Simulation a Key Element for Safety in Space, the Riskiest Environment

With the formation of the United States Space Force and the majority of NASA astronauts still having a military background, MS&T’s Chuck Weirauch reports on the use of simulation in space operations and why it remains key to success.

When the Artemis Program’s lunar lander touches down on the Moon’s South Pole in 2024, its four-person crew will have performed that maneuver perhaps hundreds of times before in a simulated lander. It will be yet another example of how simulators and simulations have become a critical element of a safety management system that has been designed to ensure the success and welfare of what is mankind’s riskiest endeavor, human spaceflight. In fact, every component of the Artemis Program will have been designed, developed, and tested with modeling and simulation technology, as well its every aspect of its mission.

To the Moon and ISS

Several aerospace companies are under contract with NASA under its Commercial Crew Program to develop manned, or what are now referred to as crewed space vehicles, to both the Moon and the International Space Station (ISS). These same and other space launch companies are also developing commercial suborbital launch vehicles for research and tourism. This unprecedented growth of the space flight industry depends more on simulators and simulation to be the key factors in the success and safety of the now-burgeoning space industry than ever before.

Sim-Based Crew Training

Historically, NASA has required hundreds of training hours in high-fidelity simulators for each of its astronauts on space flight missions, and that tradition has continued through the Space Shuttle, Artemis, SpaceX, and Boeing Starliner Programs. Each crewman in the Mercury, Gemini, and Apollo programs spent one-third or more of his total training time in simulators, and Apollo lunar landing crews used simulators during more than half of their training program. The first 13 NASA astronaut candidates for ISS, Moon and Mars missions graduated from their two-year-long initial training program in January. The first of those astronauts flying on ISS missions have completed their training for SpaceX missions in part with SpaceX part-task, full-scale spacecraft and ISS entry and egress training simulators.

Mercury simulator. Image credit: NASA.

Becoming an Astronaut

While simulation-based training is a large part of NASA’s astronaut training program, the space agency requires a strong background in the sciences and/or engineering before anyone can apply to become an astronaut candidate, as well as being in top physical condition. All basic astronaut training is conducted at Johnson Space Center in Houston, TX. Once accepted, the candidate must successfully complete a rigorous two-year basic training program before being selected as an astronaut and assigned to specialized training programs, such as those for the Artemis or ISS program. Those programs can require up to two more years, and then continue to specific training for each spaceflight mission to which they are assigned.

International astronauts train with NASA astronauts for specific missions. In December, the Canadian Space Agency (CSA) announced that a Canadian astronaut will fly on the Artemis 2 mission around the Moon now scheduled for 2023.

During astronaut basic training, astronaut candidates, known as ASCANS, will need to master a wide variety of survival skills, including SCUBA training, as well as technical knowledge. Since SpaceX Crew Dragon to the ISS and Artemis missions include a return landing in an ocean, astronauts must practice in a large pool known as the Neutral Buoyancy Laboratory located at Johnson Space Center. Since buoyancy in water can simulate microgravity conditions in space, mission rehearsals are also conducted in the pool.

A recent addition to the astronaut training program is the Virtual Reality Simulator Facility (VRSF), where they wear virtual reality headsets while suspended to simulate microgravity conditions. There, they practice extravehicular activities such as spacewalks and spacecraft robotic arm manipulation.

Most Astronauts Military

Early in the US space program, only those with a military background could be considered for basic astronaut corps training. That policy changed with the Space Shuttle program, when the Mission Specialist category was created, allowing civilian scientists and educators to fly in space on Shuttle missions. Still, as of 2016, there were more current and former astronauts with a military background than civilians, 219 out of the total of 330. Every military branch has been represented, although most have served in the Air Force and Navy. The current astronaut list includes three active-duty Army officers. A January 2020 list of 18 new Artemis Team astronauts includes 10 active-duty armed services personnel, nine men and nine women. Currently there are 48 active members of NASA’s Astronaut Corps.

