The Launch Landscape: Small Rockets

Should clarify that Madsen was kicked out of Copenhagen Suborbitals years before he murdered someone.

I think there's room for both. Going on a $ per kg metric is drastically oversimplifying the other factors that go into launch vehicle selection.

SpaceX rideshare is great if you have a mission that you want to launch to a popular orbit or an orbit near enough to a popular one that you can close the gap with on-orbit propulsion. However, the cost savings come with disadvantages. You don't get to pick your launch date, and if you miss your launch, SpaceX isn't waiting for you. It could be a long time before the next rideshare that's going to the orbit you want is available.

If you want an oddball orbit, or you want the flexibility to set your own launch date and maybe delay it if you have program delays, the smallsat launchers could make a lot of sense even if they are 5-10x the cost on a per kilogram basis.

Space missions are really expensive, and it's not the launch that's the driver of that anymore - it's the engineering, customization, and other overhead involved with developing and operating a spacecraft. You can (and should) use off-the-shelf hardware such as a finished satellite bus from somebody like SSTL or Blue Canyon, but you still have to develop the concept of operations, requirements, payload, operations plan, operations infrastructure, and staff the operating team (which is often a 24/7 endeavour, or at least an 8/7 endeavour with on-call night staff).

To put it another way: if your total lifetime mission cost is going to be $50M-75M (not an unrealistic figure for a novel SmallSat mission) and you're looking at $1M for SpaceX versus $7M for RocketLab (to use the numbers from the article), the answer may not be immediately obvious. There may be serious advantages to a dedicated launch at the cost of growing the program budget by about 10%. It's totally situational.

Not really. Astra's (and the entire small-launch market's) niche is different than SpaceX's. The focus of small-launch vehicle companies is not cost-per-kg, it's cost-per-launch. The Ride-Share model for large launch vehicles works great, until launch flexibility, short lead times, and unique destination orbits become key customer objectives. Or to put it another way, SpaceX is like the US Postal Service. Small-launch vehicle companies are like FedEx. Small-launch vehicles are the couriers to space.

It's a great point that these small launch vehicles will never be able to compete with larger vehicles like Falcon 9 on cost/kg. It does seem to me that launch factors besides costs (such as those described by others on this thread) leave room for small rocket players. I think a big question is how many players can exist in that small, dedicated launch market. It's also exciting to see how some of the small launch companies are exploring ways to differentiate themselves to carve out their own protectable segment of the market.

Are you factoring in the weight/complexity of the life support system?

Most of the rockets listed are 2-stage rockets. The first stage never makes it to orbit - it just falls back down to earth after dropping off the second stage.

The second stage often does make it to orbit, where it deploys the payload and then usually becomes orbital debris. A few upper stages (falcon 9, for example) do a small engine burn to reenter the atmosphere where they burn up.

Collecting upper stages would be... hard. Every rocket is on a different trajectory. Making some vessel that could 'collect' them would have to visit every launch trajectory that they'd each taken, which is a lot of orbital maneuvering and coordination. Then the problem of docking and collecting the stages and packaging them for reentry would be a whole series of ridiculously tough engineering challenges.

The upper stage is much smaller than the first stage, so it's usually significantly cheaper than the first stage.

Basically, recovery of the upper stage is much harder than recovery of the first stage and has less upside.

There's actually a well-funded, VC backed startup pursuing this very strategy if you're interested in checking them out! https://techcrunch.com/2020/01/16/spinlaunch-spins-up-a-35m-...

Almost all the energy/velocity needed for orbiting is "sideways" to the earth. Imagine needed to throw a baseball fast enough that it goes fast enough that the barely visible curve of earth falling away the same as the dropping of the baseball from gravity.

The ISS moves around the Earth at approximatle 28,800 kilometers per hour (17,900 mph).

For comparison, a bullet fired in a vacuum at only 2,000 kilometers per hour will reach about 15km up, or a reasonable ballon launch height.

Using a simple back of the envelope calculation on energy requirements can tell you why. A 500km orbital altitude requires about 7.66 km/s of velocity. That's 29,337 kJ of kinetic energy per kilogram, and only 4,905 kJ per kilogram of potential energy. You don't perform an air-launch to for the potential energy savings: you do it for the reduced air-loads and energy loss due to drag from beginning your trajectory in a thinner atmosphere. This trade-off is almost never worth the added engineering complexity, as seen by vertical launch completely dominating the launch space compared to air-launch.

As for a balloon launch, well, balloons have absolutely dismal maximum payloads, so there's no way you're going to be able to hoist a vehicle with enough propellant to reach upwards of 7 km/s underneath a balloon.

This is a concept known as a rockoon[0]. Unfortunately high altitude balloons become really big really quickly, and even if you were starting at orbital altitude you would still need a decent sized rocket to reach orbital velocity.

[0] https://en.wikipedia.org/wiki/Rockoon

It's a fair point! It's very challenging for many of the reasons already pointed out. I'll just add that a couple organizations have actually tried but haven't yet had success doing so: https://spacenews.com/small-launch-startup-leo-aerospace-sus...

There's actually a small Spanish company, Zero 2 Infinity, pursuing that seriously for small satellite launch and I was sort of surprised not to see them mentioned in the article. As other replies mention, you don't save much in terms of overall energy by launching form higher up. However, there are three big pluses to launching from high up in the atmosphere.

First, rocket engines are more efficient when they run in a vacuum than when they run at sea level. With SpaceX's Merlin rockets one running at sea level has an ISP of 282 but a vacuum optimized Merlin running in space has an ISP of 348 giving it almost a quarter more impulse for the same fuel expenditure.

Second, you don't waste fuel fighting drag as you work your way up through the atmosphere. That can easily be 100s of m/s of delta-v wasted.

Finally, launching higher up means saving weight on the rocket structures. You can make your rocket more nearly spherical and save weight on tank area. You can use a lighter tank structure since air resistance forces aren't an issue. And you can light your stages in parallel rather than series because they don't have to be stacked on top of each other or be optimized for different pressures.

https://www.zero2infinity.space/

On earth, about 30 feet in length due to the atmosphere, although I will admit I don't have a firm intuition for why this is the case.

[1] https://www.airspacemag.com/space/the-one-pound-problem-7188...

There isn't really a theoretical minimum size, but with the best chemical propulsion possible you're going to have an initial to final mass ratio of about 5. Now that final mass needs to include the structure of the vehicle, so you can cheat a little bit with staging but you can't make it go to zero.

In practice, the smallest orbital launch vehicle ever launched required 2600 kg to launch a 4 kg payload. Turns out that the smaller a rocket is, the less mass efficient it gets.