Monday marked the deadline for four US rocket companies to submit bids for Air Force contracts, encompassing all national security launches from 2022 to 2026. This is a hugely consequential and much-contested bid process that has implications for the American aerospace industry for the next decade and beyond.

The Air Force is seeking two providers for about two dozen launches. The prime contractor will receive 60% of the launches while the secondary contractor claims the remaining 40%. As the US military pays a premium for launch contracts to its nine reference orbits, this guaranteed revenue is extremely valuable to US companies aspiring to run a profitable launch business.

The lead-up to Monday's deadline has included heavy political lobbying from the four companies: United Launch Alliance, SpaceX, Blue Origin, and Northrop Grumman. As a result of this, Congress is considering some changes to the Air Force's procurement policy, including an on-ramp for a third provider during the 2022 to 2026 period. But so far, the Air Force is resisting this.

Here's a look at the four bidders and what is at stake for each of them.

United Launch Alliance

United Launch Alliance—a joint venture between Boeing and Lockheed Martin that enjoyed a monopoly on national security launches before the emergence of SpaceX—may be bidding for its life. To wean itself off its costly Delta boosters (as well as the Russian rocket engines that go with its workhorse Atlas V rocket), ULA has been developing the Vulcan rocket to cut costs while maintaining performance. The company says the Vulcan will be ready for its first flight in 2021.

"Vulcan Centaur will provide higher performance and greater affordability while continuing to deliver our unmatched reliability and orbital accuracy precision from our treasured cryogenic Centaur upper stage," ULA's chief, Tory Bruno, said in a news release Monday. "ULA is the best partner for national security space launch, and we are the only provider to demonstrate experience flying to all orbits including the most challenging heavy-class missions, providing the bedrock foundation for the lowest risk portfolio of two launch service providers for the US Air Force."

With increasing competition from SpaceX, Europe's Arianespace, Japan's Mitsubishi Heavy Industries, and Russian launch vehicles, ULA has been unable to capture much of the commercial market for satellite launches in the last decade. Therefore, it has largely been reliant on government business, mostly from the military. But ULA also relies on NASA through its science missions and lifting cargo and crew missions to the International Space Station.

If the company does not emerge victorious from this competition, it faces an uncertain future unless Vulcan can become commercially viable. Moreover, ULA will lose out on hundreds of millions of dollars in government money to finalize Vulcan if it does not receive an award. Historically, Boeing and Lockheed have been stingy parents, and whether or not they would pay to complete Vulcan is unclear.

One intriguing twist with ULA's bid is that its Vulcan rocket will use the BE-4 rocket engine, which is being developed and manufactured by Blue Origin—one of the four competitors in the Air Force bidding process. Blue Origin has said the Air Force competition was designed to unfairly benefit ULA.

SpaceX

The Hawthorne, California-based rocket company is the only bidder proposing to use rockets that are already flying—the Falcon 9 and Falcon Heavy boosters. This family of rockets has had a string of 49 successful launches since a static fire accident in September 2016, and according to SpaceX, it can meet all of the Air Force's desired orbits and payload specifications.

"SpaceX means to serve as the Air Force's long-term provider for space launch, offering existing, certified, and proven launch systems capable of carrying out the full spectrum of national security space-launch missions and requirements," said the company's president and chief operating officer, Gwynne Shotwell.

Since the Air Force agreed to admit SpaceX to the national security launch competition in 2015, the company has won several contracts for key missions and begun flying them for the military. These include the National Reconnaissance Office Launch 76, Orbital Test Vehicle 5, Global Positioning System III-2, and STP-2 flights.

SpaceX also likely will offer the government the lowest price on service to orbit. However, in its criteria for awarding missions, the Air Force listed price among the last of its considerations. Due to its lower price point, especially with is reusable Falcon 9 rocket, SpaceX has considerable commercial business to offset the loss of Air Force contracts. But it would hurt financially, all the same.

Blue Origin

Jeff Bezos' rocket company has bid its very large New Glenn rocket for the Air Force missions. However, when this rocket will begin flying is not entirely clear, as there are questions about whether it will be ready by the beginning of the 2022 contracting period.

What is clear is that Blue Origin does not believe the US Air Force has created a fair bidding process. Already, the company has filed a "pre-award" protest with the US Government Accountability Office. "The Air Force is pursuing a flawed acquisition strategy for the National Security Space Launch program," Blue Origin said, according to SpaceNews.

The Air Force decision to award contracts to just two companies creates a "duopoly," Blue Origin says, and it limits commercial development of strategic US assets such as rocket engines and boosters. Bezos has been investing about $1 billion a year of his own money into Blue Origin, which has largely been used to support development of the BE-4 engine and New Glenn rocket. He is likely to continue development of the New Glenn rocket without Air Force funding, but company officials say it is not fair to hold their wealthy founder against their bid.

Northrop Grumman

Northrop has been developing the Omega rocket for this competition since at least 2016. The Omega vehicle differs from the other entrants in the competition as its first and second stages, as well as side-mounted boosters, are powered by solid-rocket motors rather than liquid-fueled engines.

The bet by Northrop is that the US military, through its national security launch contract, would want to support one of the nation's most critical suppliers of solid-rocket motors for intercontinental ballistic missiles. Northrop officials have not said whether they would continue development of the Omega rocket if Northrop were to lose out on the Air Force contract.

Northrop's bid suffered a setback in May when an "anomaly" occurred during test firing of its solid-propellant Castor 600 rocket motor, the Omega rocket's first stage. From a video provided by the company, a major part of the rocket's large nozzle appeared to break apart, blasting debris around the area.

Afterward, a Northrop vice president, Kent Rominger, called the test a success. "It appears everything worked very, very well on this test," he said. "And at the very end when the engine was tailing off, we observed the aft exit cone, maybe a portion of it, doing something a little strange that we need to go further look into."

Nevertheless, the test cannot have instilled absolute confidence in the Air Force.