STS-68, Endeavour, Space Radar Lab 2, Sep. 30-Oct. 11, 1994

This month is the 23rd anniversary of the Space Radar Lab 2 mission, STS-68. I was the payload commander, flying with my crewmates Mike Baker (CDR), Dan Bursch (MS2), Steve Smith (MS1), Terry Wilcutt (PLT), and Jeff Wisoff (MS3). An ambitious follow up to the successful STS-59, Space Radar Lab 1, SRL-2 was aimed at flying the multi-frequency, multi-polarized Shuttle Imaging Radar-C, X-Band Synthetic Aperture Radar, and the Measurement of Air Pollution from Satellites sensors in the northern hemisphere late summer, to compare SRL-1’s spring mapping results to those from a contrasting season of the year. STS-68 would also test radar interferometry, a technique to create highly accurate, three-dimensional maps of Earth’s topography. (More info at www.AstronautTomJones.com)

My crewmates and I rehearsed our countdown procedures at Kennedy Space Center on August 1, 1994.

Jeff Wisoff was seated to my left, close to the galley and side hatch. Note my clear helmet visor, indicating a “practice” helmet. We kept the dark visors for the real launch day, to avoid scratching them during our practice sessions like this one.

Our launch was planned on August 18, 1994, but at dawn on that date, when Endeavour’s main engines (SSMEs) ignited, the #3 engine violated a redline constraint, and the GPCs ordered an abort and engine shutdown. They automatically called for a shutdown when the discharge temperature on MPSSSME Main Engine #3 High Pressure Oxidizer Turbopump (HPOT) exceeded its redline value. The HPOT typically operates at 28,120 rpm and boosts the liquid oxygen pressure from 422 psia to 4,300 psia. There are 2 sensor channels measuring temperature on the HPOT. The B channel indicated a redline condition while the other was near redline conditions. The temperature at shutdown was at 1563 degrees R. while a normal HPOT discharge temperature is around 1403 degrees R. The redline limit to initiate a shutdown is at 1560 degrees R. This limit increases to 1760 degrees R. at T-1.3 sec (5.3 sec after Main Engine Start). Main Engine #3 (SN 2032) has been used on 2 previous flights with 2,412 seconds of hot-fire time and a total of 8 starts. This was the first flight for the HPOT on Main Engine (SSME) #3.

What all of this meant to me on the middeck (sitting next to Jeff Wisoff), was that as I felt the SSMEs rumble to life, I began mentally counting down the six seconds til booster ignition at T-minus-zero. Braced against the massive jolt of those SRBs exploding into life, I instead felt the engine vibration die away just as Terry Wilcutt shouted “Right engine down!”, accompanied by the blare of the master alarm. This meant serious trouble.

Out the hatch window to my left, I noted the gantry structure seeming to sway left and right under the vanished shove from Endeavour’s main engines–that was US swaying back and forth. Jeff and I hurriedly threw off our parachute straps and prepared to scoot across the middeck to open the hatch; we might all have to make a beeline to the escape slides on the far side of the gantry’s 190 foot level. We stayed on intercom, waiting for the word to egress.

Within the first minute, Launch Control had our pilots executing the pad abort checklist, entering computer commands that would stop the backup flight software from jettisoning our solid rocket boosters at T+2 minutes (embarrassing and deadly). As Jeff and I cleared our seats in the middeck and stood by to open the hatch, we heard reassuring words from Launch Director Bob Sieck’s team that the computers had executed an orderly shutdown, and no fire or explosion risk was evident.

“Damn! We’re scrubbed!” Jeff opined that we’d be set back at least three weeks by the necessary engine changeout. In fact it would take six weeks for our rollback, engine change, and rollout. STS-64 would slip ahead of us and fly in early September with its LITE laser sensor payload. Our new launch date would be Sept. 30, 1994.

The launch team did a superb job on our abort–the last pad abort in the space shuttle program, and the one that came hair-raisingly close to leaping off the pad with one engine down. That would have meant an immediate scramble to perform a Return To Launch Site (RTLS) abort, flying backward through our Mach 5 exhaust plume to attempt a dicey landing back on Merritt Island. If anyone could pull it off, it would have been Bakes, Terry, Dan, and Steve. Assuredly, no one wanted to be the first to try an RTLS.

September 30 was set as our new launch date. STS-64 in the meantime had flown its successful LITE Earth-science mission, with the additional milestone of Mark Lee and Carl Meade test-flying the SAFER EVA jetpack. Our crew had taken a week-long vacation, then got back into simulations and recurring training to polish our space radar abilities. I thought we used the extra time to good effect, and we proceeded to the Cape even better prepared than we were in August. We were certainly more rested than on our first attempt.

