New Mars Forums

Mars_B4_Moon

Member

Registered: 2006-03-23

Posts: 9,776

Space Elevators in Geosynch Orbit on Fast-Rotating Worlds

Since Space elevators can be used to transport goods and people and service across a body or to offworld I guess these could be a subject both planetary or interplanetary. There has also been talk of using the Skyhook, a Lofstrom loop or Space Tethers.

Sometimes asking a dumb question is how you learn So here is a question from me exposing my ignorance on a subject, I assume the best Space Elevator Orbits are always around the center of mass of the main body and does Geostationary or Geosynchronous Orbits for Stations work on Mercury I think it is too far away. Kbd512 brought up a point in another thread about to "know what a guy doesn't know". The Tundra orbit a highly elliptical geosynchronous orbit with a high inclination and eccentricity stays in a certain area because of apogee dwell, they are good for communications satellites but maybe a nightmare as a stable space elevator. This is one thing I do not know, a stationary orbit around Mercury is very far away, Mercury also being small than Ganymede Titan and is 0.055 times the mass of the Earth has less gravitational influence, a day is longer than a year plus your craft is getting rocked by 'Solar Winds' so close to the Sun. The orbits when I have seen them are not lines they make figure eight or infinity loop shapes for stability, the geosynchronous orbit 35,786 km 22,236 mi in altitude above Earth's equator 42,164 km 26,199 mi in radius from Earth's center and following the direction of Earth's rotation. Offworld body with a period below 2.2 hours  the "cohesionless spin-barrier" – cannot be merely held together by self-gravity they will be formed of a single solid bond. In general Asteroids of size larger than 0.15 km  do not have periods P smaller than about 2.2 h. We had discussion before on Space Colonization using Space‐Elevators from the Moon Phobos, in a future we might one day Move Phobos up to geostationary orbit and make it the station, you could also put engine drives on Phobos and Hurl bits and pieces of Phobos to the surface of Mars. An idea exists to use a statite a hypothetical body that employs a solar sail to continuously modify orbits using the Sun's energy. There are lots of other Asteroids and places for offworld colonies out there and examples of fast rotating minor planets 54509 YORP, 469219 Kamoʻoalewa and 2017 BQ6.

Here is a PDF on Phobos

Space Colonization Using Space-Elevators from Phobos
https://web.archive.org/web/20141028040 … 065879.pdf

This visual illustration seems to be a simulation from a video game engine

Universal Colony - Sending a Space Elevator to Deimos!
https://www.youtube.com/watch?v=Qys0Guik7mU

Last edited by Mars_B4_Moon (2023-03-30 12:41:39)

Mars_B4_Moon

Member

Registered: 2006-03-23

Posts: 9,776

Re: Space Elevators in Geosynch Orbit on Fast-Rotating Worlds

Because nobody has made a Space-Elevator it is considered a 'fringe' subject

Here are some other newmars threads
Carbon Nanotubes
https://newmars.com/forums/viewtopic.php?id=10225
,
What is the status today of O'Neill's vision today?
https://newmars.com/forums/viewtopic.php?id=7451
,
The economics of space elevators - Are they financially feasible?
https://newmars.com/forums/viewtopic.php?id=3062&p=6

tahanson43206

Moderator

Registered: 2018-04-27

Posts: 19,221

Re: Space Elevators in Geosynch Orbit on Fast-Rotating Worlds

For Mars_B4_Moon

Thank you for the link you provided, to a NASA paper on Phobos! 

Here is a PDF on Phobos

Space Colonization Using Space-Elevators from Phobos
https://web.archive.org/web/20141028040 … 065879.pdf

Somehow you found the paper on the Wayback machine, which served it intact despite it's dating to about 2000.

I appreciating seeing familiar names in the text and in the references. 

In particular, I appreciated seeing the graphic showing the tip of the down elevator riding just above the atmosphere of Mars.

You would find discussion of this very concept in the forum archive.

One question that comes to mind, in considering the benefit of the out-facing leg of the elevator, is how much it would help to deal with the velocity difference that GW Johnson reminds us is in effect when a vessel from Earth arrives at Mars, using a Hohmann transfer.

GW Johnson has shown (records are in the forum archive) there there is a benefit to arriving at Mars on the side that is rotating against the direction of motion of the planet with respect to the Sun, because the velocity of rotation of the planet subtracts from the total velocity change needed.

Now, as I consider the paper you found, it occurs to me that there might be a compound effect, if the tip of the elevator outside Phobos is rotating in a favorable direction as Phobos passes on the far side of the planet, as the planet itself is rotating against it's orbital movement.  it is too much to hope for a zero velocity difference, but the total velocity change might be smaller than the default.

If we had someone in the group who could perform such calculations, and who could be persuaded to do so, we might end up with a bit of knowledge to share with others.

One concern that will become significant if anyone actually pursues this question, is how much strain will occur on the elevator, if an arriving vessel attaches to the tip, just at the moment of least relative velocity.  The vessel will have to be accelerated, both by Phobos, and indirectly by Mars, in order for it to possess the velocity needed to stay in orbit around Phobos, let alone around Mars.

There would be a limit to the amount of strain any cable can handle, assuming it is made of reasonable materials.

(th)

Mars_B4_Moon

Member

Registered: 2006-03-23

Posts: 9,776

Re: Space Elevators in Geosynch Orbit on Fast-Rotating Worlds

Tahanson the other option discussed rather than starting on Mars attempting to build a Space Elevator and moving product on Mars with a very expensive project and fringe idea could be to go to Minor-Planets or Asteroids testing a concept with Space Elevator-Orbital Rings? The Space Elevator or Orbital Rings are showing up in media like Star Trek, Warhammer, StarWars, Orion's Arm, the Japanese Anime Manga Battle Angel, Stellaris, Arthur C. Clarke's and Neal Stephenson's and other books and video games. The  launch loop, or Lofstrom loop is an idea for launching objects into orbit using a moving cable-like system,  the Skyhook would be a tether using momentum exchange. There are concepts for the Moon and lunar space elevator or lunar spacelift would be a proposed transportation system for moving a mechanical climbing vehicle up and down a ribbon-shaped tethered cable that is set between the surface of the Moon. People have proposed putting a future space dock at  Earth-Moon Lagrange points L1 and L2. The Space Tethers could be cables which are used for propulsion, momentum exchange, stabilization control of altitudes, here is a PDF link to 'Tethers In Space Handbook' and also a link to a PDF of Hypersonic Airplane Space Tether Orbital Launch System.

QUOTE

70
-- CONCEPTS --
Mars Moons Tether Transport System

APPLICATION: Transportation of manned vehicles and spacecraft from low Mars orbit
out to escape, or from escape to low Mars orbit, using tethers attached to the Moons of Mars.

DESCRIPTION:
Long tethers (Kevlar strength or better) are attached above and below both Phobos and Deimos to ferry vehicles and other payloads between low Mars orbit and Mars escape without the use of propulsion. For example, a vehicle is tethered upward from a low Mars orbit station, released, and then caught by a downward hanging tether on Phobos. The payload is then transferred to the upward deployed tether and released. The process is repeated at Deimos, and results in escape from Mars. The process is reversible.

Rendezvous Simulations

Quote

In any rotating tether transport system, one of the most challenging tasks will be to enable the rendezvous between the payload and the tether tip. For the tether to successfully capture the payload, the payload and tether grapple vehicle must come together at nearly the same place in space and time with nearly the same velocity. Because the payload is in free fall, and the tether is rotating, the payload and grapple vehicle will experience a relative acceleration equal to a = Vt2/L, where Vt is the velocity of the tether tip relative to the tether facility’s center of mass, and L is the distance from the tether tip to the center of mass. In the HASTOL tether designs described above, Vt is approximately 3.5 km/s, and L is approximately 500 km, so this acceleration is about 2.5 g’s. If neither grapple nor payload perform any maneuvering, the two will coincide only instantaneously, providing a minimal rendezvous window.

