Gravity - Gravity

Ian · 2003-12-09 15:01:44

What's going to be done about the issue of gravity on the mission to Mars? Could people use the theoretical particle "the graviton" to produce artificial gravity in some way in order to make things easier for the astronauts going to mars? Could some graviton generator be made?

~Eternal~ · 2003-12-09 15:37:01

Most likely the good ole' spin method will be used.

Ian · 2003-12-16 13:14:49

If they discover gravitons using particle accelerators, then a way could be found to produce them artificially and then a device could be invented that would produce gravitons for artificial gravity and for other scientific purposes.

Palomar · 2004-11-25 07:15:07

http://www.space.com/businesstechnology … 5.html]New spin on an old idea

*From space.com. Mentions "Mars Gravity Biosatellite Program," experiments on mice, bed-rest studies ("Artificial Gravity Project Pilot Study"), etc.

--Cindy

Rxke · 2004-11-25 08:03:57

Had to grin when i read, about the Mars Gravity Sat with the mice, that:

The specimens would then return to Earth under parachute after five weeks of travel.

I was imagining the fifteen white mice, each one clad in a tiny presure-suit, individually coming down on a parachute...

Would be quite as sight!

Shaun Barrett · 2004-11-25 08:48:13

Rik .. that's beautiful! :laugh:
Now I can't get the same picture out of my mind!

John Creighton · 2004-11-25 12:25:27

Rik .. that's beautiful!
Now I can't get the same picture out of my mind!

I wonder if they will sell the rights to disney?

SpaceNut · 2004-11-29 06:08:02

Mars Gravity Biosatellite would carry 15 mice into space, spin them up to create artificial gravity. To generate artificial gravity for the animals on board, the satellite will spin rapidly, making roughly one rotation every two seconds (34 revolutions per minute). This inward acceleration will simulate the force of gravity on the Martian surface - roughly one-third that of Earth.

How does a revolution every 2 seconds compare to the earths 1 for 24 hrs.?

Mars Gravity Biosatellite Program is a ground-breaking undertaking to study the effects of Martian gravity on mammals

But here was also another of those think tank items Weighty Implications: NASA Funds Controversial Gravity Shield or anti gravity.

NASA awarded a $600,000 contract last year to Superconductive Components Inc. in Columbus, Ohio to build the device.

So where is this project on the scope of being accomplished and to say nothing about the funds?

GraemeSkinner · 2004-11-29 06:14:31

Mars Gravity Biosatellite would carry 15 mice into space, spin them up to create artificial gravity. To generate artificial gravity for the animals on board, the satellite will spin rapidly, making roughly one rotation every two seconds (34 revolutions per minute). This inward acceleration will simulate the force of gravity on the Martian surface - roughly one-third that of Earth.
How does a revelotion every 2 seconds compare to the earths 1 for 24 hrs.?

The revolutions per second would surely depend on the diameter of the unit being spun to give the required gravity effect. The 34 revs per min is to simulate mars surface gravity, so it will still equate to around a third of Earths.

Graeme

Shaun Barrett · 2004-11-29 07:29:05

This is one more subject on which I've lectured long and hard here at New Mars over the past couple of years. Not that NASA, or anyone else for that matter, seems to think my angle on the problem is really practicable.

Anyhow, taking the 'centripetal gravity' solution to its ultimate and ideal conclusion, we need full terrestrial gravity simulation for as much of the flight as possible, together with a low spin rate in order to avoid sensory problems caused by the Coriolis Effect (disturbance of balance and disorientation etc.).
The answer is to have two craft, or one craft and a counterweight, tethered to each other by 1800 metres of kevlar cable and rotating around the centre of gravity at 1 rev/minute. This will give us 1g of 'gravity', just like home, and the minimal rotation rate will all but eliminate Coriolis problems.

