A Lifeline in Space
1994 — Astronauts Test a New Way to Rescue Themselves in
Space
EVA time: approximately 08:42–15:33 UTC
On September 16, 1994, astronauts Mark C. Lee and Carl
J. Meade stepped outside Space Shuttle Discovery during mission
STS-64 and deliberately did something spacewalkers normally work very hard to
avoid: they floated freely away from their spacecraft.
They were testing a new device called the Simplified Aid
for EVA Rescue, better known as SAFER.
SAFER was conceived as an emergency rescue system.
Astronauts performing extravehicular activity normally remain connected to
their spacecraft by safety tethers. But engineers had to consider a frightening
possibility: What would happen if a spacewalker somehow became completely
untethered and began drifting away?
Without some means of propulsion, the astronaut might have
no way to return.
SAFER provided an answer. The compact unit was worn like a
backpack over the astronaut's spacesuit and used small jets of compressed
nitrogen controlled by the astronaut. Unlike the much larger Manned Maneuvering
Unit used during several Shuttle flights in 1984, SAFER was not intended
primarily as a vehicle for routine untethered maneuvering. It was an emergency
system—a kind of life jacket for space.
During their six-hour, 51-minute spacewalk, Lee and Meade
took turns flying the device untethered near Discovery. They maneuvered
above and around the Shuttle's payload bay while evaluating SAFER's controls
and handling characteristics. The tests demonstrated that an astronaut who
accidentally became separated from a spacecraft could potentially maneuver back
to safety.
The technology subsequently became part of normal
spacewalking safety procedures. Astronauts conducting spacewalks outside the
International Space Station wear SAFER units as an emergency backup should
their tethers fail.
Why It Matters: SAFER addressed one of the most
dangerous conceivable emergencies during a spacewalk: an astronaut drifting
helplessly away from the spacecraft. The September 16 test transformed an
emergency-rescue concept into demonstrated technology and helped make future
extravehicular activity safer.
Also on This Day
1978 — A Total Lunar Eclipse Crosses Earth's Shadow
Greatest eclipse: 19:04:12 UTC
On September 16, 1978, the Moon passed completely through
the darkest portion of Earth's shadow, producing a total lunar eclipse.
The eclipse began when the Moon entered Earth's penumbral
shadow at approximately 16:22 UTC. The partial phase began around 17:21
UTC, and totality began at approximately 18:25 UTC.
At 19:04:12 UTC, the eclipse reached its greatest
phase. Totality lasted approximately 78 minutes and 39 seconds, ending
around 19:44 UTC. The Moon finally left Earth's penumbral shadow at
approximately 21:46 UTC.
A lunar eclipse occurs because Earth moves directly between
the Sun and the Moon. During totality, the Moon does not normally disappear
completely. Sunlight passing through Earth's atmosphere is refracted into
Earth's shadow, while shorter blue wavelengths are scattered more efficiently.
The remaining reddish light can illuminate the lunar surface, producing the
familiar copper or red appearance of a totally eclipsed Moon.
The September 1978 eclipse had an umbral magnitude of
approximately 1.327, meaning the Moon passed deeply enough into Earth's
umbra that its entire disk was immersed in the central shadow.
Why It Matters: Lunar eclipses are among the most
accessible demonstrations of celestial mechanics. Long before spacecraft
existed, observations of Earth's curved shadow crossing the Moon helped
reinforce the understanding that Earth is spherical. Modern eclipse predictions
also demonstrate the remarkable precision with which the motions of Earth,
Moon, and Sun can be calculated.
1996 — Atlantis Launches on the First American Crew
Exchange at Mir
08:54:49 UTC
On September 16, 1996, at 08:54:49 UTC, Space Shuttle
Atlantis lifted off from Kennedy Space Center on mission STS-79,
beginning the fourth Shuttle docking mission with the Russian space station
Mir.
The mission represented an important development in
American-Russian cooperation in space. Astronaut John Blaha traveled
aboard Atlantis to begin a long-duration stay on Mir, while astronaut Shannon
Lucid, already aboard the Russian station, would return to Earth aboard the
Shuttle.
