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#1 2019-09-12 18:11:39

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 17,471

Orbital Mechanics

I am no GW so here goes.

Many of our topics are fringing on the equations of the rocket and how can we get there in time.

This is true of all rockets just the numbers change for the destination and payloads that one will want along the way.

Timing is everything! In picking a time to launch, space engineers and scientists have to consider quite a number of things. Most of them have to do with getting the biggest boost possible from the big launch pad called planet Earth!

http://www.esa.int/Our_Activities/Space … nch_window

Launch Windows To Other Planets

Things like mass fraction of fuel to structure are part of the equation for the rocket to make it to orbit with a payload.

Destination changes everything...

https://www.jpl.nasa.gov/edu/teach/acti … h-windows/

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

https://www.quora.com/How-does-NASA-cal … o-the-Moon

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#2 2019-09-12 20:54:09

tahanson43206
Member
Registered: 2018-04-27
Posts: 1,677

Re: Orbital Mechanics

Amazon.com "books on orbital mechanics"

Fundamentals of Astrodynamics (Dover Books on Aeronautical Engineering)
by Roger R. Bate , Donald D. Mueller , et al. | Jun 1, 1971
4.5 out of 5 stars 69
Paperback

Introduction to Space Dynamics (Dover Books on Aeronautical Engineering)
by William Tyrrell Thomson | Jun 1, 1986

Orbital Mechanics for Engineering Students (Aerospace Engineering)
by Curtis Ph.D. Purdue University, Howard D. | Nov 8, 2013
3.8 out of 5 stars 27

Note: this book is available for rent.

The Three-Body Problem and the Equations of Dynamics: Poincaré’s Foundational Work on Dynamical Systems Theory (Astrophysics and Space Science Library)
by Henri Poincaré and Bruce D Popp | May 12, 2017

This next eBook looks appropriate for asteroid mining planning:

Orbital Dynamics in the Gravitational Field of Small Bodies (Springer Theses)
by Yang Yu

Recent Advances in Celestial and Space Mechanics (Mathematics for Industry Book 23)
by Bernard Bonnard and Monique Chyba

Essays on the Motion of Celestial Bodies
by V.V. Beletsky and A. Iacob | Aug 24, 2001

Spaceflight Dynamics: Third Edition
by William E. Wiesel | Jun 3, 2010

Some titles found on offer were not included in this list. 

If anyone has experience with any of these books, or others, please add to this topic.

(th)

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#3 2019-09-12 21:06:19

SpaceNut
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#4 2019-09-13 06:40:04

tahanson43206
Member
Registered: 2018-04-27
Posts: 1,677

Re: Orbital Mechanics

For SpaceNut and NewMars Community ...

With the launch of this new topic, we have the opportunity to create a curriculum for existing members, who range in aptitude, background and energy level.

That would be challenge enough for the teachers among us, but we have the opportunity to think about and (perhaps) design a curriculum for elementary school students of the near future, who will (I suspect) need to understand orbital mechanics the way most students understand arithmetic today.

I had to give up study of physics and advanced mathematics in order to earn a living, but I retain an interest in being able to plan a mission to intercept a Near Earth asteroid, and look forward to coming days when members of this forum may decide to tackle the problem.

As SpaceNut points out in #3 above, rocket science is involved, but space navigation requires understanding of where to point the rocket to achieve the orbital plane changes that will be needed, and then how long to apply propulsion to match orbits.

This forum has a history of diving deep into chemistry, and occasionally into advanced physics concepts (ala JoshNH4H and Void).

A topic devoted to elementary orbital mechanics should fit into the spectrum.

(th)

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#5 2019-09-13 09:09:41

Oldfart1939
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Registered: 2016-11-26
Posts: 1,798

Re: Orbital Mechanics

Two of Dr. Robert Zubrin's books address the essentials. Helps to have a Scientific Calculator handy, too.
(1) Entering Space. Robert Zubrin; Tarcher/Putnam; (1999).
(2) The Case for Space. Prometheus Books; (2019)

The books tahanson has suggested may be a bit advanced for the average reader; learn vector calculus and all will become clear.

