For entrepreneurial companies looking to develop Vertical Take-off, Vertical Landing (VTVL) rockets, tethered testing can be a very important portion of the development and testing process. While certain test data is best collected or only available by actually putting a vehicle through the paces of a flight, rather than simply relying on simulations, flight testing expose the vehicles, its crew, and the general public to a much larger level of risk than a less complex test. Tethered testing offers a happy middle ground by allowing the vehicle to lift itself off the ground under its own power while still physically restraining it from moving too far or building up too much speed. Because of this, tethered tests have been incredibly important for teams competing for the Northrop Grumman Lunar Lander Challenge and their ilk throughout industry, with teams like Armadillo, Masten, and SpeedUp having already conducted many such tests.
For regulators, tethered flights have existed in sort of a nebulous gray area, somewhere in between ground-based engine firings and free-flying tests. The confusion largely stems from a clause in the relevant statute (49 U.S.C. § 70102) that defines the suborbital rockets that require licenses or permits as "vehicle[s], rocket-propelled in whole or in part, intended for flight on a suborbital trajectory, and the thrust of which is greater than its lift for the majority of the rocket-powered portion of its ascent." The definition of "launch" from the same section uses similar terminology, including the use of the word "intended." There has been an issue of confusion over what happens when a vehicle is being designed for eventual suborbital flight but is currently operating on a flight clearly not intended reach a suborbital trajectory. Given this confusion, tethered flights have gone relatively un-regulated.
As of this morning, that will change. Teams applying for or holding Experimental Permits from the FAA's Office of Commercial Space Transportation (FAA/AST) that would cover VTVL rockets or other rockets that might conduct tethered flights received a letter this morning from FAA-AST chief George Nield. The letter reads in part:
As a matter of law, the launch of a launch vehicle requires an FAA license or permit, or a waiver from the requirement for a license. 49 U.S.C. § 70104. The governing statute does not carve out any exceptions for a launch vehicle attached to a tether. Accordingly, unless a particular activity would not otherwise require authorization ... a tethered launch is still a launch requiring FAA authorization.In many ways, this was the response that many NewSpace advocates have feared. However, after a close read, and after discussion with representatives from FAA/AST, the situation is not as dire as it might seem.
We are willing to entertain requests for waivers from the requirement that a launch operator obtain a license or permit, consistent with public health and safety. [Emphasis mine]...
Because there has been understandable confusion surrounding this issue, the FAA will not pursue enforcement actions for past unauthorized tethered operations. We will also strive to respond promptly to waiver applications.
First of all, note the sentence I bolded in that block quote. As Dr. Nield indicates, FAA/AST is not going to require an experimental permit or launch licence for each tethered flight. Instead, teams may seek waivers governing their tethered tests. Additionally, FAA/AST has anticipated that this decision will cause some discontent among many entrepreneurial companies, and have positioned themselves to respond to the waiver requests mentioned in their letter with unprecedented rapidity. Lastly, I'm told by staff representatives that the FAA/AST staff are open to pursuing reasonable ways where waivers can be given for broad categories of tethered flights, rather than for an individual flight. With this combination of efforts from FAA/AST, the staff thinks that it can enforce these restrictions, which they feel are mandated by law, in a minimally invasive way.
After conversations with FAA/AST staff, I would say that this ruling is not based on any concerns with the methods used or the reasons given by teams for conducting tethered tests. Instead, this decision was made based on recommendations from the Office of the General Counsel for the FAA, which feels that the statutes as currently written do indeed call for this activity to be regulated. In the absence of an exemption written into the law, such as exists for amateur rocketry, or a regulatory rulemaking, FAA/AST has no choice other than to enforce the law as written by the Legislative branch.