” Supplying fuel for a Mars expedition from the lunar surface is often suggested, but it’s hard to make it pay off – Moon bases are expensive, and just buying more rockets to launch fuel from Earth is relatively cheap. “


” The communications delays between Earth and Mars can be half an hour or more, so the people on the ground can’t participate minute by minute in Mars surface activities. “


” Liquid oxygen is one of the cheapest manufactured substances on Earth. In large quantities, it costs pennies per kilogram – cheaper than milk or beer. “


” The original specifications for Apollo navigation called for the ability to fly a complete mission, including a lunar landing, with no help from Earth – none, not even voice communications. “


” Speaking of photography, while the Apollo 8 crew shot hundreds of photos, there was one that got everybody’s attention: a blue-and-white Earth rising over a gray moonscape. “



All 5 Henry Spencer Quotes about Earth in picture


Supplying fuel for a Mars expedition from the lunar surface is often suggested, but it
The communications delays between Earth and Mars can be half an hour or more, so the people on the ground can


Liquid oxygen is one of the cheapest manufactured substances on Earth. In large quantities, it costs pennies per kilogram - cheaper than milk or beer.
The original specifications for Apollo navigation called for the ability to fly a complete mission, including a lunar landing, with no help from Earth - none, not even voice communications.
Speaking of photography, while the Apollo 8 crew shot hundreds of photos, there was one that got everybody
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