In November, Air Force astronaut Col. Michael “Hopper” Hopkins transferred from NASA to become the newly-created Space Forces’ first astronaut. The Space Force was stood up in December 2019. Whether the new service itself will have its own separate-from-NASA Space Force Astronaut Corps is still under debate. According to Space Force commanders quoted in a recent Air Force Magazine article, it will be decades before such an entity is formed, if ever.

Largest Flight Sim

The Vertical Motion Simulator (VMS) is considered to be the world’s largest motion flight simulator. As such, it is a key research tool for NASA’s Human Landing System (HLS) Program. The HLS is responsible for the design and development of the Artemis lunar lander. In April 2020, NASA selected three companies to design and develop the Artemis HLS (lunar lander). They are Blue Origin, Dynetics, and SpaceX.

The VMS was originally designed to support research in the development of new, experimental aircraft concepts, most recently for NASA’s X-59 Quiet Supersonic Technology aircraft. It also has been employed to model earlier lunar lander concepts such as the Altair, and vehicle docking maneuvers with the International Space Station (ISS). The VMS is housed in a ten-story tower complex at the space agency’s SimLabs division in Ames Research Center at Moffett Field in California.

The three companies contracted by NASA for the lunar lander will test their lander prototypes’ handling capabilities in the VMS for not only lunar landing, but orbital docking and atmospheric entry maneuvers as well. In the VMS, each of their “cabs” will be individually attached to the VMS base, which provides a six-degree-of-motion capability. Once a company’s lander has been selected and final testing has been completed, the Artemis astronauts will employ that lander for simulated lunar landings and other maneuvers many times well before the actual launch of the space vehicle.

Currently, a mock-up of Blue Origin’s Artemis lunar lander is undergoing testing at NASA’s Johnson Space Center in Houston, TX.

Artemis Program

But the lander is just one component of the entire Artemis Program’s Space Launch System (SLS), which is the next-generation successor to the 1960’s-era Apollo program. Boeing is the prime SLS contractor. The 322-foot-high heavy-lift SLS, the successor to the Apollo Saturn three-stage rocket launcher, is composed of two solid-rocket boosters strapped to a liquid-fueled core stage with four RS-25 engines that will launch the Orion spacecraft and its Service Module on its mission around the Moon and back during the first two autonomous uncrewed missions, Artemis I and Artemis II.

For each uncrewed and crewed mission, the SLS will produce 8.8 million pounds of thrust when it lifts off from Kennedy Space Center’s Launch Pad 39B, 15 percent more than that generated by the Saturn V Moon launch vehicle. Lockheed Martin is the prime contractor for the Orion spacecraft.

First Artemis Missions

The uncrewed 21-day Artemis 1 mission around the Moon and back is now scheduled for launch in mid-2021, while the Artemis II mission is planned for 2023. The first crewed, lunar landing Artemis III mission with the HLS is now envisioned to take place in 2024. Also planned for Artemis 3 or a later mission is the delivery of a Gateway Moon orbital space station that will also serve as a docking system and mid-point for future missions to the Moon and Mars. The Artemis system is also designed to send a crew to Mars in the mid-2030s, but a larger crew habitation module must be incorporated into the SLS for the much-longer missions to Mars.

The Artemis system will be the first space vehicle to deliver humans to Mars. That is, unless SpaceX’s Elon Musk makes good on his promise to launch his crewed Starship rocket to the Red Planet within the next four to six years, as he claimed recently. A high-altitude launch and test of the Starship to 50,000 feet altitude was scheduled for the first week in December.

All SLS components have been designed and developed through the extensive use of computer modeling and simulation technology for design, development and engineering testing and checkout. Artemis astronauts are already training for missions through the use of full-scale simulators.

And of course, all Artemis components will undergo testing that includes simulated launches before and after they are mated together at Kennedy Space Center to verify their operation. For example, the solid rocket boosters have already gone through both simulated and live-firings, while the 212-foot-tall SLS liquid-fueled core stage completed its successful Artemis 1 simulated launch countdown sequence on October 5.

