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NASA Gives Green Light to Sock a Comet
Artificial Intelligence to Command Mission
Apollo Vestiges Spotted on the Moon
Deep Space Network Upgraded for “Crunch Time”
Postcards from the
Edge:
Pioneer 10 Keeps Going and Going . . .
The Advent of Genesis
The advent of NASA’s next Discovery-class mission, “Genesis,”
at the Kennedy Space Center has set the stage for the spacecraft’s launch
aboard a Boeing Delta II vehicle on 30 July. The genesis of the Genesis mission
was a desire by researchers to capture a piece of the Sun — ions and elements
in the solar wind — and bring samples back to Earth to study the exact
composition of our star and probe the solar system’s origin. If all goes
as planned, Genesis will journey to the L-1 Libration point — where the
gravitational and centrifugal pull of the Sun and Earth are balanced —and
collect samples of charged solar particles. “This will be the first mission
since the days of Apollo to return extraterrestrial material for study,”
said Roger Wiens, a Genesis scientist from Los Alamos National Laboratory.
According to Genesis Principal Investigator, Donald Burnett, the sample of solar
system matter will allow scientists to address fundamental questions about the
solar and nebular compositions, and test theories about the origin of the Sun
and the planets at the beginning of the solar system. Once Genesis enters its
halo-like orbit, 1.5 million kilometers from Earth, the spacecraft will extend
special Collector Arrays to trap isotopic samples of oxygen, nitrogen, the noble
gases, and other elements, while an electrostatic mirror concentrates the solar
wind particles. The $216 million probe also features ion and electron monitors
to determine the ambient solar wind conditions. “The concentrator addresses
the mission’s primary scientific objectives [and] the monitors will be
used to guide the mission’s operations,” explained Dave McComas, a
Genesis co-investigator from Los Alamos.
Exposed to the solar windstorm, the Collector Arrays will capture a few millionths
of a gram of ions and particles, which will be carefully stowed in a contamination-proof
canister within a sample, return capsule. The solar samples will return to Earth
in a spectacular airborne capture over Utah’s Air Force Testing and Training
Range. The samples will then be analyzed to provide a solar matter “Rosetta
Stone,” for comparing the solar nebula’s composition to those of the
planets and other solar system bodies.
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NASA Gives Green
Light to Sock a Comet
Taking a page from a science fiction movie script, the U.S. space agency has
OK’d a mission to KO a comet in an attempt to peer beneath its icy surface.
The mission, appropriately dubbed “Deep Impact,” will intercept a
comet in deep space and use a 350-kilogram copper cannonball, equipped with
a camera, to blow a hole in the celestial body, some seven stories deep and
about the size of a football field. Scheduled for launch in January 2004, the
sharp-shooting spacecraft will take aim at its intended victim — Comet
Tempel 1 — in July 2005.
The broadside loosed by Deep Impact as it flies by Comet Tempel 1 will slam
into the cosmic snowball at 35,700 kilometers per hour and blast icy material
into space with the force of its impact. With the comet still in its the crosshairs,
a camera and infrared spectrometer onboard the flyby spacecraft, along with
ground-based observatories, will study the icy debris and pristine interior
material exposed by the spacecraft’s salvo. Researchers hope the impact
will allow them to measure freshly exposed material and study samples hidden
deep below the surface of the comet, which could help determine whether comets
exhaust their supply of gas and ice to space or seal it into their interiors.
Comet Tempel 1, discovered in 1867, makes an ideal target for Deep Impact since
it orbits the sun every five and a half years, and frequently passes through
the inner solar system, which causes evolutionary change in the mantle and upper
crust. The $279 million mission to hit this cometary bulls eye is the latest
lower-cost, highly focused Discovery mission to be approved by NASA. Three Discovery
missions have completed their flight, one is operational — “Stardust”
— and two others, in addition to Deep Impact, are under development, including
the “Genesis” mission and The Comet Nucleus Tour (CONTOUR) mission.
