Sierra Nevada Corporation’s Dream Chaser Cargo Spacecraft
on Runway (Image: SNC)
A recent, NASA-awarded cargo pact
worth billions means smoother sailing for the development of Dream
Chaser, a new space shuttle built by Sierra Nevada Corp (SNC), based in
Louisville, CO. The unique spacecraft has had a long
and arduous journey from its Soviet-era beginnings to its thrust into
today’s escalating private industry space race. The Phase 2 Commercial Resupply Services (CRS2)
is contracted for at least six Dream Chaser missions to the
International Space Station. The announcement comes roughly two years
after SNC lost a bid to taxi astronauts to the station against
competitors, Boeing and SpaceX. SNC’s resolve did not wane and the
company survived by transforming their vehicle to successfully compete
for cargo missions to the ISS. This innovative spirit puts the future of
SNC on an exciting trajectory. Mark Sirangelo, Vice President of SNC,
says the company has addressed the concerns NASA had voiced when it
decided against awarding the previous contract to SNC. He also remarked
that the government “gets a terrific vehicle to add to its fleet.” The capabilities of the newly designed
Dream Chaser Cargo System meet the upper end of the technical
requirements for a cargo mission. Including the ability to carry up to
5,550 kilograms, roughly the size of one well-fed African bush elephant.
This allows more space inside pressurized chambers for critical science
experiments and external space to carry large components to be
installed on the body of the ISS.
The lifting body vehicle will be
launched on a United Launch Alliance (ULA) Atlas V rocket and will have
the ability to return—along with cargo—by landing at any available
airport. SNC’s Dream Chaser is made of non-toxic materials meaning it
can touch down on commercial runways and be accessed immediately. The chance to showcase a reusable
spacecraft on government funded missions bodes well for a potential
pivot to commercial use. SNC is at the leading edge of private space
companies that one day might cater to a more diverse base of consumers
like universities, medical companies and individuals. To learn more about Dream Chaser’s history and development, we spoke to John Roth, Vice President of Business Development for SNC’s Space Systems. Can you give us a little history on how the Dream Chaser was inspired by a space shuttle built by the Soviet Union? The history stems from the BOR-4,
a subscale test version of a manned spaceplane that the Soviets
experimented with (some orbital launches and sub-orbital launches) back
in the 1980s. The way that it has a heritage to the Dream Chaser—it’s
not a direct heritage, but the BOR-4 had been captured by some
intelligence originally from an Australian surveillance aircraft that
caught a Russian frigate pulling a BOR-4 out of the water after one of
its flights. They didn’t know what the BOR-4 was.
It looked like some sort of space vehicle. They sent the information to
the United States to see if the US had any intel on this vehicle and
that made its way to NASA. NASA did not have any intel on the
vehicle but they thought it was a very interesting design and that
prompted some of the early design work they did in lifting bodies that
eventually led to the development of NASA’s own spaceplane concept, the
HL-20. So the NASA HL-20, if you look at it, looks very looks very
similar to the BOR-4. There’s sort of a direct link in that they have
some intelligence on the BOR-4 and that led to the development of the
HL-20 at NASA. We took over the technical details,
information and drawings etc. of the HL-20 from NASA and migrated that
into the Dream Chaser.
What was SNC’s reaction to the claim made by NASA that Dream
Chaser wouldn’t be ready for commercial crew missions and what were the
main points made when SNC appealed their contract refusal? It was kind of an interesting back and
forth. The purpose for filing against the decision was not a simple few
page thing. We took exception to a dozen or so elements of the decision
process. One of those elements happened to be the schedule and NASA’s
concern that because our vehicle was less mature than capsule designs in
general, that we wouldn’t be ready. That’s one of the things that we
didn’t quite understand. Some of the language just implied that capsules
are easier so they should be built faster. We don’t really buy that
logic. We flew the shuttle for 30 years and it’s not like lifting bodies
had no heritage. So the fact that they were trying to say “capsules are
going to take less time to develop than your lifting bodies,” doesn’t
really have any definitive facts to back that up. That’s just one of the
things that we took exception to. The schedule that we developed, which
had us launching in 2017, met their requirements. NASA chose to just be
skeptical that we were actually going to be able to hold to the
schedule. And the reaction to finally winning the Commercial Resupply Contract? As you can image we were thrilled.
There are people that have been literally working on this vehicle for
more than ten years from when they were at Spacedev.
People at Spacedev were initially the ones that took the HL-20 and
thought it could be a very cool lifting body for the future. And so just
the long haul to getting from where we started to finally knowing that
were were going to get at least six missions to the space station was
just an incredibly thrilling moment. Shouts, hugs, tears and every emotion
you can imagine. It was just relief that we were going to be able to
bring this vehicle to life. Was there a shift in vision for SNC in terms of moving from crew
transportation to cargo? And will a crew version of Dream Chaser still
be pursued by the company at any point? We are still absolutely committed to
eventually getting a crew version of Dream chaser. The team wants to do
that very badly. We don’t have a current path forward but we are not
giving up hopes that we can find a path to making a crewed variant in
addition to a cargo variant. So really the mental shift that you are
talking about came after we lost the crew competition and of course it
was a very disheartening time when we were thinking about the options
for moving forward. Originally we weren’t going to build
for cargo contract, the CRS2, because we were still in the midst of
trying to find out if we were going to win the current program and we
didn’t think we wanted to divert staff from crew program over to do this
cargo thing. Obviously once we lost the crew, we took another look at
the cargo and we had to go through major rethinking about how we could
optimize the Dream Chaser vehicle for cargo. It wasn’t as easy as simply looking at
the crew vehicle and saying, “OK we’re going to pull seats, pull out
people and stick in cargo.” It would not have been a good vehicle for
the cargo program. It would not have been competitive. We had to go
through an incredible redesign process to come up with the idea of the
cargo module and to come up with a way to make room for additional
cargo. Taking out the abort engines for
example which we don’t need for cargo. We needed to fit inside a fairing
so we had to come up with a redesign for the wings to be able to fold.
