Why has NASA sent recent orbiters to Mars on trajectories that required them to skim through Mars's atmosphere (aerobraking) before settling into their final orbits?
A) It saved money because the spacecraft used atmospheric drag to slow down rather than needing to carry enough fuel to slow by firing rocket engines.
B) It allowed the orbiters to get higher resolution pictures of the surface as it came close when skimming through the atmosphere.
C) It allowed the spacecraft to collect samples of the atmospheric gas for return to Earth.
D) Each spacecraft also carried a lander, and the lander could only be dropped to the Martian surface when the spacecraft passed through the atmosphere.
Question 2
Tycho Brahe's contribution to Kepler's Laws of Planetary Motion were
A) his detailed and accurate observations of the planet's position.
B) his observations of Jupiter's moons.
C) a mathematical explanation of epicycles.
D) a precise lunar calendar.
E) the correct explanation of lunar phases.
True-color view of Mars seen through NASA's Hubble Space Telescope in 1999
Mars from Hubble Space Telescope October 28, 2005 with dust storm visible.
Amazing NASA Pictures Collection
Amazing NASA Pictures Collection
NASA Space
Change in American Gender Attitudes, 1977-2006 Over recent decades, views of gender roles have beco