The inside story of New Horizons’ ‘Apollo 13’ moment on its way to Pluto
Flight controllers Sarah Bucier, left, Dan
Kelly and Chris Regan monitor data being sent back by the New Horizons
spacecraft as it nears Pluto, on July 8 at the Johns Hopkins University
Applied Physics Laboratory in Laurel, Md. (J.M. Eddins Jr./for The
Washington Post)
The people in the Mission Operations Center — “the MOC” — had been
tracking NASA’s New Horizons spacecraft for 9½ years as it journeyed the
breadth of the solar system. It was just 10 days away from the dwarf
planet Pluto when, at 1:55 p.m. on July 4, it vanished.
Gone.
“OUT OF LOCK,” a computer screen declared.
No more data, no connection at all. As if the spacecraft had plunged into a black hole. Or hit an asteroid and disintegrated.
Mission
Operations manager Alice Bowman called the project manager, Glen
Fountain, who was spending the afternoon of July 4 at home.
“We just lost telemetry,” she told him.
He
raced to the MOC, in the Johns Hopkins University Applied Physics
Laboratory (APL) in Laurel, Md. Also arriving within minutes was the
mission’s leader, Alan Stern, a planetary scientist. Everyone canceled
July 4 plans. They weren’t going home tonight. This was a sleep-on-the-office-floor crisis.
“I stayed on the floor, and it was probably one of the best 15- or 20-minute sleeps I’ve ever had,” Bowman says.
The
official story from NASA and APL officials over the next two days was
this was an “anomaly,” and the team had resolved the issues and gotten
the spacecraft back in shape for the Pluto flyby. But this was no mere
glitch. This was almost a disaster. This was, as Stern would later
admit, “our Apollo 13.”
The disappearance of the spacecraft
challenged the New Horizons team to perform at its highest level and
under the greatest of deadline pressures.
The nature of
the New Horizons mission
did not permit any wiggle room, any delays, any do-overs, because it
was a flyby. The spacecraft had one shot at Pluto, tightly scheduled:
When it vanished, New Horizons was going about 32,000 miles per hour and
on track to make its closest pass to Pluto, about 7,800 miles, at
precisely 7:49 a.m. July 14.
But as the New Horizons team gathered in the control room on July 4, no one knew whether their spacecraft was still alive.
The scene of all this drama is a place with a proud history but a
remarkably low profile. Raise your hand if you’ve heard of the Applied
Physics Laboratory. Raise the other hand if you’ve heard of its slogan,
“Critical Contributions to Critical Challenges.”
It’s a sprawling
place, hidden in plain sight just west of Route 29 between Washington
and Baltimore. The campus has 20 major buildings on 453 acres. It has
5,000 full-time and 400 part-time employees, making it the largest
employer in Howard County.
But its staff can’t discuss many specifics. The stealthy nature of
the lab reflects its heavy load of classified research. Major funders
include the military (the Navy, in particular), the Department of
Homeland Security and the intelligence community.
APL was
established during World War II and originally housed in a used-car
dealership in Silver Spring. It has racked up a long list of
technological achievements including missile guidance and
satellite-based navigation. Researchers here today are finding ways to
protect soldiers from blast injuries. They have created a prosthetic arm
with 26 joints and 17 motors that can curl 45 pounds, tweeze 20 pounds
between two fingers and be controlled entirely by brain signals.
When
people think of a lab that makes robotic probes that explore the solar
system, they usually think of NASA’s Jet Propulsion Laboratory in
Pasadena, Calif. But APL has a boutique spaceflight operation funded by
NASA contracts, accounting for about 20 percent of the lab’s overall
workload. APL has built and operated 68 spacecraft over the years,
including the Messenger spacecraft that recently explored Mercury. But
despite many successes, APL has never had a mission guaranteed to get as
much media coverage as New Horizons.
“This is a big deal,” says Ralph Semmel, the director of APL.
A rocket carrying the New Horizons spacecraft
on a mission to Pluto lifts off in January 2006 in Cape Canaveral, Fla.
(Terry Renna/AP)
Because New Horizons is so far away, it takes 4
1/
2 hours
for a one-way message between the spacecraft and the MOC. That means
whatever happened to New Horizons on July 4 had actually happened 4
1/
2 hours before the people in Mission Operations knew about it.
That also meant that any instructions to the spacecraft would take 4
1/
2 hours to get there.
This wasn’t like talking to a robotic vehicle parked on the moon; a signal there or back takes little more than one second.
The
team in the MOC knew that one possibility, very remote, was that the
spacecraft had hit something. It’s going so fast that it could be
disabled by a collision with something as small as a grain of rice. But
there’s no rice near Pluto and, although there are dust particles,
rocks, boulders and a few moons, space is really spacious in three
dimensions. The odds of New Horizons hitting anything during this
journey — especially while still millions of miles from the Pluto system
— are extremely low.
“That would be extraordinarily bad luck,” project manager Fountain said.
Still,
with the spacecraft lost at the edge of the solar system, no one knew
what had happened or whether they would ever hear from it again.
They
ran through the most likely causes of the anomaly. They had two fairly
simple scenarios. The first was that, for some reason, the main computer
had rebooted itself. That had happened a few times in the past.
The
second scenario was that the spacecraft sensed something amiss and, as
it is programmed to do, powered down the main computer and switched
operations to the backup computer. That had never happened before.
If
the backup computer had, in fact, taken over communications with Earth,
it would use a slightly different radio frequency and transmission
rate.
The APL team decided to check that second scenario straightaway. The
team sent a new set of instructions to NASA’s Deep Space Network — the
trio of huge radio antennas in California, Spain and Australia that are
responsible for communicating with New Horizons and many other
spacecraft. The dish in Australia began searching for New Horizons at
the new frequency.
Everyone waited.
Three o’clock came and went.
At 3:11 p.m., one word flashed on screen in the MOC.
“LOCKED.”
The big dish and New Horizons had established a radio handshake, with data following almost immediately.
Bowman thought: Thank God, the spacecraft’s there, it’s alive.
But the
crisis was hardly over. New Horizons had gone into safe mode. That
involves shutting down instruments and noncritical systems. The
spacecraft also automatically turns back toward Earth and goes into a
controlled spin of five revolutions per minute. The spinning makes
navigation easier, but it also makes most scientific observations
impossible. A spinning New Horizons could not take photos of Pluto.
The
team figured out what had gone wrong. The spacecraft’s main computer
had been compressing new scientific data for downloading much later. At
the same time, it was supposed to execute some previously uploaded
commands. It got overloaded; the spacecraft has an “autonomy” system
that can decide what to do if something’s not quite right. That system
decided to switch from the main to the backup computer and go into safe
mode.
The spacecraft had been in safe mode before — but this was terrible timing. They were just days from Pluto.
“We were down to the wire,” Bowman said.
No
one on the team got angry or lost his or her poise, she said: “All of
us, I think, were feeling terrible that this had happened, but we were
focused solely on getting that spacecraft back into an operational state
so that we could do this flyby.”
On Twitter, anyone following the mission July 4 learned of the “anomaly.”
An official New Horizons account (
@NewHorizons2015) offered an elliptical statement: “New Horizons in safe mode. We’re working it folks.”
The
APL team had to reconfigure New Horizons the way you would rouse a
drunk on a Sunday morning to get him ready for church. This required
many commands, everything made slower by the nine-hour round-trip
communication challenge across the 3 billion miles of space. Bowman
slept on her office floor a second night on Sunday.
One key
decision: return control of the spacecraft to the main computer. They
trusted the main computer, knew its quirks, had tested it repeatedly —
unlike the backup computer. Their plan didn’t require them to ask the
main computer to do the kind of heavy-duty work that caused the glitch
Saturday.
On Tuesday morning, July 7, the New Horizons team
returned their spacecraft to no-spin mode and prepared it for the Pluto
encounter.
This period of reconfiguration was a bit nerve-racking
inside the MOC, because it required another blackout period of an hour
and 15 minutes as the spacecraft lost contact with the ground.
At
10:21 a.m. Tuesday, the spacecraft popped back up on the screen —
healthy, on track, wide awake. At 12:30 p.m. Tuesday, New Horizons began
executing the encounter sequence as programmed.
Huge relief at APL: On to Pluto!
In
a news briefing Monday afternoon, with the recovery process ongoing,
Stern had described the “anomaly” of July 4 as “a speed bump.” He and
his colleagues downplayed the distressing nature of the event. That’s
standard procedure for engineers and scientists: Admit no alarm.
Proclaim competence and preparedness.
But
in an e-mail later, Stern compared the incident to NASA’s most famous
emergency: “No lives were at stake, but in terms of mission success and
time criticality, this was our Apollo 13. And it was our spacecraft and
operations team’s finest hour.”
As she stood this week in the
MOC, a few feet from a mural declaring “The Year of Pluto,” Bowman
acknowledged the obvious: “It was very intense.”