One piece of bad luck befell us: on the day we entered quarantine, five of us came down with cold symptoms. We suffered through four days in Houston of runny noses, aches and pains, and sore throats, but with constant flight surgeon attention we slowly improved. Our flight to the Cape was on the Shuttle Training Aircraft, the Gulfstream jet, to spare our sinuses the drastic cabin altitude changes experienced in a T-38.

When we arrived at the Cape, Dan Bursch stepped off the jet in his Groucho Marx disguise, telling reporters that our chances of avoiding a launch abort were better if Endeavour didn’t know he was in the launch area. Our spirits were certainly on the upswing as our three days in Florida at crew quarters drew to a close.

Our launch was timed for dawn on September 30, with Endeavour taking us into a 57-degree inclination, circular orbit, about 120 nm up. At that altitude our orbit would drift west at such a rate that we could image each of our science targets three times each day, from slightly different radar incidence angles.

The liftoff was exhilarating–this time I knew what to expect! I occupied the same seat as on SRL-1, with Jeff Wisoff to my left. No abort this time–the boosters came alive with a punch to the gut and we soared aloft. Much of the cabin dialogue we exchanged during launch is in my book, Sky Walking: An Astronaut’s Memoir. I’d asked that the side hatch window cover again be removed, so I had a terrific view of the gantry turning from gray, to red, to white-hot as the boosters lit. The following eight and a half minutes were punctuated by pyros firing to sever the boosters at two minutes, and then the attention-getting 3 g’s during the final minute of the ascent. During those final seconds I truly experienced the power of the space shuttle’s three main engines, just hurling our 100-ton orbiter toward the injection altitude and velocity. A miracle of technology and physics.

Below, another beautiful view of our dawn liftoff, as Endeavour jolts off the pad. During my second ascent to orbit, I was able to enjoy the physical and mental impressions a bit more methodically, recording my comments on a microcassette recorder during the eight-and-a-half minute climb to our 120 nm mapping orbit.

After MECO, it was off to the races, with Steve Smith and I teaming up on video and still photography of the external tank as it drifted away, below us. Then Jeff and I threw ourselves into converting the middeck into its orbit configuration, and getting the rest of the crew out of their suits and on into their orbital jobs. We had only about 5 hours until my bedtime; the Blue Shift of Steve, Dan and I were due for our first sleep period while Jeff, Mike, and Terry activated SRL-2.

Before launch, our crew had a chance to examine the Space Radar Lab and its SIR-C/X-SAR radars up close, nestled in Endeavour’s payload bay. C-band panels line the left edge, and the larger L-band panels cover most of the 12-m-long antenna. Along the port edge, next to the robot Canadarm, the German/Italian X-SAR antenna is folded downward toward the sill of the payload bay.

Below, SRL-2 is in orbit. Space Radar Lab 2 had some new wrinkles, added since our April flight of SRL-1. The JPL folks had added a gold decal that matched one the Germans and Italians had placed on the X-band antenna. And the Langley Research Center also added a label to their Measurement of Air Pollution from Satellites (MAPS) instrument, positioned right in front of the radar antennae. It all made for a spectacular view out the back windows of the cabin:

We also had about 160 radar imagery recording cassettes aboard, up from the hundred or so we took aloft on SRL-1. The radar imaging schedule was even more ambitious than in April–and I’d thought that was intense!

I had thought I was over my cold, but upon arrival in orbit and a night’s sleep, I ran into its aftereffects. My sinuses were clogged, and without gravity, NOTHING was coming “down” out of my nose. My head felt like a balloon, and my face was reddened as if by a sunburn. I took to the medical locker to find the decongestants, and over a week or so, I slowly improved. The rest of my crewmates also dealt with the congestion lingering from our colds, and the natural stuffiness from the fluid shift headward, caused by our transition to free fall.

Jeff Wisoff, assisted by the pilots and coordinating with Mission Control (MCC), got SRL-2 up and running on his long first shift in orbit. When I woke from my quick 6 hours of sleep and talked to Jeff, I found he’d been “running” flat out with the activation for his entire shift, barely having time to grab a drink or a quick snack. I got cleaned up in a hurry and took over with Dan and Steve as quickly as we could, to spell the Red Shift from their labors. Having been up more than 18 hours, they were understandably tired. We tucked them into bed and ran with our Science Timeline, our program of observations.

 

We discovered the tile damage on the first day of the flight, after opening the payload bay doors and inspecting the cargo bay. MCC determined that the heat loads on the upper half of the OMS pod were mild enough that the tile damage would not be dangerous. That greatly eased our minds. It was several days later that we discovered the source of the damage, looking up through the window and noticing a missing piece of tile just outside the outer pane. The tile tore loose during ascent and flew back to strike the OMS pod.