Artist's concept of the Artemis Base Camp. Image credit: NASA.

SpaceX, Boeing ISS Missions

The SLS is currently the only NASA launch vehicle planned for a crewed mission to the Moon under the space agency’s Commercial Crew Program, while Boeing and SpaceX have developed launch vehicles and systems to deliver crews to the ISS under that effort. The two aerospace companies do have plans for their spacecraft to journey to the Moon in the future, however. The first US human return-to flight mission took place May 30, with the SpaceX Falcon 9 rocket propelling the company’s Crew Dragon spacecraft and two crew members to a docking with the International Space Station (ISS) nineteen hours later. The Falcon 9 has also propelled Cargo Dragon spacecraft to the ISS 21 times as of December.

The second SpaceX mission to the ISS, carrying a full complement of four astronauts aboard the Crew Dragon spacecraft, lifted off from Kennedy Space Center’s Launch Pad 39A on November 15. Boeing’s Crew Space Transportation (CST)-100 Starliner, another space launch system contracted through the Commercial Crew Program, is scheduled to launch a four-person crew to the International Space Station in 2021.

Simulators New

Just as in the earlier Mercury, Gemini, Apollo and Space Shuttle manned spaceflight programs, Artemis, SpaceX and Boeing spacecraft flight crew training programs feature part-task and full-scale spacecraft mission training devices. Two full-scale Orion spacecraft replicas have been built, one a low-fidelity mockup for engineering and initial testing, and the other a high-fidelity simulator for further testing and crew training. Both feature a docking system and a hatch that will allow crews to practice egress into the lunar lander. In addition to training for their routine mission operations, the Orion mission crew astronauts have practiced launch and launch abort procedures aboard the high-fidelity spacecraft simulator, as well as with Orion part-task trainers, for example.

SpaceX

The SpaceX Crew Dragon spacecraft is much more automated than previous manned spacecraft, and is designed to fly to the ISS autonomously, just like the company’s unmanned Cargo Dragon that has successfully completed 21 supply missions to the space station. Nonetheless, the NASA astronaut flight crew must be trained to fly manually in case of emergencies and docking maneuvers.

To do so, SpaceX utilizes a full-scale replica of the Crew Dragon capsule that features all the hardware, software, controls and instrumentation found in the actual spacecraft. Instead of the hundreds of control switches and instruments found in the earlier spacecraft, the Crew Dragon employs just a few touchscreens and buttons to control all aspects of its flight in space. Other training devices include a crew part-task trainer and an ingress/egress trainer that shows astronauts how to enter the Crew Dragon and enter into the ISS, complete with a spacecraft/ISS hatch.

If you care to find out just how difficult it would be to manually dock the Crew Dragon with the ISS, SpaceX has provided an online web-based simulator for you to test your skills, and have you better understand just how much training you would need to perform this maneuver. You can find the simulator at https://iss-sim.spacex.com. This is an exact duplicate of the crew interface that you would find on a Crew Dragon display screen to complete this task.

Boeing Starliner

The Boeing Starliner program is now conducting its mission training at NASA’s Johnson Space Center in Houston, Tx. The core of the training is focused on two part-task trainers and the full-scale Boeing Mission Simulator, which replicates a full-size Starliner spacecraft. Boeing has also developed a prototype part-task trainer that employs a virtual reality (VR) headset, where the user can view a high-resolution image of the entire spacecraft cockpit and operate all of its replicated controls. The photo-realistic headset visuals are provided by Finland-based Varjo.

The part-task trainers enable Starliner astronauts to practice individual elements of their mission duties in a more classroom-like environment. The mission simulator enables the flight crew to train together for a mission. When wired into the extensive Boeing and NASA networks, all Starliner simulators will interact with launch and mission controllers to run rehearsals that are critical to preparing a crew to successfully fly a mission.