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Artificial Intelligence
to Command Mission
New HAL-like software that thinks for itself and makes decisions without help
from ground controllers will provide the brainpower for a constellation of NASA
satellites in 2002. The so-called Continuous Activity Scheduling, Planning Execution
and Replanning software — shortened to the acronym CASPER — will guide
three identical miniature satellites, each weighing less than 15 kilograms,
as part of the “Three Corner Sat” mission, which aims to demonstrate
formation flying, and innovative operations and commanding. The new-fangled
software and clever computers build on previous efforts to use artificial intelligence
to control a spacecraft — such as “Deep Space 1” — but this
new software takes advantage of more advanced technology to continuously command
a mission for about three months and respond quickly to events.
“The onboard software performs the decision-making function for the spacecraft.
Like a brain that uses inputs from the eyes and ears to make decisions, this
software uses data from spacecraft sensors, such as cameras, to make decisions
on how to carry out the mission,” said Steve Chien, principal scientist
and lead researcher in automated planning and scheduling technologies at NASA’s
Jet Propulsion Laboratory (JPL).
The specter of CASPER software controlling spacecraft for months at a time represents
a dramatic shift in the way mission operations are conducted. Typically, all
science data, good or bad, is sent back to Earth. The CASPER software will have
the ability to make real-time decisions based on the images it acquires and
send back only those that it deems important. Consequently, less time will be
needed to transmit data, freeing up power and allowing the spacecraft to concentrate
on other important tasks.
“This capability represents a significant advance from traditional ground-based
operations and [promises]...to dramatically increase mission science for this
and future missions,” said Colette Wilklow, Three Corner Sat mission operations
team member. If smart software like CASPER proves successful, similar decision-making
capabilities could be incorporated into a wide range of NASA applications including
automated ground communications stations, autonomous planetary rovers and autonomous
robot aircraft.
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Apollo Vestiges Spotted on the Moon
Evidence that long ago humans actually traveled to other worlds has been spotted
on the lunar surface by researchers pouring over photos taken by “Clementine,”
the former lunar-orbiting Defense Department probe. Misha Kreslavsky, a space
scientist in the department of geological sciences at Brown University, found
anomalies in the lunar surface in the vicinity of the Apollo 15 landing site
near the Moon’s Apennine Mountains. It was in the shadow of those mountains
that Moonwalkers David Scott and James Irwin scuffed up the lunar surface and
left 25 kilometers of tire tracks from an electric-powered car during their
three-day lunar stay in 1971.
Pouring over images from Clementine to locate fresh impacts or recent seismic
activity on the Moon, Kreslavsky spotted smudges on the lunar surface precisely
where the all-Air Force crew had landed in their lunar module Falcon. “This
is a result of my processing 52 images taken by the Clementine spacecraft through
a red filter,” Kreslavsky explained. Several anomalies can be seen on the
processed images, including a diffuse dark spot at the landing site. “All
of them but one are related to small fresh impact craters. The only one not
related to any crater, exactly coincides with the landing site,” Kreslavsky
added. The disruption in the lunar regolith, which measures a 50 to 150-meter
radius around the landing site, was probably created by the lunar module’s
engine during touchdown. “Unfortunately, the Clementine data do not allow
similar studies for any other landing sites,” Kreslavsky said.
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Deep Space Network
Upgraded for “Crunch Time”
Anticipating a population boom in interplanetary spacecraft, NASA is taking
steps to prepare its globe-girdling net of giant radio “ears” —
the Deep Space Network (DSN) — for an expected earful from the heavens.
The network, which can communicate with spacecraft as far away as Pluto and
beyond, uses clusters of antennas at three sites equally spaced round the Earth
to cover spacecraft in any direction. Each station has one 70-meter diameter
antenna, plus several smaller ones.
“We are getting ready for a crunch period beginning in November 2003,”
said Rich Miller, head of DSN planning and commitments for JPL. In late 2003
and early 2004, the United States, Europe and Japan will each have missions
arriving at Mars, two other spacecraft will be encountering comets, and a third
comet mission will launch. Several other missions will also have continuing
communication needs. “[The new] missions all happen to lie in the same
part of the sky,” said Joseph Statman, Manager of the Deep Space Mission
System Engineering Office at JPL, who described the area where the spacecraft
will cluster as a slice of the sky with Mars in the middle. “We need to
track them but we don’t have enough antennas.”
