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#1 2021-01-09 20:20:20

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 28,750

Void's Mars Starship Belly Flop Cargo Drop

This is deserving of its own topic

Void wrote:

I am wondering if there might be a sweet spot on descent where an object constructed of such could be ejected from the Starship prior to landing.  I have thought of chains before.  If you had a chain and unrolled it quickly through a small port, prior to landing you might lighten the necessary landing propellant load.  Of course the chain would impact at a rather high speed.   Really probably a really high speed.   Still you might not care if it deformed and snapped in places, as long as it did not melt.    It might drop into a sand dune, and perhaps fluidize it during a chain impact, and perhaps that would help dissipate the heat of impact enough.
Done.


So you are thinking of some sort of cargo off load via parachute drop while the ship is verticle for a landing profile in the thin Mars air once we have come out of sonic levels.

The cargo mass would lessen the fuel for landing requirements but would complicate the cargo interfering with the ships profile as it drifts down. So it needs to be steerable but its still a very large parachute.

Sort of like this while doing the belly slide in the mars air
mmu_get_jpeg.php?1a6f09a695f9fa7624cb8bfce7b2b4e58


JPADS+2K+FF+in+flight+1.JPG

So it needs to be very rapid and have some sort of pull that would cause it to clear the verticle drop quickly. So maybe some sort of exit ramp that allows the cargo to go a short distance from the ship before a drone chute would be ejected so as to pull the main chute...

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#2 2021-01-09 23:01:03

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 28,750

Re: Void's Mars Starship Belly Flop Cargo Drop

First problem is the parachute size and requirements are 3 to 4 times the size for just a few 2 -3 Tonnes of cargo to be delivered in the mars atmosphere at Mach 3 opening of the chutes at more than 3k in altitude.

This was the chute used for Mars as the glider is for earth.
333676main_D2009_0331_T0164-516.jpg

https://mars.nasa.gov/mer/mission/space … parachute/

Starship glide is short in duration and its going to be even faster as its not in a thick earth atmosphere. It would need to spiral to get enough energy speed to burn off.

What was the case for starship at this point is Starship SN8 slowly climbed off the launch pad, trailing a flickering flame of super-heated exhaust, and soared high into the atmosphere, targeting an altitude of 41,000 feet, or 12.5 kilometers, higher than most commercial airliners fly.

NASA defines “high” hypersonic speed as a “Mach number” from 10 to 25. Starship itself will be returning from orbit, reaching Mach 25 for Earth landings. At this speed, the heat of reentry will melt the engines off. You therefore need a substantial heat shield which dissipates 99% of the energy – protecting the cargo and those all-important rockets that you need for landing.

While retro-propulsion is intended to be used for the final landing maneuver on the Earth, Moon, or Mars, 99.9% of the energy dissipation on Earth reentry is to be removed aerodynamically, and on Mars, 99% aerodynamically even using the much thinner Martian atmosphere,  where "body flaps" are used to control attitude during descent and optimize both trajectory and energy dissipation during descent.


sn8_descent.jpg

It seemed to take 15 seconds to go from verticle to belly once the engines were off in the tail fall conditions with a thruster setting the glide.

Starship likely reached a speed of around 150 m/s (~330 mph) during that freefall, Starship SN8 twitching its flaps and occasionally using a burst of thrusters to elegantly and stably glide back to about 1 km (~0.6 mi) above the ground. Not circling just a straight line in what appears in the videos as about 1 minute 30 seconds.

At that point, the rocket ignited one – then two – and three Raptor engines with no apparent issue, gimballing violently and firing thrusters to flip its 9m by 50m (30 ft by 165 ft) hull ~120 degrees in a handful of seconds, ending in a tail-down landing configuration.

Which for mars is going to be even shorter since the thin atmosphere will need to spend time to burn off that amount of speed by circling or its going spat on the ground as its not going to have enough fuel to land with.

The amount of fuel you need is given by “the rocket equation”. This shows that if you want to launch 100 tonnes of payload to the Moon at a speed of 12,000 metres per second you need a staggering 2,000 tonnes of fuel and a trip to mars will not be able to bring the tonnage due to landing fuel requirements.

Starship is also designed with the goal to reach other planets and moons in the solar system after on-orbit propellant loading but the landing flaps would be removed and it would be of a different configuration.

EW3eLciU4AEKnFN.jpeg

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#3 2021-01-16 11:36:24

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 28,750

Re: Void's Mars Starship Belly Flop Cargo Drop

edlprofile.jpg


During landing, the rover plunges through the thin Martian atmosphere, with the heat shield first, at a speed of over 12,000 mph (about 20,000 kph).

Peak heating occurs about 80 seconds after atmospheric entry, when the temperature at the external surface of the heat shield reaches about 2,370 degrees Fahrenheit (about 1,300 degrees Celsius).

No escaping there is a need for even the starship to have protection on the leeward belly as it slides at the attack angle for where it will nose up for the glide.

dims?quality=100&image_uri=https%3A%2F%2Fwww.blogcdn.com%2Fwww.engadget.com%2Fmedia%2F2011%2F04%2Fcuriosity-landing2-04132011.jpg&client=cbc79c14efcebee57402&signature=b3d897d7ef89e1f98c9fb0e66348da6cab994ff4

The parachute, which is 70.5 feet (21.5 meters) in diameter, deploys about 240 seconds after entry, at an altitude of about 7 miles (11 kilometers) and a velocity of about 940 mph (1,512 kph). A parachute and powered descent slow the rover down to about 2 mph (three-fourths of a meter per second).

Starship will not have a parachute to continue the slowing of the ship and will need to use the nose up maneuver to slow the ship.

The heat shield slows the spacecraft to under 1,000 miles per hour (1,600 kilometers per hour). At that point, it’s safe to deploy the supersonic parachute.

At the point where we are a detected distance and and speed the Starship would fire its engines to start the descent.

NASA-MSL-EDL-sequence-and-Sky-Crane-landing-technique-courtesy-of-NASA-Jet-Propulsion_Q320.jpg

This is where the belly flop is to take place for the Starship landing glide...

As the descent stage levels out and slows to its final descent speed of about 1.7 miles per hour (2.7 kilometers per hour), it initiates the “skycrane” maneuver.

With about 12 seconds before touchdown, at about 66 feet (20 meters) above the surface, the descent stage lowers the rover on a set of cables about 21 feet (6.4 meters) long. A large sky crane then lowers the rover on three bridle cords to land softly on six wheels.

5331876_orig-1024x739.jpg

Starship would then do the verticle landing...

So the big question is until we have come back from LEO and the Moon with this maneuver we will not know if the Starship can preform a Mars Landing or not.

