It appears to have been a success. Now on to another one, or a hop.
6 thoughts on “Starship’s Static Fire”
Is there a practical method for turning lunar regolith into raptor fuel, or is lunar ice the best way to create fuel?
Raptor burns LOX/methane. In theory, LOX can be made from the silicates, but there is no carbon and not much hydrogen in it, so we need ice for the latter, and we don’t know if there are good carbon sources on the moon. Raptor’s primary requirement was the ability to use fuel manufactured from the Martian atmosphere, because methane can be made from carbon dioxide and water.
A few months back, you linked to a podcast by a physicist, I think, who said the lunar regolith gives off steam when heated, but I didn’t recall if he mentioned carbon. Is there any plan at Spacex for a lox-liquid H2 engine for lunar landings and returns to orbit? Or are they planning to import all the methane for use on the surface?
There is water that can be baked off. SpaceX plans to bring its propellant with it, at least to start, though eventually they could use lunar ice for LOX. They have not plans to go to hydrogen fuel.
Thanks, Rand.
From “LMT” at NASAspaceflight.org :
Industrial Lunar Methalox Production
Carbon challenge:
Raptors and other lunar methalox rockets will need ISRU LOX and LCH4 in bulk. If/when available, Artemis mission-planning options will expand. However, methane production requires lunar carbon, tbd. The relevant Chandrayaan-2 IIRS data on lunar ice is still pending: when released, the mapped data should say much about carbon content.
Meanwhile, we know the LCROSS impact experiment released volatiles from lunar ice, at measured concentrations [Colaprete et al. 2010]. Measured volatile carbon content is about a quarter of the carbon required to hit the methalox production target: i.e., oxygen : methane ratio of 3.8.
Is more carbon present, but unmeasured?
Hypothetical carbon source:
While awaiting Chandrayaan-2 results, we can note that lunar isotopic studies suggest cometary origin for much lunar ice [Greenwood et al. 2011] [Bekaert et al. 2017]. Comets have both volatile and refractory carbon; 47 observed organic molecules are listed in Rubin et al. 2019, Table 2. Volatile and refractory carbon were both seen, for example, in the coma of comet 103P/Hartley 2 [Protopapa et al. 2014].
Image: Protopapa et al. 2014, Figure 4. 103P/Hartley 2 coma volatile carbon (CO2) and refractory carbon (organics).
Application to production:
A comet’s nucleus has far more refractory carbon than volatile carbon: e.g., 23 wt% refractory carbon vs. 3 wt% CO2 [Greenberg 1998]. Within that refractory carbon, a hydrocarbon fraction exists. That fraction could be reformed by CAVoR – with some syngas steps tbd – to boost methane output to the optimum 3.8 ratio.
In fact, given CAVoR’s baseline inputs of 15 wt% water and 5 wt% organics, CAVoR is actually oxygen-limited, producing methalox at a methane-heavy ratio of 1.45. Here the comet’s abundant water can make up the difference. Doubling the power draw of CAVoR’s electrolyzer boosts O2 output, to meet boosted CH4 output, at the optimum 3.8 ratio.
—————–
Looks to me that William Barton and I might both be right about carbon sources on the Moon.
Also this:
Is there a practical method for turning lunar regolith into raptor fuel, or is lunar ice the best way to create fuel?
Raptor burns LOX/methane. In theory, LOX can be made from the silicates, but there is no carbon and not much hydrogen in it, so we need ice for the latter, and we don’t know if there are good carbon sources on the moon. Raptor’s primary requirement was the ability to use fuel manufactured from the Martian atmosphere, because methane can be made from carbon dioxide and water.
A few months back, you linked to a podcast by a physicist, I think, who said the lunar regolith gives off steam when heated, but I didn’t recall if he mentioned carbon. Is there any plan at Spacex for a lox-liquid H2 engine for lunar landings and returns to orbit? Or are they planning to import all the methane for use on the surface?
There is water that can be baked off. SpaceX plans to bring its propellant with it, at least to start, though eventually they could use lunar ice for LOX. They have not plans to go to hydrogen fuel.
Thanks, Rand.
From “LMT” at NASAspaceflight.org :
Industrial Lunar Methalox Production
Carbon challenge:
Raptors and other lunar methalox rockets will need ISRU LOX and LCH4 in bulk. If/when available, Artemis mission-planning options will expand. However, methane production requires lunar carbon, tbd. The relevant Chandrayaan-2 IIRS data on lunar ice is still pending: when released, the mapped data should say much about carbon content.
Meanwhile, we know the LCROSS impact experiment released volatiles from lunar ice, at measured concentrations [Colaprete et al. 2010]. Measured volatile carbon content is about a quarter of the carbon required to hit the methalox production target: i.e., oxygen : methane ratio of 3.8.
Is more carbon present, but unmeasured?
Hypothetical carbon source:
While awaiting Chandrayaan-2 results, we can note that lunar isotopic studies suggest cometary origin for much lunar ice [Greenwood et al. 2011] [Bekaert et al. 2017]. Comets have both volatile and refractory carbon; 47 observed organic molecules are listed in Rubin et al. 2019, Table 2. Volatile and refractory carbon were both seen, for example, in the coma of comet 103P/Hartley 2 [Protopapa et al. 2014].
Image: Protopapa et al. 2014, Figure 4. 103P/Hartley 2 coma volatile carbon (CO2) and refractory carbon (organics).
Application to production:
A comet’s nucleus has far more refractory carbon than volatile carbon: e.g., 23 wt% refractory carbon vs. 3 wt% CO2 [Greenberg 1998]. Within that refractory carbon, a hydrocarbon fraction exists. That fraction could be reformed by CAVoR – with some syngas steps tbd – to boost methane output to the optimum 3.8 ratio.
In fact, given CAVoR’s baseline inputs of 15 wt% water and 5 wt% organics, CAVoR is actually oxygen-limited, producing methalox at a methane-heavy ratio of 1.45. Here the comet’s abundant water can make up the difference. Doubling the power draw of CAVoR’s electrolyzer boosts O2 output, to meet boosted CH4 output, at the optimum 3.8 ratio.
—————–
Looks to me that William Barton and I might both be right about carbon sources on the Moon.
Also this:
https://advances.sciencemag.org/content/6/19/eaba1050