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#6 2019-09-13 09:10:16

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 3,757
Website

Re: Orbital Mechanics

I presume this is in the context of determining whether or how a rocket can get you where you want to go,  in the solar system.  That naturally divides into two areas of endeavor,  and you have to be careful how you link them.  Those are orbital mechanics and rocket vehicle design sizing.

Orbital mechanics determines the "theoretical" delta-vees required to travel from one place to another.  I'm too obsolete to know all the new tricks and trajectories,  but min energy Hohmann transfer ellipses I understand. 

It is this orbital mechanics area of endeavor that determines the "velocity requirements",  meaning that list of delta-vee burn requirements.

These relate to rocket vehicle design sizing as what I call "mass ratio-effective" delta-vee requirements.  You have to multiply the orbital mechanics delta-vees by a factor equal to or exceeding unity to allow for the losses due to drag and gravity.  Out in vacuum,  there are no drag losses,  but there still can be gravity losses.  These become significant if the burn time is measured in something more than a handful of minutes.  For really low acceleration items like ion propulsion,  the factors are closer to 2 than 1.

With the factored delta-vees that I call "mass ratio-effective" delta vees,  you can choose a vehicle design approach and use these to size the mass ratios that you must have to accomplish the mission.  If these mass ratio requirements are impractically-high,  your only two options are higher specific impulse or staging.  Or go back to orbital mechanics and investigate a different trajectory approach. 

When using the rocket equation,  be aware that changing the payload during the flight will massively change the outcome,  putting a single step calculation out of reach.  It becomes iterative at that point.  Spreadsheets help when it does. 

Also be aware that a realistic choice of vehicle inert mass fraction is critical to realistic results!!  The lightest structures are the most fragile,  and generally do not support addressing multiple sets of requirements (such as both launch and entry).

The sum of payload fraction,  vehicle inert fraction,  and propellant fraction MUST be 1.  If your payload fraction = 1 - propellant fraction - inert fraction is negative,  your stage design is utterly and fundamentally infeasible.  Period. 

In a staged vehicle,  payload is the ignition mass of next stage up,  until you consider the top stage.  For only the top stage,  payload is the "ultimate payload" you must consider as "delivered" for the mission.

If your ultimate payload fraction to initial ignition mass is under 3%,  even probe or satellite launch missions may be economically infeasible.  If your ultimate payload fraction is under something like 15-20%,  missions like landers and cargo carriers become economically unattractive.  Those are fuzzy judgement calls,  just rules-of-thumb,  but that's the mission "ballparks" you play in.

The only other thing to consider is that if you have to stage,  reusability gets much harder to do.  Only certain undemanding-entry things like first stage boosters for Earth launch have proven possible so far.  Except for re-entry capable capsules and the odd spaceplane,  that's all we have shown to be feasible technologically. 

GW

Last edited by GW Johnson (2019-09-13 09:11:20)


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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#7 2019-09-13 13:11:36

tahanson43206
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Registered: 2018-04-27
Posts: 1,677

Re: Orbital Mechanics

Striking while the iron is hot ...

There exists a quorum of heavy hitters in this topic, and more are potential contributors.

For OldFart1939 ... thanks for the Zubrin suggestions. 

For GW Johnson .... thanks for additional insights on mission planning.

In another topic, Calliban has been gradually building up a set of posts which may lead toward a mission. 

In the mean time, I'd like to offer a challenge for the NewMars community ... many others are certainly possible, and the best will (likely) win support.

Apophis is swinging inside GEO in 2029.  I propose an exercise to design a mission to land a ton (Metric) of probe (equipment and supplies) on the body.

The mission could be designed as a one-and-done launch from Earth.

Alternatively, the mission could be designed as a two phase effort, with the first phase to place a vehicle in LEO with an inclination designed to match the plane of Apophis as closely as possible, and with velocity as close as possible to optimum for an intercept burn.

