The global rivalry between China and the United States is most often viewed in military or economic terms. But even more paramount is the battle for supremacy in the field of Things Riding on Top of Other Things. China has held the unofficial crown ever since a photo of a bear riding a horse at a Chinese zoo made its way onto the Internet. But today, in the culmination of a years-long Manhattan Project–style effort, the United States responded with a space shuttle riding on top of a modified 747. Your move, Beijing.