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#151 2021-09-14 13:55:35

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,571
Website

Re: Scouting Mars for Landing Sites

The engineering lander needs to drill down closer to 10 m.  That's deeper than you would probably want to attempt with a power digger with a crew on Mars.  Stuff deeper than that is out of reach of a crew until some real mining and drilling infrastructure is in place. 

Canadrill was supposed to reach 10 m down,  perhaps 20 if you took spares and extra parts.  Unfortunately,  it seems lost to us.

I'm as yet unsure how deep the ESA drill was going to go.  I have yet to finish reading the Finnish boy's thesis.  But 10 m would be a good criterion to judge by.

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#152 2021-09-14 15:18:22

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 7,297

Re: Scouting Mars for Landing Sites

This post is a follow up on the research done by SpaceNut ...

To matti.anttila

This email is coming to you from a member of the NewMars forum, which is
an activity of the Mars Society.

One of our members found your thesis while helping with research in
support of a notion to send a landing pad engineering probe to Mars in 2022.

In another paper to which you were a contributor, the plans for exoMars
were shown in detail.  That probe appears to be on track for launch in 2022.

However, exoMars is a scientific mission.

The proposed engineering probe would do no science at all, except
incidentally as engineering data might be accumulated.

My reason for writing is to inquire if you are in position to suggest an
approach to the problem that can be achieved in one year.

If you are interested in the NewMars initiative, you are welcome to
visit the NewMars.com/forums pages.

The topic of interest is:

http://newmars.com/forums/viewtopic.php?id=10004

Thank you for all the work you put into your thesis and other papers I
have had a chance to see!

(th)

(th)

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#153 2021-09-14 19:38:28

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 23,078

Re: Scouting Mars for Landing Sites

Th. the Exomars is a sampling core style just larger than the perseverance. but good luck with th email...

GW Johnson may (I repeat ** may **) be completely re-writing the Landing Pad probe proposal.  Now's a good time to think about what you would like to see in a proposal that might fly in 2020.   One of the papers you found shows that ESA's exoMars is scheduled for launch in September 2022 on a Proton.

Our lander (if a miracle occurs and we actually cause it to happen) would launch in the same window.

You appeared to be concerned about shadow on the solar panels, and had an idea for a fuzzy whisker cleaning tool of some kind.

Remember to keep the functions separate and not to confuse them.  The drill goes down looking for water.   The rover roams for many meters around the drill, testing the soil with a pounder of some kind.

Funds may be a problem to say the least if no one picks up the concept to send.

Solar panel levels drop with dust settling on then so cleaning dust that sticks will take a bit more than tilting the panels.

Shade on a panel means less power and since we have no control of panel alignment on landing thats a design upgrade need to ensure that we have enough. Sensing the suns position might be possible but we need to design a solar alignment sensor. Which would be used to turn the lander slowly just to get the panels into the correct position.

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#154 2021-09-15 06:02:20

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 7,297

Re: Scouting Mars for Landing Sites

For SpaceNut re #153

Thanks for picking up on the opportunity to rethink the the entire lander design!

One detail I'm hoping you'll add to your vision of adaptive solar cell arrangements is that the rover itself ** does not ** move.  If you reread the draft(s) you'll find that rotation of the lander is specifically NOT wanted, and in fact, is planned to be prevented by ribs below the lander body.

However, there is no reason (that I can think of anyway) why the solar cell panels need to be permanently mounted.  Permanent mounts are certainly the cheapest and least complex system for mounting, and I'll bet that permanent mounts weigh the least.  Mass is always a constraint.

GW Johnson appears to be leaning toward lots of small landers instead of one big one, in order to cover as many potential landing sites as possible with a launch in 2022.  This means the mass of individual landers is constrained.

Every gram you (and design team) allocate to moving the solar panels or cleaning them is subtracted from the total mass available.

It is tradeoffs like that the folks at JPL have been making for many years, and it is good to see such thinking open for viewing by the entire population of Earth with Internet access.  We'll be lucky if six people ever read this topic, but the potential is there.