Others have suggested gradually slowing the rotation rate on the way out to Mars, in order to reduce the 'gravity' to 0.38g just in time for the landing. In this way, the astronauts will be fully adjusted to martian surface gravity when they start work.
Conversely, the rotation rate could be increased gradually on the return journey, until a full 1g is achieved - thus preparing the astronauts for terrestrial conditions again.
I think this makes a lot of sense but I wonder whether it's still better to have 1g for as much of the mission as possible.

I admit this is the physiologically ideal situation but that it does make for a more mass. And people have raised understandable objections of excessive complexity, untried technology, as well as the extra kilograms.
But it does have the very attractive redeeming feature that all the seriously detrimental physiological effects of 180 days in zero-g outward and another 180 days in zero-g homeward (not to mention 500 days in 0.38g on Mars) are eliminated.
There may be good practical arguments in favour of reducing the radius of rotation and increasing the rate of spin, or never going higher than 0.38g on the outward leg and allowing zero-g on the way home, but I still think some form of rotation is going to be essential.
I while I may be forced to change my mind eventually, my present attitude is: If we're going to do it at all, let's do it right - 1800 metres and 1 rev/minute!

GraemeSkinner · 2004-11-29 22:36:30

Others have suggested gradually slowing the rotation rate on the way out to Mars, in order to reduce the 'gravity' to 0.38g just in time for the landing. In this way, the astronauts will be fully adjusted to martian surface gravity when they start work.
Conversely, the rotation rate could be increased gradually on the return journey, until a full 1g is achieved - thus preparing the astronauts for terrestrial conditions again.
I think this makes a lot of sense but I wonder whether it's still better to have 1g for as much of the mission as possible.

Changing the level of gravity virtually from the start will make the transition less noticable in gravity level. But the required gravity level should be in place a while before arrival then the astronauts have time to practice moving and working at that level of gravity so more can be done whilst on Mars. Being ready for the level of Mars gravity is the main thing so they can get as much done during their stay. Maintaining 1g for as much of the mission as possible would reduce the chances of the astronauts having a gradual change, and perhaps would reduce the effectiveness of the Mars surface work.

Graeme

Shaun Barrett · 2004-11-29 23:01:54

Good point, Graeme.
I suppose a lot depends on how long it takes astronauts to adjust to different 'gravities'.

Shaun Barrett · 2004-11-29 23:02:54

Good point, Graeme.
I suppose a lot depends on how long it takes astronauts to adjust to different 'gravities'.

::Edit:: Apologies for the repeated post. ::

GraemeSkinner · 2004-11-29 23:10:31

If I was the astronaut I'd care more about being ready for the Mars surface, the cost of the mission, and likelyhood of limited time there would require you to be as prepared as possible for the surface. How would you feel on the return leg, would you want to maintain the 0.38g for a while or return as quick as possible to 1g?

Graeme

Shaun Barrett · 2004-11-30 01:47:10

O.K.
On the way out, my preference would be to maintain 1g for about 5.5 of the 6 months, then reduce to 0.38g, allowing a week or two at that level before landing.
For the return trip, my ideal set-up would be to begin with a week at 0.38g, then increase the 'gravity' in about 0.05g steps on a weekly basis. This would bring the astronauts back up to a full 1g over a three month period. I think a controlled and monitored exercise regime tailored to the gradually increasing 'gravity' could be devised by NASA doctors to ensure the astronauts were fully re-adapted to terrestrial conditions.
The final three months in full Earth 'gravity' would ensure that the first martian explorers would step out of their landing capsule looking, and feeling, strong and healthy.

This latter point would not only be good for the crew but would be good for public relations. With no artificial gravity, the astronauts would have to be dragged out of the capsule on stretchers and would spend months in rehabilitation, probably suffering permanent bone-loss and long-term debility.
The public would see them leave in perfect health and arrive home as physical wrecks.
What would that do to the Mars exploration program? ???

It's not just a matter of money and convenience either; it's potentially much more serious than that. A trip to Mars is a looong trip! We're looking at about 180 days outward, about 500 days on Mars, and about 180 days homeward. That's nearly a year and a half in 0.38g and about a year in zero-g.
As I've said before, even being generous and pretending the whole 860 days were spent in 0.38g, coming home would be like an 80 kg (180 lb) man suddenly weighing 210 kg (465 lb). This would feel like he was carrying his twin brother on his back and a 25 kg (55lb) dumbell in each hand!!
And it ignores the fact that his heart would feel like it was pumping blood which suddenly weighed 2.63 times as much as normal blood.
I have expressed serious doubts that a human could tolerate returning to Earth after such a mission. It seems quite possible to me that one or more of the astronauts might actually die!

My previous ranting on this subject met with agreement from Adrian, as I recall. And Phobos, a well-loved former contributor to New Mars, immortalised the concept of artificial gravity for Mars Direct by agreeing we should "set that sucker on the spin cycle"!! :laugh:

GraemeSkinner · 2004-11-30 01:57:05

So if prolonged exposure (if thats the correct term) to 0.38g is going to be a problem could they increase the effect of the lower Martian gravity for a period of time each day to something closer to 1g so that during their 500 or so days on the surface is not going to be at a constant 0.38g? Then when they set off on their return journey they can return to 1g quicker and maintain that level all the way back to Earth. At least then they can avoid the stretcher when they're back on Earth.

Graeme

Shaun Barrett · 2004-11-30 07:43:02

Yes, Graeme.
There is a theoretically sound way to create a 1g environment on Mars. It involves constructing a circular railway.
There was a discussion about it back in 2002 on http://www.newmars.com/forums/viewtopic.php?t=1766]THIS PAGE.
It might be worth doing this for people who are only on Mars for a limited 'tour-of-duty' and who wish to return to Earth eventually.
I don't think it's a practical idea for all future martian colonists, though. So, if humans can't adapt to permanent residence in 0.38g, I don't think colonisation will be an option.

SpaceNut · 2004-11-30 09:54:43

Good points by both GraemeSkinner and Shaun Barrett on the dynamics of changing the gravity while not only going to mars but also for the return process home after the extended stay.

I believe the Japanese contribution to the ISS needs to be moved up for when it will be launched aboard the next few shuttles if I recall correctly on the centrifuge.

This tool would allow for all the needed research into the gravity question.

Earthfirst · 2004-11-30 12:32:45

I think that the g forces should be increased to 2 g's or maybe 4 g's that way when people get there they will be very strong! They will be able to left heavy objects no problem, and by having strong people you do away with the need for transport cars, and lething mechines. People like on the will find it more faster to hope 10ft rather than walk. Human in mars .38 will be super man, why would you want to weaken than. To maintian their earth weight they could wear heavy suits. Like if weight is 200 lbs on earth you would weigh 78 lb on mars, by adding a 128 lbs of weight to their suit on on mars they will hardy notice any difference from working on earth. The same on the moon, people there could easly pick up rocks the size of house and just carry it on their head. But you would use extra energy because you would be moving extra mass around, but feel the same weight on earth due to the extra mass. It is a simple solution to a problem, why would you want to agaist to to mars gravity, it would just weaken you! The long jump on mars would be very long in deed.

Austin Stanley · 2004-11-30 15:30:31

Spending a couple of months in high gravity isn't going to turn anyone into superman. Plus it may not be very safe. The astronauts would be more likely to break bones or injure themselves in some way on there trip there. Also heavier gravity would put much more stress on the heart. There is about as little data on the human effects of long duration high-g's as there is on low-g's.

Mars_B4_Moon · 2023-08-09 11:36:15

Bumping an old thread with some weird spooky science?

Smoking-gun evidence for modified gravity at low acceleration from Gaia observations of wide binary stars

https://phys.org/news/2023-08-smoking-g … -wide.html

A new study reports conclusive evidence for the breakdown of standard gravity in the low acceleration limit from a verifiable analysis of the orbital motions of long-period, widely separated, binary stars, usually referred to as wide binaries in astronomy and astrophysics.

