What are the currently available microgravity platforms?

 

The major characteristics of the space environment are: microgravity and radiation. But someone may ask; can microgravity be experienced on the Earth? The answer is yes! This is because there are so many platforms or facilities that can supply microgravity on the Earth; these are known as terrestrial microgravity platforms. There are four major classifications of microgravity platforms or facilities (Figure 1):

-orbiting microgravity facilities (this supplies real or true microgravity); 

-non-orbiting microgravity facilities (this supplies real or true microgravity);  

-ground microgravity analogs; and 

-ground microgravity simulators.

     Figure 1: Microgravity Platforms 

The choice of the platform to use depends on so many factors. The focus of the specific experiment is the key to selecting the right platform. Some factors that may determine the choice of a particular platform can include: accessibility (most platforms are scarce and expensive); type of the experimental sample [size or volume, plant, animal, cells, microorganisms, solid, materials, chemical (hazardous or not) etc.]; the duration of microgravity supplied by the platform (e.g. seconds, minutes, hours, days, months); microgravity quality in g (10^-2, 10^-3, 10^-4, 10^-5, or 10^-6); and accessible altitude (for orbiting and non-orbiting platforms).

 

It has been observed that most tests in physics and microbiology require short time scales only while macrobiological tests would need long time scales. Also, physics experiments need more true (real) microgravity while biological experiments in many cases might be done in simulated or analog microgravity.

References and Further Reading

Ferranti, F., Del Bianco, M., Pacelli, C., 2021. Advantages and limitations of current microgravity platforms for space biology research. Appl. Sci. 11 (1), 68. https://doi.org/10.3390/app11010068.

 

Funmilola A. Oluwafemi and Adhithiyan Neduncheran (2022). Analog and Simulated Microgravity Platforms for Life Sciences Research: Their Individual Capacities, Benefits and Limitations. Advances in Space Research. 69, 2921-2929. ISSN 0273-1177. https://doi.org/10.1016/j.asr.2022.01.007. https://www.sciencedirect.com/science/article/abs/pii/S0273117722000199#.

What is the difference between microgravity and reduced gravity?

What is the difference between microgravity and reduced gravity?

It is well established that the major characteristics of the space environment are: microgravity and radiation. Microgravity is a state of weightlessness (like floating) or a state of very low gravitational pull, whereby only minute gravity is experienced by an object. In the real sense, there is no zero gravity, because zero gravity does not exist in the universe. The existence of microgravity starts after the Karman line (at an altitude of 100 km (62 mi) above the sea level). Each planet, moon, asteroid or any other celestial body have individual gravitational pull that is defined by their size, density, mass and proximity to other celestial bodies. The more massive the object in the solar system, the larger its gravitational field. Therefore, gravity comparism of such object to the Earth’s gravity generates the answer if there is reduced gravity or hypergravity on such a celestial body. Hence outside every celestial body and outside the Earth exists microgravity (Figure 1), but on every celestial body exists reduced gravity or hypergravity compared to the gravity of the Earth (1G). The amount of gravity depicts how a body bounces on a celestial body (video). 

    

Figure 1. The solar system

 

Figure 1 shows the solar system, the dark portion annotates where microgravity exists, while on the planets or very close to the planet (or any other celestial body) exists reduced gravity or hypergravity when compared to 1G. Table 1 explains further.

Table 1. Shows if gravity of celestial body is reduced or hypergravity compared to the Earth

Note that on the Earth exists gravity, while there are equipment or facilities that can supply microgravity or hypergravity. Therefore, microgravity can be simulated or mimicked on the Earth; while hypergravity can also be supplied by centrifuge. These simulations could be done for experimental purposes, deducing some scientific benefits. 

Further reading

Funmilola Oluwafemi (2021). Gravity Variation on the Growth of Maize Shoots.  Multidisciplinary Digital Publishing Institute (MDPI). Proceedings of 1^st Electronic Conference on Universe (ECU): General Relativity and Gravitation Section. Sciforum-042524, 22-28 February. https://doi.org/10.3390/ECU2021-10184.