WASHINGTON (Reuters) -The U.S. Space Force has awarded about a half dozen small Golden Dome contracts to build competing missile defense prototypes, kicking off a race for future deals worth tens of billions of dollars, according to two sources briefed on the matter.

The awards went to several companies including Northrop Grumman ( NOC ), True Anomaly, Lockheed Martin ( LMT ) and Anduril, the sources said.

The contracts mark a significant step forward in the Pentagon's efforts to track and destroy enemy missiles, and include prototypes of space-based interceptors and related systems. While Reuters could not determine the size of the contracts, a July Pentagon presentation seen by Reuters suggested awards for interceptor contracts would be about $120,000 each.

The contracts have not yet been publicly announced, though a Space Force spokesperson confirmed the awards, declining to name the contractors. The spokesperson said that contracts under $9 million do not need to be publicly disclosed.

Winners of these initial awards will compete for final production contracts that could be worth tens of billions of dollars.

The contracts will fund the development of competing prototypes for phase interceptors that will shoot down a missile as it enters space, and the fire control stations to coordinate the signals from satellites and help interceptors launch and find their targets.

The Space Force awarded Northrop Grumman ( NOC ) and Anduril contracts valued at $10 million, according to values printed in the July Pentagon presentation, the sources said.

Names of the companies that won contracts in both these award pools have not previously been reported.

The government had asked contractors to develop four different versions of interceptors to address threats at various altitudes and speeds that have yet to be awarded.

A third source said the four interceptor pools may be consolidated into three.

A Northrop spokesperson declined to comment. Anduril, Lockheed and True Anomaly did not immediately respond to a request for comment.

The government has structured the various interceptor competitions with "prize pools" to incentivize rapid development. The largest pool of $340 million would be split among companies that successfully complete an on-orbit test, with first place receiving $125 million and fifth place receiving $40 million, according to the July presentation.

The ultimate prize is substantial: production contracts worth $1.8 billion to $3.4 billion annually, according to the July presentation. However, industry executives estimate it could cost between $200 million and $2 billion to build and test a single space-based interceptor prototype.

The space-based interceptor program represents a new approach to missile defense, placing weapons in orbit to destroy threats earlier in their flight path than current ground-based systems allow.