Saturday, October 14, 2017

The BFR and its role in SpaceX's satellite Internet service

Elon Musk is CEO and Lead Designer at SpaceX.

SpaceX started with their Falcon 1 booster followed by several versions of the Falcon 9. The Falcon Heavy will fly later this year and the rocket that will take the first person to Mars is called, for now, the Big F***ing Rocket or BFR.

The Falcon1, Falcon 9, Falcon heavy and the BFR (source)

The 150-ton BFR payload will be 10 times that of the Falcon 9. It will have an have an extra landing-guidance engine for reliable reusability and SpaceX also expects to be able to soft-land and reuse the second-stage payload rocket as well as its protective nose cone, substantially reducing cost per launch. (Note that Boeing is also planning a Mars mission so they may be planning their own BFR).

The following is speculation, but I think the BFR will play a significant role the SpaceX satellite Internet service.

SpaceX applied to launch their 4,425 satellites in two phases -- an initial deployment of 1,600 satellites and a final deployment of 2,825. That is a lot of satellites and the FCC has required licensees to deploy their full constellations within six years of their grant, but last month they relaxed that constraint, establishing milestones of launching 50% of a constellation within six years and allowing another three years to complete the constellation. The FCC has delayed licensing SpaceX's plan until spectrum sharing agreements are reached by satellite operators, so the clock has not yet started running on their six and nine-year milestones.

SpaceX plans to send a BFR to Mars in December 2022, and they won't give me any details, but they will surely be used "locally" before that. They plan to begin launching operating Internet satellites in 2019 and those will be launched by Falcon 9 or Falcon Heavy rockets, but the BFR should be available to launch many of the planned 4,425 satellites before the FCC deadline and it will be used for replacement satellites when they are eventually required.

SpaceX estimates the satellite mass as 386 kg and the BFR can carry a 150-ton payload so, if they fit perfectly, a BFR could launch about 350 satellites at a time, but they won't fit perfectly, so let's say 300 per launch. SpaceX Senior Director Tom Ochinero says they will be capable of up to six launches per month. Using the BFR, 4,425 satellites in nine years sounds feasible and relatively cheap. (Elon Musk has estimated that future versions of the BFR may carry up to 1,000 tons).

The BFR may also play a role in debris mitigation. When they are taken out of operation, satellites are de-orbited and they burn up in the atmosphere, but there is some risk of debris hitting the Earth. Bloomberg reported that the FCC had challenged SpaceX's assessment of risk of human casualty from falling debris and SpaceX responded the following month. Recently two Senators have also asked the FCC to investigate the risk of collisions and debris.

The BFR may render the debate moot. In a recent presentation, Elon Musk speculated that the BFR might be used to capture orbiting satellites and return them to Earth, as illustrated here:

SpaceX hopes to recapture satellites in the future (source)

I will conclude with the following image that illustrates how the BFR got its name -- it is a BFR. If you are interested in the BFR and its role in Elon Musk's plan to colonize Mars, you should definitely read the post this illustration is taken from.


Still not sure how big it is? Check out this view of a BFR in Boston:


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Update 10/20/2017

In a talk at the 2017 International Astronautical Congress in Australia last month, Elon Musk summarized SpaceX's technology progress, including 18 successful booster landings, and described the BFR design and economics and its applications -- launching satellites, shuttling to the International Space Station and travel to the Moon, Mars and between distant cities on Earth. It is a terrific talk, well worth watching:



On October 15, Musk followed up his talk with an “Ask Me Anything" (AMA) discussion about the BFR on Reddit. You can read a good summary of the AMA discussion, which includes video excerpts from the IAC talk and a concept video on terrestrial travel here. if you have time on your hands to geek out, you can see the entire AMA session here.

Last, but not least, SpaceX has posted a terrific 39-slide presentation on the project. It's a "Steve Jobs" kind of presentation -- long on images illustrating a concept and short on words. (I'm a big fan of that presentation style and try to force it on my beleaguered students). The presentation also includes links to a couple of animations and a video illustrating a hypothetical terrestrial travel scenario. Here are four of the slides to whet your appetite: