Of all the items unveiled in NASA’s proposed fiscal year 2006 budget Monday, the decision to eliminate funding for a servicing mission to the Hubble Space Telescope was by far the most controversial.

Yet, though NASA officials now seem adamant and united in their conviction that such a mission — by either humans or robots — is too challenging to achieve, rescuing Hubble is not as complicated or difficult as they would have the public believe.

Faced with a tight budget and the conclusion of a National Academy of Sciences panel that a robotic mission was too risky, the space agency threw in the towel and decided to cancel all funding for a Hubble repair attempt.

As noted by NASA comptroller Steve Isakowitz, “We have decided that the risks associated with the Hubble servicing at this time don’t merit going forward.”

Not surprising, reaction to the decision was immediate and heated. As noted in a Florida Today editorial Wednesday, “The Hubble decision — which we believe is wrong because of its historic work in studying the universe — is certain to set off a fight in Congress among backers who rightly see its premature demise as a waste.”

NASA’s position was made even more controversial by its rejecting the conclusions of the national academies panel, which had advocated reinstating the shuttle-servicing mission and noted how shuttle astronauts had serviced Hubble four times previously with great success.

Even more significant: Based on NASA’s own budget and scheduling plans, launching a manned shuttle mission to Hubble actually is much simpler and in the long run far less costly than even the academies panel concluded.

Let’s run some numbers. According to NASA’s proposed budget, the entire cost for all shuttle operations in FY 2006 will be $4.531 billion. Of this, $366 million goes for fixing the shuttle, leaving $4.165 billion to launch five missions to the International Space Station.

Putting a shuttle into orbit in 2006 will cost about $833 million — not the $1 billion often quoted in the media and by politicians.

Even this number is deceptive, however. Whether NASA flies no shuttles, as it has done for the last two years, or eight, as it did in 1997 during the height of the shuttle-Mir program, the program’s fixed annual overhead cost remains about $4 billion.

Put another way, NASA’s per-shuttle-mission cost decreases the more missions it flies, a basic fact of business that sometimes escapes career and elected officials alike. Thus, authorizing a sixth Hubble mission in 2007 would not add much expense to the program.

Should the agency instead stick to its present policy — established for safety reasons — of limiting the number of missions per year to five, then the actual additional cost for adding a Hubble flight to the shuttle fleet’s manifest in 2007 would be zero, the costs deferred until 2010 when the space station’s completion is delayed by this one mission.

This is why eliminating funding today for the robot mission instantly kills it, because its costs must be paid now so the mission design can be completed. In contrast, deleting funds for a shuttle flight to Hubble does nothing to impact that mission, because its development is already complete. Almost everything necessary for a shuttle mission to Hubble already has been built, so it costs practically nothing to reactivate at any moment.

Nor is lack of time a reason to prevent a Hubble-servicing mission. In June 2004, NASA officials testifying before the national academies panel on the telescope’s status said the best time to schedule a shuttle mission would be March 2007. Then — assuming all goes well with the shuttle’s return to flight and the subsequent ISS rendezvous — the station would be in a symmetrical configuration that would allow a short delay in its assembly.

During those same hearings, NASA officials also testified it would take, at most, 12 months to 18 months to train a crew for a Hubble mission.

To get a Hubble-servicing attempt mounted in March 2007, NASA does not have to decide whether to fly until next fall at the earliest. If necessary, the decision could even be delayed until early spring 2006, by which time the agency hopes to have completed its first two shuttle flights, as well as proven the success of its shuttle repairs and resumed space-station construction.

House Science Committee Chairman Sherwood Boehlert, R-N.Y., was incorrect when he noted Feb. 7 that “Congress will have to make a decision about Hubble very soon — probably no later than the end of March — if a servicing mission of any kind is to have a realistic chance of moving forward.”

Congress and NASA actually have plenty of time — as much as a year — to consider the problem.

The real factor inhibiting the Hubble repair mission is fear — fear by too many at NASA that the flight is too risky. This fear seems puzzling, considering these are the same people advocating sending humans back to the moon and eventually to Mars, journeys that will be far more dangerous than a short hop to Hubble.

To understand how inexplicable this is, compare the Hubble situation with one of NASA’s greatest triumphs: the decision to send Apollo 8 to the moon 37 years ago. In the spring of 1968, George Low, manager of the Apollo program, realized the lunar module that would land men on the moon was behind schedule and would not be ready for the planned inaugural flight in December.

Rather than play it safe and delay the mission, Low decided to fly Apollo 8 without the lunar module, and not limit the mission to Earth orbit as originally planned. Instead, he took a calculated gamble and sent the mission to the moon, even though the chances of success were estimated at the time at only 50 percent.

He realized if the United States was going to fulfill its commitment to send a human to the moon by the end of the decade — as pledged by President John F. Kennedy — NASA would have to take some risks. Low considered the goal of reaching the moon worth such risks.

The situation today is no different. If NASA truly intends to return to the moon, it is going to have to take far greater risks than presented by a mission to Hubble, risks probably as great as those accepted by Low and NASA in the 1960s.

Few would argue against the Hubble Space Telescope’s value to humanity and how it is easily worth the much smaller risks associated with sending humans back to fix it. Yet the instrument’s precarious situation exists almost entirely because outgoing NASA Administrator Sean O’Keefe has been unyielding in his conviction that a human mission to Hubble is too risky. So the final decision whether to save Hubble will rest on the person President Bush picks to replace him.

If Bush picks someone with the foresight and courage of a George Low, that person could provide a clarity that would not only save Hubble, but also would prove to everyone, in and out of NASA, the agency is serious when it says it wants to send humans back out into space.