GX

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Fact sheet
Galaxy Express (GX)
Function	Medium expendable Launch vehicle
Manufacturer	Galaxy Express (JAXA/ULA/IHI)
Country of origin	Japan/United States
Size
Height	48m
Diameter	3.3m
Mass	190,500 kg (210 tons)
Stages	2
Capacity
Payload to LEO	3,600kg (4 tons)
Payload to 800km SSO	1,814kg (2 tons)
Launch History
Status	In Development
Launch sites	Tanegashima
First Stage - Atlas III
Engines	1 RD-180
Thrust	4,148.7 kN (932,670 lb_f)
Specific impulse	311 sec
Burn time	132 seconds
Fuel	RP-1/LOX
Second Stage - GX
Engines	1 liquid
Thrust	118 kN
Specific impulse	323 sec
Burn time	480 seconds
Fuel	LNG/LOX

This article is about a Japanese space launch vehicle. For other uses, see GX (disambiguation).

The GX expendable launch vehicle is a rocket currently under development by the Galaxy Express Corporation, a joint venture between United Launch Alliance (ULA), IHI Corporation (IHI), the Japan Aerospace Exploration Agency (JAXA), and several other Japanese companies. It will use the boost stage of the Atlas III rocket, provided by ULA, and a newly-designed upper stage made by IHI. The upper stage will be fueled by liquefied natural gas (liquid methane) with liquid oxygen as the oxidizer, making it the only space vehicle to use that combination of fuel and oxidizer.

The GX is intended to compete in the commercial satellite-launch sector. The program began as an effort to upgrade Japan's J-I rocket, which launched only once. Thus, GX was originally known as JII, albeit briefly. For a time, the program was termed J1-Upgrade, before finally settling on the current name in January of 2003.

JAXA reported that a full-scale second-stage engine had been successfully test-fired in October 2007. JAXA is developing this engine, the responsibility for which would eventually be turned over to the Galaxy Express venture.

In late December 2007, The Yomiuri Shimbun newspaper reported that the GX program was being subjected to a thorough review, mainly because of unexpectedly high additional costs. It also claimed that ULA partner Lockheed Martin had discontinued production of the first stage engine, thereby requiring a redesign, likely costly, to move to another engine. The paper said that the 15 billion yen that JAXA requested for the GX project was eventually slashed to 5.6 billion yen in the Fiscal 2008 budget.

The GX would launch from the Tanegashima Space Center, south of Kyūshū, Japan. Initial launch capability for GX is currently scheduled for 2011.

In May 2008, it was reported that the Space Development Committe, who are overseeing the project, were considering its cancellation.^[1]