For the second year in a row, Elon Musk earns a spot on the 10 Who Made a Difference list because there’s no denying the influence his startup rocket company continues to assert on U.S. space policy and the broader launch market.

Musk’s Space Exploration Technologies (SpaceX) turned heads in June when it announced a firm $492 million contract with Iridium Communications to launch the mobile satellite services operator’s second-generation constellation of 72 satellites. The implied $6.8 million price per 800-kilogram satellite placed into a 780-kilometer orbit marked a return to prices not seen since Russian and Ukrainian rockets first entered the commercial market in the 1990s. An official with a non-U.S. company looking to launch a telecommunications satellite into geostationary orbit recently sought price quotes from SpaceX, China Great Wall Industry Corp. and the Indian Space Research Organisation. SpaceX, the official said, was the least expensive of the three.

The Iridium contract followed closely on the heels of the Falcon 9 rocket’s successful June 4 debut. The medium-lift rocket carried a full-scale engineering model of the Dragon cargo capsule SpaceX intends to launch for real in late September. That flight will mark the first of three demonstration missions SpaceX is obliged to fly under NASA’s Commercial Orbital Transportation Services program before the company begins making regular cargo runs to the international space station under a $1.6 billion contract awarded at the end of 2008.

Although SpaceX has successfully launched just one satellite to date — a 180-kilogram remote sensing craft for Malaysia aboard its Falcon 1 small rocket — the company claims a $2 billion backlog of U.S. government, commercial and international missions.

In April, U.S. President Barack Obama toured SpaceX’s Cape Canaveral, Fla., launch site with Musk before giving a landmark space policy address defending his proposal to outsource the launch of astronaut crews to commercial companies like SpaceX.