Henry Spencer opened with the observation that many people start with plans for sub-orbital. But lots of people really want to get into orbit. There are several issues going from sub-orbital to orbital.
Henry trotted out some old slides. He made the point that it isn't just altitude, but velocity that you need to stay in orbit. To get into sub-orbital you need about as much fuel in mass as payload. To get into a real orbit, the ratio is closer to twenty to one, you need 19 kilograms of fuel for every kilogram of payload.
The sub-orbital market is a hundred kilometers up to five hundred kilometers. You get a better view as you go higher. People will want to the better view, but the higher you go, the rougher the re-entry is. One of the early Mercury (?) rockets went up to 14 G's, few customers will want that kind of hardship.
Long term there will be a market for inter-continental flights, to quickly get to another continent. They'll want to fly out of airports, like LAX. The ballistic flights will need to run on schedule. There is also a problem with sonic boom at take off, and re-entry.
Henry's conclusion is that a ballistic market is not a short term market.
Going to orbit
There are several benefits to launching from sub-orbital rocket. The vehicle going to orbit will have to be small. There is a market for nano-satellites, about 10 cm on each side. Most of these are solar power radios, it is hard to do much else useful. Once you get up to a cube 20 cm on a side, and can have 6 to 8 kilograms, you have many more options.
When you piggyback on a large launch, the price is in the tens of thousands of dollars. One problem with piggybacking is you have to wait until the primary load is ready. Several people commented that they had had to wait any where from a couple months to four years. You are also at the mercy of going where the primary load goes. There will be something of a market for nano-satellites.
It would be really nice to get people into orbit. The minimum package is two people and about hundred pounds. It makes sense to have one person who knows how to pilot the rocketship. Most people aren't going to want to spend a year learning which buttons to push and what to do in emergencies.
Henry talked about having one vehicle to get up to 50,000 feet and then launching a smaller craft to climb to orbit. He discussed some suggestions people have for the first stage, and reviewed some problems.
In orbit you are at least an hour away from the ground, as opposed to sub-orbital which can get you on the ground in minutes. So to be in orbit you need life support and power. If you want to land at specific places, you will need more time. Communication can be a problem, you'll need to have some kind of radio. He listed a few other issues.
The American space program has push for escape systems, but haven't really used them.
Henry says that to have reliable reusable crafts will need well trained personal. There are problems with flying in different conditions, like different weather.
In addition to various technical problems, there are things like getting credibility with investors, and dealing with regulatory organizations.
By the end of his talk there were about 80 people in the room.
The full agenda
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