For accelerations lower than about 0.1 nanometer per second squared, the observed acceleration is about 30 to 40% higher than the Newton-Einstein prediction. The significance is very high meeting the conventional criteria of 5 sigma for a scientific discovery. In a sample of 20,000 wide binaries within a distance limit of 650 LY two independent acceleration bins respectively show deviations of over 5 sigma significance in the same direction.

Because the observed accelerations stronger than about 10 nanometer per second squared agree well with the Newton-Einstein prediction from the same analysis, the observed boost of accelerations at lower accelerations is a mystery. What is intriguing is that this breakdown of the Newton-Einstein theory at accelerations weaker than about one nanometer per second squared was suggested 40 years ago by theoretical physicist Mordehai Milgrom at the Weizmann Institute in Israel in a new theoretical framework called modified Newtonian dynamics (MOND) or Milgromian dynamics in current usage.

Moreover, the boost factor of about 1.4 is correctly predicted by a MOND-type Lagrangian theory of gravity called AQUAL, proposed by Milgrom and the late physicist Jacob Bekenstein. What is remarkable is that the correct boost factor requires the external field effect from the Milky Way galaxy that is a unique prediction of MOND-type modified gravity. Thus, what the wide binary data show are not only the breakdown of Newtonian dynamics but also the manifestation of the external field effect of modified gravity.

The study carried out by Kyu-Hyun Chae, professor of physics and astronomy at Sejong University in Seoul, used up to 26,500 wide binaries within 650 light years (LY) observed by European Space Agency's Gaia space telescope. The study was published in the 1 August 2023 issue of the Astrophysical Journal.
For a key improvement over other studies Chae's study focused on calculating gravitational accelerations experienced by binary stars as a function of their separation or, equivalently the orbital period, by a Monte Carlo deprojection of observed sky-projected motions to the three-dimensional space.
Chae explains, "From the start it seemed clear to me that gravity could be most directly and efficiently tested by calculating accelerations because gravitational field itself is an acceleration. My recent research experiences with galactic rotation curves led me to this idea. Galactic disks and wide binaries share some similarity in their orbits, though wide binaries follow highly elongated orbits while hydrogen gas particles in a galactic disk follow nearly circular orbits."
Also, unlike other studies Chae calibrated the occurrence rate of hidden nested inner binaries at a benchmark acceleration.
The study finds that when two stars orbit around with each other with accelerations lower than about one nanometer per second squared start to deviate from the prediction by Newton's universal law of gravitation and Einstein's general relativity.

Implications of wide binary dynamics are profound in astrophysics, theoretical physics, and cosmology. Anomalies in Mercury's orbits observed in the nineteenth century eventually led to Einstein's general relativity.

'Unique prediction of 'modified gravity' challenges dark matter theory'
https://phys.org/news/2020-12-unique-gr … heory.html

'New MOND theory able to account for cosmic microwave background'
https://phys.org/news/2021-10-mond-theo … owave.html

Last edited by Mars_B4_Moon (2023-08-09 11:36:35)

Mars_B4_Moon · 2023-10-07 06:37:04

Could Modified Gravity Be the Answer to Planet 9?

https://www.universetoday.com/163533/co … -planet-9/

Mars_B4_Moon · 2023-10-24 13:18:58

Photonic Crystals imitate gravitational effects on light: Implications for 6G and Beyond

https://www.spacedaily.com/reports/Phot … d_999.html

Mars_B4_Moon · 2023-10-28 07:18:49

LIGO surpasses the quantum limit

https://www.spacedaily.com/reports/LIGO … t_999.html

Laser Interferometer Gravitational-Wave Observatory

Mars_B4_Moon · 2023-11-01 04:02:46

Can There Be Double Gravitational Lenses?

https://www.universetoday.com/164004/ca … al-lenses/

The alignment of large clusters of galaxies is the usual culprit whose gravity bends distant light to give us nature’s own telescopes, but now part-time theoretical physicist Viktor T Toth poses the question, “Can there be multiple gravitational lenses lined up and can they provide a ‘communication bridge’ to allow civilisations to communicate?”

Last edited by Mars_B4_Moon (2023-11-01 04:08:00)

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Re: Gravity - Gravity

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