This leads to how do we boot strap the Mars landing site to prepare the way for a successful Starship landing. This is to reduce risk of failing on the first and follow up attempts before men go to Mars.

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#4 2021-01-17 11:29:57

Void
Member
Registered: 2011-12-29
Posts: 6,976

Re: Void's Mars Starship Belly Flop Cargo Drop

------
I appreciate your hard analysis of how to possibly do it in some manner, in atmosphere.
I had not intended to develop this idea very much, but since you are into it, I have been prompted to think it through.
Some of these notions border on the silly, but still, if I might try to get them just across the line of silly, they might have merit.  Possibly limited merit.
------
First of all, I want to describe my notion of what might be desired to accomplish:
I visualize it a bit like nesting birds method of raising young.  First of all their eggs have to have an investment of a yoke.   After that many nesting birds will bring food to their young.
Then the young leave the nest, and may soon be on their own for food and other issues of survival.
So, at this time I can think of three materials to "Feed" the young.  There very well may be others.   Copper, Aluminum, and Stainless Steel.
I want to deliver those during the time when the ability to produce them in quantity on Mars does not yet exist.   When the ability to produce those items on Mars comes into existence, then the birds have left the nest, and it is unlikely that the practice would continue.   However, while it was a useful thing it would nourish the fledgling settlements.
In order to claim that this might be possible at all, I will reference "Rods From God".
These are to be kinetic weapons, that are very unlikely to deliver a useful cargo, but would instead be likely to just destroy things they impact.   Still it is a starting point.
I see the derivative devices to be imagined to either piggy back on a Starship's leeward side, or be fully able to have their own heat shield.   The piggy back versions, would be more likely to go where you want them to, without adding expensive guidance systems to them.
It is expected that when these things reach the ground, their nature will be strongly altered by the forces of impact.   The hope would be to still retrieve useful "Scrap" materials.
I started this type of thinking some time back, and one of the items I imagined would be a chain of materials.  I imagined a situation where the Starship would release it just before needing to fire the engines.   If it were a chain or Copper or Aluminum, I would not expect it to survive on the leeward side of the Starship without protection.   Stainless Steel might survive.   But we expect some crashes of Starship, or some deliberate scrapping of them so Stainless Steel while having worth, would not be as desired as Copper or Aluminum, I expect.
I don't want you to obsess over the chain notion.  It was just an early attempt.   If you did do it you might involve a parachute as you have been thinking, to reduce it's terminal velocity.
I have evolved away from trying to eject something from a cargo hold during the "~7 minutes of terror".   Instead I see either assisting these things into the atmosphere using the Starship as the shield, or detaching these things prior to atmospheric entry.   In that later case, then they have to have their own means of heat shield, and unfortunately some type of steering method would be needed.
Where they might impact, will be of importance.   I see sand dunes, open water ice, and CO2 snow pack as being somewhat favorable receivers.   There may even be the possibility of impacting an ice covered lake, punching through the cover, into the water.   For Aluminum I have anxieties about combustion, as Aluminum may very well do that if it is hot and proximate to a source of Oxygen.   H2O or CO2.
Another important factor would be to take in the fact that having an impactor(s) impacting close to the Starship could cause a Starship crash from a RUD.   So timing will be very important.
So, for Aluminum, it may be necessary to use sand dunes to impact into.  I am not sure.
While a "Rod From God" wants a very high velocity to do it's task, I want these to have a large footprint in the atmosphere, so that the terminal velocity is strongly reduced.   So, I see them as being hollow.
-----
I guess I will just jump into my current favorite proposal.    Say you made an external tank for the Starship, that clamped onto it's leward side.   But I don't necessarily restrict it to that.  Say you had an electric propulsion interplanetary device, and made the propellant tanks in a certain manner.....
I am thinking of a Stainless Steel shell with a thick inner coating of Aluminum or Copper.
For the moment, I am setting aside how chemical reactions might happen between LOX and the Aluminum or Copper.  In the case of electric propulsion, your propellant should not be reactive.
My intention is to use the fact that the Aluminum or Copper might melt during atmospheric entry, and flow down to the down side.  A phase change to help handle the heat of atmospheric entry, either as a stand alone device or piggy-backing on a Starship.
We might retain some of the propellants to boil them off to help cooling, however that is then against the intention of squandering propellants.   In reality a heat shield it likely to be desired on the exterior of the tank, but if the metal melt method is available then the amount of heat shield needed may be reduced.
I have not stated the shape of the external propellant tank.  That can be considered later.
So, then supposing you impact a sand dune, then you have contamination problems.
If you impact CO2 snow pack, that is rather thin, but it might flash off some of the heat of impact.   But contamination may be an issue, and so reduce the quality of the delivered product.
Korolev Crater looks like an interesting option.   Very thick water ice.   And in fact in the winter, I think it would also be covered by CO2 snow pack???
I am presuming the least amount of contamination in that case.   However we don't want the materials to penetrate too deep into the ice, as that would be lots of trouble to retrieve.
And again the Aluminum combustion problem may show up.   A hollow tank impacting and shattering, may not produce a lasting void where combustion could occur.   If it instead has a "Blow-out" sort of explosion where a encased body of water can occur, then the combustion of Aluminum may be abated/avoided.
And that's what I have for now.
Done.

Spelling might not be too bad this time.  I was able to work on it without my computer bogging down this time.

Last edited by Void (2021-01-17 11:36:34)


Done.

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#5 2021-01-17 12:32:04

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 28,750

Re: Void's Mars Starship Belly Flop Cargo Drop

On earth we can use the parachute all the way to the ground but on Mars we can not and must use retro propulsion for those last approximate under a minute.

Pushing payload out the open hatch at parachute level currently is with a heatshield shell still attached.

https://mars.nasa.gov/insight/entry-descent-landing/

insight speed at 3800 mph to start the process with a starship nose up needing to happen when its still at 8500 mph

the heat shield is jetisonned at 5.7 mile altitude at a speed of 268 mph to start parachute process for the payload

https://www.grc.nasa.gov/WWW/K-12/rocket/atmosmrm.html

the parachute plus seperates from the would be carrier and payload at 0.62 miles altitude traveling at 134 mph

https://www.grc.nasa.gov/www/k-12/airpl … osmre.html

Parachute function buoyancy drops as speed gets lower since the level of pressure is not rising to hold open the parachute as it continues towards the ground.

https://www.nasa.gov/mission_pages/msl/ … 16477.html
https://mars.nasa.gov/resources/4873/pr … s-on-mars/
https://mars.nasa.gov/resources/5205/se … /?site=msl

The time of day as well is a cause for additional reasons for the parachutes in ability as the one size does not fit all...

