The U.S. Defense Advanced Research Projects Agency (DARPA) is pursuing a worthy cause in its latest bid to develop an airborne small-satellite launcher, but recent history and the current budget outlook make it difficult to be optimistic about the initiative’s chances for success.

The Airborne Launch Assist Space Access (ALASA) program aims to develop an air-launched rocket capable of placing 45-kilogram satellites into low Earth orbit at a cost of about $1 million, or about $22,000 per kilogram. The current cost of launching small satellites is three times that amount, DARPA said in a Nov. 3 procurement notice.

Although it is unclear how DARPA calculated current launch costs — $66,000 per kilogram for small satellites seems a bit low — the case for a system like ALASA is unassailable. The difficulty and high cost of securing rides to orbit for small satellites has long had a depressing effect, not only on space-based research and technology development but also on implementing potentially game-changing concepts like Operationally Responsive Space, whereby low-cost capabilities are deployed quickly as emerging needs or gaps are identified.

There also are good arguments for airborne launch systems, among them the increased flexibility that comes with not being tied to the assets of a given range. In theory, depending on the orbit desired, a system like ALASA could launch satellites from anywhere in the world.

But DARPA’s recent track record with air-launched rockets is sobering. One such effort was the $88 million Responsive Access Small Cargo Affordable Launch, or RASCAL, program, which was hatched in 2003 with essentially the same objective as ALASA. RASCAL managers set their hopes on a 1950s-era experimental jet propulsion technology that would hurl the carrier aircraft beyond the atmosphere to deploy an expendable two-stage rocket, but the only thing that soared was the program’s projected cost. RASCAL was abandoned after a couple of years and considerable taxpayer expenditure.

Meanwhile, DARPA embarked on another program dubbed Force Application and Launch from Continental United States that funded several satellite-launch concepts including AirLaunch LLC’s QuickReach vehicle, which was to be deployed from the cargo bay of a C-17 aircraft. Today the United States has little if anything to show for that effort.

To be fair, DARPA does have one qualified success with air-launched rockets: It funded the initial development of Orbital Science Corp.’s Pegasus, which has flown 40 missions and during the 1990s was the U.S. government’s primary means of launching small satellites. But a rising price tag — NASA in June 2010 ordered a Pegasus launch and associated services for $40 million — and a cheaper alternative in the form of excess missile assets have quashed demand, and the vehicle is seldom used today.

DARPA is by its charter a risk-taking institution whose managers are encouraged to take on projects with a high likelihood of failure — so long as the potential payoff also is high. That’s a good thing. The agency also has a high turnover rate among its program managers — also by design — and the result is a short institutional memory. That also can be positive, inasmuch as forgotten failures cannot deter future risk-taking and innovation. But given the scarcity of technology investment dollars these days the lessons of past investments gone bust cannot go unheeded.

It wasn’t hard to predict failure on the RASCAL program given the $88 million budget estimate that got the program sold. That’s just not enough money — not even close — to develop a launch system, let alone one that requires one or more technological leaps, if not breakthroughs.

DARPA is budgeting nearly twice that amount for ALASA — $164 million — and that’s a good sign. But the program is highly ambitious; DARPA is looking to push the state of the art in propulsion technology, fuels and fuel production, and flight control systems. Even with a larger budget for ALASA, one must wonder whether it is sufficient to see the effort through to a proof-of-concept demonstration.

If ALASA fails to get off the ground, future proposals aimed at changing the economics of launching small satellites — something that is sorely needed — will be greeted with little enthusiasm by the Pentagon planners and lawmakers who make project funding decisions. Should DARPA request significant funding for ALASA in 2013, Congress should make sure the agency fully understands what it is getting into, and has budgeted accordingly, before signing off on the program.