My guess is that you will find any kind of sensor you need readily available from electronics supply websites.

Regarding funding .... these principles bear repeating from time to time ....

Mars Society is a tax exempt organization of long standing.  It is eligible to accept donations for work in science, education and charitable purposes.

A large corporation, or a wealthy individual, can hope for identification with an achievement on Mars, such as naming of a base where preparations have been made for the first human landing. 

The key (from my perspective) is to build a team able to carry out the steps needed to achieve the goal.

GW Johnson has pointed to JPL as an example of an organization with a proven track record of successful team achievement.

However, Earth has produced a number of teams competing in this arena, and we will surely see more in the years ahead.

If anyone is at all curious to see what developing teams look like, there are videos in the Mars Society archive that report on the robot competitions of recent years.

Update later: For SpaceNut ... you could consider mounting your dust bunny whisk on the rover.  It needs to come back to the rover to recharge anyway.

Why not whisk the solar panels at night when they are off duty?

You had mentioned keeping the electronics warm in an earlier post.  That will consume some power. 

There will be a power budget, just like the mass budget.

(th)

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#155 2021-09-15 06:43:51

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 7,297

Re: Scouting Mars for Landing Sites

Post #154 included mention of Mars Society robotics competitions.

Anyone who might be interested can find video about Mars Society robotics competitions in past years in the video archive.

The tests have been designed to test the ability of a robot to open a door of an equipment cabinet.

It occurs to me that the initiative of GW Johnson could be an opportunity for a global competition to design a pair of robots for the 2022 launch.

I would expect that previous teams (from universities for the most part) would be enlisted.

The mission would be relatively simple compared to the Mars Society challenges, but the difference would be that the winner would fly (if it works), and runners up could fly if they are good enough to function at all.

As I understand the thinking of GW Johnson (and I could be wrong, or he could change his thinking), the goal now is to try to assemble a number of robot pairs so that multiple landing sites can be explored from a single Falcon Heavy launch.

We have a year, and as SpaceNut has reminded us, we can't be starting from scratch for this undertaking.

Fortunately, it appears there are a significant number of capable teams already in place around the world.

(th)

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#156 2021-09-15 08:19:57

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 7,297

Re: Scouting Mars for Landing Sites

It has come to my attention that some members of the forum correspondent pool may not be aware of the correct spelling and display format for the word: SpaceX

Because we expect to be interacting with SpaceX in future projects, it is desirable/preferable for all of us to make an effort to use the correct spelling and display format.

To help with that, Google came up with this Wikipedia entry:

Space Exploration Technologies Corp.  (SpaceX) is an American aerospace manufacturer, space transportation services and communications company headquartered in Hawthorne, California. SpaceX was founded in 2002 by Elon Musk with the goal of reducing space transportation costs to enable the colonization of Mars.
SpaceX - Wikipedia
en.wikipedia.org › wiki › SpaceX
About Featured Snippets

(th)

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#157 2021-09-15 08:59:41

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 7,297

Re: Scouting Mars for Landing Sites

This is a special request for kbd512 ...

In (trying anyway) helping GW Johnson to prepare correspondence, I ran across a need that might be perfect for your talents, if you are at all interested ..;.

In order to stimulate donations of massive amounts of money to fund a Mars Lander competition, it would be helpful if individuals or organizations could look forward to securing naming rights on features of Solar System objects where they have made a significant contribution.

Your Senator Cruz ** might ** be the perfect ball carrier for a Senate Resolution, if you can persuade him to consider it...

A key concept is for the US Senate to declare that it reserves the right to name an object or a location on an object in the Solar System where an American citizen or organization has made a significant contribution.
I will take that up with kbd512.

It might add a bit of zip to the concept to consider Texas based organizations as having special entre to this naming opportunity.

I don't know of that would pass muster in the primary resolution, but the Office of Senator Cruz could definitely publish an assertion that a Texas based entity that donates (say, $150,000,000 US) would receive priority attention from the Senator's office.

Note: Google is upset about the word entre ... I intend for the spelling to be understood as meaning "consideration for admission"

This usage has nothing to do with food.