Lucid had arrived at Mir in March. Delays in launching
STS-79 extended her mission to 188 days, establishing at the time both a
new American space-duration record and a world record for a woman.
STS-79 also carried the first double SPACEHAB module,
providing additional room for equipment and supplies. During the docked portion
of the mission, the Shuttle and Mir crews transferred thousands of pounds of
water, supplies, experiments, and equipment between the two spacecraft.
The launch itself had encountered unusual delays. Atlantis
had been rolled back from its launch pad twice because of threats from
Hurricanes Bertha and Fran—the first time a Shuttle had undergone two
hurricane-related rollbacks during a single processing cycle.
Why It Matters: STS-79 conducted the first exchange
of American long-duration crew members aboard Mir. The Shuttle-Mir program
required American and Russian flight controllers, engineers, astronauts, and
cosmonauts to learn how to operate together for extended periods—a body of
experience that helped prepare both nations for their partnership aboard the
International Space Station.
2015 — A Sounding Rocket Fires a Record 44 Rocket Engines
Time not established
On September 16, 2015, a NASA Black Brant XI sounding
rocket launched from Andøya, Norway, carrying the Charged Aerosol
Release Experiment II, or CARE II.
The flight investigated dusty plasmas—mixtures
containing electrically charged particles and small grains of matter that occur
naturally in portions of Earth's upper atmosphere and elsewhere in space.
But the mission also achieved an unusual engineering record.
During the flight, 44 rocket engines were fired,
earning recognition from Guinness World Records for the greatest number of
rocket engines fired during a single flight. Only three provided the principal
propulsion for launching the vehicle. Four others served as spin motors, while
many of the remaining motors were used to create the artificial exhaust cloud
required for the scientific experiment.
The mission is a useful reminder that not all significant
space research requires an orbital spacecraft. Sounding rockets can carry
experiments above most of Earth's atmosphere for relatively brief flights,
allowing scientists to investigate phenomena that are difficult or impossible
to reproduce at ground level.
Why It Matters: CARE II combined an unusual
engineering achievement with scientific investigation of the upper atmosphere.
Sounding rockets remain an important—and comparatively economical—bridge
between laboratory research on Earth and longer-duration experiments conducted
in orbit.
The Bigger Picture
September 16 reminds us that exploring space requires more
than simply finding ways to travel farther from Earth.
The 1978 lunar eclipse represents astronomy in one of
its oldest forms: watching the predictable motions of celestial bodies from the
ground and learning about the geometry of our solar system.
The 1994 SAFER experiment addressed a very different
problem. Once humans began leaving their spacecraft to work in the vacuum of
space, engineers had to devise ways of protecting them when something went
wrong.
Two years later, STS-79 demonstrated another
essential development: cooperation. The United States and Russia, whose earlier
space programs had developed largely as rivals, were exchanging crew members
aboard Mir and learning how to conduct long-duration missions together.
And the CARE II mission reminds us that even in an
era of sophisticated planetary probes and enormous orbital laboratories,
relatively small sounding rockets continue to make valuable contributions to
space science.
Together, these events illustrate four complementary aspects
of humanity's relationship with space: observing it, learning to survive in
it, learning to work together within it, and continuing to devise new ways to
study it.
The history of space exploration is therefore not simply a
succession of destinations. It is also the story of gradually acquiring the
knowledge, technologies, safeguards, and partnerships necessary for human
beings to operate beyond their home world.
At a Glance
1978 — 19:04:12 UTC — A total lunar eclipse reaches
greatest eclipse; totality lasts approximately 78 minutes and 39 seconds.
1994 — Approximately 08:42–15:33 UTC — Astronauts
Mark Lee and Carl Meade conduct an STS-64 spacewalk and perform the first
in-space tests of the SAFER emergency maneuvering system.
1996 — 08:54:49 UTC — Space Shuttle Atlantis
launches on STS-79, beginning the first American long-duration crew exchange at
Russia's Mir space station.
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