In the new age of space travel and exploration, commercial space companies are not only boasting immense growth and innovation, but are reaching out to fill niche markets as well. In addition to launchers that can send orbiters and payloads into space, there are also new breeds of commercial satellites, new engines, and a slew of other concepts that promise to make the industry more promising and cost effective.
A case in point is the small satellite launch company Firefly Space Systems, which recently unveiled its planned Alpha launcher. Aimed at the small satellite launch market, it’s designed to launch satellites into low-Earth orbit (LEO) and Sun-synchronous orbits for broadband communication using an unconventional aerospike engine, it is also the first orbital launcher to use methane as fuel.
The Firefly Alpha is a specialized design to launch light satellites at low cost into low Earth Designed to carry payloads of up to 400 kg (880 lb), the Alpha features carbon composite construction and uses the same basic design for both of its two stages to keep down costs and simplify assembly. Methane was chosen because it’s cheap, plentiful, clean-burning and (unlike more conventional fuels) self-pressurizing, so it doesn’t require a second pressurization system.
But the really interesting thing about the two-stage rocket assembly is that the base of the engine is ringed with rocket burners rather than the usual cluster of rocket engines. That’s because, while the second stage uses conventional rocket engines, the first stage uses a more exotic plug-cluster aerospike engine that puts out some 400.3 kN (or 40,800 kg/90,000 lb) of thrust.
Aerospike engines have been under development since the 1960s, but until now they’ve never gotten past the design phase. The idea behind them is that rockets with conventional bell-shaped nozzles are extremely efficient, but only at a particular altitude. Since rockets are generally used to make things go up, this means that an engine that works best at sea level will become less and less efficient as it rises.
The plug aerospike is basically a bell-shaped rocket nozzle that’s been cut in half, then stretched to form a ring with the half-nozzle forming the profile of a plug. This means that the open side of the rocket engine is replaced with the air around it. As the rocket fires, the air pressure keeps the hot gases confined on that side, and as the craft rises, the change in air pressure alters the shape of the “nozzle;” keeping the engine working efficiently.
The result of this arrangement is a lighter rocket engine that works well across a range of altitudes. Because the second stage operates in a near vacuum, it uses conventional rocket nozzles. As Firefly CEO Thomas Markusic put it:
What used to cost hundreds of millions of dollars is rapidly becoming available in the single digit millions. We are offering small satellite customers the launch they need for a fraction of that, around US$8 or 9 million – the lowest cost in the world. It’s far cheaper than the alternatives, without the headaches of a multi manifest launch.
Meanwhile, SpaceX has been making headlines with its latest rounds of launches and tests. About a week ago, the company successfully launched six ORBCOMM advanced telecommunications satellites into orbit to upgrade the speed and capacity of their existing data relay network. The launch from Cape Canaveral Air Force Station in Florida had been delayed or scrubbed several times since the original launch date in May due to varying problems.
However, the launch went off without a hitch on Monday, July 14th, and ORBCOMM reports that all six satellites have been successfully deployed in orbit. SpaceX also used this launch opportunity to try and test the reusability of the Falcon 9′s first stage and its landing system while splashing down in the ocean. However, the booster did not survive the splashdown.
SpaceX CEO Elon Musk tweeted about the event, saying that the:
Rocket booster reentry, landing burn & leg deploy were good, but lost hull integrity right after splashdown (aka kaboom)… Detailed review of rocket telemetry needed to tell if due to initial splashdown or subsequent tip over and body slam.
SpaceX wanted to test the “flyback” ability to the rocket, slowing down the descent of the rocket with thrusters and deploying the landing legs for future launches so the first stage can be re-used. These tests have the booster “landing” in the ocean. The previous test of the landing system was successful, but the choppy seas destroyed the stage and prevented recovery. Today’s “kaboom” makes recovery of even pieces of this booster unlikely.
This is certainly not good news for a company who’s proposal for a reusable rocket system promises to cut costs exponentially and make a whole range of things possible. However, the company is extremely close to making this a full-fledged reality. The take-off, descent, and landing have all been done successfully; but at present, recovery still remains elusive.
But such is the nature of space flight. What begins with conceptions, planning, research and development inevitably ends with trial and error. And much like with the Mercury and Apollo program, those involved have to keep on trying until they get it right. Speaking of which, today marks the 45th anniversary of Apollo 11 reaching the Moon. You can keep track of the updates that recreate the mission in “real-time” over @ReliveApollo11.
As of the writing of this article, the Lunar module is beginning it’s descent to the Moon’s surface. Stay tuned for the historic spacewalk!
Sources: universetoday.com, gizmag.com