(th)

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#158 2021-09-15 15:22:08

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,571
Website

Re: Scouting Mars for Landing Sites

Just to let the whole team know,  I am in the process of re-writing the lander proposal to reflect a small rover from a fixed lander.  The dropped-ball soil tester goes on the rover,  and whatever coring drill we can come up with,  on the fixed lander.  This is the same size class as the MER probes:  Spirit and Opportunity.

The idea would be to land the probe atop where we think the buried ice might be,  at any given candidate site.  The rover then moves from there to where the later ships would really be landed,  testing soil bearing strength all along the way.  The fixed lander just drills down,  trying to determine if the massive ice is really down there,  close enough to the surface to be useful to a crew (which is where the 10 m comes from),  and not too salty or too contaminated with perchlorates. 

The soil tester drops a hard,  heavy metal ball from a known height.  This makes an indentation in the soil.  I've figured out how to photograph this with the rover camera,  and scale impression diameter relative to (known) ball diameter from the photo back here on Earth,  which also determines impression depth from the spherical geometry.   The ball's Mars weight is also know,  Drop height times Mars weight is potential energy.  Divide that PE by the impression depth to get a measure of the impact force.  Divide that impact force by the impression area to get a measure of soil bearing pressure at soil failure.  (This is a test used at Earthly construction sites).

Now,  based on Earthly construction site practices,  divide your soil failure pressure by about factor of 3,  to get the best estimate of allowable soil bearing pressure.  You cannot safely exceed that with factored touchdown weights,  or unfactored launch weights once refilled.  That is how you size your landing pad area.

I have re-written the letter proposal,  but not yet the appendix with the details. I sent this to TH,  for all of the team to look at. 

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#159 2021-09-15 17:33:11

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 23,078

Re: Scouting Mars for Landing Sites

keeping stuff related within the topic

tahanson43206 wrote:

Submitted to the VP web site:

Dear Vice President Harris:

This message is impelled by the doubt of some that you and President Biden do not have a space policy.  I think you have so much on your task list that space doesn't show up very high.

I'd like (as an ordinary citizen) to try to help.

The Mars Society has been around for a while.

SpaceX and Elon Musk have announced intentions to send people to Mars, and they have succeeded in sending a Tesla Roadster into a Solar orbit that extends past the orbit of Mars.

I am a moderator (Junior Grade) in the NewMars.com/Forums.  NewMars is an activity of the Mars Society.

Dr. GW Johnson is a retired aerospace engineer who has (bravely in my estimation) decided to attempt to define an activity that would (if fulfilled) lead to landing a number of small engineering probes on the surface of Mars, with launch date in September 2022.

Dr. Johnson is (I understand) in the process of constructing the specifications for a global competition to design/build/test engineering landers to (a) dig for water and (b) pound the soil to determine suitability for landing humans in 2025.

Here is my ask:

Please consider allocating $100,000 (or more if appropriate) for support of any college, university or high school which decides to attempt to design/build/test a pair of robots to handle the requirements of the challenge.

Best wishes for success in all your endeavors!  I am one of many who are counting on your growth and development to be able to handle the top job when the time comes.

(th)

(th)

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#160 2021-09-15 17:35:21

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 23,078

Re: Scouting Mars for Landing Sites

tahanson43206 wrote:

For the record .... This is most likely an automated response ...

It seems (to me at least) highly unlikely that every message posted to this site could possibly be reviewed by a person.
There would simply be too many.  Still, it's nice to know a "friendly" computer processed the message, encrypted it, and stored it in the cloud.

September 15, 2021

   
Thank you for contacting the Biden-Harris Administration.

President Biden and Vice President Harris value every opportunity to engage with the American people, and the Administration is grateful for your outreach. Our country faces many challenges, and messages like yours help us better understand how the Biden-Harris Administration can serve American families.

We take careful note of the suggestions, thoughts, questions, and stories we receive, and we’re working hard to ensure you receive an appropriate response.

Sincerely,

The Office of  Vice Presidential Correspondence

I do congratulate you for the effort and who knows it may flow up the chain of command to at least have a visitor of two to the site to investigate what we are talking about.