OldFart1939 suggested putting new batteries in a Scientific Calculator, and that is certainly an option.

GW Johnson has used the power of modern spreadsheet software to compute missions in a different context.

I am confident that it will turn out there are multiple highly advanced applications for mission planning running on computers around the world.

NASA, ESA, the Japanese Space Agency, Russia, India, China .... all these entities and (probably) many more have the human expertise and software tools needed to plan for missions like this one.

The opportunity for ** this ** group is to see what can be accomplished by a group of volunteers with varied backgrounds but with a shared set of interests.

(th)

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#8 2019-09-13 15:55:04

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,471

Re: Orbital Mechanics

GW has done some of the number crunching in other topics for the Falcon 9 heavy use of which its capable of performing such a mission as a geo satelite is heavier than what we would be trying to thrown at it in order to catch it.
Once found I will copy them here...

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#9 2019-09-13 16:41:04

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,471

Re: Orbital Mechanics

Post with calculation:
http://newmars.com/forums/viewtopic.php … 93#p133793
http://newmars.com/forums/viewtopic.php … 89#p134889

http://newmars.com/forums/viewtopic.php?id=7581
http://newmars.com/forums/viewtopic.php … 18#p134818
http://newmars.com/forums/viewtopic.php … 16#p138416
http://newmars.com/forums/viewtopic.php … 23#p152823


Reading some of the topics also show that we could land a dragon on the asteriod as well as return home with samples..
http://exrocketman.blogspot.com/
http://exrocketman.blogspot.com/2017/03 … -data.html

It just might even be possible to do a 1 or 2 manned mission thats a short stay as well.

I think that some posts in the red dragon mission would also be of benefit...

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#10 2019-09-14 07:57:43

tahanson43206
Member
Registered: 2018-04-27
Posts: 1,677

Re: Orbital Mechanics

SearchTerm:ThreeBody
SearchTerm:MissionPlanning

For SpaceNut re #9

Thanks for the list of threads and references you provided.  It will take some time (for me at least) to review them all, but the first two I visited were meaty collections from 2017 or so, when the participants were in a particularly creative mood.

I'd like to offer you a glimpse of something that could happen, without expenditure of funds, that would give NewMars forum (and the Mars Society) some sustained visibility in the space interest community.

In the midst of the topics I viewed from #9 above, I found a link to a nicely designed web site which offers the ability to create mission launch plans for a wide variety of vehicles, from a wide variety of Solar System bodies, and with numerous other parameters available for configuration.

What I'm about to describe may already exist, and that would certainly be the optimum outcome of this inquiry.

Project Description:  Web site page to offer Three Body Problem solutions

Detail:
1) This site would enable a user to enter an object to reach, from a list including other

2) The site would offer the user a choice of starting locations, from a list including other

3) The user would be invited to enter a payload to be delivered to the destination

4) Other options would include optimization for time or cost (as just two examples)

The site would deliver a list of rocket components needed, a launch location on the source object, and whatever else seems useful to a mission designer.

Two phase solutions could (and probably should) be offered, since so many existing historical missions have involved launch, coast and burn again patterns.

The site would need to be hosted somewhere, so negotiations with Mars Society management would be a part of the activity.

This would not be a trivial exercise, and it could easily take over a year, but on the other hand, I don't see any need for anyone to lay out funds unless individuals decide to invest in books or something else to help them with their contribution.

Edit 2019/09/15 ... rather than clutter the forum database with comments on links SpaceNut (and others) have or may provide in support of this topic, my idea here is to add notes to this post.  The process may take a month or more, because SpaceNut has gifted forum readers with similar lists of links in other topics.

(th)

Last edited by tahanson43206 (2019-09-15 09:39:54)

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#11 2019-09-14 09:07:09

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,471

Re: Orbital Mechanics

Sort of like a mars wiki of launch from earth software driven application or many that can be utilized to fashion a mission plan with. Able to choose from a rocket to making a payload calculation for the selected destination sort of thing.

Google results for the topic as it relates to rocket selection to destination.