The radar imagery returned resulted in wonderful images, like the one below, all across the disciplines of the Earth sciences. As we woke for our first work shift, Jeff, Terry, and Bakes called us upstairs to see a spectacular volcanic eruption in Kamchatka. Everyone grabbed a camera to capture images out the windows, while the radar lab obtained thousands of detailed images, revealing details obscured by the eruption plume.

The eruption was a true serendipitous gift from nature. If we had launched in August as planned, we would have missed this rare geological event. Now we had a ringside seat.

Our wide-angle 90mm lens on the Linhof camera captured the view below. The Linhof produced a 4×5-inch film negative, with incredible detail. Each magazine held 100 frames, and we refilled magazines with fresh film inside a light-tight bag, stowing the exposed film in canisters and manually spooling a new roll into the magazine. The film reloading was part of our nightly housekeeping routine. But it was hard to tear ourselves away from the windows!

We were able to monitor Kliuchevskoi’s eruption for a solid week, using the SRL to track eruptive phases as weather fronts came and went across Kamchatka. During a TV downlink to MCC, I described how the radar beams interacted with lavas of varying roughness, using three samples from Hawaii to illustrate the viewing geometry. I had chunks of aa, pahoehoe, and andesite lava aboard–in free fall, I had to take care to not release rock dust or slivers of lava into the cabin from their ziploc bags.  The andesite sample was a more viscous, stiff lava, erupted from some of the more recent cinder cones on Mauna Kea.

Our shift work was 12 hours on, an 8-hour sleep shift, plus 4 hours for “post-sleep” and “pre-sleep”. In those periods, we talked things over with the Red Shift guys, had breakfast, dinner, and exercise, and took care of necessary housekeeping. One of the challenges was giving Jeff, Terry, and Bakes a good night’s sleep by keeping quiet in the middeck. Even opening a locker could wake up that crew in their sleeping bags, inside their bunks, so we tried to get our lunch like church mice, then eat on the flight deck. Once I dumped a chunk of scrambled eggs that I’d insecurely anchored to a tortilla–it went flying all over the flight deck, and Dan had to help me gobble up the floating egg debris. Dan’s homemade chocolate chip cookies crumbled in their ziploc–getting them out without crumbs floating everywhere required true astronaut skill. From home, with the help of the JSC Space Food Lab, I’d brought TastyKake chocolate cupcakes and Butterscotch Krimpets, enough snacks to carry me through the 11-day mission.

In the test above, Steve had a laser on his headstrap, and his job was to rotate his head to put the laser dot on a series of targets about 6 feet away on the middeck lockers, forward. The sequence of pointing was random, and the package Steve was wearing recorded his eye motions as well as his response and pointing time. Looks a little like The Terminator if you ask me. Mike Baker helps with the checklist. Note the tortillas in the ziploc bag on the Middeck Equipment Rack (MER) behind Baker, with the galley to the right.

When I enlarge the photo, I see my crew notebook also velcroed to the lockers above Mike’s left shoulder. And I’m actually visible behind Mike, taking a look out the side hatch window (or scrubbing the bathroom!).

The recorders were adapted from digital tape machines that flew in recon aircraft to record digital imagery data. One of the three on our flight deck failed about 8 days into the mission, so Jeff and Steve removed it and replaced it with a spare recorder that’d been flown up underneath our middeck floor. Pretty handy mechanics. Within 4 hours they had the new machine up and running again.

All too soon, our 11 days in orbit were coming to a close. We remained an extra day in orbit hoping for added science, and to await improving weather at Kennedy Space Center, but Mission Control directed us home to a landing at Edwards Air Force Base in California on Oct. 11, 1994. Commander Mike Baker, assisted by pilot Terry Wilcutt, brought Endeavour to a gentle landing on Runway 22 at Edwards. Our orbiter performed superbly from start to finish of this successful mission to Planet Earth.

Just after wheels stop on Endeavour, I was to unstrap from my middeck seat and stand up. The blood pressure measurement gear would record my response to standing erect in 1-g, once again. I knew when the equipment was working when my left arm’s pressure cuff inflated, but it never recovered after touchdown. The taped data from entry, however, were good, and so was the audio tape I made as we rode back through the atmosphere. I have to give credit to the designers for creating a rig that would work inside our pressure suits, and yet still be easy enough to don and operate. After return to Houston, I sent the investigators an apology for the verbal tirade I recorded, grousing about the troubles I had getting the batteries replaced and activating the system. My only excuse was being up for a very long day…around 18 hours by the time we landed, and we still had postflight medical tests to endure.

STS-68 is a highlight of my speech, “Sky Walking: An Astronaut’s Journey” — contact me here at my speaking information page.