As news leak would not hurt either....

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#161 2021-09-15 18:33:52

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 23,078

Re: Scouting Mars for Landing Sites

I wanted to comment about the solar orientation which is done before the ship makes contact to the land and has plenty of time once the heat shield is gone to allow for the sensing and turning of the ship as it approaches the landing site.

Something else needed is a downward looking camera on the lander able to determine if we are landing on bedrock as the ship needs to move off from that trajectory to be able to make use of the staves that are meant to hold the drilling rig platform stationary while in use.

Be aware that the MER technology is pretty old even if we could fine parts to build them its going to take along period of time to reproduce them. These had quite the problem with actuators while the were building and testing them. It was only due to over ordering that they ended up being able to build 2 for the 800 million that was spent on them.

They also needed several program upgrades as the code was stepping on itself causing it to enter safe modes several times after the duration of time was extended multiple times.

The MERS bounced around quite a lot with the air bags so these are going to be more like the units tested with the orion capsule than the cocoon of them.

Nasa has a habit of building what are sand box units to be able to test out problems that might happen and use them to solve when the real deals get stuck as it happened. It might be possible to see if these are still viable for conversion into the plan with modifications.
That said it seems that time has passed working hardware to the dumpster most likely so this is looking like its a fresh build with in the scope of technical mission goals.

Landing is a fresh design not only for the lander but for the shape of the protective shroud since we are still working on a tall drilling tower.
These changes to rover and tower means a new back shell will get designed since we are not staying inside of the size shape for the current MSL/ Persaverence design.


Looking back at the post 147 the images look to me like the drill bit and sample tube are the assembly that is put into the head to drill and retain the sample and if that is the case we are going to need to alter that drill sample length if we are using that design type.

I have the latest copy on my machine to read later when I have a bit more time to focus.

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#162 2021-09-16 08:58:32

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 7,297

Re: Scouting Mars for Landing Sites

For SpaceNut re #161

Your interest in the problem of the shadow we can expect from the tower shape of the lander led me to think about the situation a bit ...

For one thing,  we know (from GW Johnson documents) the lander **base** is intended to be fixed to prevent rotation due to torque created by the drill.

While I think the risk of rotation of the lander by the drill is small, GW Johnson has added insurance against that possibility.

However, there is nothing that precludes the mount for the solar panels from being able to rotate around the vertical axis of the tower.

We have already seen (per GW Johnson documents) that rotation of the solar panels in the horizontal axis is already included in the plan.

By adding rotation of the entire solar panel assembly around the tower, we allow for tracking the Sun through out the day, and for rotating the panels to upside down position for overnight protection from dust in the air,

If you are able to win the argument for mass needed for your little rabbit's foot dust bunny remover, you could mount that on the rover pounder, so it can tend the solar panels at night while it is recharging from the lander.

***
Related now to the tower .... The tower provides the opportunity to establish optical and radio beacons.  The drill operation is done once.

After the water is either found to be present, or is found to be absent, the drill component still has the important duty of supplying power for the rover pounder, power for communications with Earth and the rover, and power for keeping components warm over night.

After humans land, the drill can be moved to where it is needed.

However, in the ** mean ** time, the tower can serve as a beacon for arriving space craft, who will want to land (presumably) on the well pounded regolith tested by the pounding rover.  The optical component would save a similar function to light houses on Earth, for assistance to overland travelers who should have radio but may not in an emergency.

The lander needs to be designed to survive for at least two (Earth) years, so it is functional when the Starships show up.

***
I have printed Draft #6, and expect to take scalpel to it later today.

(th)

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#163 2021-09-16 11:11:01

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 7,297

Re: Scouting Mars for Landing Sites

Correspondence: Reply from Dr. Greig of University of Texas at El Paso regarding Mars Lander / drill

1 of 1
20210912 Question for Dr. Greig from Dr. Johnson
Inbox
NewMarsMember

Tom Hanson
Sun, Sep 12, 7:20 PM (4 days ago)
For Dr. Greig, Dr. Johnson asked if you could help? I have no idea if anyone at UTEP can help, but if you can find such a person, this would be a great time for

Tom Hanson
Wed, Sep 15, 12:15 PM (1 day ago)
to Amelia, me, Tom

Dear Dr. Greig.