the engines then turn on at 164 feet to further slow to 17mph and fire to a hover with about 2mph

https://en.wikipedia.org/wiki/InSight

Mass
Total mass during cruise: 694 kg (1,530 lb)
Aeroshell: 189 kg (417 lb) Aeroshell Diameter (backshell and heat shield) : 2.64 meters (8.67 ft)
Cruise stage: 79 kg (174 lb)
Propellant and pressurant: 67 kg (148 lb)

Lander: 358 kg (789 lb)
InSight's lander payload has a total mass of 50 kg (110 lb)

deliverd to surface 408 kg or (899 lb)

https://en.wikipedia.org/wiki/Mars_Science_Laboratory

The spacecraft flight system had a mass at launch of 3,893 kg (8,583 lb),
consisting of an Earth-Mars fueled cruise stage (539 kg (1,188 lb)),
the entry-descent-landing (EDL) system (2,401 kg (5,293 lb) including 390 kg (860 lb) of landing propellant),
and a 899 kg (1,982 lb) mobile rover with an integrated instrument package

Curiosity rover has a mass of 899 kg (1,982 lb)

So more fuel plus structure is removed from landed payload drops versus not doing and having more payload delivered to the surface still in the starship as the wasted mass required to land smaller part mass .

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#6 2021-01-17 15:52:05

Void
Member
Registered: 2011-12-29
Posts: 6,976

Re: Void's Mars Starship Belly Flop Cargo Drop

------

I am happy that you gave a response, but I think it is quite inappropriate, except that it describes what I am not proposing to do.
OK, lets suppose 3 divisions of method for 3 different purposes.
1) Landing delicate instrumentation on Mars.  (Nasa has just been brilliant at this one).
2) SpaceX Starship methods.  (This is a proposed but not proven method to land humans and cargo on Mars).  I think they will get there in some fashion eventually.
3) Crash Cargo.  (This would primarily be to deliver usable scrap to Mars).
In your analysis you mostly spoke of #1, and to a small degree suggested #2 as support for it.
Let me complain just a little.  The title of this topic was assumed by you, as (th) objected to my post to another topic on electric motors.   
Being a specialist has been very good for about 80 years.  It is no longer likely to be.   Having the ability to link across topics is a skill that while uncomfortable to the methods of this site, will likely be the way forward in the next 80 years.   This is not the WWII era.  Those who keep trying to repeat the solutions of that time, are directly in opposition to the flow of current reality.   While they may hold back reality for a little while, the consequences will be the need to pay back and to also pay penalties.  You can consider that to be a kind and considerate tip from a generalist.  I would pay attention if I were you(s).  Reality is into a mirror shift, and like what you had, it will not serve you now.  Not just the minor shift but also the major shift.  Things are likely to get very interesting.  Me?  No, I just have a dirt nap comming.  I am not likely at all to tilt at windmills.
Inventing what has already been invented and established is not the way to win.  It is excellent however, to have those foundations.  So, thank you for the review.
From the beginning I felt that to fufull this topic, as I might name the topic would be stony ground very hard to produce a good from it, but not necessarily impossible.
I dispute the need to eject the parachute for the method I have in mind.  You might want to to save it from damage, but the projectile will still be moving at hundreds of miles per hour on impact.   The value of the parachute would need to be evaluated against the value of the materials crash landed.   The consequences of cases, then would determine the path to take.
You should not require retro rockets, but I do not entirely oblivate them from consideration.
Now, my intention was that certain items be delivered to the surface of Mars as useful materials.  Not as finely manufactured materials maintained as finely manufactured.
So, perhaps you could restudy what I presented and offer a decent reply.
Done.

Last edited by Void (2021-01-17 15:52:37)


Done.

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#7 2021-01-17 17:35:45

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 28,750

Re: Void's Mars Starship Belly Flop Cargo Drop

The mars parachute takes about 1:09 the parachute deploy fully to produce drag after the drone chute is open to pull the main chute to its performance levels. The test article mission was done at an altitude (42 kilometers) and speed (1.8 times the speed of sound) mimicking what the system will go through above Mars, to make sure everything is tested under as close to realistic conditions as possible.

GW Johnson's Atmosphere Models for Earth, Mars, and Titan

https://ntrs.nasa.gov/api/citations/201 … hment=true
Supersonic Disk-Gap-Band simulation

https://ntrs.nasa.gov/api/citations/200 … hment=true
Atmospheric Environments for Entry, Descent and Landing (EDL)

The dynamic pressure is a function of the speed that is forcing the mars air into the parachute which as the speed is reduced collapses the parachute causing the payload to speed up...

This is why Nasa was working on the Adapt program for a deployable foldable heat shield material since that increases drag and for the use of an inflatable parachute.

https://www2.jpl.nasa.gov/adv_tech/ball … m-plnt.pdf
A LIGHT-WEIGHT INFLATABLE HYPERSONIC DRAG DEVICE FOR PLANETARY ENTRY

These are intended to slow the ships speed but its still in testing and development phase...

This the earth landing profile for starship

nS-5MfzUlMiw3Y-0vRNRZTL08xO4g-KM-5Q_LjLwAO4.png?width=960&crop=smart&auto=webp&s=2b8fcc24f71372139c865b63d773559ec7398093

As can be seen the mars analog did not start the glide at a high enough altitude since it took so much time to flip around for the glide.
The same is true for the nose up to go verticle for the landing which is not long enough due to verticle speed still yet to be reduced.

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#8 2021-01-18 14:18:36

Void
Member
Registered: 2011-12-29
Posts: 6,976

Re: Void's Mars Starship Belly Flop Cargo Drop

If you choose to read though the materials I presented, you might find that their are already at least 3 options.

Still, I have come to the conclusion that I am incompatible with the drift of this web site.  I am wasting my time, and very likely annoying other people.  It seems to me that if such an unproductive process is in place that generates negative consequences, then the best thing to do is to stop. 

I appreciate that you tried to communicate with me, but I see no signs that we can achieve anything of merit.

I very much look forward to seeing how this web site has changed character in the future.  I support it not being compatible with people like me.  It will be interesting.

I will post one more post at another location.

Done.


Done.

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#9 2021-01-18 18:27:52

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 28,750

Re: Void's Mars Starship Belly Flop Cargo Drop

1 Nasa is not delivering anything for the space x run rocket to mars if ever as its got the SLS to go to mars
2 Starship until it can land back on earth its got not even a chance of performing at all for returning from mars except in a one way direction
3 smashing to little tiny piece is not much better than digging up unprocessed ore....

https://www.physicsclassroom.com/class/ … -Free-Fall

https://www.omnicalculator.com/physics/free-fall

Free fall calculations along the parachute path shows the rate of slowing the ship and its unknown how long the nose up glide can be in the thin atmosphere as the earths is in a much thicker location and it fell like a rock....

landing.png

So back to calculating and proving at if at all is it possible on Mars based on real number....

