Defense Secretary Leon Panetta speaks during a House Armed Services Committee on Wednesday. The committee is hearing testimony on the Defense Departments budget request for fiscal year 2013. (Mark Wilson/GETTY IMAGES)

Congress is looking at today’s threats, debating the reductions found in President Obama’s defense budget requests for next year, and probably not thinking about the world in 2022. That’s when the impact of some of its decisions will be felt.

I am thinking specifically about Navy shipbuilding and the nation’s nuclear carrier fleet. Carriers are interesting because they take 10 years to build, another two to three years in shakedown cruises before they become operational — and then they last up to 50 years.

What will the threats be over that period of time? How many of these $12 billion fighting machines does the United States need? Does the carrier fleet get sized for peacetime or for war? Does their mere presence in an area deter war? Are the president and Congress taking a long-enough view in making their decisions?

At Monday’s Senate Armed Services Committee hearing, Defense Secretary Leon E. Panetta said of the proposed fiscal 2013 budget: “We’ve maintained the 11 carriers in the Navy in order to ensure that we have sufficient forward presence. There’s nothing like a carrier to be able to allow for quick deployment. . . . And that’ll give us a great capacity to be able to show our force structure in the Pacific.”

But as Navy experts say, you need that number just to keep one in the Indian Ocean, another in the Western Pacific, and enough in reserve for contingencies, such as today’s need to keep two available for South Asia/Middle East use. The general standard for carriers is seven months on station and 25 months at home port or dry dock.

The nuclear ones also must have their power generators refueled. For example, the new budget contains $1.6 billion to refuel the reactor of the USS Abraham Lincoln, which just days ago passed through the Strait of Hormuz after weeks in the Persian Gulf aiding in the Afghan war. Refueling beginning in the next 12 months will keep the Lincoln out of action for a year.

The new fiscal 2013 budget contains no money for CVN78, the USS Gerald R. Ford, although the Navy has identified the need for another $881 million for cost overruns in what has become a $12.3 billion ship. Its funding began in 2001, and money to pay off the overruns has been pushed into the fiscal 2014 and 2015 budgets.

The first of a new class of nuclear-powered carriers, the Ford is projected to save money in the long run by having a new reactor power plant that requires 50 percent fewer people to run it while generating far more electricity than the previous class of nuclear carriers. Overall, including the flight crews, the Ford will have some 3,800 personnel. That’s almost 1,200 less than the current carriers.

Of course, the Ford has had its problems. It became a test bed for new equipment and construction techniques. Along with the new power-generating nuclear reactor, the Ford will have a new electromagnetic catapult-launching system and a new phased-array radar to replace five radars on the earlier carriers.

The catapult-launching system had to be built and then tested on land, since there was no ship deck built that could handle it. Those tests are ongoing at a site in Lakehurst, N.J., while parts of the finished system have begun to be installed in the Ford, which is being built at the Huntington Ingalls shipyard at Newport News, Va.

The electromagnetic system, which has taken a decade to develop, will permit controlled acceleration and stoppage when launching aircraft.

The Ford — more than 50 percent complete, with some 4,000 employees working on it — is being put together much like a Lego set. Modules are put together elsewhere then brought to the ship. There will be some 500 of them, each one thoroughly tested after being connected to existing wiring and other systems.

A December report by the Defense Department’s Director, Operational Test and Evaluation office raised a number of issues that still need fixing, including software related to the ship’s self-defense capability and its new phased-array radar. Another issue was completing a “manning construct,” a detailed examination of the crew size needed to operate the carrier. Since the Ford is to be able to increase the number of sorties launched per day to some 160, about 30 percent more than current carriers, the manning structure is considered crucial.

The Ford is expected to be in the water by the summer of 2013. At that time what is called a pre-commissioning unit will be put together and a prospective commanding officer assigned. Their job in part will be to put together the crew, which will grow until shortly before the ship construction is completed and the ship is delivered for commissioning. That is now expected in 2015, though it could slip. After the Navy takes over there will be further testing with the Navy crew and fixes made before a real shakedown cruise takes place.

Meanwhile, the process for the next carrier, CVN79, the USS John F. Kennedy, has been underway since 2007. Some $2 billion has already been spent on the Kennedy’s design and research and development. The fiscal 2013 budget has $781 million for it, $173.5 million for more research and development and $608.2 million in procurement funds. The Kennedy has already slipped, and prospects are it will not be received by the Navy until 2019 — and thus not operational until perhaps 2022.

Navy shipbuilding, as you can see, is a complex and costly process. Panetta told the Senate committee Monday and the House Armed Services Committee on Tuesday that we have 285 Navy ships today and will have the same number five years from now. The new goal is getting to 300 by the end of 2022. I doubt it, but more important, why will we need 300 ships in 2022 if the ones we keep building are so much more effective than the ones we had in the past?