Focusing
on what went wrong with the landing of SpaceX is to ignore the many other
things that went astonishingly right.
By Rand Simberg in PJ Media
Most reports of Saturday morning’s
flight by SpaceX to the International Space Station note that the primary
mission was successful, but that the company “failed” to stick the landing. For
example, Andy Pasztor at the Wall Street Journal once again
lived up to his reputation of a willing (and often unfair) basher of the
company, and initially used the word “botched” to describe it in the lede graf.
(“It now says “spoiled,”
though the headline still says the company “stumbles,” but here is a version of
the original from Marketwatch.)
Though, to be fair, the rest of the piece seems well reported.
But to focus on what went wrong is
to ignore the many other things that went astonishingly right, and just how close the company came this time to achieving
their long-time goal of recovering the first stage of the Falcon rocket. As
with the too-much-bewailed loss of its test vehicle in Texas this past summer (and the destruction of SpaceShipTwo this past Halloween), it is important to understand
that this was a test flight and, as with any test flight, they were pushing the
envelope to find out how the system worked in practice as opposed to theory. It
was an experiment, and the only failed experiment is one in which nothing is
learned.
In the ’40s, ’50s and ’60s, the NACA
and, later, NASA had many flight-test programs to learn how to do new things,
gradually expanding performance envelopes, often breaking airplanes (and
killing pilots), but with the advent of the Shuttle and reliance (some would
say over-reliance) on computer simulations, the agency has developed a tendency
to instead spend months and years in analysis, without flying. The very first
(delayed) flight of the Shuttle was not only all the way to orbit, but with a
crew. The X-34B program in the ’90s was in fact canceled before it ever flew,
even though the vehicle was complete, because NASA, in its risk aversion
after the loss of a planetary probe, decided in retrospect that it shouldn’t be attempted without sufficient redundancy in key systems.
But SpaceX has picked up where the
government left off, building, flying, testing and learning, then rebuilding
and reflying. Its first three Falcon 1 flights all failed to deliver their
payloads, but with each failure, they learned a lesson that was applied to the
next flight. On the fourth flight, they succeeded, as on the fifth. The larger
Falcon 9, based on the lessons learned from the Falcon 1 program, has never had
a primary-mission failure. Now, they’re flight testing again, with the first
stage, but only after it has completed its crucial job of getting the second
stage and payload on their way to orbit.
The company understands that the key
to reducing launch costs is to minimize the degree to which hardware is thrown
way. The first stage, with its nine engines, is reportedly about 70% of the
total vehicle cost, and the easiest part to recover, in theory. They’ve been
attempting it from the beginning, but it had always broken up on entry. With
the realization they’d have to sacrifice some performance in order to save
enough propellant to safely enter and land, they increased the size of the
vehicle to allow it to carry more. Since then, they have been slowly
approaching a successful recovery, first with soft landings in the water, which
still destroyed the vehicles, and then, this past weekend, with the first
attempt at a precision landing on a hard surface.
What had to go right this weekend
for them to land the stage intact? First, after stage separation, it would have
to relight its nine engines to slow down from about 3000 mph to an entry speed
that wouldn’t break up the vehicle. After entry, another relight would have to
occur to aim the vehicle toward the drone ship on which it was planned to land,
and fins would be deployed to help steer it. Finally just before entry, one
more relight would be required for a soft landing, with guidance continuing to
be aided by the fins. It would be the most precise flight ever achieved
(previous water landings hadn’t been particular about location).
With the exception of the final
landing itself, almost everything went according to plan. The vehicle entered
intact, flew to the ship, and (apparently literally) hit the deck, because the
hydraulic fluid that controlled the fins ran short by 10% of that needed to
control and softly land. But in so doing, it accomplished another major
“first,” not just for a private company, but for any space ship. Previous
Falcon flights had demonstrated the ability to enter the stage intact by
retrothrusting (as opposed to simply braking against the atmosphere), but this
was the first time such a vehicle had not only survived entry, but flown
precisely to a pre-designated location, without wings.
Pictures of the drone ship being
towed into port in Jacksonville, Florida, on Sunday showed some charring, and
the company reported that while the ship itself was undamaged, some of the
support equipment on the deck would have to be rebuilt or replaced. And as Elon
Musk, the company’s CEO, tweeted Saturday morning, they would piece together
what happened “from telemetry, and…actual pieces.”
Musk had previously “estimated” a “50% chance” of
success (though more recently he admitted that this figure was arrived at, shall we say “ex
posteriori” aka a wild-ass guess). So I expect that while he would have
preferred a total success, he and the company must actually be quite elated. He
later noted that they would have a 50% margin on the fin hydraulics on the next
attempt, in February, so barring some analysis indicating why they
underestimated the amount required on this flight that requires some other
change, it would appear that their chances of success for that one will be much
greater than 50%.
It’s interesting to note that while
the company had been doing flight tests in Texas, first with its early
“Grasshopper,” and more recently with the converted first stage that it lost
last summer, that may be over. We’ve heard of no more flight tests, either in
Texas or (as the company had long been planning) in New Mexico at Spaceport
America. That is, they may now feel confident in moving forward by testing only
on operational launches, with no more need for dedicated test vehicles and flight
tests.
If they succeed next month, it will
be another huge first: the first time that a spaceship has landed on earth
since the last Shuttle retired, and the first time any spaceship has landed on
earth vertically, using only propulsion. The next step will be to determine how
much it will take to reliably (and rapidly) reuse the stage. If the answer is
“not much,” it will mean a revolution in reducing the cost of access to space.
SpaceX’s competitors are watching carefully. CNES, the company that builds Europe’s
Ariane, recently announced its own project to make its vehicles reusable, though not for many years. Tory Bruno, the new CEO of the
United Launch Alliance, which operates the Atlas and Delta launch systems, will
be announcing the company’s plans for its own new launch systems next month,
and many (including me) will be surprised if reusability isn’t a key part of
them.
Rand Simberg is a recovering
aerospace engineer and a consultant in space commercialization, space tourism
and Internet security. He offers occasionally biting commentary about infinity
and beyond at his weblog, Transterrestrial
Musings.
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