Not surprised to find Chemical Mars Lander Designs “Rough-Out”

That calls out Rough Correlation of Entry Ballistic Coefficient vs. Size for “Typical” Mars Landers

https://en.wikipedia.org/wiki/Mars_landing

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#10 2021-01-18 18:45:49

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 16,759

Re: Void's Mars Starship Belly Flop Cargo Drop

For Void re possible hiatus ....

Your suggestion of a way of delivering useful materials to the surface of Mars without aerobraking deserves to be studied.

Unfortunately, it seems you lack the scientific and engineering training to be able to develop your idea.

If you leave now, you will miss out on the potential value that might come your way, if a person with the needed education and experience were to take up your innovative idea.  As is the case with so many of your ideas, this one is so far out of the box the average person thinks it is outrageous at minimum and impossible at the outer limit.

I recommend you respectfully ask more highly trained members of the forum to think about your idea, and see if it might be made to work.

Your thin skin leads me to wonder if you are willing to accept participation by others.

To the best of my knowledge, at NO time in all the years you've been posting here has anyone interfered with your efforts.

In the case of the delivery of mass to the surface of the planet without aerobraking, I am expecting to find that many decades of study of fluid dynamics contains within the resulting documentation clues about how the material might be shaped so that the resulting delivery is contained within a nice compact bundle.

Edit#1: After thinking about your idea for a while, it occurred to me that the field of military ballistics is ** exactly ** the right one to take your idea seriously.  For many decades (and probably centuries) serious research has been conducted at great expense all over the world, to find ways of delivering lethal payloads to the interior of fortified bunkers.

Considerable progress has been made, and potentially some of that knowledge could be adapted to your (to me very interesting) idea.

The need (in this case) is to deliver a payload of valuable material to the interior of a planet without losing much (or ideally, ** any ** ) of that payload to scatter.

As it happens, a person who has studied ballistics is within contact range of this forum. 

Please let me know if you'd like to have your idea given a preliminary evaluation.

(th)

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#11 2021-01-20 21:19:43

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 28,750

Re: Void's Mars Starship Belly Flop Cargo Drop

Since he first and possibly more starships will try to land on an unprepared landing site where by until one can be build and judged to not be needed the idea to lessen the payload mass on landing by ejecting it to mars with its own cargo landing capabilities still does have some merits even thou the amount of cargo will be partially the structure and fuels to make these smaller payloads possible from the max 100 mT which could be had if it could land on Mas with out any issues.

Gw has given best estimates on the landing pad / legs requires on the starship and that is not what space x is designing towards so the issue for a safe mars landing is a big deal breaker at this point without a solution to lessen mass on landing for the smaller starships landing feet....

Ship empty structure is in the 120 mT area from those numbers given by GW.

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#12 2021-01-31 11:26:56

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 28,750

Re: Void's Mars Starship Belly Flop Cargo Drop

The fuel for retro propulsion on each lander that exist the belly of the starship lowers the payload to the ground so we will need less of that and a substitute for the end landing cushion.

I was remembering that the Orion at one time did have air bags for cushioning the landing and that test trials had been done. Even if these where under the heat shield and opened just before impact the effective cushioning might be enough under some payload numbers.

Z713.jpg


Concept-of-Operations-of-the-Airbag-Landing-Sequence-of-the-Orion-CM.png

So the drop is taking a path of parachutes, retro propulsion to control landing with a final bag cushion to make the mass safe for landing.

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#13 2021-01-31 19:50:57

Void
Member
Registered: 2011-12-29
Posts: 6,976

Re: Void's Mars Starship Belly Flop Cargo Drop

Thanks Spacenut, I don't want to rule out any tools for consideration and combination.
(th), actually I feel that I am rather tolerant of reasonable criticisms.   The reason I have been taking a break, is that I feel your style and mine are almost incompatible.   But I feel that over time you may very well add a lot of value to this site.   And sometimes it is best to let the "kids" have the sandbox.   
Now don't over inflate this tiny issue, but I do not recall that I ever mentioned excluding air braking from a balistic delivery.   There will be some no matter what, and I fully intend to exploit it.   
Starship will have a terminal velocity for Mars, and I would expect that if you landed one fully loaded, and another empty, you would have different terminal velocities.
So, in my world, the more cross section of air your impactor has, the lower the terminal velocity.
One early version I may have considered would be a very big beach ball.   The two major problems would be heat of entry, and terminal velocity.   I really don't have that much use to make precise calulations, as estimations can to a large degree suggest directions to go in a matrix of possibilities.
I believe that I will try to suggest where we have had problems, clashes.   You have a very important desire to keep a topic "Clean".   We had a mutual problem with electric motors.  You had a vision of what you wanted there.   I put a little "Bookmark" to potential future topic, and Spacenut added some landing assistance.   You were concerned that young people reading about electric motors would be so dissapointed.   And perhaps they would be.   But you should know that I was a shop electrician apprentis around 1975, I was trained for a more technical job, but shop electrician was what was avaiible.   I worked with others who were better at it than me, and they were surprisingly tolerant of my idiocy.  It was only for a year perhaps, and then I took a different apprentiship.   There was classroom training and I did very well with that.
It was a mining facility, so you can be sure that their were big motors and little ones.   Some gigantic.  I have to look for them but I still have the classroom books.  Where I am likely rather fuzzy on some things from so long ago, I can still look things up if I need to.
You wanted a topic that was like a book, apparently, and I guess that was OK.
But I saw connections.   Electric Motors>Electric Motors from Starships>And then I mentioned one option where a ballistic delivery could be done by piggybacking a device to the leward side of Starship.   You may not even have an internal cargo bay for this variant of Starship.   Maybe it is all tanks and engines, mostly, and the only cargo is on the outside of the Starship.
One interesting variant would be an atmospheric skip Starship.   It would enter the atmosphere with its balistic cargo load, and provide heat shielding, release the cargo, and fly back to orbit.   Don't know how efficient that might be.   No landing leggs needed.   Extra large tanks, but you would have to have a refueling depot in the radiation blasted orbit of Mars.  However, If you had a refueling depot, you could seek protection from that.  And of course we do not know if we can get Hydrogen from the moons of Mars, but eventually most likely Oxygen and Carbon.   The Hydrogen you could lift from Mars to orbit.   There have been some who say that Demos, may be the best place in the solar system, provided you could put habitat inside of it.   And we may find that children have to be raised in synthetic gravity.  There is a whole lot of "Don't Know".   So hedging our bets might be a good idea.
A cargo you might want for this would be electric motor parts.   In some cases, you might not even care if the cargo melts and shatters.   However, I think that it is becomming more likely that in some cases good parts could be delivered without rocket engine landing.   But with 3D printing, the demand for that is much less.   These cargo's could be for making electric motors.   So in the beginning most of your electric motors would be salvaged from Starships, (Perhaps).   Then with balistic materials delivery, you could begin to manufacture motors, but with labor shortages, and lack of infrastructure, you might not start mining right away.   However, over time I would expect almost everything to be sourced locally. 