There was about a dozen major things that we had to address to see if we
could really make this crew vehicle to what we thought would be an
exceptional cargo vehicle. Amazingly, we did that and were able
to turn our vehicle into what we think is the most optimum cargo vehicle
for NASA because we’re the only ones that can do all three of the
missions they want to do in every single flight. Which means pressurized
and unpressurized cargo up, disposal and return. We can do all three of
those in every flight and we’re the only vehicle that can. What are the plans for launch and landing sites? Will the Kennedy Space Center play a major role? The contract right now for the cargo
missions is based on launches out of Kennedy and landing at the shuttle
landing site facility at Kennedy. Obviously we’d have an option—if they
wanted—to discuss with us launching and landing from somewhere else but
that’s our baseline concept in the CRS2 proposal. We have been working
with a lot of different airports and spaceports both in the US and
internationally who are interested in being able to land Dream Chaser at
their facilities. We have had a number of discussions with those
airports and spaceports. We have a few that are public like Houston and
Alabama and a few others that we have been working with that have
elected not to go public yet. We are moving forward towards plans to
look at eventual FAA licensing for landing Dream Chaser at other places
than Kennedy. That right now is not part of our cargo contract.
Will the Dream Chaser eventually be utilized for other types of missions?
We are looking at other variants or modifications to the current
structure. For example, we’ve done a lot of work on a free-flying
science mission. We’ve installed more standard racks very similar to the
racks that are inside the space station. So they can put the same kind
of science experiments they run on the ISS, on a free-flying science
mission for Dream Chaser.
We’ve done some conceptual designs of how it would look if we did
that. We’ve done designs for longer duration vehicles meaning you want
to be in orbit for some months or a year instead of the days or few
weeks that we would do on cargo missions. Those are variants of the same
vehicle and we have looked at a number of different ones like that.
We’ve been in discussions with different customers about those kinds of
variants.
There is going to be a commercial market. NASA is certainly a
customer now. We think Europe is certainly going to close on missions.
We still believe that there is potential for missions with commercial
customers like pharmaceutical companies and bio-farm companies that are
interested in starting to look at doing zero-g manufacturing and zero-g
experiments like they do on the space station.
Will SNC compete for the next round of commercial crew contracts that NASA is expected to award in 2020? That is certainly on our radar scope,
yes. That is something we are very interested in doing. We do need to
try and find the best route in working on the crew version. First, it’s
going to take some investment funding and that could be either internal,
external, or a combination. The second thing is that we absolutely want
to make sure we are successful on the cargo missions. So we’ve got to
make sure the resources are directed towards making that cargo design
and getting that vehicle built. Whether we can actually go after that
contract or not when it gets to that point, is going to be matter of
whether we can get the right resources to get there. When will the public see Dream Chaser fly for the first time? Well that’s really up to NASA. NASA
has not yet signed any of the task orders for specific missions. We have
our first meetings in the next few weeks but they announced as part of
the contract that the first cargo missions will begin in 2019. It
doesn’t mean all three providers will be contracted to do cargo mission
in 2019 so we still have to wait on NASA to see what our schedule will
be for the first flight.
Robin Seemangal focuses on NASA and
advocacy for space exploration. He was born and raised in Brooklyn,
where he currently resides. Find him on Instagram for more space-related content: @not_gatsby
Cayte Bosler is a Brooklyn-based freelance journalist who has
contributed to The Atlantic, National Geographic, and Fast Company. You
can find her on Twitter and Instagram.
February 1, 2016: One of the most tragic events
in the history of space exploration is the loss of the space shuttle
Columbia and all seven of its crew on February 1, 2003—a tragedy made
worse because it didn’t have to happen. But just as it is human nature
to look to the future and wonder what might be, so too is it in our
nature to look at the past and wonder, “what if?” Today, 13 years after
the event, Ars is rerunning our detailed 2014 examination of the biggest
Columbia “what if” of all—what if NASA had recognized the danger? Could
NASA have done something to save the crew?
If we die, we want people to accept it. We
are in a risky business, and we hope that if anything happens to us, it
will not delay the program. The conquest of space is worth the risk of
life.
—Astronaut Gus Grissom, 1965
It is important to note at the outset that
Columbia broke up during a phase of flight that, given the current
design of the Orbiter, offered no possibility of crew survival.
—Columbia Accident Investigation Board Report
At 10:39 Eastern Standard Time on January 16, 2003, space shuttle Columbia
lifted off from pad 39A at the Kennedy Space Center in Florida. A mere
81.7 seconds later, a chunk of insulating foam tore free from the orange
external tank and smashed into the leading edge of the orbiter's left
wing at a relative velocity of at least 400 miles per hour (640 kph),
but Columbia continued to climb toward orbit.
The foam strike was not observed live. Only after the shuttle was
orbiting Earth did NASA's launch imagery review reveal that the wing had
been hit. Foam strikes during launch were not uncommon events, and
shuttle program managers elected not to take on-orbit images of Columbia
to visually assess any potential damage. Instead, NASA's Debris
Assessment Team mathematically modeled the foam strike but could not
reach any definitive conclusions about the state of the shuttle's wing.
The mission continued.
In reality, the impact shattered at least one of the crucial
reinforced carbon-carbon heat shield panels that lined the edge of the
wing, leaving a large hole in the brittle ceramic material. Sixteen days
later, as Columbia re-entered the atmosphere, superheated
plasma entered the orbiter's structure through the hole in the wing and
the shuttle began to disintegrate.
At Mission Control in Houston, the flight controllers monitoring Columbia's
descent began to notice erratic telemetry readings coming from the
shuttle, and then all voice and data contact with the orbiter was lost.
Controllers continued to hope that they were merely looking at
instrumentation failures, even as evidence mounted that a catastrophic
event had taken place. Finally, at 9:12 Eastern Time, re-entry Flight
Director LeRoy Cain gave the terrible order that had only been uttered
once before, 17 years earlier when Challenger broke apart at launch: "Lock the doors."
It was an acknowledgement that the worst had happened; the mission
was now in "contingency" mode. Mission Control was sealed off, and each
flight controller began carefully preserving his or her console's data. Columbia was gone, and all seven of its crew had been
killed. NASA refers to this most rare and catastrophic of events as an
LOCV—"Loss of Crew and Vehicle."
Frozen
Columbia is lost. There are no survivors.
