SpaceX installs orbital Starship heat shield prototype with robots

[Elderberry]

TESLARATI  By Eric Ralph 8/14/2020

SpaceX has begun large-scale Starship heat shield installation tests with the help of robots delivered last month in a sign that the company has already begun preparing for the rocket’s first orbital flight test campaign.

Designed to eventually replace SpaceX’s workhorse Falcon 9 and Falcon Heavy launch vehicles, Starship is a fully-reusable two-stage rocket powered by methane and oxygen-fueled Raptor engines. Just like Falcon 9, Starship’s first stage (known as Super Heavy) will launch the combined spacecraft and upper stage to an altitude of 70 to 100 km (40-65 mi) and velocity of ~2.5 to 3 kilometers per second (1.5-1.9 mi/s). Super Heavy will separate, boost back towards land, and either land back at the launch pad or on a floating platform.

SpaceX already has extensive experience launching, landing, and reusing orbital-class rocket boosters thanks to Falcon 9 and Heavy, which have completed 57 landings and been reused 39 times in less than five years. The Starship upper stage, however, will have to survive orbital-velocity atmospheric reentries some 3 to 5 times faster and exponentially more energetic than Super Heavy boosters. To do so routinely while keeping Starship cost and complexity low and reusability high, SpaceX will have to develop an unprecedentedly effective heat shield that is easier to install, maintain, and reuse than anything that has come before it.

More:https://www.teslarati.com/spacex-starship-heat-shield-prototype-robots/

[Elderberry]

Isn't methane an unusual fuel for a rocket?  Plentiful I know....but just wonder what the difference is compared to what was used previously.

@mrpotatohead

The wild physics of Elon Musk's methane-guzzling super-rocket

https://www.wired.co.uk/article/spacex-raptor-engine-starship

To get humans to Mars, SpaceX is building the mighty Starship spacecraft, powered by the Raptor engine - one of the first to be powered by methane and designed to be reused 1,000 times

No methane-powered rocket has ever made it to orbit, with Starhopper’s test hop the other day being the first time a methane-powered rocket engine had actually taken flight. Methane prevents a build-up of deposits in the engine compared to other fuels like kerosene, a process known as coking, while its higher performance allows for lower costs.

Of course, Raptor’s other major innovation over its predecessor is the use of methane, which harkens back to SpaceX’s ultimate goal. SpaceX isn’t the only company moving to methane, as rival firm Blue Origin – headed by Amazon CEO Jeff Bezos – is also developing its own methane engine, called the Blue Engine 4 (BE-4). With numerous benefits, it’s a switch that almost seems long overdue.

Most previous rocket engines have relied on using fuels like kerosene in place of methane. But the main benefit of using methane is that it has a higher performance than other fuels, meaning the rocket can be smaller. Its lower cost, too, means the total cost of launching can be brought down.

It’s also believed that methane could be available on the surface of Mars or elsewhere in space to be used as fuel – perhaps by mining water and carbon dioxide – known as in-situ resource utilisation (ISRU). “You could reasonably easily extract methane from the Martian surface, and potentially the lunar surface,” says industry analyst Caleb Williams from the consulting firm SpaceWorks.

[Joe Wooten]

Thanks!

I also watched a youtube video on the use of methane in rockets.  Pretty cool.  I hope it works as well as they think it will.

HYdrogen works in rocket engines very well. The RS-25 (Shuttle), J-2 (Saturn Rockets) and the Centaur are all hydrogen fueled engines. Methan will work slightly less efficiently than hydrogen will, with the lower efficiency more than made up by allowing a smaller volume fuel tank to be used, and cheaper than hydrogen because natureal gas needs little processing to make pure methane, whereas hydrogen requires expensive processing of natural gas or water to make. Methane using engines were tested back in the late 50's and early 60's, but the US went ahead with the hydrogen fueled engines because the research and testing were more advanced and NASA had a fetish for using the highest specific impulse over cost. Also the Saturn 5 would not have been able to put up as much payload if they had gone with methane instead of hydrogen. Musk and Bezos are going with methane to make it cheaper to operate.

[The_Reader_David]

For a reusable rocket, hydrogen is a bad choice:  it slowly degrades containers by getting into the interstices between metal atoms (or molecules in a ceramic or plastic), especially when stored under pressure.  I'm guessing that's the point of using methane instead.