Here is a quote of me, by me, from the other balistic topic of yours.

Helicopter + Frisbee + Solar Concentrating Mirrors >>> And other things?
https://www.walmart.com/ip/Plastic-Disc/176904523
https://www.walmart.com/ip/Plastic-Disc/176904523
What I want would be something like the following:
1) Can be stacked well in a starship cargo hold to be lifted to LEO.
2) Can be connected into arrays of solar concentrating mirror for space propulsion from LEO to Mars.   (Ballistic Capture or Hohmann Capture methods).   This would most likely be a electric drive, but I do wonder, since Hydrogen is considered for Nuclear Thermal, why not have a look at solar thermal?   Perhaps a solar thermal preheat, and then finish it with microwaves?
3) Upon atmospheric entry and travel at Mars, it should have holes and not helicopter blades to make it spin, and maybe the spin would help stabalize it and maybe possibly have some lift somehow.   I think that getting a proper shape for atmospheric stability is going to be a dominant property need.
4) For a heat shield, I prefer just metal, but ablatives might also have been sprayed on the the convex side.   So unlike a space capsule, the heated surface would conduct heat to the convex leward side, and that along with having a large surface area would possibly negate the need for an ablative heat shield, or tiles.   I certainly prefer not to waste money and propulsion on a heat shield.
5) In some cases can "Sled down a slope".   Might even be icy/snowy.  You might need a "Smart" version for this.  Less smart ones could impact CO2 Snow/ice or perhaps a sand dune.
6) If it gets dented up, perhaps a rubber mallot could do some good.   It would be a blt like a shock absorber spring.   You might have delivered a usable solar device to Mars.
https://en.wikipedia.org/wiki/Sledding
Note: in the above, there is even something I was not aware existed.  Sand sledding.  How about that!
7) I would start with stainless steel.   It should be possible to test these things to some degree from orbit and down to say a pressure of up to 12 mBar.   But it may be possible to have other materials included in it's structure.

-------
I am very happy that I steped away, and that you started that topic.
So, I do believe that another interesting route might be to make a tire, and roll it down an inclined slope, rather than skiding it.
So, a "Rubber" tire would work ok for the rolling, and may not shatter, either from impact or centrifugal force.   However, if you used such on Titan, it may shatter, except that it might retain heat for a while from aerobraking into the atmosphere.   But I don't think it would be a good heat shield.   Hmmmm.......   Well I guess you could put an ablative coating on it.   So you might have indeed tires rolling down an incline.
In fact, I wanted my tire at first to be stainless steel, which sounds like it would be very brittle.   However if it is heated to a relatively high temperature in atmospheric entry, it may behave more like rubber.   My current thinking is that although it would be mostly hollow, you may have Aluminum or Copper inside, and as the stainless steel heated up on entry, that would melt.  You would heat shield using a phase change.   And that heat might be retained for the balance of the 7 Minutes of terror.   Your tire might already be spinning, and then it impacts on a downsloping inclined plain.   Rolls down to a flat spot and eventually stops.
I am having fun thinking of methods to deliver cargo that is not actually messed up as much during delivery.   It is just a little fun.   Maybe this thing has a parachute involved as well.  Just to get the terminal velocity down.
------
I mentioned helicoptor blades.   Perhaps we could have a reverse roton.   I prefer not to have rocket engines on it's blades.   I just see it as looking like a dandelion seed.   If it can survive atmospheric entry, it might store up spin, so that when it gets to the ground the terminal velocity might be OK.   However then you have the likely problem that it will likely tear itself apart if the blades hit the ground.   It is just fun stuff to think about.   Of course it would have to really spin, but It would be breaking it's fall, not lifting a load.   If the "stem" of the "Seed" were to poke into a sand dune like a harpoon, maybe this would work out well.   Even a "Crash" should yield processed materials for re-process, but the less damage to the structure, probably the better.
I will be willing to respond in either of the two topics, but elsewise think to be quiet.   If we work on understanding perhaps we can be more compatible (th).   Some quiet time from me won't hurt, just slow things down a bit.
Done.


Done.

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#14 2021-02-01 20:19:01

SpaceNut
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Re: Void's Mars Starship Belly Flop Cargo Drop

I have added the post here as well since much of its content applies here as well.

Void wrote:

OK, I guess I will make another run at this.
(th), you can move this post if you like.
Spacenut was trying to get me to look at: https://mars.nasa.gov/mars2020/timeline … MSF0951a18
-Peak heating will be

Peak heating occurs about 80 seconds after atmospheric entry, when the temperature at the external surface of the heat shield reaches about 2,370 degrees Fahrenheit (about 1,300 degrees Celsius). Safe in the aeroshell, however, the rover gets up to only about room temperature.

It does need thrusters, to stay on course, because:

As it begins to descend through the atmosphere, the spacecraft encounters pockets of air that are more or less dense, which can nudge it off course. To compensate, it fires small thrusters on its backshell that adjust its angle and direction of lift. This “guided entry” technique helps the spacecraft stay on the path to its downrange target.

Parachute:

Parachute Deployment
The heat shield slows the spacecraft to under 1,000 miles per hour (1,600 kilometers per hour). At that point, it’s safe to deploy the supersonic parachute. To nail the timing of this critical event, Perseverance uses a new technology – Range Trigger – to calculate its distance to the landing target and open the parachute at the ideal time to hit its mark.

The parachute, which is 70.5 feet (21.5 meters) in diameter, deploys about 240 seconds after entry, at an altitude of about 7 miles (11 kilometers) and a velocity of about 940 mph (1,512 kph).

In the thin Martian atmosphere, the parachute is only able to slow the vehicle to about 200 miles per hour (320 kilometers per hour). To get to its safe touchdown speed, Perseverance must cut itself free of the parachute, and ride the rest of the way down using rockets.

So, not using a parachute or vertical thrust, an impact of about a velocity of about 940 mph (1,512 kph), would be expected.  I confess, I would think the impactor would be very mangled if it impacted strait down, and I still have deep reservations about an inclined plain path intercepting a slope covered with CO2.  I guess you might still have wreakage to gather.  I won't completely dismiss the notion, but am concerned about its value.
A supersonic parachute proportional to the above example, but for a "Backpack" ejected from a Starship, perhaps would yield about 200 miles per hour (320 kilometers per hour).   This is more plausable.
For a impact using a parachute, it could be allowed to have a smaller proportional parachute, up to the point where the impact is just to intense to be practicle to deliver salvage of use.
So, this quote suggests that a parachute could slow down more than 1 ton???   I think that if parachutes were to be used it would be because the materials of the parachutes would be valuable.

