Gravity

From Marspedia
Jump to: navigation, search

Mars has a mass of 6,419 · 1023 kg. Compared with Earth this is only a little bit more than a tenth. This results in a lower Gravity as the planet is also less dense than Earth.

The gravitational acceleration is 3,71 m/s², compared to 9,81 m/s2 on Earth. The resulting weight of any body on the surface of Mars is only a bit more than a third, compared with the same body on Earth. Mass and inertia remain the same, however.

Impact on physics and nature

  • Dust storms on Mars reach high altitude. Scientists found the cause in the low gravity, allowing the sand grains to bounce much higher.
  • The low gravity and lack of continental drift has allowed the growth of the highest mountain in the solar system, e.g. Olympus Mons.
  • A rock thrown on Mars will fly much further than on Earth.

Impact on humans

The development of human embryos might be different. Also, the long term consequences for the health of human beings is unclear. Constant physical exercise has proven to be beneficial on the ISS to reduce calcium loss and maintain muscle mass. However the difference between no gravity and low gravity is still unknown.

The absence of gravity during interplanetary travel could also undermine the fitness of explorers or settlers to perform their jobs upon their arrival at Mars.

Potential methods of preventing calcium loss

Daily exercise appears to reduce, but not eliminate, calcium loss in a zero-gravity environment.  Two hours/day has limited calcium loss to 12%, and 4 hours/day limited it to 5%, during stays on Mir and the International Space Station.

The stress placed on bones by normal gravity causes a certain amount of interstitial fluid flow within bones, which may be important in preserving bone calcium.  It might be possible to stimulate this effect using, as a medication, a signaling protein called a growth factor that allows fluid to leak out of blood vessels.

If research identifies a specific gene as the regulator of low-gravity calcium loss, then a more refined version of this approach might be possible.  Scientists could attempt to design a medication that targets this specific gene and holds its expression at the same level as it would be in Earth gravity.[1]

Impact on technology

  • The pressure on bearings for the same service is lower, causing less friction and abrasion. Or lighter bearings can be used.
  • A space elevator is easier to build.

Impact on plants

  • Plants have grown normally on the ISS and should grow on Mars. The effect on their internal structure of the low gravity is unknown.

Impact on Settlement design

Icedome Scene 6.jpg

For the 2019 Mars Society settlement design contest, Kent Nebergall proposed the Eureka base design. This design addresses most of the potential problems that might arise from lower gravity by building the settlement about a pair of rotating ring structures capable of simulating Earth gravity by centripetal force. Usually planned for spaceships, artificial gravity using centripetal force could be implemented on Mars.

The design[2] addresses a number of social and technological issues, as well as artificial gravity.

Cutaway view through the gravity rings











References

  1. McCormack PD. (2005). Chronic health hazards in human space exploration. http://www.marspapers.org/paper/McCormack_2005.pdf
  2. https://macroinvent.com/wp-content/uploads/2019/03/Eureka-Mars-Settlement-Concept.pdf