, as described in Post#10
Section 1: Opening
Summary of a trip, from ticket through delivery to passenger pickup vehicle on Mars
Last edited by tahanson43206 (2020-05-11 11:50:51)
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This slot is reserved for development of an article, as described in Post#10
Section 2
This is a candidate location for discussion of the critical path items
1) Balloon landing package (instead of parachute or rockets)
2) Tether deployment system (instead of rockets)
3) Details of configuration of tether at Phobos
Last edited by tahanson43206 (2020-05-15 12:08:20)
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This slot is reserved for development of an article, as described in Post#10
Section 3
The landing package is imagined as prepared at Earth (in LEO) for shipment to Mars
1) Balloon fabric not inflated
2) Hydrogen packaged as water to be electrolyzed during passage
3) Structure of landing package (designed for use after landing in Mars construction)
4) Electronics for control of landing (Small, compact, to be reused unless designed for use on Mars)
Last edited by tahanson43206 (2020-05-15 12:11:23)
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This slot is reserved for development of an article, as described in Post#10
Section 4
Passage to Mars
This section would be highlighted by processing of water to make hydrogen for landing, and oxygen for however needed.
Last edited by tahanson43206 (2020-05-15 12:12:45)
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This slot is reserved for development of an article, as described in Post#10
Section 5
Docking at Phobos
Details of navigation
Details of facilities at Phobos
(a) Initial (ie, none)
(b) Early
(c) Eventually
Last edited by tahanson43206 (2020-05-15 12:13:51)
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This slot is reserved for development of an article, as described in Post#10
Section 6
Details of tether system
Last edited by tahanson43206 (2020-05-15 12:14:16)
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This slot is reserved for development of an article, as described in Post#10
Section 7
Descent ... tether, release, flight, landing
Last edited by tahanson43206 (2020-05-15 12:15:02)
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This slot is reserved for development of an article, as described in Post#10
Section 8
Landing and immediate post-landing processing
Primarily handling of passenger and baggage
Secondarily removal of Hydrogen and preparation of fabric for transportation
Last edited by tahanson43206 (2020-05-15 12:18:01)
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This slot is reserved for development of an article, as described in Post#10
Section 9
Post Landing
1) Fabric to shelters
2) Hydrogen to storage
3) Metal structures to on site application
4) Electronics
Last edited by tahanson43206 (2020-05-15 12:16:51)
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This slot is reserved for development of an article, as described in Post#10
Section 10: Endnotes
References
Summary of contributors
For-more-information link(s)
Last edited by tahanson43206 (2020-05-11 11:49:16)
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This post is copied from the Phobos Docking topic. It was developed in response to a question by GW Johnson, and an observation by SpaceNut.
It shows that the velocity of an object (such as a balloon) dropped from the height of Phobos would be ** greater ** than was the velocity of the Curiosity rover package when it entered the atmosphere of Mars.
For SpaceNut re #44
Thank you again for your support of this topic!
Your prediction CAN be tested. The computations of a Computational Fluid Dynamics program would be helpful, but ** only ** a live test will confirm whether your prediction corresponds to reality, or something else happens.
Regarding the fall .... "fast" is probably a good word to apply to the rate of descent just as the balloon enters the outer fringes of the atmosphere.
Google gives 3.711 m/s^2 as the acceleration of gravity at the surface of Mars.
https://www.universetoday.com/14859/gravity-on-mars/
The surface gravity of Mars can therefore be expressed mathematically as: 0.107/0.532², from which we get the value of 0.376. Based on the Earth's own surface gravity, this works out to an acceleration of 3.711 meters per second squared.Dec 16, 2016
Wikipedia gives the altitude of Phobos as: 5,989 km
With an altitude of 5,989 km (3,721 mi), Phobos orbits Mars below the synchronous orbit radius, meaning that it moves around Mars faster than Mars itself rotates.
