Another question.. if you are building a radio telescope in space, could you just use a thin foil that folds out like origami for the reflector?
If the BFR (the rocket behind the starship) is successful then yes it could mean the ability to launch very large telescopes in to space. The scientific community would be very exited about this possibility. However, this doesn't necessarily make it very low cost. One launch of the BFR would still likely be much more than an a Falcon Heavy launch.
> if you are building a radio telescope in space, could you just use a thin foil that folds out like origami for the reflector?
Yes! This technology already exists and it is really pretty amazing to see in action. Right now most of them are used on communications satellites or for synthetic aperture radar satellites. See the videos below:
Animation of the radar antenna on SMAP:
https://smap.jpl.nasa.gov/resources/83/smap-antenna-deployme...
Actual video of a large communcations antenna (12m diameter) being deployed. Skip ahead to ~2:15 for the actual unfurling.
https://www.youtube.com/watch?v=_mFnNDzxKFk&feature=emb_titl...
BFR isn't a name that's still in use. Poster you're responding to was correct in calling it Starship: "SpaceX's Starship spacecraft and Super Heavy rocket (collectively referred to as Starship)" (from https://www.spacex.com/starship).
Starship projects to be significantly less expensive than Falcon Heavy _or_ Falcon 9. With total reusability of both stages and a construction built toward little to no refurbish or rehab, the cost per launch is nearly completely dictated (order of magnitude) by fuel costs, and project to be ~$2 million. This is an order of magnitude reduction in $/kg over the Falcon 9.
https://www.space.com/spacex-starship-flight-passenger-cost-...
As a side note, I don't really believe the $2 million price tag either based on my own experiences. Mission specific planning/services/verification tend to push prices of launches 10s of millions of dollars above the "sticker prices" that SpaceX puts on their website.
Nothing against SpaceX, I am a fan of everything they have done to decrease launch costs. They have significantly changed the game in terms of lowering launch costs. But it is really hard to take Elon's wild numbers that he gives the press at face value.
[1] https://www.theverge.com/2018/9/18/17873332/spacex-elon-musk...
What really needs to happen is the ability to build mirrors in LEO so they don't have to be built to survive the launch.