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#26 2020-06-22 16:34:48

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

Re: Human Business and flight plan for mars

The moon allows for a topping off of fuel tanks with lunar oxygen but is a problem for targeting the mars system with additional speed as now you need even more fuel to slow down...

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#27 2020-06-22 17:49:34

tahanson43206
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Re: Human Business and flight plan for mars

For SpaceNut re elderflower's suggestion ...

The idea of gaining speed by swinging by the Moon on the way to Mars probably would be a better fit in the Orbital Mechanics topic.

As you know, a vehicle swinging by the Moon to gain momentum would not have time to do much refueling.

I am hoping GW Johnson will be willing to take a look at the suggestion.

It is possible the mass of the Moon is insufficient to make much of a difference, but I think it is well worth investigating.

(th)

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#28 2020-06-22 19:41:13

SpaceNut
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Re: Human Business and flight plan for mars

question forwarded into orbital mechanics

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#29 2020-06-22 20:06:11

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,571
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Re: Human Business and flight plan for mars

I can do more-conventional orbits,  but not gravity assists.  I am not an expert in orbital mechanics.  And I have no software that does orbits. I just do it essentially pencil and paper.  Sorry.

GW

Last edited by GW Johnson (2020-06-22 20:06:26)


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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#30 2020-06-24 10:22:12

elderflower
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Registered: 2016-06-19
Posts: 1,262

Re: Human Business and flight plan for mars

OK. I just wondered. Thanks GW.
I dare say that somebody in Nasa would have thought of it and worked it up if it is realistic.

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#31 2020-06-24 10:55:38

tahanson43206
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Re: Human Business and flight plan for mars

For elderflower re #30

Thanks for asking the question!  Hopefully others will be interested to follow your lead.

In continuing my follow up on your original question, I learned today that a potentially more useful feature of a lunar fly-by is a plane change.

According to Google, which served up citations about lunar fly-by, the technique was first used by the Soviets in 1959.

This is the citation that I'm picking up on for plane change:

Lunar Gravity Assist for Asteroid Missions. Some asteroid enthusiasts humorously see the Moon mainly as an object to offer gravity assists, not to mine the Moon. A "gravity assist" entails using a fly-by with the Moon to divert the trajectory of a payload and to impart delta-v, saving large amounts of fuel.

Lunar Gravity Assist for Asteroid Missions - PERMANENT.com

Since this is a topic that combines business planning with Mars as an objective, Lunar fly-by maneuvers should be of interest to ** all ** mission planners, as an on-field assistant when needed to solve particular problems of timing or resource availability.

(th)

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#32 2020-06-24 12:16:52

GW Johnson
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From: McGregor, Texas USA
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Re: Human Business and flight plan for mars

All the Apollo lunar missions,  including Apollo-8,  used a lunar flyby trajectory that was close enough at 60 miles altitude to put them on a free-return course for Earth.  I suppose that might qualify as the effectiveness of gravity assist.  Bear in mind that they had to fire the service module engine out of sight around the far side of the moon in order to enter (and leave) lunar orbit.  Bear also in mind that the lunar orbit direction was retrograde,  opposite to what you might want for a gravity assist that adds speed.  But there are effects of a measurable magnitude.

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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#33 2020-06-24 12:55:43

tahanson43206
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Re: Human Business and flight plan for mars

For GW Johnson re #32

Thanks for the reminder of Apollo mission plans.  Your point about firing a rocket on the far side of the Moon rang a bell ... Articles I've run across while investigating elderflower's original question have made the point that the most effective moment to fire a rocket for a trajectory change while maneuvering around the Moon is at the deepest point in the curve around the Moon.  The energy invested then by the mission planners is magnified by the Moon's influence, as I understood the articles.

(th)

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#34 2020-06-25 02:11:25

elderflower
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Re: Human Business and flight plan for mars

Not just the Moon, TAH. That applies to any body that you want to exploit for a change of velocity. Its called the Oberth Effect.

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#35 2020-06-25 08:08:10

tahanson43206
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Posts: 7,297

Re: Human Business and flight plan for mars

For elderflower re #34

Thanks for the timely reminder of the Oberth Effect!

I asked FluxBB to show all the posts that mention the Oberth Effect, and it found 25, starting with this one:
http://newmars.com/forums/viewtopic.php … 861#p58861

One post was particularly interesting because the author made the point that while the Oberth Effect and Gravity Slingshot share a ** lot ** of characteristics, they are not the same.  The Wikipedia article on the Oberth effect looks as though it is worth study.  There are several YouTube videos available.