The Mars 2020 rover, Perseverance, is based on the Mars Science Laboratory's Curiosity rover configuration. It is car-sized, about 10 feet long (not including the arm), 9 feet wide, and 7 feet tall (about 3 meters long, 2.7 meters wide, and 2.2 meters tall). But at 2,260 pounds (1,025 kilograms), it weighs less than a compact car.

I don't think that that weight includes the sky crane or it's propellants, cables, etc.   So, maybe the picture could be better.
Still, it would be much less than a Starships capacity for cargo.   Which then says either don't care about that, or put a multitude of them on the Starship and eject them all, or build a mini-Starship for a lesser number of them.   In other words, the method may not be worthless to think about.   And if you forget parachutes at all, you could have one big backpack and a whole lot of scrap.
So, I am not satisfied that this method will be worthwhile.   But I am not done with it.  Scrap from crashes might not be overlooked so this might have value.
I know that Elon Musk indicates that the Mars settlement(s) must be self sufficient, but a snap of the finger will not make it so.   There will be a time interval between first human or robot landing, and self sufficiency.  I think it is likely to take a significant period.  So, for some materials it might be considered to try the above method(s).
By a backpack on a Starship, I indicate that this device would be on the leward side, above the engines and some way up to the nose or to the nose.
An interesting notion just occured to me, that in this case, you might actually land the Starship with the backpack on, and not save propellants, but possibly have an easy way to release it from the ship to the ground.   Then the Starship does not have to lift a cargo hold back to orbit(s).  And so then would save propellants, and if it is to be unloaded/scrapped, then it is on the ground fairly intact.   Also, I would suggest that for this method, less engine power is needed to land the ship safely.  That might matter.
However, a release during the 7 minutes of terror, would reduce the terminal velocity of the Starship, and that would be helpful, if it could be done safely.  You would save propellants on landing and on lifting off.  However for this Starship you could lift little or no cargo to orbit after than, unless you put a new backpack onto it.
You could simply deliver backpacks to Martian orbit, and send this version up to bring them down one at a time.
Clearly a ~vertical impact will shatter the device, to a degree, less for 200 mph and parachute, and severly at 940 mph and no parachute.
A vertical impact would likely be best done into relatively pure ice such as Korolav Crater, or maybe some created ice body???   Mainly because with a metal detector and means to dig you should be able to retrieve much of it.
My understanding is that the Martian atmosphere is so thin that Meteors will shatter on impact.   We this is not about collecting Meteors though.
For the backpack, I have a notion of structure, which might be improved by others or myself, presuming anyone ever uses this method.
I choose to name 3 classes of materials.
1-Delicate (Machinery and humans, animals).
2-Moderate (Strong Machine Parts, and some Foods).
3-Processed Materials.  For the moment I choose to view only Stainless Steel, Aluminum, and Copper.
I exclude the class 1 from this proposed hard lander.
I have begun to include some possible members of class 2.
I do, of course include class 3.
So, I have something that was induced in my head by Dr. Robert Zubrin.   Stress ratios for atmospheric entry.
Entering Earths atmosphere from LEO ~ 8.0
Entering the Mars atmosphere from interplanetary space, probably a Hohmann Transfer ~ 6.5
Entering the Mars atmosphere from low Martian orbit ~ 4.0
For me this works better than actual speeds.  If Starship can survive entering Earths atmosphere, at ~8.0 for stress, then either form of entry to the Martian atmosphere should be easier.
So, then bogus thinking or not, if bare Stainless Steel is good for the Leward Starship for descent from LEO, it should be fine for leward side where the backpack would be, for both Martian entry modes.
Stainless Steel https://en.wikipedia.org/wiki/Stainless_steelless , Steel as a backpack "Shell". 
Melting points of Stainless Steel:
https://en.wikipedia.org/wiki/Stainless_steel
That's a nice web site good temperature tables.   Remember, that if needed heat shield could be on the backpack.
OK, I came up with this for Copper, I hope it is appropriate: Copper Foam.
https://www.americanelements.com/copper-foam-7440-50-8
So, the backpack can have a lot of Voids, if you want to reduce it's terminal velocity.
Similarly I hope that Aluminum Foam can be made.
https://en.wikipedia.org/wiki/Metal_foam
So, now there is a possible fill for the backpack with possible useful thermal and impact modifying characteristics.
So, those 3 above are what I called class 3 materials.
I am hoping that the nature of this backpack would be that you might include some class 2 items inside.
------
Another thing I have mentioned is precision and accuracy of impact.   By having the Starship take the backpack approximately to where it is wanted, part of the problem is solved for impacts.   Either a ~vertical impact, or an inclined plain impact on the crater rim of Korolav Crater, or similar places.   It may be that the crater rims are large enough that it would usually work to impact an incline rim.  And those might be covered with snow.
If you want more precision than that you have to invest in the control devices to allow it, and those would be destroyed on impact.
However maybe you could build a sliding place and go ahead and add navigation and thrust to these impactors.   It would be quite alot about what such junk is worth on Mars, relative to the expense of getting it there.
$$$$$
I'm pooped.   You realize that I only mentioned the impactors as a passing throught, and now much has been invested.   I hope that some type proves to be of use.   I have a few more that are different than this one.
No spell checking today.   My computer gets bogged down as soon as I linger at NewMars.com
Done.

Spacenut, a couple of points.  Nuclear is OK in my book, but the south facing rim of Korolav, would be a good place to frack, so as to store high heat from solar concentrators in the summer also for use in the winter.

As far as the mirrors falling out of the sky, that remains to be seen what heat shield protection they need.  It would depend on their surface area and inertia.   Also I a hoping that some of the built up heat of the windward side will conduct to the leeward side and be radiated off.   Not proven, but the heat shielding if needed should not need to be anything as strong as for the windward side of Starship.
But there is much to learn.   The heat stress for entering Martian atmosphere is ~4.0 relative to for LEO into the Earth's atmosphere, ~8.0.  So it may be about 1/2 as hard.   I was surprised by that.   It seems that coming from the Earth to Mars by Hohmann, is ~6.5 in relative stress.  These are ratio's that I created based on speed numbers that I have read about.   And remember, it is Stainless Steel most likely.  Falcon 9 fairings have heat shields, but I believe that they are not Stainless Steel.   Honestly, you might catch me wrong to the degree that their must be some heat shield, but I would go ablative, as the mirrors are only going to enter the atmosphere, and will also bang hard on the ground a get scrapped up.

