As Elon Musk dreams of missions to Mars, fellow billionaires Paul Allen and Richard Branson focus on breakthrough spaceflight closer to home: cheap cargo trips to Earth orbit.

From startups to aerospace giant Boeing, entrepreneurs and for-profit companies are working to shake up a $6 billion commercial launch business whose crowded schedules may require yearslong waits to loft $200 million communications satellites.

Instead of heavy boosters fired from conventional pads, the new rocketeers envision smaller spacecraft taking off from venues as varied as the remote South Pacific and a giant plane dwarfing Howard Hughes's famed Spruce Goose. Cut-rate rides will let them loft the latest miniature satellites, which are being built for as little as $10,000 and deployed in swarms to monitor crops, create Web hot spots and track weather systems.

"Any time you start shaving zeros off the cost of doing something, people will start trying something they never tried before," said A.J. Piplica, chief operating officer of Generation Orbit Launch Services Inc., which is designing a lightweight rocket fired from a Gulfstream business jet.

Allen and Branson's ideas will be showcased this week in Colorado Springs, Colorado, at the Space Symposium trade show. The entrepreneurs share Musk's aim of paring spaceflight costs. But unlike the Space Exploration Technologies Corp. founder, they and their lower-profile peers are focused closer to Earth.

The alternative-launch ventures have the potential to slash prices in a field still attuned to government contracts and multimillion-dollar satellites, said Marco Caceres, director of space studies for Fairfax, Virginia-based consultant Teal Group.

For years, annual satellite deployments ran in a range of 70 to 150, Caceres said. Now, with units as petite as a credit card, the pace is quickening. The 2014 tally included 303 satellites from 1 kilogram (2.2 pounds) to 1,000 kilograms with a market value of $1.9 billion, according to Teal Group data.

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"That's the trend for the future," Caceres said. "If someone says we might be launching thousands of these satellites a year, it's not an outrageous statement."

The new launch operators are challenging incumbents such as United Launch Alliance, a Boeing-Lockheed Martin Corp. joint venture. The catch, Caceres said, is keeping rates to less than the $12 million U.S. companies typically pay to put payloads on Russian-made Dnepr rockets, converted Cold War-era missiles that offer the cheapest lift.

"The launch part of the space industry is like a stuffy old man's golf club: very elite," said Peter Beck, chief executive of Rocket Lab USA, which is developing light rockets to be fired from New Zealand. "Nothing's moving too fast, just old guys smoking cigars."

Rocket Lab plans to charge $4.9 million to fly cargo in its lightweight, all-black Electron, an 18-meter (59-foot) rocket that would be overshadowed by a 34-meter Dnepr. It's targeting startups and universities whose small satellites can't wait two years to hitchhike as a secondary payload on a larger rocket.

The company intends to start commercial trips in 2016. New Zealand's empty skies boast few air-traffic constraints, and its southerly latitude lets rockets reach more orbital paths than from traditional ranges such as Kennedy Space Center in Florida or California's Vandenberg Air Force Base, Beck said.

Established commercial-launch firms are paying attention. Lockheed is a strategic investor in Rocket Lab. Orbital ATK is manufacturing the rocket for Stratolaunch, a unit of Allen's Vulcan Inc.

Stratolaunch wants to ditch ground launches altogether. It's building the world's biggest aircraft -- the 385-foot wingspan would eclipse Hughes's 1940s wooden flying boat -- to ferry rockets to 30,000 feet, then release them to soar into orbit. Vulcan declined to comment before a presentation Monday at the Space Symposium.

A single-use rocket with a reusable carrier plane is a twist on the approach taken by Musk's SpaceX, which is trying to cut launch costs with boosters that can be recycled. SpaceX plans a cargo mission Monday to the International Space Station, with another attempt to have the spent rocket land vertically on an "autonomous spaceport drone ship" at sea.

While air launches have been conducted for more than 20 years, they're gaining notice as the satellite industry expands. Starting in the stratosphere means a rocket is already part of the way toward orbit, freeing it from lugging the propellant just to get off the pad.

Branson's Virgin Galactic will use a custom-built carrier plane similar to Allen's Stratolaunch. Virgin's WhiteKnightTwo only has four engines to the six on the Stratolaunch plane, and was originally designed to hoist a suborbital tourist craft.

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"When we first dreamt this up, the last thing we thought about was satellites," Branson said in unveiling his launch plans in 2012. "But suddenly you realize, good grief, we've got the best launch vehicle for a satellite ever."

His SpaceShipTwo rocket plane for leisure trips crashed during an Oct. 31 trial, killing one pilot, after its release from the mother ship. Virgin Galactic's satellite launcher, using different technology, may be tested in 2016.

Even Boeing, a veteran of U.S. space missions dating to the 1960s, plans to start test firing a 24-foot rocket from one of its F-15E fighters this year under a contract for the Pentagon's research agency. It's trying to provide satellite rides for less than $1 million that could be put into motion on a day's notice.

"You have companies that probably would have had zero interest just a few years ago that are very active now," said Micah Walter-Range, director of research and analysis with the Space Foundation, the Space Symposium organizer.

Some of the new entrants weren't even around a few years ago. Generation Orbit Launch Services, the company fitting rockets to Gulfstreams for $2 million shots into space, was founded in 2011. The Atlanta-based startup has 10 letters of intent for 200 to 250 launches a year, COO Piplica said.

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"You have potentially thousands of small satellites going to orbit," said Dick "Rocket" David, CEO of Cape Canaveral, Florida-based industry researcher NewSpace Global. "You're going to see new players emerge who may clean up."