One distinction that I found in one of the NewMars posts (or perhaps in one of the recommended links) is that firing the rocket is best accomplished (or achieves the most benefit) when the speed is greatest.  However, as the poster at the link above (from 2004) pointed out, there is a navigation challenge for the mission planner, to design the flight path and the momentum input so the desired outbound trajectory is achieved.  The desired outbound trajectory may NOT coincide with the maximum impulse benefit, depending upon variables such as the mass of the body to be used as a fulcrum, the velocity of the vehicle making the trip, and accuracy of impulse execution during the flight.

I can sympathize with those who have the capability of performing such calculations by hand (or nearly so) as was indeed done during the early years of the US and Soviet space programs.

As I have posted previously in this forum, I would like to see an online (or inexpensive phone) app that allows an ordinary space traveler to plan a flight from body A to body B the way a citizen on Earth today can plan a trip using GPS and a device containing the software, or a smart phone running an app.

Thanks again for your original question of GW Johnson.  I come away from this series with the impression the greater benefit of a gravity assist by the Moon is a plane change, as compared to the relatively small benefit of velocity increase for a trip to Mars.  I would like to see this potential benefit examined by a qualified team or perhaps even an individual, to see if trips to objects such as the stray fragment of matter that passed through the Solar System recently might be reached more rapidly and at less energy cost that would be the case with unassisted departure from LEO.

There is a longer term concern however ... as traffic builds up in the vicinity of the Moon, the risk of a collision by performing this maneuver becomes greater, to the point it might be discouraged by whatever traffic control agency comes into being in the Earth/Moon system.

(th)

Last edited by tahanson43206 (2020-06-25 08:08:46)

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#36 2020-06-25 11:15:21

GW Johnson
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From: McGregor, Texas USA
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Posts: 4,571
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Re: Human Business and flight plan for mars

Just musing in my ignorance,  I would think the gravity assist effect is bounded by zero at the lower end,  and by the body's speed through space at the upper end.  The moon's orbital velocity about the Earth is quite modest.  So any increase in velocity with respect to the Earth would also have to be quite modest. Not zero.  But not very dramatic,  either.

GW

Last edited by GW Johnson (2020-06-25 11:16:30)


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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#37 2020-06-25 11:35:48

tahanson43206
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Posts: 7,297

Re: Human Business and flight plan for mars

For GW Johnson re #36

First, thank you for the good news for the test for your wife, followed immediately by best wishes to find and correct whatever ** is ** going on!

Second, thanks for offering inspiration to someone not currently registered as a contributor to this forum, who might have education, experience ** and ** the software tools to help answer some of the questions that keep coming up in this forum, and (of course) in numerous other locations on the Internet.

In the absence of such a person, existing members of the forum have the opportunity to investigate this question, and come back with a link to one or more resources, ** and ** a concise, carefully written explanation of the answer (assuming there ** is ** an answer).

In the past, JoshNH4H has asked thought provoking questions for which there ** is ** no answer in known physics. 

What I am hoping will show up in this topic (or the orbital Mechanics topic) is a review of the thought process for selecting gravity assist, with or without an addition of impulse, to solve various Solar System navigation problems.

An example would be finding the optimum solution for a mission to Apophis, which remains on its regular path which will bring it quite close to Earth (inside GEO) in 2029 (as I recall).

A plane change is required.  The traditional navigation plan would NOT include a visit to the Moon.  Fuel would be expended to accomplish the plane change and orbit matching.  My question (for the hypothetical contributor) is whether there is a benefit to be achieved by planning a course around the Moon, with or without additional impulse.

(th)

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#38 2020-06-25 16:42:35

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

Re: Human Business and flight plan for mars

We still have a long laundry list of needs for a manned mission as they are currently not in production.

Cargo launchers are not human launchers.

Habitat spaces are not entirely an ISS mocule or a bigelow inflatable.

No cargo refuelers, fuel depots ect.

Life support is not the ISS as we need to resupply it to make it work long enough.

No lander is capable of tonnage to mars surface let alone the moons as we have not built them even if the parts exist to do so.

We have not a commercial insitu processing for mars refueling let alone a energy source that we can deliver other than a heavy solar battery combination.

We have no ready made garden or other life support systems for the surface that we can depend on to work without up'ing the energy needs to make it work.

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#39 2020-11-22 18:09:49

SpaceNut
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Posts: 23,078

Re: Human Business and flight plan for mars

A Baseline Strategy for Human Mars Mission

https://www.nasa.gov/feature/mars-human … entations/

Nov 17, 2015
Mars Human Landing Site Workshop Presentations
Return to page: NASA Seeks Ideas for Where on Mars the Next Giant Leap Will Take Place

Please note that the files are currently being processed for Section 508 compliance.