Thank you for your reply to our inquiry, and for your helpful suggestion.

I am serving as a correspondent in this situation ( a sort of secretary
perhaps) and will forward your reply immediately.

Please note that we (that is, Dr. Johnson and team)  are working on a
concept that ** might ** develop into a global competition if the
conditions are right.

UTEP would certainly be among those organizations who might be eligible
to participate.

Mars Society (of which NewMars is a small part) has  been conducting
robotics competitions for years.

This would be a larger version of those, if we can (somehow) sprinkle
the tea leaves so it comes to pass.

(th)

On 9/15/21 11:58 AM, Greig, Amelia D wrote:
> Hello Tom,
>
> No-one at UTEP is working on drill based ISRU technologies. We have programs on the Arc Mining concept you saw the presentation on and thermal ice mining capture systems, but not the actual drill part.
>
> Not sure if it fits in with the ideas for the rover part, but Sarbajit Banerjee from Texas A&M is working on a landing pad development idea for the Moon. Could be of interest?
> https://www.nasa.gov/directorates/space … on_System/
>
> Amelia
>
> Dr. Amelia Greig
> Assistant Professor
> Mechanical Engineering
> UTEP Aerospace Center (cSETR)
> The University of Texas at El Paso
>
> Engineering Building A-109
> El Paso, Texas, 79968
>

(th)

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#164 2021-09-16 11:47:48

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 7,297

Re: Scouting Mars for Landing Sites

https://www.nasa.gov/directorates/space … on_System/

Regolith Adaptive Modification System (RAMs) to Support Early Extraterrestrial Planetary Landings (and Operations)
Sarbajit Banerjee
Texas A&M Engineering Experiment Station

Vehicle landing on launch pad of lunar surface with Earth in background.
Graphic depiction of Regolith Adaptive Modification System (RAMs)
Credits: Sarbajit Banerjee
The “Regolith Adaptive Modification system (RAMs)” was conceived for selective reinforcement and fusing of native Lunar surface materials. The current concept was evolved from a previous NASA NIAC proposal focused on flexible lightweight landing platforms. Much of the current Lunar regolith modification research is focused on using technologies that require significant presence and infrastructure for success, such as sintering and geo-polymerization. In contrast, the RAMs system is uniquely suited for supporting deployment during early landings, but can also be used for more mature construction activities after establishment of Lunar and Martian settlements. Rather than bringing all the material, equipment, and power supplies needed to modify regolith for dust control and other foundation support for foldable landing pads, fixed landing pads or roads, RAMs uses novel microcapsule delivery systems that deliver precursors (nanothermite mixtures and organosilanes) which activate upon deployment to spot-weld anchor points binding the surface structures to the underlying regolith through in situ formation of advanced high-strength steel pegs. This same system delivers additional subsurface regolith stabilization precursors that are impelled deeper within the soil and activated by the initial exothermic reaction resulting in an underlying continuous layer of thermite-fused and geopolymerized regolith constituting a bulwark that provides additional load-bearing capacity. Dust mitigation and bearing capacity are accomplished, therefore, by both reaction/solidification chemistry and a physical mesh barrier.

The novel technologies in the RAMs concept are: 1) a built-in microcapsule-based welding and regolith solidification system consisting of safer nanothermite mixtures and soil stabilizers designed to activate sequentially to form pig iron-based anchors as well as advanced high-strength and ductile steel anchors if needed. These anchors will extend along the rim of the platform and penetrate into the regolith matrix; 2) the use of energy stored within the chemical bonds of regolith components as the primary source to power in situ spot welding and creation of embedded alloy frameworks. This system will anchor assets like flexible pads to a planetary surface by generating in situ the equivalent of seismic grade alloys if needed (in terms of yield strength and elongation performance), e.g., if pig-iron is not strong enough. These alloys enable the platform to withstand the thermal and mechanical stresses incumbent during repeated propulsive landings. Importantly, both the nanothermite and the encapsulating systems are lightweight as well as safe to fly.

