The Senate Commerce Committee, which numbers among its wards both Conrail and the National Aeronautics and Space Administration, is considering a plan to shift $460 million in excess Conrail dollars to NASA, which could use the money.

Commerce Committee staff members confirmed the plan, described as the brainchild of Chairman John C. Danforth (R-Mo.). The plan is included among several items to be discussed by committee members if they meet Wednesday, as scheduled, to set spending targets for departments and agencies under their jurisdiction.

"It has a good chance of passing the committee," a staff member said, "but I don't think you should describe the support as bipartisan."

The fact it is even being discussed shows the parlous state of NASA's finances in the aftermath of the destruction of the shuttle Challenger in January.

In the House, space programs and Conrail are handled by different committees and "we don't think the House is very enthusiastic about this," a Senate staff member said.

Rep. John D. Dingell (D-Mich.), chairman of the House Energy and Commerce Committee, which is sitting on Conrail legislation, confirmed that view yesterday when he said: "Conrail's assets should not be nibbled to death for NASA, for agriculture or for any other pet program."

NASA is fighting for White House approval and funds to build a replacement shuttle, which would costs between $2 billion and $3 billion. That is the long-range problem. The short-term problem is that the House and Senate Armed Services committees have moved to cut $566 million in Air Force funds earmarked to NASA for military use of the shuttle. That would wipe out about one-fourth of the shuttle program's operating budget for fiscal 1987.

Meanwhile, federally owned Conrail is sitting there in the Northeast making money. It has a cash balance of about $960 million. If $460 million of that was taken, Conrail would still have the $500 million that Transportation Secretary Elizabeth Hanford Dole says is needed to ensure Conrail's health after it is sold. In addition, according to Conrail Chairman L. Stanley Crane, about $360 million remains available in an overfinanced pension plan.

The Senate, with Danforth leading the way, has passed legislation approving Conrail's sale to Norfolk Southern Corp. for $1.2 billion. However, that plan is dead in the House, although other proposals -- including a sale to the public -- have been kicking around.

The transfer of $460 million from Conrail would not affect its sale to Norfolk Southern, to which Danforth remains committed, staff members said.

Conrail was created by Congress in 1976 from the wreck of the PennCentral and five other northeastern railroads. It consumed $7 billion in tax dollars before it turned the corner in 1982. Under existing legislation, it is supposed to start in 1988 repaying the federal government some of what it owes; Danforth's proposal would, in effect, expedite that schedule regardless of whether Conrail remains federal property.