—President George W. Bush in a national address, 14:04 EST, February 1, 2003
The world of human space flight paused—first to mourn, then to
discover what had happened. Congress laid that responsibility on the
combined shoulders of the Columbia Accident Investigation Board
(referred to, in typical NASA acronym-dependent style, as "the CAIB" or
just "CAIB," which rhymes with "Gabe"). In the months after Columbia, the CAIB stretched its investigative fingers all through NASA and its supporting contractors.
My own memories of the time immediately following the accident are
dominated by images of somber meetings and frantic work. I was a junior
system administrator at Boeing in Houston, and because we supported the
shuttle program, we had to locate and send cases and cases of backup
tapes—containing everything that happened on every server in our data
center during the mission—over to NASA for analysis.
In August 2003, the CAIB issued its final report.
Behind the direct cause of the foam strike, the report leveled damning
critiques at NASA's pre- and post-launch decision-making, painting a
picture of an agency dominated by milestone-obsessed middle management.
That focus on narrow, group-specific work and reporting, without a
complementary focus on cross-department integration and communication,
contributed at least as much to the loss of the shuttle as did the foam
impact. Those accusations held a faint echo of familiarity—many of them
had been raised 17 years earlier by the Rogers Commission investigating Challenger's destruction.
In the end, Columbia's loss ended not only lives but also careers at all levels of NASA. A number of prominent shuttle program managers were reassigned. It is likely that Columbia's
destruction factored heavily into the resignation of NASA Administrator
Sean O'Keefe. Many involved with the mission—including many still
working at NASA—to this day struggle with post-traumatic stress and
survivor's guilt. All pending shuttle missions were put on hold, and Columbia's three surviving companion ships—Discovery, Atlantis, and Endeavour—were grounded.
NASA looked inward, and we wondered if we'd fly again.
A path not taken
To put the decisions made during the flight
of STS-107 into perspective, the Board asked NASA to determine if there
were options for the safe return of the STS-107 crew.
—Columbia Accident Investigation Board Report
That's the way events actually unfolded. But imagine an alternate timeline for the Columbia mission in which NASA quickly realized just how devastating the foam strike had been. Could the Columbia astronauts have been safely retrieved from orbit?
During the writing of its report, the CAIB had the same question, so
it asked NASA to develop a theoretical repair and rescue plan for Columbia
"based on the premise that the wing damage events during launch were
recognized early during the mission." The result was an absolutely
remarkable set of documents, which appear at the end of the report as
Appendix D.13. They carry the low-key title "STS-107 In-Flight Options Assessment,"
but the scenario they outline would have pushed NASA to its absolute
limits as it mounted the most dramatic space mission of all time.
NASA planners did have one fortuitous ace in the hole that made the plan possible: while Columbia's STS-107 mission was in progress, Atlantis was already undergoing preparation for flight as STS-114, scheduled for launch on March 1. As Columbia
thundered into orbit, the younger shuttle was staged in Orbital
Processing Facility 1 (OPF-1) at the Kennedy Space Center. Its three
main engines had already been installed, but it didn't yet have a
payload or remote manipulator arm in its cargo bay. Two more weeks of
refurbishment and prep work remained before it would be wheeled across
the space center to the enormous Vehicle Assembly Building and hoisted
up for attachment to an external tank and a pair of solid rocket
boosters.
Enlarge/Endeavour undergoes processing at OPF-2. Atlantis
was in a similar state while Columbia was flying its final mission.
NASA
So an in-orbit rescue was at least feasible—but making a
shuttle ready to fly is an incredibly complicated procedure involving
millions of discrete steps. In order to pull Atlantis' launch
forward, mission planners had to determine which steps if any in the
procedure could be safely skipped without endangering the rescue crew.
The desperate race
The scenarios were to assume that a decision
to repair or rescue the Columbia crew would be made quickly, with no
regard to risk.
—Columbia Accident Investigation Board Report (Appendix D.13)
But even before those decisions could be made, NASA had to make
another assessment—how long did it have to mount a rescue? In tallying Columbia's supplies, NASA mission planners realized that the most pressing supply issue for the astronauts wasn't running out of something like air or water but accumulating too much of something: carbon dioxide.
Weight is a precious commodity for spacecraft. Every gram of mass
that must be boosted up into orbit must be paid for with fuel, and
adding fuel adds weight that must also be paid for in more fuel (this
spiral of mass-begets-fuel-begets-mass is often referred to as the tyranny of the rocket equation).
Rather than carrying up spare "air," spacecraft launch with a mostly
fixed volume of internal air, which they recycle by adding back
component gasses. The space shuttle carries supplies of liquid oxygen
and liquid nitrogen, which are turned into gas and cycled into the
cabin's air to maintain a 78 percent nitrogen/21 percent oxygen mixture,
similar to Earth's atmosphere. The crew exhales carbon dioxide, though,
and that carbon dioxide must be removed from the air.
To do this, the shuttle's air is filtered through canisters filled
with lithium hydroxide (LiOH), which attaches to carbon dioxide
molecules to form lithium carbonate crystals (Li2CO3),
thus sequestering the toxic carbon dioxide. These canisters are
limited-use items, each containing a certain quantity of lithium
hydroxide; Columbia was equipped with 69 of them.
How long those 69 canisters would last proved difficult to estimate,
though, because there isn't a lot of hard data on how much carbon
dioxide the human body can tolerate in microgravity. Standard mission
operation rules dictate that the mission be aborted if CO2
levels rise above a partial pressure of 15 mmHg (about two percent of
the cabin air's volume), and mission planners believed they could
stretch Columbia's LiOH canister supply to cover a total of 30 days of mission time without breaking that CO2
threshold. However, doing so would require the crew to spend 12 hours
of each day doing as little as possible—sleeping, resting, and doing
everything they could to keep their metabolic rates low.
If the crew couldn't sustain that low rate of activity, NASA flight surgeons believed that allowing the CO2
content to rise to a partial pressure of 26.6 mmHg (about 3.5 percent
cabin air volume) "would not produce any long-term effects on the health
of the crewmembers." This would enable the crew to function on a more
"normal" 16-hour/8-hour wake/sleep cycle, but at the cost of potential
physiological deficits; headaches, fatigue, and other problems related
to the high CO2 levels would have started to manifest very quickly.