Tuesday Presentations PM
Mars Human Landing Site Workshop (pdf) https://www.nasa.gov/sites/default/file … tagged.pdf
Human Landing Sites Study (HLS2) Overview (pdf) https://www.nasa.gov/sites/default/file … tagged.pdf
Polling Strategy (pdf)
Candidate Scientific Obj. for the Human Exploration of Mars & Implications for the Identification of Martian Exploration Zones (pdf) https://www.nasa.gov/sites/default/file … tagged.pdf
ISRU & Civil Engineering Needs for Future Human Mars Missions (pdf) https://www.nasa.gov/sites/default/file … ewg_v2.pdf
Pioneering Space Through an Evolvable Mars Campaign (pdf)
Orbiter Reconnaissance for Landing Sites for Humans (pdf)
Mars Landing Site Selection: A Crew Perspective (pdf) http://www.nasa.gov/sites/default/files … g_site.pdf
Planetary Protection Considerations in the Selection of Landing Sites for Human Mars Missions (pdf)
East Melas Chasm Exploration Zone (pdf)
Human Exploration of Valles Marineris: The Past, Present, and Future of Life on Mars (pdf)
Mars Landing +50 Years (pdf)
The Eastern Outlet of Valles Marineris: A Window into the Ancient Geologic and Hydrologic Evolution of Mars (pdf)

Wednesday Presentations AM
Equatorial Opportunities for Humans on Mars (pdf) https://www.nasa.gov/sites/default/file … tagged.pdf
Assessing Gale Crater as a Potential Human Mission Landing Site on Mars (pdf)
NASA Landing Site / Exploration Zone for the First Human Missions (pdf) https://www.nasa.gov/sites/default/file … tagged.pdf
Ground Truth Assessment of Gale Crater Using MSL Data for Characterization of Potential Human Mission Landing Site and ISRU (pdf)
Sinus Meridiani Landing Site for Human Exploration—A Mesoscale Fluvial System (pdf)
Southern Edge of Meridiani Planum (pdf)
The Land of Opportunity: A Human Return to Meridiani Planum (pdf)
Columbia Base: The Dawn of a New Era (pdf)
Zephyria Planum Hills—A Source of Deep Resources (pdf)
Apollinaris Sulci (pdf)
Exploration Zone: Gusev Crater-Apollinaris Sulci (pdf)
The Hebrus Valles Exploration Zone: Access to the Martian Surface and Subsurface (pdf)

Wednesday Presentations PM
The Hypanis Fluvial-Deltaic-Lacustrine System in Xanthe Terra (pdf)
Jezero Crater Watershed, Isidis Basin, Sulfate Deposits and Syrtis Major: A Compelling Exploration Zone for Human Exploration (pdf)
Nili Fossae (pdf)
Aram Chaos Exploration Zone (pdf)
An Exploration Zone in Cerberus Containing Young and Old Terrains, Including Fossae/Faults and Shergottite Distal Ejecta (pdf)
Southern Nectaris Fossae: A Microcosm of Martian Geology (pdf)
Exploring an Exhumed, Intercrater Basin in Martian Cratered Highlands: The Hadriacus Palus and Cavi Example (pdf)
Habitable Noachian Environments and Abundant Resources in the Mawrth Vallis Exploration Zone (pdf)

Thursday Presentations AM
McLaughlin Crater (pdf)
Exploring Habitability, Hydrology, and Climate Change on Mars at Columbus Crater (pdf)
Huygens Crater: Insights into Noachian Volcanism, Stratigraphy, and Aqueous Processes (pdf)
Noctis Landing (pdf)
Mars Human Science Exploration and Resource Utilization: The Dichotomy Boundary Deuteronilus Mensae Exploration Zone (pdf) https://www.nasa.gov/sites/default/file … tagged.pdf
Manned Mars Mission EZ: Eastern Rim of Hellas Basin (Promethei Terra) (pdf)
The Hellas Rim: Ancient Craters, Flowing Water, and Abundant Ice (pdf)
A Resource-rich, Scientifically Compelling Exploration Zone for Human Missions at Deuteronilus Mensae, Mars (pdf)
Ismenius Cavus: Ancient Lake Deposits and Clay Minerals Surrounded by Amazonian Glaciers (pdf)
The East Rim of Hellas: Mars' Mesopotamia (pdf)
Hale Crater—Ancient Water Science, Contemporary Water Resource (pdf)
Western Noachis Terra Chloride Deposits (pdf)