Mission Planning Software - Fusion LVC - fusionlvc.com
https://www.fusionlvc.com

Designed as an environment to collaborate through the entire training process. Real-time distributed mission planning, rehearsal, execution and After Action Review. Intuitive access to authoritative sources, applications, documents files and assets.

Flight Planning Software - IFR & VFR Flight Planner by ...
https://www.rocketroute.com/flight-planning-software

Flight planning software has made planning simpler and faster than could have been imagined in the not-so distant past! No matter how simple or complex a proposed journey is, there will be a suitable flight planning software out there to assist in the safe and accurate planning of it.

ROCKET MISSION
https://rocketmission.com

ROCKET - Referencing the optimism, hope, and forward-looking spirit of the Space Age. Aesthetically, this is embodied with classic, modern style. MISSION - Referencing the quality and hand-crafting of Mission Style Furniture of the Arts and Crafts Movement.

Space Mission Design Tools | NASA
https://www.nasa.gov/smallsat-institute … sign-tools

NASA.gov brings you the latest images, videos and news from America's space agency. Get the latest updates on NASA missions, watch NASA TV live, and learn about our quest to reveal the unknown and benefit all humankind.
Orbital Trajectory Analyzer Takes Mission Planning to New ...
https://spinoff.nasa.gov/Spinoff2016/t_5.html

Orbital Trajectory Analyzer Takes Mission Planning to New Heights ... which launched from a United Launch Alliance Atlas V rocket in 2009 with a mission to gain information about the Moon’s surface in the hopes of finding areas of high scientific value. ... While clients sometimes want to use specific software tools for their mission, if a ...

Designing A Rocket In Six Easy Steps – Rocketology: NASA’s ...
https://blogs.nasa.gov/Rocketology/2015 … easy-steps

Jul 09, 2015 · Designing A Rocket In Six Easy Steps. Let’s say you need to build a new rocket. Where do you start? Well, what kind of rocket are you going to create? All rockets, after all, are not created equal – the world is full of a variety of rockets, all designed for different purposes. ... A bold mission requires a bold rocket. Blueprint of ...

GROUND SYSTEMS DEVELOPMENT & OPERATIONS
https://www.nasa.gov/sites/default/file … ew_web.pdf

the first crewed flight of Orion atop the SLS rocket on a deep space destination. Last year, we accomplished so much toward our ... software and our communications systems are well underway. Launch countdown planning and launch ... The Ground Systems Development and Operations Program and Jacobs Engineering, on the Test and Operations Support ...

I have some reading homework to do as well tahanson43206.

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#12 2019-09-18 05:13:12

tahanson43206
Member
Registered: 2018-04-27
Posts: 1,677

Re: Orbital Mechanics

For SpaceNut re topic ...

In one of your earlier posts here you included a link to an earlier discussion.

In one of the posts you reported finding a link to a web site set up to perform comparisons of various vehicles in various situations.

I'm hoping members of this forum will be interested in developing a web site to do mission planning for the asteroid mining problem discussed elsewhere.

The date of the posting was: 2017-01-21 23:09:37

A link to the post itself is: http://newmars.com/forums/viewtopic.php … 40#p134140

The web site is: http://silverbirdastronautics.com/LVperform.html

A suggestion for a forum created web site might use the Silverbird example as a starting point:

Title: Mars Society NewMars Forum

Subtitle: Asteroid Navigation Calculator

Selection Category #1:  Gravitational Reference Frame

Choices could be:

1) Solar
2) Earth
3) Mars
4) Jupiter
5) Saturn
6) Add as needed

Selection Category #2: Destination

These would be displayed depending upon #1

For Example, if the choice is Solar, then bodies which orbit the Sun would be listed, including asteroids

Selection Category #3: Launch point

This category could get complicated in a hurry ...

If the launch point is from Earth, then the Silverbird example is appropriate.

However, a burn may be needed from an existing orbit.  I'm thinking here of a parking orbit for a mission intended for Apophis.