Projections for demands on the network from November 2003 to February 2004 indicate
the greatest need for increased communications capacity will be at the station
located in Madrid, Spain. To prepare for the rain of radio signals on the plain
in Spain, NASA will build a 34-meter wide advanced dish antenna to add about
70 hours of spacecraft-tracking time per week when Mars is in view. The new
antenna should be completed at the Madrid complex by November 2003, and will
accompany other improvements in the capabilities of existing antennas at all
three of the network’s tracking complexes. As part of the upgrade, older
hardware and software systems will be phased out and replaced with ones that
are more reliable and, in some cases, automated. Also, the DSN complexes in
Spain and Australia will receive processing equipment that will allow operators
to combine signals from multiple on-site antennas, increasing their sensitivity
to distant transmissions.
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Postcards from
the Edge:
Pioneer 10 Keeps Going and Going . . .
All but given up for lost, the famed “Pioneer 10” spacecraft answered
a call from Earth, ending speculation that the plucky probe launched 29 years
ago had finally fallen silent. In a test of communication technologies for future
interstellar missions, scientists operating a radio telescope antenna established
contact with the small spacecraft in April, the first time the spacecraft had
been heard from since August of 2000. “Pioneer 10 lives on,” declared
Pioneer 10 Project Manager Larry Lasher of NASA Ames Research Center. “The
fact that we can still stay connected with the spacecraft is fantastic. We are
overjoyed,” Lasher added.
Now orbiting more than 11 billion kilometers from Earth, well beyond the orbit
of Pluto and approaching the vasty deep of interstellar space, signals from
Pioneer 10 take almost 22 hours to make the round trip between Earth. Although
Pioneer 10’s feeble signal had been tracked by the Deep Space Network as
it headed toward the constellation Taurus, the dogged spacecraft stopped broadcasting
last summer. “We [had] been listening for the Pioneer 10 signal in a one-way
downlink non-coherent transmission mode since last summer with no success,”
Lasher said. “We therefore concluded that in order for Pioneer 10 to talk
to us, we need[ed] to talk to it.” A signal was sent to the spacecraft,
which locked onto it and finally radioed a faint reply
Launched on 2 March 1972, Pioneer 10 was the first spacecraft to pass through
the asteroid belt and the first to obtain close-up images of Jupiter. Following
its encounter with the Jovian giant, Pioneer 10 explored the outer regions of
the solar system, studying energetic particles from the sun, and cosmic rays
entering our portion of the Milky Way. In 1983, it became the first man-made
object to leave the solar system when it passed the orbit of distant Pluto.
The spacecraft continued to make valuable scientific investigations in the outer
regions of our solar system until its mission officially ended in March 1997.
In addition to these feats, Pioneer 10 carries the now-famous gold-anodized
“greeting card” from Earth complete with an image of a man and woman
au naturel.
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March 2001
7 March — Russian space officials set 19 March as the date for dumping
the Mir space station. They want to wait until the craft drifts closer to Earth
before giving it the final shove toward a fiery plunge into the Pacific Ocean.
8 March — The Space Shuttle Discovery launched from the Kennedy
Space Center towards the International Space Station (ISS), hauling a new resident
crew into orbit along with fresh supplies, critical construction equipment and
the outpost’s first science research rack.
EUROBIRD and BSAT-2A successfully launched into orbit atop an Ariane 5 rocket
from Kourou, French Guiana. The two new communications satellites will serve
customers on the islands of Great Britain and Japan.
11 March — A giant research balloon intended to circle the globe
at the edge of space was forced down by shifting high-altitude winds less than
24 hours after its launch. NASA hoped the Ultra Long Duration Balloon would
circumnavigate the Earth at a height of 20 miles, scraping along the edge of
the atmosphere to study outer space.
18 March — The XM-2 “Rock” satellite aboard a Boeing Sea
Launch Zenit-3SL launched from the Odyssey floating launch platform in the Pacific.
The XM Radio satellite will provide digital radio entertainment broadcasting
to the U.S.
19 March — The Russian Space Station Mir was sent into a gradual
deorbit. Launched in Feb 1986, Mir was visited by 111 spacecraft. Astronauts
occupied it for 4591 days and performed 79 space walks.