Just to be clear, the 3,721 miles given above is the distance from Phobos to the surface of Mars (more or less)
www.space.com › 20346-phobos-moon
Facts about Phobos:
Semi-major axis around Mars (distance from planet's center): 5,826 miles (9,376 km) Closest approach: 5,738 miles (9,234 km) Farthest approach: 5,914 miles (9,518 km)I am attempting to find a source to provide an elevation where the atmosphere of Mars becomes "sensible". This source gives a reading for pressure at the top of Mount Olympus:
https://marsed.asu.edu/mep/atmosphere
But on top of Olympus Mons, 22 km (14 mi) high, the pressure is only 0.7 millibar.
3,721 miles is 5988 kilometers and change
For the sake of computing the rate of travel of a balloon dropped from the elevation of Phobos, it seems we might use the height of Mount Olympus as a reference point, although the atmosphere itself may extend up as high as 40 kilometers above the surface.
Thus, we could use 3,700 miles (or 5954 kilometers and change) as the distance the balloon would fall before it encounters serious resistance
Edit#1: 6.6 km/second is the figure delivered by https://www.calculatorsoup.com/calculat … r-vuas.php
Answer:
v = 6647.6 m/sWell SpaceNut ... most folks would consider that speed to be "fast" on a human scale.
It ** is ** (for me at least) sobering!
Edit#2: For comparison, here is a discussion of the landing of Curiosity:
https://www.technology.org/2019/03/21/t … s-on-mars/
When it entered the Martian atmosphere, it was going 5.9 kilometers a second, or 22,000 kilometers an hour.
This article is only a year old, and it provides a wide ranging summary of attempts to solve the Mars landing problem.
If humanity is going to build a viable future on the surface of Mars, we’re going to need to crack this problem. We’re going to need to develop a series of technologies and techniques that make landing on Mars more reliable and safe.
I suspect it’s going to be much much more challenging than people are expecting, but I’m looking forward to the ideas that will be tested in the coming years.
A big thank you to Nancy Atkinson who covered this topic here on Universe Today more than a decade ago, and inspired me to work on this video.
Source: Universe Today, by Fraser Cain.
If anyone has read this far, the speed of arrival of Curiosity at Mars is given as LESS than the speed of a balloon dropped from Phobos.
If I've made an error anywhere along the line above, i'd appreciate someone pointing it out. I'll fix it as soon as I see it.
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Last edited by tahanson43206 (2020-05-14 10:04:50)
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The reality that the component of velocity imparted to an object released for a dead fall from the altitude of Phobos is greater than the velocity of Phobos itself in orbit suggests (to me at this point) that there is little to be gained by expending the energy that would be needed to accelerate to the rear of Phobos, to arrive at a near zero velocity with respect to Mars.
The implication (that I am seeing, at this point) is that the balloon concept is ** much ** closer to the vision of JP Aerospace (John Powell).
As most forum readers are no doubt aware, Mr. Powell has been slowly and steadily advancing toward realization of a vision of delivering a balloon vehicle to orbit.
It would follow that (assuming Mr. Powell is successful at some point) he would then want to return the balloon vehicle safely from orbit to the staging balloon in the upper Earth atmosphere, and this would mean he would be dealing with a more severe problem than would be faced by the same vehicle pushing off from Phobos for a trip to the surface of Mars.
I still think there is a good chance Void's original vision, of a spherical balloon successfully making the descent from the elevation of Phobos to the surface of Mars, may turn out to be viable. The successful solution will include measures to enable the material of the balloon envelope to survive the heating to be expected. I am confident that a very low mass object can survive encounter with an atmosphere. The question to be answered, either by computer modeling or actual experiment, is what combination of materials and gas is most able to survive a descent to the surface of Mars.
Whatever the optimum combination turns out to be, then the next question will be how to insure the gas inside the balloon, and the material of the balloon envelope, will be of economic value on Mars, and therefore worth the investment of bringing the package from Earth to Phobos.
In the mean time, it would seem appropriate to investigate to see if John Powell has been thinking about the flying balloon's ability to descend from orbit. It would seen (to me at least) that the descent of the JP Aerospace vehicle at Mars would be ** much ** easier than the same journey from Earth LEO, due to the reduced gravity of Mars as compared to Earth.
The aircraft balloon design Mr. Powell is working on would seem more likely to be able to provide passenger service than the spherical balloon idea.
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Last edited by tahanson43206 (2020-05-14 10:23:09)
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The next stage of this investigation is to find out where JP Aerospace may be in it's progress toward orbital balloon flight.