Thursday Presentations PM
Exploration Zone In the Newton Crater (pdf)
Arcadia Planitia: Acheron Fossae and Erebus Montes (pdf)
Site Selection for the First Sustainable Mars Base (pdf)
Protonilus Mensae (pdf)
Midlatitude Ice-rich Ground on Mars: an Important Target for Science and In Situ Resource Utilization on Human Missions (pdf) http://www.nasa.gov/sites/default/files … etails.pdf
That first stop will be talked about for generations: Writing History (pdf)
Ausonia Caves Kasei Valles: Complementary Exploration Zones (pdf)
Mars Exploration Program—A Pathway to Future Missions (pdf)

Friday Presentations AM
Human Landing Sites Study (HLS2) Group Discussion (pdf) https://www.nasa.gov/sites/default/file … tagged.pdf
Mars Surface Crew Operations Study (pdf) https://www.nasa.gov/sites/default/file … tagged.pdf
Noctis Landing Take Home (pdf)

Last Updated: Aug 7, 2017
Editor: Tricia Talbert

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#40 2021-04-25 09:23:44

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

Re: Human Business and flight plan for mars

Status of Dragon crewed is still being baselined for its use and capability for future use.

Starliner is still not flown with a crew but soon.

Orion SLS still coming soon but has not done what's needed to make it to being viable yet.

nasa gateway project is still in build plan stage

The new ships still in the wings for atlas replacement not anywhere near ready for flights.

New Origins ship the Glenn is still moving forward but not even a good contender yet.

Northrup Grumman bought up the orbital atk product line but they seem to be just filling existing contracts for ISS and not really going to the bat for future uses.

Space x starship is still in build and blow it up mode....

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#41 2021-04-25 10:09:56

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

Re: Human Business and flight plan for mars

Starliner must make a repeat unmanned visit to ISS on the experimental contract. If they don't screw that up again, then it can fly with a crew.  If that contracted experimental crew flight is successful,  then they can begin the contract commercial crewed flights,  just like Spacex.

SLS fitted with Orion and its ESA-supplied service module is incapable of entering (and leaving) lunar orbit with the smaller upper stage of the Block 1 configuration.  It can reach cis-lunar space,  but not around the moon itself.  That requires the larger upper stage of Block 1B.  I have yet to see one of those in any sort of testing.

The very-elongated orbit of Gateway makes it easier for a Block 1-B SLS/Orion to reach it,  at the cost of only certain arrival windows being feasible.  It makes landings on the lunar surface have a bigger delta-vee cost,  though.  Block 1 SLS/Orion cannot reach it,  although Block 1 SLS without Orion can.  But if you make the modules a tad smaller than 37 metric tons,  Falcon-Heavy can also reach it.

Those module sizes were originally set to rule out the use of any launcher but SLS.  Given the now-projected low launch rate and high price of SLS, I think they shot themselves in the foot setting those module weights too high.  They need Falcon-Heavy,  and they know it,  but are having a really hard time admitting it,  especially since contracts have been issued at the high module weight.

I have seen in press releases that Gateway will measure radiation exposures.  Not word about shielding radiation exposures!  Cited "radiation" is only GCR.  Not a word about solar flares!  A big flare event WILL kill a crew!  We've seen them before.  The 1972 event was the worst seen so far.

All the new rockets,  including Starship/Superheavy,  New Glenn,  and the Vulcan replacement for Atlas-5,  will have to go through the "build it and blow it up" phase.  Spacex was out the gate first,  but that's a long horse race.  And it's just an inherent part of the development process. 

I saw this before when I was young.  With the original Atlas,  the Titans,  the Juno,  the Jupiter versions,  the Redstone,  Vanguard,  and some others.  I was surprised (and pleased) not to see a Saturn blow up,  although I saw lots of Saturn-5's big F-1 engines blow up before they ever flew the rocket vehicle.  You will see some fireworks,  and not just from Spacex,  before this round is over.

GW

Last edited by GW Johnson (2021-04-25 10:12:58)


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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#42 2021-07-24 15:11:21

kbd512
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Registered: 2015-01-02
Posts: 4,612

Re: Human Business and flight plan for mars

GW,

The Deep Space Gateway or whatever they're calling it now should have a water wall radiation shielding in polyethylene tanks.  It's in all of their design concepts.  If they really do design something without radiation shielding, then I want to see what the Astronaut Office has to say about that.

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