Google’s research arm, Google X, is called the company’s Moonshot Factory. One reason the company picked the word “Moonshot” was to remind people to tackle big problems that may well blow up in their faces.

Last month, after years of promotion, Google ended a test trial of its Internet-connected glasses, called Glass. While the device seemed to have promising commercial applications in hospitals or on factory floors, its first pass at the consumer world was unsuccessful.

The very public failure of Glass points to a bigger question. After patiently abiding a steep increase in research and development spending on efforts that range from biology to space exploration, Wall Street is starting to wonder when — and if — Google’s science projects will pay off.

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