PARIS — Orbital Sciences Corp. will get most of its planned revenue from NASA for the Oct. 28 launch of Orbital’s Antares rocket despite the rocket’s failure because the milestone that triggered payment was the rocket’s ignition and liftoff, not launch success, Orbital and its prospective merger partner, Alliant Techsystems (ATK), said Nov. 24.

Under Orbital’s $1.9 billion Commercial Resupply Services (CRS) with NASA, Orbital’s obligations are not counted in launches, but in kilograms delivered to the space station.

The Oct. 28 launch was the third of a then-planned eight cargo runs for NASA to meet the 20,000-kilogram requirement, with subsequent missions using a larger version of the Cygnus payload module, built by Thales Alenia Space in Italy.

Since the failure, officials from Dulles, Virginia-based Orbital have said the failure will not result in any substantial new costs to Orbital.

Planned 2015 revenue and profit will remain intact, the company has said, even though it must use someone else’s rocket for one or two CRS missions while Antares is refitted with a new first-stage engine that Orbital has not publicly identified. Antares would then resume flights in 2016 and fulfill the CRS contract terms with two or three final missions.

Because Orbital will be using a larger version of the Cygnus capsule, the company says it can meet the 20,000-kilogram requirement for CRS with four more flights instead of the five planned originally.

ATK officials have said that after a detailed review of Orbital’s plans, they believe Orbital can deliver on its promise, and that the companies’ merger remains on track even as a shareholder vote was delayed seven weeks, to Jan. 27. A Nov. 24 filing with the U.S. Securities and Exchange Commission (SEC) gives some indication of how it is that the explosion of a rocket carrying a commercial payload and grounding the vehicle for about two years can be, in financial terms, a wash for Orbital.

While the CRS contract with NASA is based on a service-delivery model, NASA and Orbital structured it so that Orbital receives milestone payments tied to launches. It is not uncommon in launch contracts to make “intentional ignition” a milestone that, for example, signals the end of one contractual relationship and the beginning of another — even if ignition and liftoff are followed by explosion and failure.

For Orbital’s CRS contract, each launch has two milestone payments. The first payment is for ignition and liftoff. The second is for final mission success. With the payload destroyed, NASA will not be paying Orbital the expected $48 million for mission success.

Orbital had taken out an insurance policy for that piece of the mission and will thus receive $48 million in insurance proceeds. Orbital said the insurance “will cover the entire final milestone payment.” It was unclear whether Orbital had also insured itself for the cost of its insurance premium.

Orbital did not disclose the amount of the milestone payment it expects from NASA for the launch.

With the launch vehicle paid for by NASA as scheduled, and the insurance proceeds covering the rest, the Oct. 28 failure looks revenue-neutral to Orbital.

Instead of eight launches for CRS, Orbital will conduct seven. Much of the savings from reducing the total number of CRS launches will be redirected to finance the purchase of one or two third-party rockets. There may be costs to Orbital for accelerating the introduction of the new Antares first stage, from 2017 previously to 2016 since the failure. But Orbital said the bottom line effect in 2015 is no big deal.

ATK and Orbital agree the failure may affect Orbital’s bid for a follow-on CRS contract. The Orbital-ATK merger terms assumed Orbital would not only complete the current CRS contract but win a follow-on NASA contract for at least six more station-resupply missions through 2020. Orbital’s CRS-2 contract bid is due in December, but NASA is not expected to make a contract award until May — well after the ATK and Orbital shareholders vote.

ATK officials have said they will monitor Orbital’s post-launch-failure activities, and NASA’s response, and can always review the merger up until the day it is approved by U.S. regulators.

In the meantime, according to the SEC filing, the ups and downs of the two companies’ stock prices will not affect the merger. Under the transaction’s terms, each Orbital shareholder will receive 0.449 shares of ATK, whose sporting goods division is being split off into a separate company to be 100 percent ATK-owned.

Arlington, Virginia-based ATK’s Aerospace and Defense division is merging with Orbital in a transaction that appears to leave the combined entity in Orbital’s control but in fact is a purchase of Orbital by ATK.

The new company, Orbital ATK, will be based at Orbital’s current headquarters, with Orbital Chief Executive David W. Thompson keeping that role for the enlarged company.

When the transaction is completed, ATK shareholders will own 53.8 percent of Orbital ATK, with Orbital shareholders owning the rest.