However, in another topic, someone (or several posters) discussed the idea of parking rapid deployment vehicles to visit objects that enter the Solar System without prior awareness by humans.  The thought there (as I understand it) was to have such vehicles ready to fly out to intercept and "dock" with such objects in order to study them.

Selection would need to be provided for payload mass, such as 1 Metric ton delivered to an asteroid

The output of the calculator would be one or more burns needed to achieve the objective.

There are (no doubt) other selections needed, and I'm hoping others will add to the list.

(th)

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#13 2019-09-18 19:25:08

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,471

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#14 2019-09-19 05:41:07

tahanson43206
Member
Registered: 2018-04-27
Posts: 1,677

Re: Orbital Mechanics

SearchTerm:CalculatorHomework

The purpose of this post is to hold results of study of links provided by SpaceNut in post #13.

The purpose of the investigation is to collect ideas and examples for a calculator to be hosted by the Mars Society, and supported by NewMars forum.

At this point, at the start of the investigation, I do not know of any publicly available mission planning calculator for Asteroid Mining missions.

Some of the links quoted below were damaged during copy See Post #13 for the originals.

Notes:
This blog site is authored by

Copyright 2019 Robert Clark

  While I did not find anything relating to celestial navigation, I DID note the detailed and comprehensive discussion of rocket designs and prospective applications.  Recommended.

Rights: © Copyright. 2011. University of Waikato. All rights reserved. Published 28 June 2016

Notes: This is an educational page.  It allows students to experience the laws of physics by trying various launch parameters.
In the case of the present initiative, the intention is to provide an application that works similarly to a GPS navigation aid on a device carried by a user.
The intention is NOT to provide education to the user.  Instead, the educations of multiple people will be embedded in the application. Thus, just as a GPS application embodies the educations of many people, the legacy of those educations will live long after the creators have laid down their slide rules in an Asteroid Miner's Navigation App.

OpenRocket is my favorite rocket simulation software for Windows. 

RASAero is a free rocket simulator software for Windows. 

Rocket Propulsion Analysis Lite is another rocket simulation software for Windows.

ORT Modeller (Open Rocket Toolkit) is the next free rocket simulator software. 

Water Rocket Fun is a free water rocket simulation software for Windows.

Notes: While the present initiative does not anticipate specification of rocket components at a detailed level, some of these offerings appear capable of assisting in learning about how that might be done.

Notes:
This site offers a variety of software projects.  The rocket simulation appears to be written for a model rocket.  The Matlab code is quite readable (for me at least) so I hope it will be interesting to others.  While this particular offering does not appear to address the issue of orbit changes, it may be helpful for someone interested in studying Matlab.

OpenRocket is a free, fully featured model rocket simulator that allows you to design and simulate your rockets before you build and flying them.

Notes: The site offers a downloadable program.

Notes:

Notes:

Notes:

Notes:

Notes:

Last edited by tahanson43206 (2019-09-19 18:09:54)

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#15 2019-09-19 10:33:47

tahanson43206
Member
Registered: 2018-04-27
Posts: 1,677

Re: Orbital Mechanics

For SpaceNut re topic ...

The content in this Wikipedia topic looks promising.  However, the Wikipedia editors are unhappy with it.

https://en.wikipedia.org/wiki/Orbital_i … ion_change

The underlying physics would seem (to me at least) applicable to the Asteroid Miner's Navigation App.

The most potentially useful tip I found in this article was the suggestion that the location where two orbital planes intersect is the optimum location to initiate propulsion to change from one plane to the other.  However, the angle between the planes will surely be a significant factor in the calculation.

In addition, I question whether an object entering the Solar System from outside can be said to have an "orbital" plane.  Perhaps this is just a nomenclature issue, since the object will be following a path which curves around the Sun, and that curved path will (most likely) lie on a plane which passes through the Sun.

The wikipedia article cites this reference: http://www.braeunig.us/space/orbmech.htm#maneuver

I'd appreciate someone able to evaluate this site for accuracy to post a comment.  The author seems to have been updating the site for quite some time.

