It's hard. If you want to compare, it should be an aircraft carrier and a spaceship. The space field is basically blank or at a very low level of understanding for human beings. Although all countries are clamoring for space strategy and so on, they are just loud slogans, including the United States. Although the United States has some actions, it is still far from being truly formed. Therefore, the development of space plane is not very clear at present. The main reason is that the space strategy has not been fully determined, that is, what is the purpose and value of developing space planes.

The difficulty of the aircraft carrier is obvious to all. 5 years in the army, 30 years in the air force, 100 years in the navy, and the aircraft carrier is a giant in the navy. Aircraft carriers, including shipbuilding, power, carrier-based aircraft, information systems, personnel training, etc., are almost the crystallization of advanced technology and human wisdom. The maintenance cost is extremely huge. Therefore, the aircraft carrier can be said to reflect the comprehensive national strength of a country to some extent. Comprehensive consideration, the difficulty of the aircraft carrier should be greater than the first three items. But for the spacecraft, its development degree and direction have not yet been determined, so it is difficult to judge.