The man who broke the space walk record
We speak to the man who performed humanity’s furthest free flying space walk.
Bruce McCandless II was born 8 June 1937 in Boston, Massachusetts. He was selected amongst 19 astronauts by NASA in 1966 and served on two Space Shuttle flights, STS-41-B in 1984 and STS-31 in 1990. On the former of the two he performed the first untethered space walk (pictured above) using a propulsion system known as the Manned Maneuvering Unit (MMU), and on the latter he helped deploy the Hubble Space Telescope.
All About Space: How did it feel to work at NASA in the 1960s and 70s?
Bruce McCandless: The ‘60’s and ‘70’s were indeed exciting times within NASA. We were strongly mission oriented and committed to overcoming obstacles as they arose. The “Apollo 1” fire was a tragedy of epic proportions, but was investigated and dispositioned within NASA, leading to a reinforced focus upon safety. Once we got the manned Apollo missions flying, starting with Apollo 7, progress was fast and furious. Each mission was different, significant, challenging, and flown on two-month intervals. This required a great variety of intense mission-specific training and development. Once Apollo 11 was successful in landing on the moon and returning safely to Earth, one of the first things that management did was to slip the Apollo 12 mission by two months and give everyone some much-needed time off!
AAS: Would you have liked to have flown on one of the Apollo lunar missions?
BC: Yes, of course I would like to have flown on one of the lunar missions. Shortly after my [astronaut] group (Group 5, aka “The Original Nineteen”) reported to the then Manned Spacecraft Center, we met with NASA Administrator James Webb. He told us that “The Plan” for the lunar program was to fly four Saturn I’s and two Saturn V’s per year for the foreseeable future. As the youngest member of my group, I envisioned being assigned to one of the later Apollo missions, believed to run through Apollo 20 – at least. When the program was truncated at Apollo 17, I was certainly not the only surprised and disappointed astronaut. Even without flying on a mission, my time in support roles in Apollo was both rewarding and fascinating – never a dull moment!
AAS: When did you find out you would be testing the Manned Maneuvering Unit (MMU) on STS-41-B?
BC: In early 1983 I was called into the office of the Director of Flight Crew Operations and offered a choice: a) continue in training as a prospective Shuttle Pilot, anticipating an assignment in that capacity “some day”, or b) fly on STS 41-B in about a year as a mission specialist in charge of flight testing the MMU. I considered that an easy choice and opted for the specific MMU flight test assignment, which would not preclude later assignment as a pilot, should appropriate circumstances arise. Note that prior to the Shuttle era any crewmember could perform an EVA (Extra Vehicular Activity), and frequently did. Once in the Shuttle era, however, it was decreed that the commander and pilot were “indispensable” to the safe return of the vehicle, and consequently could not be risked on a sortie into vacuum [space].
AAS: Were you nervous about using the MMU?
BC: No, I was not nervous. Rather, I was elated to have finally successfully woven my way through the mysterious and fog-shrouded labyrinth of landing a flight assignment. By virtue of my involvement in the development activities associated with the SKYLAB M-509 Astronaut Maneuvering Research Vehicle and with the Shuttle MMU, I was, if anything, “over-trained.”
AAS: How did it feel when you began your untethered space walk outside the Space Shuttle?
BC: My general feeling was one of relief – relief that all of the preliminaries (competing for assignment to the flight, training, earlier mission activities, etc.) had finally been completed – and that I was at last poised to actually fly the MMU. Drawing upon my role as CAPCOM (Capsule Communicator) during the Apollo 11 “First Walk on the Moon,” I had crafted my “first words” as follows: “That may have been ‘one small step’ for Neil, but it’s a heck of a big leap for me!” This was intended to break the tension within Mission Control, and I am reliably informed that it did so. That I was able to remember and utter such words was a testimonial to my relaxed, anticipative state of mind.
AAS: What checks on the MMU did you have to perform?
BC: The actual MMU checks were rather minimal. I did verify that the electrical systems appeared to be working normally, and my EVA-partner, Bob Stewart, held a hand in front of each thruster, one by one, to verify that it operated when commanded. After that I did some single-axis maneuvers (e.g. somersault, roll) within the confines of the [Shuttle’s] Payload Bay to verify controllability and to relieve physiological concerns that such maneuvers might be vertigo inducing. After that I was free to maneuver to ever increasing distances from the Shuttle, and did so.
AAS: What was it like to use the MMU?
BC: The feeling was a combination of professional satisfaction in showing that all the efforts put into the MMU had culminated in a “nice flying machine” and personal elation in being able to totally disregard gravity – at least for a while. This was early in the Shuttle Program (10th flight) and we were still “working the bugs out” of numerous Shuttle-related systems, so having developed (along with C. Edward Whitsett and the Martin Marietta Aerospace Group) and demonstrated one that worked as advertised from the very first use was something of which we could be, and were, very proud.
AAS: Would you say being so far from the Space Shuttle was more fascinating than frightening?
BC: Flying out to a distance of 100 meters from the Shuttle was indeed fascinating and yielded a spectacular viewpoint. Alas, I had intended to yaw around 180 degrees, to face away from the Shuttle, to contemplate the beauty and emptiness of a space devoid of apparent man-made objects, but there was so much conversation over the three radio channels (Mission Control, the Commander, and Bob Stewart) that I forgot to do so. Unexpectedly, I got very cold while maneuvering at a distance from the Shuttle. On considering the problem it became apparent that the life support system was designed to maintain the comfort of a person working at a moderate level of physical exertion – and I was using only my fingertips on the controllers. Briefly shutting off the heat rejection subsystem (sublimator) solved that problem. Post-flight, the Flight Surgeon from Mission Control noted that my heart rate (as displayed on telemetry) was normal and constant throughout the EVA, confirming my feelings of being relaxed and in-control at all times.
AAS: Were you worried the MMU would malfunction? What would’ve happened if it had stopped working?
BC: No, all systems on the MMU were redundant; that is, there were two of everything – two batteries, two tanks of nitrogen propellant, two independent sets of thrusters, two sets of electronics, etc. In the event of any single failure, I could have identified it, isolated it, and returned to the Shuttle using the remaining capabilities of the MMU. In the (highly unlikely) event of a near-simultaneous disabling double failure, I had the capability of manually shutting off all propellant flow at the tank valves and waiting for the Shuttle to come and “scoop me up” up in the Payload Bay. The STS 41-B Commander, Vance D. Brand, had in fact trained in the Shuttle Mission Simulator for this eventuality. While it was unneeded as a rescue maneuver, towards the end of the second and final EVA on STS 41-B, I inadvertently knocked a PFR (portable foot restraint) loose. This device, conceptually equivalent to a set of snowboard boot bindings on an aluminum plate, went slowly drifting off, eluding my grasp even as I lunged to try to grab it. Vance asked permission from Mission Control to attempt to retrieve it, and, hearing no response after a reasonable interval, set out in hot pursuit. I scampered down the starboard sill of the Payload Bay and held out my right hand. Vance then “flew my hand” into position where all that I had to do was close my fingers on the errant PFR to retrieve it. This both demonstrated the precision maneuvering capabilities of the massive Shuttle and gave us the record of “first flight to lose and recover a piece of hardware on the same mission.”