I found a well written, lengthy and nicely detailed essay about the company, and am pasting a couple of notes here:
https://www.blimpinfo.com/airships/can- … aces-idea/
Source: Science 2.0 – science20.com
By Robert Walker May 3rd 2017
ICBM mylar inflated decoys)
The reference to ICBM mylar inflated decoys is the first hint I have seen about research done by the US military investigating survivability of balloons at orbital speeds.
If the balloons survived ejection from a moving ballistic missile, (and at this point I have no information one way or the other), then presumably they would be able to survive a "drop" from Phobos.
The entire article by Mr. Walker seems to me to do a decent job of summarizing the status of the JP Aerospace initiative in 2017.
A key technology concept is the ability of a sufficiently lightweight airfoil to "fly" above the height achievable by a traditional heavier than air craft.
For a Mars lander, I would expect a balloon airfoil to fly quite well in the upper atmosphere of Mars, ** if ** it can survive the rigors of encounter with the upper atmosphere at the velocity of Phobos, which is in excess of 2 kilometers per second.
Edit#1: Tethers have been discussed in this forum, from time to time.
Because of the surprise (to me for sure) of the 6 km/s velocity of a body dropped from the height of Phobos at Mars, I am less confident it can survive the heating it will encounter when it meets the thin atmosphere. SpaceNut's suggestion of a heat shield makes sense, although I would be thinking of making the entire balloon envelope of a heat resistant material, ** and ** rotating the balloon as it interacts with the atmosphere.
However, tethers provide a (potentially) attractive alternative to free fall, and they also (potentially) allow for two-way travel.
If a 3700 mile tether is stretched out in front of Phobos, and if the balloon vehicle accelerates directly down toward Mars, the tether will cause the balloon vehicle to arc toward Mars on a path that could (if planned correctly) allow the balloon to release from the tether with a zero (or near zero) horizontal velocity and a zero (or near zero) vertical velocity.
At that point, at about the elevation of the top of Mount Olympus, the balloon would descend under the influence of Mars' gravity, but buoyancy would begin to take effect, so that at the surface of Mars, buoyancy would be fully in effect, and the balloon would hover just above the surface.
The cable/tether from Phobos, meanwhile, would swing back up to orbit, where it would trail behind Phobos for parking until the next drop.
The nature and strength of the tether remain to be determined.
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Last edited by tahanson43206 (2020-05-14 17:52:02)
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Speaking of JP Aerospace there are topics in which we have talked about that companies effort to get to orbit.
Airship to Orbit?
baloon launcher - Cheap way to get to space
Air Transportation on Mars - Gravity's affect on Air travel on Mars
Airship part-way to Orbit
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For SpaceNut re #24
Thanks for adding links to earlier Forum posts on JP Aerospace!
The one about Air travel on Mars looks particularly interesting in the context of this topic ...
And! Speaking of ** this ** topic .... I'd like to add to Post #23 which brought up the (not new) idea of running a tether from Phobos ...
It came to me overnight that the tether does NOT have to reach all the way to Mars for it to solve the problem of velocity accumulated by a Dead Drop from the altitude of Phobos. Instead, the length of the tether can be adjusted to deliver the balloon at an altitude which is low enough so the heat resistant fabric of the envelope CAN withstand the heating that will occur.
Use of a tether ALSO greatly reduces the need for propellant to accelerate the landing package away from Phobos.
So now (at least as of this morning) I am encouraged to think that a combination of Phobos as a base, use of a tether to deliver a balloon landing package to the right elevation to insure success, and the balloon concept that Void originated, can work.
I wish I had the facility with math to make these components work quickly and easily, but perhaps there is a forum member who would be willing to take a look at it. Beyond that, there are surely forum readers who are not yet registered who have the skills (and resources) available to help.
In another post recently, a link was provided to a web site where the author provided a summary of the various options tried to date for landing on Mars. In the article, the author concluded with a summary of the difficulties Mars presents for landing, since it has an atmosphere, but the atmosphere is just barely sufficient to permit its use for bleeding off momentum prior to a safe landing.
GW Johnson covered the same issues in a recent post in this topic.
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