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April 2001
7 April — The improved 3-stage Proton launch vehicle, with a new
digital flight control system and enhanced first stage engines launched the
Ekran-M No. 18, a UHF television broadcasting satellite, from the Baikonur Cosmodrome.
The 2001 Mars Odyssey launched from Cape Canaveral by a Boeing Delta 7925. The
first spacecraft in the revamped NASA Mars Exploration Program, Mars Odyssey
carries a 6-meter boom with a gamma ray spectrometer for remote sensing of Martian
surface mineralogy, as well as an infrared imager and a radiation environment
monitor. Mars Odyssey will reach Mars orbit in October.
11 April — Russian officials gave the green light to California
millionaire Dennis Tito to become the first tourist in space despite reservations
from NASA. Tito took his final exam by practicing maneuvers in a Russian Soyuz
capsule simulator outside Moscow. Launch is set for 28 April on a mission to
the International Space Station. Tito will reportedly pay $20 million for the
flight and will spend about a week on the station. Tito will be accompanied
into orbit by Soyuz commander Talgat Musabayev and flight engineer Yuri Baturin.
Their mission is to dock their fresh Soyuz vehicle to the station and then fly
a used one back to Earth.
18 April — India successfully fired its biggest satellite rocket,
the Geo-synchronous Satellite Launch Vehicle (GSLV-D1), into orbit after the
maiden test launch was aborted last month due to technical trouble. The rocket
blasted off from the spaceport in Sriharikota on India’s southeastern coast
near the Bay of Bengal. Taking 10 years to build, the launch propelled India
into the ranks of a select club of countries able to fire big satellites deep
into space and could also give the nuclear-capable nation the ability to test
a range of military technologies.
19 April — The Space Shuttle Endeavour launched from the Kennedy
Space Center for the ISS, sending up the SSRMS robot arm, also called Canadarm-2,
used on the Orbiter itself. Despite the need to replace a bad electronics box
in the cockpit, NASA remained on track for launch.
28 April — A Soyuz rocket carrying two Russian astronauts and the
first space tourist, Dennis Tito, blasted off from Baikonur for the ISS. The
rocket delivered supplies and a new Soyuz lifeboat to be used as an escape pod
for the station’s crew. Because the rocket propellant stored inside the
lifeboat degrades over time, Russian flight rules call for Soyuz lifeboats to
be replaced every six months.
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Basics of Space Medicine & Physiology: Space Motion Sickness
By Eleanor A. O’Rangers, Pharm.D.
Space motion sickness (SMS) is one of the most common medical complaints occurring during spaceflight. The first case of SMS was reported by Soviet cosmonaut Gherman Titov, who reported feeling as if he were “flying upside-down” shortly after entering earth orbit on Vostok II. Thereafter, he described dizziness exacerbated by head movement, and later, he became motion sick. In the U.S., SMS was not observed until the Apollo program, presumably because astronauts were restrained in their flight couches, had limited head mobility with in-flight helmet use, and limited cabin space for free-floating activity.
The incidence of SMS, based upon data from the Apollo, Skylab and Space Shuttle
programs, approaches 70% (this incidence is similar to the Russian cosmonaut
experience). Repeat spaceflight does not appear to reduce susceptibility to
SMS. Symptoms are usually experienced within one hour of entering weightlessness,
and generally resolve within 3 to 4 days. Symptoms include flushing, malaise,
loss of appetite, nausea, vomiting, headache, impaired concentration, lack of
initiative and irritability. Because SMS is so common, Space Shuttle crew workload
is typically light during the first 24 hours of a flight, and EVAs are restricted.
It is also noteworthy that SMS can occur with transition from different gravity
environments. Approximately 90% of cosmonauts returning from missions lasting
several months have reported SMS upon return to earth. SMS is a serious operational
issue that could impact mission success. Emergency egress could be difficult
for those with SMS (vomiting in an EVA suit could suffocate an astronaut). Moreover,
with the potential for SMS recurrence when transitioning into another gravitational
environment (not to mention balance problems!), imagine how this could impact
a landing on Mars (a transition from 0-G to 0.38-G?) Protracted SMS on the Martian
surface could also exacerbate interpersonal conflict, and may affect nutritional
status of an astronaut as well.