Hypersonic Airplane Space Tether Orbital Launch System

Mars-Earth Rapid Interplanetary Tether Transport

https://web.archive.org/web/20211205195 … nSpace.pdf

A new edition of the Tethers in Space Handbook was needed after the last editionm published in 1989. Tether-related activities have been quite busy in the 90’s. We have had the flights of TSS1 and TSS1-R, SEDS-1 and -2, PMG, TIPS and OEDIPUS. In less than three years there have been one international Conference on Tethers in Space, held in Washington DC, and three workshops, held at ESA/Estec in the Netherlands, at ISAS in Japan and at the University of Michigan, Ann Harbor. The community has grown and we finally have real flight data to compare our models with.

https://web.archive.org/web/20051218225 … 5Bogar.pdf

The Boeing Company - Phantom Works has led a team in a Phase I study which has shown the technical feasibility of a completely new concept for moving payloads and passengers from the surface of the Earth into low Earth orbit at low cost and low acceleration levels without the use of rockets as the main source of propulsion.

Real studies have been done and concepts have been made reality

Other ideas are fringe science and still part of science fiction.

Some scifi books propose giant mountainous pillars assembled on a body like supports for a bridge going high enough until a Ring can be constructed,  I have no real idea what kind of supports would work and how they would build such a span across a minor planet in space. I do not know how they would deal with atmospheric changes or the dangerous of micro meteorites. 

On a smaller Asteroid perhaps in the far future you could possible have a giant Space Station much larger than your Space Station made famous by Arthur C. Clarke and the 2001 Space Odyssey and movie directed by Stanley Kubrick, the miles long Station would eat or encircle an asteroid, change its rotation and adjust or pint itself to match the size needed for that Asteroid.

James Cline wrote a paper to NASA describing a "mooncable"

: It had been thought that all the original Mooncable-related documents had been lost or mysteriously stolen over the decades, but several old scanned pages of the 1972 documents have now been found and converted to useful format, and are displayed below.

'Some Original Documents of the Mooncable Concept of 1972'
https://web.archive.org/web/20120426001 … inals.html

Last edited by Mars_B4_Moon (2023-03-30 12:46:43)

tahanson43206

Moderator

Registered: 2018-04-27

Posts: 19,221

Re: Space Elevators in Geosynch Orbit on Fast-Rotating Worlds

For Mars_B4_Moon re #4

I was surprised to find your mention of James Cline, but not surprised to find that he had rescued some pages about Mooncable.

Mr. Cline has originated and published a number of interesting ideas, including a concept for a magnetic launcher.  While I thought his vision for Earth was (and is) unrealistic (for a number of reasons) I thought his concept would work well at the Moon, where it would cycle vehicles between L1 and the Lunar back side.

(th)

Mars_B4_Moon

Member

Registered: 2006-03-23

Posts: 9,776

Re: Space Elevators in Geosynch Orbit on Fast-Rotating Worlds

Thermal life of space Elevators
https://www.researchgate.net/publicatio … _Elevators

Scientific return of a lunar elevator
https://www.sciencedirect.com/science/a … 4616300637

On Earth the problem of an extremely strong cable extends from Earth’s surface to the height of geostationary orbit 35,786 km or 22,236 miles or beyond

Jerome Pearson and a study for NASA Institute of Advanced Concepts

'LUNAR SPACE ELEVATORS FOR CISLUNAR SPACE DEVELOPMENT'
https://web.archive.org/web/20160303194 … earson.pdf

LiftPort Group a privately held Washington state corporation founded by Michael J. Laine focused on the construction of a space elevator using carbon nanotubes

https://web.archive.org/web/20090423044 … .com/wiki/

Where is the money? KickStarter project comments thread has many comments from backers asking what has happened
https://web.archive.org/web/20121122041 … d/comments

LiftPort was to be penalized due to an alleged illegal offering of shares of the company in year 2010, LiftPort Group entered into a Consent settlement with the State of Washington agreeing to cease and desist specified activities

At the Moon useful sites Earth-Moon Lagrange points L1 and L2.

'Asteroid Mining Startup Runs Into Trouble in First Mission'
https://gizmodo.com/astrofargo-asteroid … 1851092388