After the carbon dioxide scrubbers, the next most limited consumable was oxygen. Columbia's
liquid oxygen supplies were used not only to replenish breathing gas
for the crew but also to generate power in the shuttle's fuel cells
(which combined oxygen with hydrogen to produce both energy and potable
water). The amount of liquid oxygen on board could be stretched past the
CO2 scrubbers' 30-day mark by drastically cutting down Columbia's power draw.
The remaining three consumable categories consisted of food, water,
and propellant. Assuming that the crew would be moving minimally, food
and water could stretch well beyond the 30-day limit imposed by the LiOH
canisters. To preserve propellant, the orbiter would be placed into an
attitude needing minimal fuel to maintain.
Exactly when the crew of Columbia would enact these
power- and oxygen-saving measures depended on a short decision tree. In
the scenario we're walking through, the assumption is that NASA
determined on Flight Day 2 (January 17) that the foam strike had caused
some damage, followed by at least another day to gather images of Columbia using "national assets" like ground-based telescopes and other space-based sources (i.e., spy satellites) under the control of USSTRATCOM.
If that imagery positively identified damage, Columbia would
immediately enter power-down mode; if the images didn't show anything
conclusive, the crew would conduct an EVA (extra-vehicular activity—a
spacewalk) to visually assess the damage to the wing, then power things
down.
In either case, Flight Day 3 would mark the start of many sleepless nights for many people.
No do-overs, no mistakes
This rescue was considered challenging but feasible.
—Columbia Accident Investigation Board Report
Planning the inspection EVA would have taken most of Flight Day 4
(January 19), but the hard deadline of the lithium hydroxide canisters
remained set at Flight Day 30 (February 15) regardless of what happened
on the ground. Work would simultaneously have had to begin at the
Kennedy Space Center to accelerate the processing of Atlantis.
"Accelerate" is a prosaic word for the herculean effort that would
have been needed. Activities that normally take place across weeks or
months would have to happen in hours or days. Civil servants and
contractors at KSC would have to begin 24/7 shift work, keeping the
lights on and the process running every hour of every day, for a minimum
of 21 days, to power Atlantis through checkout and make it ready to launch.
Three unceasing, brutal weeks of 24/7 shift work—and that's with
absolutely no margin factored in for errors or failures. The Orbital
Processing Facility team, the Vehicle Assembly Building team, and the
Launch Complex 39 pad team would have had to get every one of the
millions of steps right, and every component of Atlantis would have had to function perfectly the very first time, or it would all be wasted.
Enlarge/ A rescue mission would require preparing a shuttle
for launch far faster than had ever been done before.
NASA / CAIB Report, Appendix D.13
So many things would have to happen. First, Atlantis' computers
would have to be reprogrammed to accommodate the changes in the
mission. Fortunately, the flight software developed for STS-114's
International Space Station (ISS) rendezvous could be adapted to instead
rendezvous with Columbia, though most of the specific rendezvous parameters would have to be altered. The changes would be uploaded to Atlantis' computers
during the DOLILU—the Day of Launch Input Load Update, the standard
last-minute software update that shuttles on the pad receive two hours
prior to launch. Usually, DOLILU loads include flight control updates to
accommodate the day's observed weather patterns, but this particular
DOLILU load would change the entire flight profile. It would be the
largest on-pad software update ever attempted.
In order to push Atlantis through processing in time, a number of standard checks would have to be abandoned. The expedited OPF processing would get Atlantis
into the Vehicle Assembly Building in just six days, and the 24/7 prep
work would then shave an additional day off the amount of time it takes
to get Atlantis mated to its external tank and boosters. After
only four days in the Vehicle Assembly Building, one of the two
Crawler-Transporters would haul Atlantis out to Launch Complex 39, where it would stage on either Pad A or Pad B on Flight Day 15—January 30.
Enlarge/ Under troubled skies, Atlantis makes its way out to
the pad atop one of the Crawler-Transporters to embark on STS-129.
Once on the pad, the final push to launch would begin. There would be
no practice countdown for the astronauts chosen to fly the mission, nor
would there be extra fuel leak tests. Prior to this launch, the
shortest time a shuttle had spent on the launch pad was 14 days; the pad
crews closing out Atlantis would have only 11 days to get it ready to fly.
Even as workers at Cape Canaveral frantically tried to beat the
clock, more work had to happen at the Johnson Space Center in Houston: Atlantis still needed a crew.
The right stuff
[I]t would be important to have a high degree
of confidence in the astronautsʼ ability to quickly adapt to the
micro-gravity environment.
—Columbia Accident Investigation Board Report (Appendix D.13)
Columbia carried seven astronauts, who by Flight Day 15
would be halfway through their unexpectedly extended 30-day mission.
This presented a problem for NASA: space shuttles were designed to
accommodate five to seven astronauts, and Atlantis would need its own crew in order to launch and rendezvous with Columbia. When Atlantis returned, it would carry not only the astronauts it launched with, but also Columbia's rescued crew—so to minimize crowding, what was the minimal crew count Atlantis could get away with at launch?
After analysis, it was determined that Atlantis would need a
minimum crew of four. A two-person pilot and commander team would be
required to actually fly the rendezvous and actively keep station with Columbia—which
NASA estimated would mean at least eight or nine hours of manual flying
(and potentially much more than that). Another two-person team would be
required to don suits and perform the rescue EVA tasks—tasks which NASA
would have had to design from scratch.
As with every other task involved with the rescue, there was no room for error, and there would be no second chances. Atlantis
would be launched with an all-veteran crew, with selection for the
mission biased heavily toward astronauts who demonstrated fast
adaptation to microgravity (there was no time to be space-sick) and high
aptitude at EVA and rendezvous. The report names no names, but it does
indicate that an assessment revealed a pool of nine EVA candidates,
seven command candidates, and seven pilot candidates available in
January 2003 whom NASA felt could have undertaken the mission.