(th)

Last edited by tahanson43206 (2019-09-19 21:00:18)

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#16 2019-09-26 04:49:28

elderflower
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Registered: 2016-06-19
Posts: 1,149

Re: Orbital Mechanics

Objects from and going to space beyond the solar system have hyperbolic orbits relative to the sun. These are open ended curves, unlike elliptical orbits which are closed curves. There is a special case of a parabolic orbit which can be seen as an infinite ellipse or a hyperbola whose legs have parallel tangents. The object in this case would head out in the same direction as the one from which it came but in a reverse sense.

Last edited by elderflower (2019-09-26 04:55:38)

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#17 2019-09-26 06:59:42

tahanson43206
Member
Registered: 2018-04-27
Posts: 1,677

Re: Orbital Mechanics

For elderflower re #16

By any chance, do you have insight into how an application can be designed to compute the navigation that would be needed to match "orbit" with objects entering the Solar System on hyperbolic curves?  If my supposition is correct, that [the planes of] all such orbits must intersect the Sun, it should be possible to find intersection points for some existing elliptical orbits (such as the Earth's) and then compute burns needed to move from one to the other.


Edit: wording corrected 2019/09/27 Thanks to elderflower for catching the error.

(th)

Last edited by tahanson43206 (2019-09-27 04:25:29)

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#18 2019-09-26 18:17:08

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,471

Re: Orbital Mechanics

Calculating half of a parabolic curve involves calculating the whole parabola and then taking points on only one side of the vertex. Ensure that the equation for the parabola is in the standard quadratic form f(x) = ax² + bx + c, where "a," "b" and "c" are constant numbers and "a" is not equal to zero.

78458327.jpg

images of equations

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#19 2019-09-27 04:06:42

elderflower
Member
Registered: 2016-06-19
Posts: 1,149

Re: Orbital Mechanics

TAHanson.
The sun is not intersected by any of these curves, which are known as conic sections. The sun is always the focus of the curves (neglecting the influence of other bodies - even that of Jupiter is tiny unless the object approaches quite closely). A closed orbit has two foci and is an ellipse unless the two are coincident in which case it is a circle.
The plane of the orbit must include the Sun but may be at any angle to the plane of the solar system. To match orbits with one of these objects you will have to achieve solar escape velocity, like the Voyagers, and the plane of your probes orbit must match that of the object. Getting from the plane of the ecliptic (Earth's orbit) to the plane of the object's orbit will involve a lot of delta V unless an object turns up with a plane that is close to that  of the solar system.
I am sure that the esteemed Dr Johnson will have a spreadsheet that will give you pretty good numerical answers to this question.

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#20 2019-09-27 04:33:11

tahanson43206
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Registered: 2018-04-27
Posts: 1,677

Re: Orbital Mechanics

For elderflower re #19

Thanks for catching the error of wording in #18. It has been corrected.

A design for a probe to match orbits with an interstellar visiting object will almost always require plane changes, so planning should include the delta V required.

Part of the problem (I gather) is that such objects are unlikely to be detected early enough for planning the most efficient possible flight plan, which might include close passes by large objects to change planes.

(th)

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#21 2019-09-27 04:55:11

elderflower
Member
Registered: 2016-06-19
Posts: 1,149

Re: Orbital Mechanics

You are right  TAH. For early detection you would need very large telescopes looking in all directions.
Even if you did have a probe sitting on a pad, fuelled and ready to go you have to get accurate orbital parameters of your incoming target before you can design your mission and that will take several sightings over a few weeks. Then you may not be able to get the desired angle change by passing close to a planet as they may not be conveniently placed. So you have to wait for the next one. It is not likely that even a falcon heavy with an additional stage could deliver the necessary dV to a decent instrument package without a flyby boost from one ore more planets.

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#22 2019-09-27 12:15:41

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 3,757
Website

Re: Orbital Mechanics

I don't have much at all,  except a spreadsheet with multiple worksheets that does Hohmann transfer ellipses.  What was said about parabolas and hyperbolas is true,  but I don't have anything worked out for orbits like those. 

