Spaceflight is entering a new era of civilian space tourism, commercial spacecraft, and missions to return to the Moon. However, most of today’s launches do not include capabilities for in-space rescue. Much like the early days of U.S. Navy submarines, where there were no options for rescuing survivors trapped in sunken ships, there are limited options for the rescue of distressed spacecraft in low Earth orbit.
History can provide some answers. The Apollo 13 lunar module was adapted to sustain its crew on the journey back to Earth after an oxygen tank exploded. SkyLab missions and the final space shuttle mission servicing the Hubble Space Telescope traveled with rescue rockets and spacecraft. However, a reliable method of modern in-space rescue has yet to be adopted.
According to Grant Cates, Aerospace Senior Project Leader, the best time to plan for an in-space rescue is before the need arises. We caught up with Cates to explain more about what can be done now to mitigate risk and discuss the needs of this new era of space travel.
What exactly is in-space rescue?
In-space rescue refers to rescuing astronauts from a disabled spacecraft in space, analogous to rescuing sailors from a sunken submarine. Only after tragic accidents were submarine rescue capabilities developed. The hope is to have in-space rescue capabilities in place before we need them.
Why did you start investigating the issue of in-space rescue?
The Columbia Accident Investigation Board report described how the tragic outcome of the Space Shuttle Columbia could have been avoided had officials recognized the shuttle’s thermal protection system was compromised. During launch, a large piece of insulation broke loose from the External Tank and struck the leading edge of Columbia’s wing. In an in-space rescue scenario, the next shuttle planned for launch, Atlantis, could have been adapted for a rescue mission. It would have been challenging — as it would have required conservation of resources and spacewalks between the two vehicles — but feasible.
After the loss of Columbia, I began working on in-space rescue scenarios for future space shuttle missions. NASA established a policy of designating the next shuttle planned for launch as a rescue vehicle and needed to ensure the shuttle could be launched in a timely fashion. My job was to develop the probability assessment of rescue capability for each mission.
What are some of the gaps for in-space rescue capability currently?
Currently, in-space rescue plans and capabilities are not in place prior to launching crewed missions. For example, the Inspiration4 mission did not have a docking mechanism. If a problem arises, a docking mechanism can provide a method for conducting a rescue.
That gap could be closed by requiring all crewed spacecraft have a docking mechanism, preferably one compatible with all other spacecraft. Another challenge to consider is having the capacity to launch a rescue craft in a timely fashion. In the instance of Inspiration4, the Falcon 9 Crew-3 mission timeline could potentially have been accelerated for use as a rescue.
What are some near-term solutions for crewed launches?
The near-term solutions require two fundamental actions to be taken. The first is to ensure crewed spacecraft have docking mechanisms. Eleven years ago, the partner nations of the International Space Station (ISS) adopted the International Docking System Standard (IDSS). Any spacecraft with an IDSS compliant docking mechanism can dock with any other like-equipped craft. Installation of IDSS compliant docking systems on spacecraft will help to close the existing gap.
The second action required is to develop and implement plans for launching timely rescue missions. This requires an available rocket, rescue vehicle, launch complex, and personnel to conduct a launch campaign successfully within days from call-up. The most expedient option would be to ensure when a crewed spacecraft is launched, there is another spacecraft and rocket available to launch within the rescue timeframe.
What are some ideas you’d like to see explored for future development?
To help make in-space rescue practical, it will be important that future crewed spacecraft have the capacity to support the crew and passengers for additional time in the event of contingencies.
In addition to launch capabilities, we could explore how to utilize assets already in space. The ISS could serve as a safe haven for distressed spacecraft. Alternatively, space rescue vehicles could be stationed at the ISS and deployed in the event of a distressed spacecraft. The ISS could serve the function of an orbiting rescue station in space.
Another idea is to revisit the lessons from Apollo 13. That mission demonstrated the life-saving power of having two ships capable of sustaining the crew. Future missions going beyond low Earth orbit should consider the value of redundant capabilities in deep space.
How would a rescue launch-on-demand system operate, and who would be responsible for coordination?
Either a legislative mandate or governmental regulation for launch-on-need rescue capabilities for crewed spacecraft in orbit would most likely be necessary. Alternatively, private industry could unilaterally decide to develop launch-on-need rescue for crewed missions as a safety enhancement.
Responsibility for coordination begins with the operator of the distressed spacecraft, making the rescue need known. This information would then be relayed to the rescue organization. Both NASA and the U.S. Space Force have space launch capabilities, both develop and operate spacecraft, and both have the ability to develop and employ space rescue capabilities given the mandate and adequate funding. The Space Force is already responsible for rescuing NASA and commercial astronauts on land and at sea if a crewed launch aborts during ascent or if the crew comes down somewhere other than the planned landing/splashdown zone at the end of the mission.
Extending the Space Force rescue responsibilities into space could be synergistic with its desire for responsive space capabilities that enable replacement of failed satellites in orbit, reconstitute space capabilities in an adversarial situation, establish national emergency capabilities or respond to an emerging international threat. The same rocket needed for crew rescue could be outfitted with ready spacecraft and launched on-need to support these missions as well.
We have partnerships with other spacefaring nations. How might international collaboration be used to solve this in the future?
There are presently three nations that have the capability to launch humans to space — China, Russia, and the United States. Other nations will likely develop spacefaring capabilities in the near future. Use of the International Docking System Standard for crewed and cargo spacecraft will facilitate future rescue capabilities with interoperable docking capabilities.
The Outer Space Treaty states that nations must come to the aid of astronauts in distress. What the treaty does not do is compel nations to develop rescue capabilities. Spacefaring nations could pool resources to ensure rescue capabilities are developed and ready for any eventual emergency.
Grant R. Cates is a senior project leader for The Aerospace Corporation’s Space Architecture Department, providing discrete event simulation-based analyses to NASA, the U.S. Space Force, and others. He is the author of the newly released Aerospace Center for Space Policy and Strategy paper The In-Space Rescue Capability Gap.