The four astronauts chosen to fly Atlantis would have faced
an extraordinarily compressed training schedule—and also a tremendous
amount of professional and personal pressure. The tight timeline would
mean that the two Atlantis astronauts selected to actually
spacewalk between the shuttles for the rescue EVA would likely be
training underwater at NASA's Neutral Buoyancy Lab
almost every single day of the two weeks, breaking the entire
multi-hour spacewalk up into tiny component maneuvers and procedures and
walking through each to commit them to memory. Simultaneously, the two
astronauts selected to pilot the shuttle would have spent that time in
the large motion-base simulators in Building 9 at the Johnson Space
Center, working through every moment of the rendezvous, station-keeping,
and landing from start to finish.
Enlarge/ Looking down into NASA's Neutral Buoyancy Lab
It's also certain that the media would have exerted its own
tremendous pressure, attempting to thrust cameras and lights into every
corner of the preparation—as much as they would be allowed to do so,
anyway. "Space disaster" and "rescue mission" are golden ratings words.
Clear Lake in Houston and Cape Canaveral in Florida would have been
swarmed with TV trucks; the Johnson Space Center sign on historic NASA Rd 1 would likely have been a constant backdrop on TV news both local and national.
And throughout the frantic weeks on the ground, Columbia's crew would wait.
Slow time
This powerdown would have supported only the most basic vehicle control and crew support and communication equipment.
—Columbia Accident Investigation Board Report (Appendix D.13)
While work on the ground would proceed in a controlled frenzy, time on Columbia
would lengthen and draw out in slow misery. The crew would have
potentially undergone a brief flurry of activity if they needed to do an
EVA to confirm the damage to the orbiter's left wing; additionally,
they would have needed to maneuver Columbia into a tail-first
"gravity gradient" attitude so that the Earth's pull on the shuttle's
empennage would keep the orbiter's orientation fixed relative to Earth
without the need to expend any propellant. After that, though, the
stranded crew could do very little other than wait and try not to move
or breathe too much.
Enlarge/ STS-107 mission specialists Laurel B. Clark, Rick D.
Husband, and Kalpana Chawla relaxing in their bunks on Columbia's
middeck.
The crew wouldn't even be able to watch their own rescue's TV
coverage, because the orbiter would be in a tightly restricted low-power
mode in order to conserve its energy. Appendix D.13 includes a
description of what systems would be shut down, and among them are "all
cameras, camera heaters, TV monitors, and video equipment."
An oft-asked question is whether or not Columbia could have
docked with the ISS, which would have had consumables to spare. There
are numerous reasons why this would not have been possible, but the
overriding one comes down to simple physics: Columbia would
have had to execute what is known in orbital mechanics terminology as a
"plane change" maneuver—applying thrust perpendicular to its orbital
track in order to shift to match the ISS' inclination. Plane change
maneuvers require tremendous amounts of energy—in
some cases, even more energy than was required to launch the spacecraft
in the first place. Appendix D.13 dismisses the possibility of an ISS
rendezvous with just two sentences:
Columbia's 39 degree orbital inclination could
not have been altered to the ISS 51.6 degree inclination without
approximately 12,600 ft/sec of translational capability. Columbia had 448 ft/sec of propellant available.
The crew would be playing the long game, carefully conserving
resources for the burst of activity that would have to occur at the end
of the mission. As previously noted, the primary consumable of
consequence would be the carbon dioxide scrubbers, so rest and sleep
would have been the crew's main mission. Columbia's orbital
period would mean that during their quiet exile, the crew would see more
than 300 sunrises break over the curving lip of the world.
How long would it feel? How many card games can you play? How many
jokes or stories can you tell? How many times do you turn the proposed
rescue over in your mind while you sit in a sleeping cubicle, unable to
bathe and surrounded by your own stink and the stink of six other tired
and scared people, counting each of the 30,000 interminable minutes?
It would have been more than 20 days of endless, drifting purgatory.
Russian roulette
This new risk to the Orbiter would weigh heavily in the decision process on launching another shuttle and crew.
—Columbia Accident Investigation Board Report (Appendix D.13)
Appendix D.13 is written under the assumption that the damage to Columbia's wing was recognized and acted upon, but that is actually the first of two major assumptions underlying the rescue mission. The second assumption has its own set of enormous issues: given that Columbia was disabled by a foam strike, NASA would have to be willing to subject Atlantis to the exact same risk.
The obvious terrifying question here is whether or not there was anything NASA could do in the near term to prevent Atlantis from being disabled by the same type of foam impact—and the answer is a quiet no.
The foam chunk that sheared off of Columbia's external tank
was part of what's called the left "bipod ramp," one of two
hand-sculpted structures flanking the large bipod struts that secure the
orbiter's nose to the forward part of the external tank. To form the
bipod ramps, orange BX-250 insulation is sprayed over the fittings that
attach the bipod to the external tank. It's allowed to dry, then it's
shaved by hand into wedges that cover the fitting elements. Coupled with
a layer of ablative materials atop the fittings, the foam ramps both
protect the attachment points from heat during launch and also sheath
them in an aerodynamic shape.
And, as it turns out, bipod ramps broke off six times before STS-107.
Much of the CAIB report is given over to discussing the specifics of
the external tank's insulating foam—what it's made of, how that material
performs, and how often foam has sheared off of the ET and impacted
with an orbiter. What is clear from the report is that the STS-107 foam
strike was not a unique event—it was a relatively common occurrence that
in this particular instance occurred at precisely the right (or wrong)
time to cause catastrophic damage to one of the very few things on the
shuttle without any form of redundancy.
The Atlantis rescue mission would face the exact same
vulnerability. It would fly with an already-prepared external tank, and
as the Appendix clearly states in the scenario outlined, Atlantis would fly without any time added to the processing schedule to perform any assessments or repairs on the external tank used.
This is another reason why the rescue crew would be made up of four
astronauts instead of launching with more crew—to expose as few humans
as possible to the risk of death.
Gravity ballet
Success Criteria: The safe return of the rescue vehicle (Atlantis) and both crews.