A parabola has one focus just inside the curve,  the central body occupies that location,  in a two-body problem.  If your departure speed is exactly escape speed,  your path is parabolic. 

An ellipse has two foci inside the closed curve.  The central body occupies one of those locations,  the other is empty.  If your speed is under escape,  your path is an ellipse about the central body,  in a two body problem.

A hyperpola has two open curves nose to nose (but not touching).  There is a focus inside each of the two open curves.  If your speed is greater than escape,  your path follows one branch of the hyperbola,  the one with the central body at that focus,  in a two body problem.  The other branch with the unoccupied focus exists mathematically,  but has no meaning for orbital mechanics.

That's what I know. And not a lot more.

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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#23 2019-09-27 14:04:34

tahanson43206
Member
Registered: 2018-04-27
Posts: 1,677

Re: Orbital Mechanics

For elderflower re #21 ....

Thanks for your reply, and for development of the scenario to match "orbit" with an interstellar visitor.   At the risk of stretching too far for a solution, in recent years there has been theoretical discussion of use of electromagnetic radiation (primarily lasers) to accelerate very small light sail vehicles carrying ultra-dense electronics to visit nearby star systems.  The technology involved could (I presume) be adapted to the challenge of visiting interstellar visitors.

It would make the most sense (to me at least) to place an intercept system in orbit (L1 for example) so that it can be swiveled to point as needed for a given mission. I hope this scenario will be of interest to one or more current members, and (potentially) it will inspire others to become active members to help this topic along.

(th)

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#24 2019-09-27 14:12:56

tahanson43206
Member
Registered: 2018-04-27
Posts: 1,677

Re: Orbital Mechanics

For GW Johnson re #22 ...

This is a theoretical question, since there is at present no method (I know of) to attract young people with the needed skills and experience to participate in this forum, but, for the sake of discussion ... could you evaluate work such a person might do to implement a software solution for mission planning?

I understand that ALL space faring nations have young people (and no doubt quite a few seniors) able to do exactly that.  What I am looking for is the equivalent of a GPS device the average person with a smartphone can operate.  On Earth, current technology supports navigation on the surface of the Earth.  That technology uses software that (as I understand it) solves 3 dimensional orbital mechanics in real time for vehicles navigating the surface of a sphere which is rotating and moving in orbit. 

Edit: The target application would solve for navigation between celestial objects, also in real time.

(th)

Last edited by tahanson43206 (2019-09-27 14:14:39)

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#25 2019-09-28 10:12:50

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 3,757
Website

Re: Orbital Mechanics

Tahanson43206:

I'm not sure how to answer your theoretical question,  because that kind of navigation analysis is way,  way,  way-to-hell-and-gone outside my areas of expertise.  I know little about avionics,  and even less about computer anything.  My expertise lies in aerodynamics,  thermodynamics, mechanics of motion and machinery,  propulsion,  a little bit of structural analysis,  and similar. 

Along the way I picked up a little hard-knocks real-world chemistry of propellants and of fuel-air combustion,  and some hard-knocks real-world materials,  including hazardous materials.  Most of this is pencil-and-paper-type design analysis capability,  not which computer codes to apply.  When I entered the work force,  we were all still using slide rules,  and only resorted to mainframe (!!) computer analysis when forced to (and it was punch cards in trays in those days). 

What I did during my career remained that kind of analysis for the most part,  although I did use (and write) some trajectory and propulsion-sizing codes,  in FORTRAN or BASIC.  What I wrote automated what I had been doing pencil-and-paper.   The trajectory stuff was for flights in the atmosphere,  usually 2-D Cartesian.  I did use a spherical-coordinate trajectory code for space launch at LTV Aerospace back in 1974.  It was called NEMAR,  and is probably long gone,  being written in an early FORTRAN. That is where I learned the trick of using an adaptive time step.  NEMAR had that feature.

GW

Last edited by GW Johnson (2019-09-28 10:16:26)


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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