Yes, I think it was said that you could ski on the Moon on just the dust.   Don't know how true.  But a lesser effect must exist on Mars, where gliding down an incline may be possible.

Done.

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#15 2021-02-02 10:15:45

SpaceNut
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Re: Void's Mars Starship Belly Flop Cargo Drop

particularly part 2 and 3 analysis relates

Calliban wrote:

Assumption: impactor is shaped like a bullet, using friction with regolith to slow down on impact.

Type 1 landing (cheapest): aeroshield deceleration only. Typical impact velocity is 1000mph = 450m/s. Note that impact velocity will be smaller for a smaller projectile, as air resistance will have more effect. We can calculate peak deceleration based upon the penetrative depth of the projectile into its target. For a solid projectile made from solid metal say, density would be ~5000kg/m3. The density of Martian regolith is ~2000kg/m3; density of ice = 1000kg/m3. So a 1m long projectile will penetrate ~2.5m into regolith and 5m into ice. Deceleration = 4100g in regolith 2060g in ice. Deceleration time = 0.1-0.2 seconds. Typical pressures on projectile 1m long and 0.5m wide = 26-51MPa. Yield strength of plain carbon steel ~400MPa (for comparison).

Type 2 landing (intermediate cost): aeroshield and parachute. Typical impact speed ~200mph for an object with the mass of Opportunity. Deceleration on impact = 400-800g. Note: for small payloads impact speed will be less. For deceleration of 800g, typical pressures on 1000kg projectile would be 10MPa.

Type 3 landing (expensive): aeroshield, parachute, rocket deceleration. Deceleration on impact ~0g.

Some figures for tolerance to shock:

Shock capability of mechanical wrist watches: 5000g. This would suggest to me that most solid machine parts would survive a type 1 landing if they were properly packaged. Things like drill bits, rhodium bushes for cast basalt fibres, etc.

Rating of electronics built into military artillery shells = 15,500g. This suggests that we should be able to fit each impactor with a radio location device that allows us to track its landing position. It also suggests that well packaged electronics can survive a Type 1 landing.

Brief human exposure survived in crash = >100g. This suggests that only type 3 landings will be suitable for human beings, although there may be options to consider for very small 1-man capsules.

Complex machines like computers and mechanical equipment, will require either a type 3 landing, or maybe a type 2 landing for some relatively small assembled payloads. We could potentially deliver individual components with a type 1 landing and then assemble them into what we need on Mars. Metals, chemicals, food, etc, could all be delivered using a type 1 landing. A successful type 1 and type 2 landing requires that individual payloads are quite small <1 tonne, as they need to decelerate to speeds <1000mph on impact in the thin Martian atmosphere.

For a type 1 delivery to make financial sense, the entry vehicles should be dumb with no active guidance after atmospheric entry. If the sensible Martian atmosphere is 100km deep, this may mean that payloads end up impacting the surface a few kilometres from the intended impact point. I don't think that is a big deal so long as we know where they have landed, I.e we can track them.

I don't see it making much sense trying to deliver payloads like this on a Starship and ejecting them prior to entry, when the Starship already has its own purpose built rocket driven landing system. A vehicle carrying payloads intended for type 1 or 2 landings does not need to decelerate for Mars orbital injection or landing. It would be an expendible bus that would release its payloads shortly before crashing into the top of the Martian atmosphere. I would anticipate that type 1 delivery would only make sense during the early stages of Mars colonisation, as it is most useful for delivery of food, materials and solid machine parts; things that we would ultimately aim to manufacture on Mars rather than ship from Earth. When Starship travel to and from Mars becomes routine, shipping costs will be reduced to the point where it will no longer be beneficial to risk the sort of damage that could occur in a type 1 landing.

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#16 2021-02-02 10:16:52

SpaceNut
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Re: Void's Mars Starship Belly Flop Cargo Drop

The space shuttle's tiles were designed to absorb the heat of re-entry, as the 77 tonne orbiter went from 28,000 km/h to zero.

Mars payload insertion to mars with cruise stage is 15mT at orbit where after firing the engines to break inward towards the planet we are delivering under 2 mT to the surface....Curiosity had the largest aero-shell ever sent to Mars, measuring 4.5 meters across. The parachute deployed in a fraction of a second, and when fully inflated, experienced 32,000 kilograms of force. If you were on board at the time, you would experience 3.6 times as much force as crashing into a wall going 100 km/h wearing your seatbelt.

PIA14835.jpg

https://aerospace.illinois.edu/news/dev … icles-mars


vehicle entering the Martian atmosphere at hypersonic speeds of up to Mach 30 and then slow down quickly due to air friction. Once they reach Mach 3, they deploy a parachute and fire their retrorockets to slow down further.

The problem with heavier missions, according to Putnam, is that parachute systems do not scale well with increasing vehicle mass.

5-theincredibl.jpg

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#17 2021-02-02 14:12:22

SpaceNut
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Re: Void's Mars Starship Belly Flop Cargo Drop

I was reminded by Voids alternative ship posts that a cargo variant simular to a shuttle z ship could be created to allow for a cargo pod to be delivered to an on orbit starship to have them attached by some means to the leeward side much in the way a triple core Falcon Heavy is constructed so that a payload would follow a ballistic delivery to mars.

This cargo pods could be the size of the Falcon upper stage and carried into the thick mars atmospher on the starships back. The cargo would use retro-propulsion to land with legs as the Falcon first stage does.

Hmaz9cV.png

avGHYeZGmu7RN3qDicynFA-1200-80.jpg

Of course it would land on a runway after delivering its payload to the waiting starship.

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#18 2021-02-02 14:30:35

SpaceNut
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Re: Void's Mars Starship Belly Flop Cargo Drop

I  also reminded in shoveling snow early had nearly forgotten that GW had worked out the Red Dragon landing in which the ship capsule without parachutes and substituting more fuel could land safely on mars was possible. That would raise the deliverable with the Red Dragon capsule and cargo to 15 mt to the surface.....

SpaceX drops plans for propulsive Dragon landings

Post gives table of "exrocketman" articles that relate to Mars landers other than a Spacex Starship or Red Dragon

"exrocketman" site is my blog at http://exrocketman.blogspot.com

That was "Reverse-Engineered Dragon Data" dated 6 March 2017,  before Red Dragon was cancelled,

GW post of payload

Red Dragon drag numbers
more on the numbers for the capsules descent

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#19 2021-02-03 18:22:43

SpaceNut
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Re: Void's Mars Starship Belly Flop Cargo Drop

Sums up the physics...