—Columbia Accident Investigation Board Report (Appendix D.1
There would have been three launch windows during which Atlantis would be able to launch and reach Columbia;
one at 23:09 EST on February 9 (Flight Day 25), another at 22:40 EST
the next day, and a final one the day after that at 22:05 EST. Columbia
would be made ready to meet its companion ship three days prior to the
first launch window. The crew, potentially suffering from the effects of
carbon dioxide poisoning, would revive the shuttle's systems enough to
push it into a slightly elliptical higher orbit, which would give Atlantis a better set of opportunities to make the rendezvous.
Any of the three launch windows would have provided a working margin to reach Columbia
before its supply of carbon dioxide scrubbers was exhausted, but
earlier was obviously better. The first launch window provided a
substantially earlier rendezvous time on February 10; the latter two
windows both meant a rendezvous on February 13. The later rendezvous
time would leave, at most, 36 hours of margin before Columbia could no longer support life.
Weather is one of the major unknowns when planning a shuttle launch—not just at the launch site but also at the multiple places around the world
that must be kept ready for an emergency landing if the orbiter needs
to abort its attempt to reach orbit. The CAIB report shows that luck
would have been on NASA's side here; a review of observed weather
conditions on the proposed launch days showed that there was nothing
happening in the atmosphere that would have hindered the launch.
More worrying, though, was that the three windows all opened at
night. A night launch would substantially reduce NASA's ability to
observe foam damage during Atlantis' flight to orbit, which was
particularly ominous in light of the reason behind the rescue mission.
Because of this, an additional EVA was added for Atlantis' crew after reaching Columbia—they would carefully examine Atlantis' wings and tiles for any damage.
Enlarge/Endeavour lifts off from pad 39A for STS-130 in
February 2010. This was the final night launch of the space
shuttle program.
NASA
Assuming all went well and there were no countdown delays, Atlantis would have lifted off on the evening of February 9, 2003. At that point, Columbia's
crew would have long since set a shuttle program record—they would have
been in space for 25 days, eight days longer than the previous longest shuttle mission.
In order to lower the nitrogen content in their blood and be ready to
don their suits as soon as possible, the two EVA crew on Atlantis would possibly have been required to breathe pure oxygen from the moment they entered the orbiter's cabin on the launch pad.
Enlarge/Endeavour
on approach to the ISS, showing details
of forward flight deck windows,
upper flight deck rendezvous
windows, and airlock docking assembly aft
of the flight deck.
NASA
Atlantis would arc upward into orbit, approaching Columbia from below in what's called an "R-bar approach"—that is, an approach along an imaginary radial line connecting Columbia with the Earth's center. (Contrast this to a V-bar approach, which would be an approach along Columbia's velocity vector—that is, from the front or back, rather than the top or bottom.) Columbia would already be oriented tail-first and "upside down" relative to the earth; Atlantis would approach "right side up" beneath it. Atlantis
would swing slowly up into place, each shuttle growing larger and
larger in the rendezvous windows in their respective flight decks'
ceilings.
Finally, Atlantis would ease to a halt 20 feet (six meters) from Columbia. Atlantis would be yawed 90 degrees to Columbia, pointing at three o'clock to the older orbiter's 12 o'clock, in order to keep their vertical stabilizers from striking.
This would have been the first time two space shuttles were
simultaneously orbiting, and the challenges would have been
considerable. Each shuttle would have its own flight control room
operating in NASA's Mission Control Center—and, with the ISS also
requiring a flight control room, this would have tasked the control
center to capacity (both from a perspective of technical and human
resources). Moreover, Atlantis would have needed to be under
constant manual control for the duration of the rendezvous, because even
at a distance of 20 feet, orbital mechanics would keep the two
spacecraft moving at different velocities and they would drift apart in
short order, with Atlantis at the lower altitude constantly trying to race ahead of Columbia.
Enlarge/
Space shuttle cockpit mockup from the CCT-2
(Crew Compartment Trainer)
at NASA's Space Vehicle
Mockup Facility. The middle console contains
most of
the attitude and translation controls Atlantis' commander
and pilot would have used to fly the rendezvous with Columbia.
Steven Michael
While Atlantis' pilot and commander settled in to trade off
the task of holding the shuttle steady for nine hours, the other two
crew—called "EV1" and "EV2" in the report—would already be suited and
standing by in the airlock. As soon as they were given a "go," EV1 and 2
would open Atlantis' airlock and retrieve an expandable boom, with which EV2 would assist EV1 in moving across the gap to Columbia. Extra lithium hydroxide canisters would also be transferred between the two shuttles to give Columbia some breathing room—literally—along with a pair of spacesuits for Columbia's
crew to wear. Incongruously, the Appendix notes that the suits would
need to be transferred, "powered up, and pressurized" to preserve their
water supplies, which would no doubt look quite odd.
Enlarge/ NASA animatic showing Atlantis
EV1 and EV2 in
the gap between the two shuttles' cargo bays. EV2's feet
are
fixed in a portable foot restraint, and the astronaut is moving
EV1
across the gap with a boom.
NASA / CAIB Report
Two undoubtedly stir-crazy Columbia crewmembers (referred to as "CM1" and "CM2") would already be suited and waiting in Columbia's airlock to assist in the transfer from Atlantis. EV1 would parcel the supplies from Atlantis into Columbia's airlock, then assist CM1 and CM2 out of the airlock and help them negotiate the path back to Atlantis.
Shell game
There would be a number of activities that
would be attempted for the first time during this conceptual inspection
and rescue mission.
—Columbia Accident Investigation Board Report (Appendix D.13)
From here, the complexity of the mission begins to ratchet up to
maximum. Depending on how tired and compromised they were physically,
"CM1" and "CM2" could help spell the Atlantis pilot and commander at their station-keeping exercises (assuming that CM1 and CM2 were Columbia commander Rick Husband and pilot William McCool), but the two extra space suits would be put to considerable use. Atlantis' two EVA crewmembers would remain outside, and while CM1 and CM2 were removing their suits, the two Atlantis crew would use their SAFER jet packs to check over Atlantis' tiles and leading edges for damage (Columbia
lacked SAFER packs, and the inspection EVA its crew would have gone
through would have involved much more strenuous techniques to clamber
along the orbiter's structure and get a look at the wing).
