Long-term space travel poses significant health risks to humans due to microgravity, including muscle atrophy, bone density loss, and sleep disorders. NASA categorizes these challenges under the RIDGE acronym, which covers radiation, isolation, distance, gravity, and environment.
The equivalence principle suggests that artificial gravity can be simulated through acceleration. While linear acceleration requires constant, energy-intensive thrust, rotational acceleration using a tethered system is considered a more cost-effective alternative for creating artificial gravity in space.
A tethered system involves two capsules rotating around a common center of mass. To simulate Earth's gravity, the rotation speed depends on the tether length: a 20-meter tether requires nearly 10 RPM, a 200-meter tether needs about 3 RPM, and a 2000-meter tether requires just under 1 RPM.
Engineering a stable tethered system presents major challenges, primarily regarding angular momentum and balance. Maintaining high rotational speeds over long distances requires precise control, and rapid rotation can cause vestibular side effects for astronauts, complicating long-term human presence in space.