GW Johnson wrote:

For "ballistic" delivery to the surface of Mars,  feasibility depends upon the size of the object.  Bigger objects will have higher ballistic coefficents,  due to the square-cube scaling rules,  even if all densities and proportions are preserved.  That's just physics that applies to everybody.

Higher ballistic coefficients penetrate deeper into Mars's atmosphere beore they come out of hypersonics (with all the plasma and heating) at about Mach 3 speeds.  That's in the neighborhood of 0.7-1 km/s velocity,  angled steeply downward.  And that's also just physics,  although somewhat complicated to calculate.  It applies to everyone's concepts that do any sort of atmospheric entry. 

If you are half a ton to a ton in total mass,  you reach that Mach 3 point fairly high up at 15-25 km altitude on Mars,  and there is time to deploy a chute,  and enjoy some further deceleration from it. Terminal velocities will be in the neighborhood of half to three quarters of a Mach number on Mars (depending upon the chute canopy loading),  which translates to around 150-200 m/s.  Very hard payloads might survive that more or less intact,  but we are talking big solid chunks of steel,  or solid stones,  or something else like that.

If you are well over a ton,  you come out of hypersonics much lower,  near 5-10 km,  and there is simply not time to deploy a chute,  much less have it actually decelerate you.  You will still be over Mach 2 at impact.  More likely still about Mach 3.  Impact velocity will be 0.7 to 1 km/s,  and failing terminal retropropulsion,  there is not a thing you can do about that!  Again,  it's just physics that everyone is subject to.

If the payload is small (quarter-ton sizes) so that a chute can get you down to around half a Mach at impact,  and the impact forces can be withstood by real-world fabrics,  you can use an airbag to cushion the impact,  and thus have shock-hardened electronics survive.  We landed two small rovers that way on Mars. Nothing living can survive that,  though.  Too many gees.  Again,  physics.

This kind of entry requires really good orbital approach control:  you have to come in straight at the limb of the planet.  Your trajectory has to be essentially tangential to the ground,  and at the correct altitude above it.  Mars entry interface is listed as 130 or 140 km by Justus and Braun,  I believe. What that really means is that propulsive course correction capability is absolutely required.  So says the physics.

My guess would be that if your payload sent that way to Mars is many tons,  then after the final course correction,  but before (!) entry interface,  you separate it into multiple fractional-ton portions,  each with its own heat shield and parachute and airbag equipment.  You'll need something more sophisticated than a timer to sequence these devices,  as Mars's atmosphere is rather variable in density,  per Justus and Braun. 

These payloads will come down as a shotgun pattern,  separated from each other by several 10's of km,  at least. You'll need a radio transmitter on each to find them all. The vagaries of aerodynamic drag just do not permit a precise landing point.  Damned physics again.

GW

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#20 2021-02-03 18:47:22

SpaceNut
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Re: Void's Mars Starship Belly Flop Cargo Drop

Aother alternative to parachutes and heatshield

RobertDyck wrote:
GW Johnson wrote:

For "ballistic" delivery to the surface of Mars,  feasibility depends upon the size of the object.  Bigger objects will have higher ballistic coefficents,  due to the square-cube scaling rules,  even if all densities and proportions are preserved.  That's just physics that applies to everybody.

I haven't read this whole discussion, but we've discussed ballistic coefficient many times. This is an image of ADEPT. It's a carbon fibre fabric that opens like an umbrella. It increases surface area to resolve the cube-square problem. This is the technology that Robert Zubrin included with his original Mars Direct plan of 1990. Yes, NASA was already working on ADEPT in the late 1980s. Baseline configuration for Mars is 40 metric tonnes payload. Mars Direct was smaller than that: 25.2 tonnes hab, 28.6 tonne ERV, taking from "The Case for Mars" 1997 soft cover edition.
139-main-image1.jpg

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#21 2021-02-07 11:31:56

Void
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Re: Void's Mars Starship Belly Flop Cargo Drop

------
I have some notions that I would like to try to resolve.....
First of all, I think all of my asperations about delivering certain substances to Mars in a crash mode have been resolved.  They are possible, the only remaining question is are they of use against just using a Starship to land them?  And that might be reveaied down the road.
I have taken deep notes from what I think GW Johnson has said.  As I remember, mach 3 or 4 are the limits for impacts, where you might hope to recover the substance of the impactor.  It seems that the impactor at higher speeds will just vaporize and distribute it's materials so far that recovery of an asset is not really to be expected.
And I take that as truth, and would not dream of disputing it.  I am very pleased to get this advice.

I have some strong reservations about what I say here, in light of GW Johnsons counsel.
However I do still think that even vaporized ice may stay with the Moon, particularly in the shadowed craters.   I guess the jury is still out, but it seems possible that somehow the Moon clings to water as it travels around the surface.   I guess we have things to learn.
Quote Me from my head:

I do recall from long ago, however, that if you pushed a payload of ice to impact the Moon's surface some of the impactor will vaporize but some will remain as ice.
I sort of remember that maybe 60% would remain as ice.  Obviously this would be a pointless thing to do on the day noon side of the Moon.  But this does bring the question that while you would not want to waste time impacting Mars with ice, would it be worthwhile to do it for the Moon?

For instance down the road, might the Earth/Moon send impactors of materials to Mars and maybe Mars or the asteroid belt to the Moon?  Water ice, Carbon to the Moon?
And now another question.  I think that maybe it might be possible to get away with higher speed impacts than 3 or 4 times the speed of sound, if your impactor is impacting ice or CO2 ice.   I don't think I expect anyone to know.
If I trust, I would trust GW Johnson.   However, I am not sure that any of his experiences involved a situation where one object colliding with another was an ice.   Particularly on Mars, the ice may be in the surface materials.   For instance CO2 ice over water ice, if it were Korolev crater in the Martian winter.

I actually don't care, it am just interested.   My concerns were to deliver materials at a likely approximate maximum speed of 940 mph.   It seems that is well possible.  Beyond that I don't care except that I am curious.
Ceres is also an item of interest.  If it has an Ammonia/water/brine ocean(s) down below???
I actually think that it is likely that more of the old Martian atmosphere will be found underground on Mars than would have drifted into space, but still perhaps Ceres could figure large in terraforming Mars.
I have a tendency to collect little items.  One I got ahold of recently was that it is believed by someone that Mars would only loose about 17 inches of water over a billion years of time.
Personally I think that at some point the Martian atmosphere collapsed into the ground as things got cold, clathrates I am supposing.  However indeed some atmosphere has gone into space.
I fear that sometimes some notions of what is real get locked in along the way and then it becomes witch trial criminal to say anything else.  I suspect that that is where we are.   But clearly I am not the one who knows for sure.
Done.


Done.

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