CM1 and CM2 would remove their suits and then get them ready for reuse; they would be returned by EV1 and EV2 to Columbia and stashed in the airlock, which would then be pressurized and opened. Two more Columbia
crewmembers would already have donned the spare suits shuttled over
earlier and thus become CM3 and CM4, and the same procedure would be
repeated as with CM1 and CM2.
Enlarge/ Another view of the crew transfer between
Columbia and Atlantis.
NASA / CAIB Report, Appendix D.13
The report spells out a best-case scenario where the suit donning and
doffing goes off without a hitch, and in that case, all the transfers
could be done without stopping for a break. This would mean that Atlantis' EV1 and EV2 crewmembers would be outside for somewhere between 8.5 to nine hours in a single EVA.
However, that outcome is hardly a given. Putting on a space suit is a
complex procedure on the ground, in full gravity and with multiple
sharp-eyed assistants helping out. Putting on a suit in Columbia's
middeck, possibly while still attempting to shake off the effects of
carbon dioxide poisoning, is a much dicier operation. It's made even
more complicated by the fact that for each successful crew transfer, the
number of helpers is reduced. It's possible that the operation would
have stretched to multiple EVAs—instead of nine hours, it could have
taken more than three times as long.
After the first two two-person transfers, the next transfer would
consist of a single person: CM5 would go across alone, with EV1 and EV2
assisting. This would be done because Columbia had a crew of
seven, and one person would have to do the transfer by themselves.
Leaving the last two crewmembers, CM6 and CM7, to operate as a pair at
least meant that the two would have had each other's assistance in
donning the well-used spacesuits. Ars consulted a number of sources to
gauge the difficulty of donning spacesuits without any assistance from
unsuited crew. Though none would speak on record, the consensus is that
it would involve what was universally categorized as an extremely high degree of difficulty.
Shooting star
There would be no possibility of recovering Columbia.
—Columbia Accident Investigation Board Report (Appendix D.13)
Prior to their exit, the last two members of Columbia's crew
would have some final tasks to carry out. The orbiter would need to be
readied to be placed under ground control so that it could be deorbited.
There was no chance of recovery for the shuttle itself. Even if the
wing could have been patched and cold-soaked and the shuttle's reentry
profile altered to raise the reentry angle of attack and lower the
temperature at the wing leading edge, it is unlikely that it would have
survived. Further, even if successful reentry were possible, the shuttle
could not be landed entirely from the ground—there was no way for
Mission Control to have extended the shuttle's landing gear or the air
probes necessary to judge velocity once in the atmosphere. Those
functions (as well as starting the shuttle's auxiliary power unit) could
only be invoked by physically throwing switches in the cockpit during
approach and landing.
The remaining shuttle fleet gained the ability to land totally under ground control in 2006, with the development of the RCO IFM cable,
a 28-foot (8.5-meter) braided cable that the crew could use to
physically link the cockpit with the shuttle's avionics bay and patch
Mission Control into the required switches.
Enlarge/
The landing gear switches (left) are in front of the
commander's
station. They are among the few systems that
could not be operated
remotely by ground control.
Steven Michael
For Columbia, this wasn't an option. CM6 and CM7 would have
had to proceed to the shuttle's flight deck and toggle a number of
switches into place, giving Mission Control on the ground direct command
of Columbia's guidance and maneuvering systems.
CM6 and CM7 would then depart, sealing the airlock behind them and leaving Columbia to find its own way home. Atlantis
would back slowly away from its sister ship, and its crew of 11 would
busy themselves preparing for their own crowded reentry ordeal—never
before has an orbiter landed with 11 crewmembers, and even simple things
like seating would be complicated. Some crew would literally have to
sit strapped to the floor during reentry.
At some point over the next few hours or days, ground controllers would command Columbia
to close its cargo bay doors and orient itself for what would be its
final task. The shuttle would roll its damaged thermal tiles to face
Earth and perform a retrograde burn with its large OMS engines. Shortly
after that, it would cross the entry interface.
Contrary to popular belief, the heat a spacecraft faces on reentry isn't generated by simple friction but rather by ram pressure—the
fast-moving shuttle compresses the air in front of it, forming a
massive shock zone in which air molecules ionize and break apart. As Columbia
descended, an observer on the flight deck would see the windows glow
and flare with plasma. After a short time, that plasma would invade the
shuttle's structure through the hole in its wing. Columbia's last act would be to brighten the sky over the
South Pacific, first as one glowing star and then breaking apart into
many. The remains of the oldest shuttle would pepper the surface of the
Pacific, and it would be no more.
Enlarge/ Glowing, ionized trail from Atlantis' re-entry on the
final flight of the space shuttle program. Photographed from
the ISS on July 21, 2011.
NASA
Ad astra per aspera
It should be noted that although each of the
individual elements could be completed in a best-case scenario to allow a
rescue mission to be attempted, the total risk of shortening training
and preparation time is higher than the individual elements.
—Columbia Accident Investigation Board Report (Appendix D.13)
We all love Hollywood endings, but it's difficult to envision the
rescue mission coming together with the required level of perfection.
For example, in researching this article, I was unable to discover the
number of times a shuttle has gone through an Orbital Processing
Facility, Vehicle Assembly Building, and launch pad processing flow with
no errors or faults. Based on the complexity of the machine, I suspect
that it has never happened before.
And yet, when faced with a challenge of this magnitude and with such
tremendous consequences, it's incredibly attractive to imagine NASA
rising to the task. As an agency, NASA simultaneously represents the
best and worst of the United States of America—it is responsible for
some of the greatest engineering achievements in the history of
humankind and has accomplished a long list of goals originally deemed
impossible. At the same time, the agency is also crippled by a lack of
direction and leadership; it has gone from being an organization capable
of putting human beings on other worlds to an organization that lacks
even the means to put them into low Earth orbit without assistance.
The mission to rescue Columbia, though, represents the kind
of task that NASA, since its beginnings, has demonstrated an unswerving
ability to execute. There would have been a clear goal, there would have
been hard timing requirements, and the agency's massive pool of
engineering talent would be empowered to accomplish the goal at any cost
and without restriction.