Pluto, right, and its moon Charon are pictured
from about 3.7 million miles away in this July 8 photo from New
Horizons. (NASA/via Reuters)
NB~~~~~~~~~~~~~~~~
But
in an e-mail later, Stern compared the incident to NASA’s most famous
emergency: ""“No lives were at stake, but in terms of mission success and
time criticality, this was our Apollo 13. And it was our spacecraft and
operations team’s "finest hour.”""
Pluto and Us
by Charles Krauthammer
We need a pick-me-up. Amid the
vandalizing of Palmyra, the
imminent extinction
of the northern white rhino, the disarray threatening Europe’s most
ambitious attempt ever at peaceful unification — amid plague and
pestilence and, by God, in the middle of Shark Week — where can humanity
turn for uplift?
Meet
New Horizons,
arriving at Pluto on July 14. Small and light, the fastest spacecraft
ever launched, it left Earth with such velocity that it shot past our
moon in nine hours. A speeding bullet the size of a Steinway, it has
flown 9½
years to the outer edges of the solar system.
Charles Krauthammer writes a weekly political column that runs on Fridays.
To Pluto, the now-demoted “
dwarf planet”
that lives beyond the Original Eight in the far distant “third zone” of
the solar system — the Kuiper Belt, an unimaginably huge ring of rocks
and ice and sundry debris where the dwarf is king.
After 3 billion miles, New Horizons will on Tuesday shoot right
through Pluto’s mini-planetary system of five moons, the magnificently
named Charon, Styx, Nix, Hydra and Kerberos.
Why through?
Because, while the other planets lie on roughly the same plane, Pluto
and its moon system stick up at an angle to that plane like a giant
archery target. New Horizons gets one pass, going straight by the
bull’s-eye. No orbiting around, no lingering for months or even years to
photograph and study.
No mulligans. And no navigating. Can’t do that when it takes 4½
hours for a message from Earth to arrive. This is a pre-programmed, single-take, nine-day deal.
For
what? First, for the science, the coming avalanche of new knowledge.
Remember: We didn’t even know there was a Pluto until 85 years ago when
astronomer
Clyde Tombaugh found a strange tiny dot moving across the star field.
Today,
we still know practically nothing. In fact, two of the five moons were
not discovered until after New Horizons was launched. And yet next week
we will see an entirely new world come to life. “We’re not planning to
rewrite any textbooks,” said principal investigator Alan Stern in a
splendid
New York Times documentary on the mission. “We’re planning to write them from scratch.”
Then
there’s the romance. The Pluto fly-by caps a half-century of solar
system exploration that has yielded staggering new wonders. Such as
Europa, one of Jupiter’s moons,
with its vast subterranean ocean under a crust of surface ice, the most
inviting potential habitat for extraterrestrial life that human beings
will ever reach.
Yes, ever. Promising exoplanets — the ones
circling distant stars that we deduce might offer a Goldilocks zone
suitable for water-based life — are being discovered by the week. But
they are unreachable. The journey to even the nearest would, at New
Horizons speed, take 280,000 years. Even mere communication would be
absurdly difficult. A single exchange of greetings — “Hi there,”
followed by “Back at you, brother” — would take a generation.
It’s the galactic version of the old Trappist monastery joke where
every seven years one monk at one meal is allowed one remark. A young
novice arrives and after seven years a monk stands up at dinner and
says: “The soup is cold.”
Seven years of silence. Then another monk stands and says: “The bread is stale.”
Seven years later, the now-aging novice rises and says: “If you don’t stop this bickering, I’m outta here.”
Which
is what a conversation with Klingons would be like, except with longer
intervals. Which is why we prefer to scour our own solar system. And for
more than just the science, more than just the romance. Here we are,
upright bipeds with opposable thumbs, barely down from the trees, until
yesterday unable to fly, to communicate at a distance, to reproduce a
sound or motion or even an image — and even today barely able to manage
the elementary decencies of civilization — taking
close-up pictures and chemical readings of a mysterious world 9½
years away.
One
final touch. Every ounce of superfluous weight has been stripped from
New Horizons to give it more speed and pack more instruments. Yet there
was one concession to poetry. New Horizons is carrying some of Clyde
Tombaugh’s ashes. After all, he found the dot. Not only will he fly by
his netherworldly discovery, notes Carter Emmart of the American Museum
of Natural History, he will become the first human being to have his
remains carried beyond the solar system.
For the wretched race of beings we surely are, we do, on occasion, manage to soar.
Read more from Charles Krauthammer’s archive, follow him on Twitter or subscribe to his updates on Facebook.
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Hickok