As with Titov, head movements appear to provoke and/or exacerbate SMS. Astronauts
and cosmonauts have also reported that changes in their perception of body orientation
can also elicit SMS (e.g. Titov’s report of “flying upside-down”).
The most widely accepted explanation for SMS is the sensory-conflict theory.
The middle ear, which assists in balance, body orientation and the perception
of movement, “senses” that “down” is the pull of gravity
towards the ground. The eyes provide visual cues that the brain interprets as
“normal” on earth: the ceiling is “up”; the ground is “down.”
Moreover, the sense of touch also contributes to the perception of “up”
and “down”: the ground is felt beneath the feet. During spaceflight,
however, the body is freed from the 1-G orientation of earth. The senses must
adapt to a new, weightless environment. The middle ear no longer senses “down”
and perception of motion may be disrupted. The eyes, on the other hand, still
recognize “up” as the ceiling and “down” as the floor of
the spacecraft cabin . . . but the feet no longer feel the floor. Other crew
members floating “upside-down” relative to the cabin ceiling and floor
are also initially disconcerting. The brain is believed to be temporarily “confused”
with the conflicting sensory information it is receiving (relative to the “normal”
earth environment) and responds by triggering SMS. It is believed that the brain
and sensory adaptation to weightlessness occurs rapidly, which may be correlated
with the subsequent improvement in SMS over the first few days of spaceflight.
The actual physiology of these adaptive changes is being actively investigated
but as yet is incompletely understood. The headward redistribution of body fluids
in weightlessness may also play a role in eliciting SMS.
SMS is treated with medications once it occurs. Unfortunately, the identification
of those prone to SMS has been mostly unsuccessful, so prophylaxis is not encouraged.
It appears that medications used on earth to treat motion sickness have had
success in treating SMS. In the past, scopolamine, with or without dextroamphetamine
(“scope-dex”), was the treatment-of-choice for SMS in the U.S. manned
spaceflight program. However, these medications are not without problems. Scopolamine
is associated with side effects such as dry mouth, blurry vision, dizziness
and sedation, which could impact crew performance. Moreover, there is some evidence
that scopolamine may delay brain and sensory adaptation to weightlessness; some
astronauts discontinuing scopolamine during spaceflight had SMS recur despite
being several days into a mission. Dextroamphetamine, on the other hand, is
only available as a tablet (which may be a problem to administer if an astronaut
is vomiting) and has the potential for abuse. Therefore, the identification
of alternate treatments— including non-oral routes of administration —
for SMS was desirable. Beginning on STS-26, intramuscular injections of promethazine
(Phenergan®) were administered to counteract SMS, with apparent success
in many astronauts. Intramuscular injections and/or suppositories of promethazine
are now the treatment-of-choice for SMS in the U.S. manned spaceflight program.
Nevertheless, promethazine does not alleviate SMS in all astronauts, and identification
of additional medications may be advisable. With regards to non-medication treatments,
biofeedback control has been examined as a means of preventing and controlling
SMS, but has been unsuccessful. Preflight adaptation training devices, which
are intended to acclimate astronauts to the weightless environment, may offer
promise in enhancing treatment of SMS. Nevertheless, additional research on
understanding the physiology of SMS and brain and sensory adaptation to weightlessness
and transition from differing gravitational environments must be accomplished
before complete prevention of SMS can be realized.
References
1. Graybiel A, Miller EF, Homick JL. Experiment M131. Human Vestibular Function
in Biomedical results of Skylab (http://lsda.jsc.nasa.gov/books/skylab/Ch11.htm.)
2. Sensorimotor Integration in A Strategy for Research In Space Biology and
Medicine In the New Century, Space Studies Board, National Research Council,
Washington, D.C.: National Academy Press, 1998, pp. 63-79.
3. Lathan CE, Clement G. Response of the neurovestibular system to spaceflight
in Churchill SE (ed.) Fundamentals of Space Life Sciences Malabar, FL: Kreiger
Publishing Co., 1997, pp. 65-82.
4. Reschke MF, Harm D, Parker DE et al. Neurophysiologic Aspects: Space Motion
Sickness in Nicogossian A, Huntoon C, Pool S (eds.) Space Physiology and Medicine,
3rd edition Philadelphia: Lea & Febiger, 1994, pp.228-260.
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