The will to win would not be lacking, but technical challenges are
ignorant of will and drive—look, for example, at the liquid oxygen tank
explosion that crippled the Apollo 13 command and service module in
1970. That explosion was the result of a combination of events that
occurred prior to launch, with potential blame stretching from the
tank's manufacturer all the way to the crew itself. The error-free rescue of Columbia
would have depended not just on the flawless execution of teams at all
of the NASA centers but also on an unknown number of events that
happened days, weeks, months, or even years in the past leading up to
the mission.
In researching this article, I spoke with a large number of current
and former NASA personnel, both inside and outside of the Missions
Operation Directorate. All were polite, but none would talk on-record
about the feasibility of the proposed Atlantis rescue mission.
The formal response I received from NASA's Public Affairs Office
respectfully but firmly informed me that the CAIB report is NASA's full
and official statement on the matter:
From NASA’s standpoint, there is nothing further to add
to the Columbia Accident Investigation Report (Chapter six and its
appendices) related to the "what if" scenario of rescuing the STS-107
crew. As you are aware, it is spelled out very clearly that there would
have to have been a very large number of "knowns" to have executed a
rescue or repair mission for Columbia at that time.
...
Beyond that, we respectfully decline any specific interviews on the
subject and reference you to the CAIB report for the detailed analysis
provided during the investigation of the Columbia accident.
Ultimately, Appendix D.13 is a well-informed, research-backed
exercise in speculation, constructed by engineers who were intimately
familiar with shuttle program operations. My telling of the rescue's
story is not intended to criticize or damn NASA for its actions, nor am I
attempting from a position of historical privilege to second guess the
decision-makers who to this day must live with the grave consequences of
the choices made. Columbia and its crew almost certainly could
not have been rescued without too many "ifs" having fallen the other
way. I can tell the story of what might have been the most awe-inspiring
moment in all of human space flight, but I am profoundly unqualified to
speculate beyond the boundaries of the CAIB report.
It's an amazing story—but it's only a story.
The long road back
It is unlikely that launching a space vehicle
will ever be as routine an undertaking as commercial air
travel—certainly not in the lifetime of anybody who reads this. The
scientists and engineers continually work on better ways, but if we want
to continue going into outer space, we must continue to accept the
risks.
—Columbia Accident Investigation Board Report
It took 907 days after Columbia's destruction for NASA to return to flight. STS-114—flown by Discovery instead of Atlantis—lifted
off from the Cape on July 26, 2005. I remember it very well—now as a
not-so-junior system administrator, I watched helplessly as the sheer
number of Boeing employees streaming the countdown and launch video from
NASA TV saturated our site's Internet link, which somewhat hilariously
almost caused site management to try to request a launch hold (Boeing's
Houston office provided shuttle support, and some of those support
activities needed that same Internet link to function). The launch was a
success.
Starting with STS-114, no shuttle would fly without a rescue shuttle
on standby. These planned emergency flights (numbered STS-3xx) were
called LON missions,
for "Launch On Need." In the event of trouble on a shuttle mission,
crews would rendezvous with the ISS and shelter there for up to 50 days,
while the LON shuttle would be made ready to fly to retrieve them.
The one exception to this was the final Hubble servicing mission,
STS-125. The orbital height and inclination of the Hubble made the
mission totally incompatible with an emergency ISS rendezvous in the
event of trouble, so a plan based partially on the Atlantis/Columbia rescue was drafted. The STS-125 LON mission would have been dubbed STS-400. Because the ISS wasn't available, STS-400's Endeavour needed to be ready to launch on short notice; this led to the final instance of what was already a rare sight: two shuttles staged at LC-39 simultaneously
The LON missions were never needed, and the shuttle program finished
without any other significant incidents. Foam strikes were not
eliminated, but post-launch analysis of each shuttle was increased. It
is a virtual certainty that future NASA manned spacecraft will return to
their rightful place on top of launch vehicles rather than being slung
on their sides. NASA's culture continues to evolve; it is impossible to
say at this point if the lessons of Columbia have been fully inculcated into the agency.
I was there for the aftermath and the return to flight, but
agency-wide policy changes are things that happened far above my pay
grade. The thing I remember more than anything else, the single most
vivid memory of them all, is of the memorial service the Tuesday after Columbia's destruction.
February 4, 2003
This cause of exploration and discovery is
not an option we choose—it is a desire written in the human heart. We
are that part of creation which seeks to understand all creation. We
find the best among us, send them forth into unmapped darkness, and pray
they will return. They go in peace for all mankind, and all mankind is
in their debt.
—President George W. Bush, addressing personnel at the Johnson Space Center
We arrived at the Johnson Space Center at about 9:30am, having been
told that space would be limited for the service, which was to start at
noon. After a half-mile of walking and a security checkpoint, we stood
in the central mall by Building 16, lost amid a sea of people. The stage
and podium were far away on the other side of the grassy field, and we
passed the two-and-a-half hours in uncomfortable, standing silence.
After a long wait, Air Force One, trailed by three F-15s, circled on its
way down to Ellington Field. The crowd swelled to its maximum just
after 11. At noon, with no fanfare, President Bush and First Lady Laura
Bush walked together to their place on the stage. They held hands, which
stuck in my mind—even the most powerful man in the world holds hands
with his wife.
There was an invocation, and then words from NASA's director and the
chief of the Astronaut Corps. Both paid tribute to each astronaut
individually, and the Corps chief clearly had to fight to keep back
tears. The president stepped to the podium next and spoke eloquently
about the human spirit. The only even vaguely political words that left
his mouth were ultimately topical—he said that the space program would
continue. Then he, too, spoke of each astronaut individually, praising
their daring and dedication.
A ship's bell tolled seven times, once for each of Columbia's
crew, and then four NASA T-38s flew over in the missing man formation.
The jets moved in low and fast, streaking toward us in a wedge less than
250 feet off the ground. As they passed overhead, the second jet back
on the left side of the formation peeled sharply upward, right as the
roar of the engines hammered at us. The missing man jet arched high and
straight as the formation continued onward, now with an empty spot to
recognize that there were men and women who were no longer with us.
I have never before witnessed anything so profoundly moving as that
trio of jets hurtling low over the rest of the campus, with their
missing comrade thousands of feet above and rocketing higher still. I
will remember it forever.
Godspeed, Columbia.
No comments:
Post a Comment