2021 Phase I Selections
2011-2021 Consolidated List

Last Updated: Apr 8, 2021
Editor: Loura Hall
Nasa
National Aeronautics and Space Administration
Page Last Updated: Apr 8, 2021
NASA Official: Brian Dunbar

The link to this article is courtesy of Dr. Amelia Grieg, University of Texas at El Paso

(th)

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#165 2021-09-16 11:51:33

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 7,297

Re: Scouting Mars for Landing Sites

https://www.esa.int/Newsroom/Press_Rele … et_in_2022

SCIENCE & EXPLORATION
6–2020: ExoMars to take off for the Red Planet in 2022

This post is to show the correct spelling and display for the ExoMars rover mission.

(th)

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#166 2021-09-16 12:04:58

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,571
Website

Re: Scouting Mars for Landing Sites

It would appear that ESA has a drill rig,  but it is only to drill down about 2 m.  They re looking for life remnants,  not ice. 

I wonder if it can go any deeper? 

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#167 2021-09-16 13:13:46

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 7,297

Re: Scouting Mars for Landing Sites

For GW Johnson ...

Re Post #166 and beyond .... Hopefully a forum member can dig into the question.  Ideal would be correspondence with a member of the ESA team working on the launch.

While following a list of topics, I found this: http://newmars.com/forums/viewtopic.php … 586#p83586

This post is by SpaceNut back a way, when he reported upon some drill experiments.

SpaceNut .. any chance you can update that post?

Was the equipment suitable for the lander project?

Update: to save everyone time, the top link in the post by SpaceNut is dead.

This one is live: https://www.nasa.gov/centers/ames/resea … drill.html

(th)

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#168 2021-09-17 18:30:27

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 23,078

Re: Scouting Mars for Landing Sites

The post about Ingenuity got me to thinking about getting one for the lander since the payload mass is so tiny. It would be a good selling point for scouting mars faster.

Exo Mars and eromars were also about sample return so will post the links for other topics as well

2nd try....

Mars Sample Return (MSR) Mission
Mars Sample Return (MSR)
ESA Mars sample return mission


ExoMars - ESA Mars rover
ExoMars to be "Upgraded"

I also noticed that they called the drill  the "Mole"

Rxke wrote:

NASA update on the work...

Small, lightweight... Hopefully they build them in droves, could be interesting to take drillings at a variety of places...

Roland Piquepaille has some more info that's not on the current NASA page.


before they were called spirit and opportunity of which we have 7 or 8 topics for these
Mars Exploration Rovers (MER)

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#170 2021-09-17 20:23:08

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 23,078

Re: Scouting Mars for Landing Sites

Since we want a tower for the stationary drill on the lander the back shell will need redesigning to allow for the combination of segmentation of the drill and to be able to extend the towers height from being stowed to fully upright for use once we land.

https://mars.nasa.gov/mars2020/spacecraft/overview/

The MER's used the air bags that cocooned the ships rovers on landing bouncing and rolling before coming to a stop, so I would say this is out unless we have seperate EDL's
http://www.nasa-ksc.org/Airbag_Mer.pdf

Table 2 gives mars edl back shell Diameter comparisons but not height for the inside demensions
https://ntrs.nasa.gov/api/citations/200 … 024230.pdf
Aerothermodynamic Design of the Mars
Science Laboratory Back shell and Parachute Cone

https://ntrs.nasa.gov/api/citations/201 … 011479.pdf
Independent Assessment of the Backshell
Pressure Field for Mars Entry, Descent, and
Landing Instrumentation 2 (MEDLI2)

https://marsnext.jpl.nasa.gov/workshops … nts_v6.pdf
EDL Engineering Constraints

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#171 2021-09-18 06:11:00

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 7,297

Re: Scouting Mars for Landing Sites

For SpaceNut .... Re #170

Out of curiosity, are you aware of an height limit for the lander with the drill tower?

