There are essentially three areas in the world where clusters of private companies have started to develop small launch vehicles.

The first such cluster emerged in the United States nearly two decades ago with SpaceX, which was then followed by Rocket Lab and about a dozen other serious companies. Next came China, with a profusion of quasi-private companies leveraging technology from the country's state-owned launch enterprises with private funding. The final region that has emerged in the last five years is in Europe.

This European small launcher race has essentially followed a US model, with venture capital and investors backing a number of privately led efforts to develop commercially viable small satellite launchers. Much of this activity has been clustered in Germany and Great Britain, but Spanish and French companies are also in play.

Because none of the dozen or so European companies have actually attempted an orbital launch attempt yet, it can be difficult to tell who is making real progress and who is not. Many, if not most, will probably never reach orbit. However, one of the best barometers of a company's health and legitimacy is the funding it has been able to secure.

Germany's Isar Aerospace has been a clear leader in this area. Prior to this week, the Munich-based company had raised about $165 million, a reasonable amount of cash for a launch startup building a small rocket. On Tuesday, Isar announced that it had doubled this total with a $165 million Series C round.

"The strong interest and commitment from our international investors signals their confidence in our vision and technological capabilities," said Isar's chief executive, Daniel Metzler, in a statement. "Today, and even more so tomorrow, space technologies are key to enabling innovation, technology, and security."

As a very general rule with launch startups, companies that have raised about $100 million in funding should be taken seriously. When a company raises $250 million or more, it is on a viable path toward building a vehicle that will one day reach orbit.

Isar says that its Spectrum rocket—which is capable of lifting about 1 metric ton to low-Earth orbit—is planning for a debut launch from Andøya, Norway, during the second half of 2023. That timeline is probably aspirational, but given the capital raise announced this week, Isar appears to have the funding needed to get its Spectrum vehicle into orbit.

This is an interesting time for commercial space in Europe. A single, large legacy company, Arianespace, has dominated launch for decades. It has received billions of dollars in government funding and guaranteed launch contracts from member nations of Europe. However, as the commercial sector in the United States, led by SpaceX, has eroded Arianespace's commercial business, the continent has started to embrace a new approach.

Were a company like Isar Aerospace to succeed in launching its Spectrum rocket, it might go a long way to breaking the monopoly Arianespace has had on government contracts.