An alien spaceship traveling at 0.610c toward the Earth launches a landing craft. The landing craft travels in the same direction with a speed of 0.790c relative to the mother ship (as measured by aliens on the mother ship). As measured on the Earth, the spaceship is 0.230 ly from the Earth when the landing craft is launched. (a) What speed do the Earth-based observers measure for the approaching landing craft? (b) What is the distance to the Earth at the moment of the landing craft's launch as measured by the aliens (mother ship)? (c) What travel time is required for the landing craft to reach the Earth as measured by the aliens on the mother ship? yr (d*) What travel time is required for the landing craft to reach the Earth as measured by Earth-based observers? yr (e*) What travel time is required for the landing craft to reach the Earth as measured by those on the landing craft? yrSpacecraft 1, containing students taking a physics exam, approaches the Earth with a speed of DJ'OOC (relative to the Earth), while spacecraft 11, containing professors proctoring the exam, mOves at 0.260c (relative to the Earth) directly toward the students. The professors stop the exam after 56.0 min have passed on their clock. (a) For what time interval (in minutes) does the exam last as measured by the students? min B (b) For what time interval (in minutes) does the exam last as measured by an observer on Earth? min U What If? Suppose one of the professors proctored the exam by traveling on spacecraft I and stopped the exam after 56.0 min elapsed on her clock. (c) For what time interval (in minutes) does the exam last as measured by the professors on spacecraft II? min B (d) For what time interval (in minutes) does the exam last as measured by an observer on Earth? min U