Symptoms of Age-Related Macular Degeneration (AMD) An early symptom of wet AMD is that straight lines appear wavy. An Amsler Grid chart can help spot this early distortion of vision. You may also notice a small blind spot, resulting in a loss of central vision.
Traveling at approximately 29,000 km/h (18,000 mph) the shuttle orbits Earth every 90 minutes. By using current technology and a spacecraft powered by chemical rocket engines, a trip to Mars could take between six to nine months.
Getting people safely to and from destinations in deep space poses challenges that the engineers of NASA's last crewed spaceship, the now-retired space shuttle, never had to consider. (No space shuttle ever traveled beyond Earth orbit.).or example, if a problem develops aboard a spaceship in LEO, astronauts can theoretically be on the ground in less than an hour. But it would take days for a vehicle out by the moon or beyond to get home, said NASA Orion Program Manager Mark Geyer.