Why would you want to make the tower anything other than fixed in size and structure?

My understanding is that there is a lot of vertical distance to work with inside a Falcon Heavy cowling (which may be the same as Falcon 9).

It would be helpful to know the dimensions inside the standard cowling, if they are available to the public.

GW Johnson was planning to use retro rockets at the top of the tower to accomplish a soft landing.

Has he given up on that idea? I haven't studied Draft #6 so am not up the latest version.

Hopefully, I'll have time for Draft #6 and the work done by kbd512 in the Nuclear Safe topic.

(th)

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#172 2021-09-18 09:25:11

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 23,078

Re: Scouting Mars for Landing Sites

Payload shroud height back shell that delivers the payload to mars. The shroud is used for launch compression through earths atmosphere to protect the payload. The third stage, cruise and back shell, heat shield and payload are sent on the path from orbit to mars as the shroud is jetisoned once in orbit.

This is how a payload is delivered to mars of which the cruise stage and back shell makes the trip from earth orbit to mars once the boost stage fires.

The spacecraft consists of several mechanical components – the cruise stage, descent stage, backshell, and heat shield – plus the rover.

substitute tower plus our small rover for the sky crane and large rover.
mission-parts-web2.jpg

The tower must fit with in the height of the back shell.

here is the sizing comparison which is not showing values for the skycrane that the rover is folded under inside of the back sheel and heat shield assembly.

Perseverance Rover
Mass: About 2,260 pounds (1,025 kilograms), including a robotic arm with a 99-pound (45-kilogram) turret at the end
Dimensions: 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), with a robotic arm that is about 7 feet (2.1 meters) long


The engines at the top of the tower require thermal protection shield to keep exhaust plume from damaging the payload so that compounds the problem of mass at launch and mass for parachute use.

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#173 2021-09-18 09:39:14

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 7,297

Re: Scouting Mars for Landing Sites

For SpaceNut re #172

Thank you for this helpful addition to the topic!

Now I have a question for you ...

The engines at the top of the tower require thermal protection shield to keep exhaust plume from damaging the payload so that compounds the problem of mass at launch and mass for parachute use.

Why do you suppose a heat shield is needed for the top of the drill tower?

The rockets are directed away from the lander (a) and (b) the atmosphere through which the lander is travelling will be moving faster than the exhaust of the rocket, so the atmosphere will carry the exhaust away and behind the landing spacecraft.

Have you checked Draft #6 to confirm the retro rockets are still there?

I'm hoping to get to study of Draft #6 this weekend.

(th)

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#174 2021-09-18 10:02:16

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 23,078

Re: Scouting Mars for Landing Sites

Thrust from the angle towards the ground is reduced in effectiveness as the amount of change goes from vertical to sideways. So at a 45' angle the thrust is only half of what is needed so the angle to get the most out of its going tocause the plume to be close to if not in the payload area.

Notice how high above the Orion capsule the retro rockets are to keep the plume away from the capsule.
38418057711_788f9b8cab_b.jpg

Here is the spacex crew test, notice the black is the heat shield material to protect against the plume burn through
video-spacex-crew-dragon-escape-system-1200x630_1_1024.jpg

close up of the engine area
Crew-Dragon-SuperDraco-static-fire-Oct-2019-SpaceX-mosaic-1.jpg

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#175 2021-09-18 10:16:52

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 7,297

Re: Scouting Mars for Landing Sites

For SpaceNut re #174

Thanks for these helpful examples of how to design retro-rockets so they work as needed, and do not injure the payload.

Your examples do NOT show the reverse flow of arrival at Mars.  The examples are ALL of vehicles headed INTO the atmosphere.

That said, the idea of designing heat resistant plates into the shell of the rover under the rockets makes sense.  The heat resistant material does NOT need to be installed anywhere else.

On the ** other ** hand, gases blown back by the atmosphere of Mars will certainly touch the top of the lander above the retro-rockets, so some thought would seen worth giving to that possibility.

All-in-all, it seems to me this is a useful discussion.

SearchTerm:retrorocket design for Mars lander

(th)

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