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Mars... Flood Reign O'ver Me
The Red Planet Mars, on the surface a desiccated desert, is showing increasing
signs of a water-laden past and perhaps present. A flood of new evidence pooled
from dramatic images from the Mars Global Surveyor (MGS) spacecraft have whetted
the appetites of scientists divining the Red Planet’s past. New high-resolution
imagery from MGS shows evidence of ground ice on Mars as recently as 10 million
years ago. More striking is that the signs of geologically recent ice deposits
are near Mars’ equator, where the frosty deposits were probably no deeper
than 5 meters below the surface. “If ground ice was present within 5 meters
of the surface only a few million years ago, it is very likely to persist today
within about the upper 10 meters,” said University of Arizona planetary
sciences professor Alfred McEwen. “This is especially interesting because
it is an equatorial region of Mars, more accessible to exploration.”
Equally exciting, piles of crater-topped debris caused by the teakettle-like
explosion of water through volcanic lava flows point to recent liquid water
in Mars’ past. According to a model devised by researchers, so-called “rootless
cones” formed after volcanic eruptions melted frozen water near the surface
of Mars 10 million years ago — practically yesterday in geological terms.
The melting caused floods that carved channels and seeped into the ground. “We
think lava flows have advanced over the wet ground causing steam explosions
that built these rootless cones,” said Laszlo Keszthelyi, a senior researcher
at Arizona’s Lunar and Planetary Laboratory. “It means Mars is not
dead geologically. Volcanic eruptions and water floods are something ongoing
into the current geologic era.”
Few doubt that rivers run through Mars’ past; the largest flood channels
in the solar system reside on the Red Planet, in fact. A system of gigantic
ancient valleys (some as much as 200 kilometers wide) lies partly buried under
a veneer of volcanic lava flows, ash fall and wind-blown dust in Mars’
western hemisphere. New observations made with MGS’ laser altimeter reveal
slope valleys northwest of the huge Martian volcano, Arsia Mons, and south of
Amazonis Planitia, site of a postulated ocean. The best explanation is that
the slope valleys were formed by catastrophic floods 50,000-times larger than
the Amazon River, said James Dohm of the University of Arizona. At their peak,
the floods would have filled a large ocean hypothesized for northern Mars —
dubbed “Oceanus Borealis” — in about 8 weeks. “The Tharsis
region has had pulses of major magmatic activity that triggered catastrophic
floods that sculpted the surface, ponded, perhaps forming oceans and lakes that
in turn perturbed the climate, “ Dohm said.
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The Dust Bowl
The largest dust storm seen on Mars since NASA’s Mars Global Surveyor (MGS)
spacecraft arrived in 1997 is currently raging across half the planet. “This
is by far the largest storm we’ve seen during the Mars Global Surveyor
mission,” said Philip Christensen, principal investigator for MGS’
thermal emission spectrometer. “We expect that the storm will continue
to grow, perhaps becoming a global storm of the type that was seen during the
Mariner 9 and Viking missions in the 1970s,” Christensen added.
Scientists first noticed the incipient storm in mid June when a dust cloud appeared
in the Hellas Basin in the southern hemisphere. A week and a half later, the
storm began to intensify and expand. Since then, the dust storm has grown to
beyond Grapes of Wrath proportions, expanding well into the northern hemisphere
and wrapping more than halfway around the planet. “This storm began as
a small dust cloud inside the Hellas Basin, a nine-kilometer-deep impact crater
in Mars’s southern hemisphere,” says Christensen. At first the cloud
did little, alternately growing and retreating as days passed, but never expanding
until June 27th. “That’s when the storm exploded,” added Christensen.
“It crossed some critical threshold and really began to grow.” By
early July the dust cloud had spilled out of the Basin and enveloped much of
the planet.
No one knows exactly how Martian dust storms grow to such proportions, says
Christensen. “One theory holds that airborne dust particles absorb sunlight
and warm the Martian atmosphere in their vicinity,” he explained. “Warm
pockets of air rush toward colder regions and generate winds. Strong winds lift
more dust off the ground, which further heats the atmosphere.” Whatever
the cause, this isn’t the first time that visitors to Mars have been greeted
by billows of talcum-fine powder. Mariner 9 arrived at Mars in 1971 (the first
spacecraft to orbit the Red Planet) only to find the surface of the entire globe
obscured by a worldwide haze of dust. Only Olympus Mons, a giant volcano 24
kilometers high, peeked above the clouds.
NASA scientists will monitor the current dust storm over the next few months
to see how this powdery tempest develops and test their predictions of more
storms to come. “Atmospheric scientists have been waiting for a beautiful
storm like this,” says Christensen. “The data we’re collecting
are marvelous, and I suspect there will be a rush of papers in the months ahead
answering some of the questions we have about these events.” Fortunately,
the storm should not have a major impact on the planned arrival of another spacecraft,
the 2001 Mars Odyssey, in October. “We’ll use the instruments on Global
Surveyor to monitor the atmosphere on an hourly basis, providing the Odyssey
spacecraft team the information they need to keep Odyssey at the proper height
where it can safely fly through the atmosphere,” Christensen said.
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Viking's Silver
Anniversary
On July 20th, the U.S. space agency, NASA, and other space enthusiasts celebrated
the silver anniversary of Viking’s soft-landing on the surface of Chryse
Planitia, becoming the first successful mission to land on the Red Planet, as
well as the first successful American landing on another planet. The treasure
trove of images and data from the twin Viking landers and orbiters remains a
valuable scientific resource for the study of Mars.
The Viking 1 lander operated on the surface until November 1982, and together
with its twin, Viking 2, took 4,500 unprecedented images of the surrounding
surface and more than three million weather-related measurements, while the
two orbiters took 52,000 images representing 97% of the Martian globe. Viking
also poked and prodded the Red Planet, looking under rocks and sifting grains
of regolith into a suite of biology instruments in the search for life. For
most scientists, the $1 billion probes provided a definitive “No!”
to the question: “Is there life on Mars?” But to others, the negative
reply was less persuasive.
Picking up where Viking left off, scientific teams are now readying experiments
to repeat the question. The European Space Agency’s (ESA) Mars Express,
targeted for a June 2003 liftoff, will be a major part of the truth squad. Once
in Mars orbit, the ESA spacecraft will cast off the British-built Beagle 2 lander,
which will “carry on where Viking left off,” said Colin Pillinger,
lead scientist for the lander and professor at The Open University’s Planetary
and Space Sciences Research Institute in Britain. “Beagle 2 will go back
to Mars with an analytical method, which detects every atom of carbon in all
its forms. This time we should be able to find a body if it exists...even if
organic matter has been degraded by processing in the hostile environment of
Mars,” Pillinger said.
Outfitted with the most sophisticated analysis system built to date, “Beagle
2 far exceeds what Viking was doing,” said Everett Gibson, an adjunct scientist
on the lander. Among its abilities, Beagle 2 can sniff out the presence of methane,
which could point to Martian organism’s “exhalations,” a product
of metabolism. Finding a methane signature would also shore up the notion that
Mars may harbor a subsurface biota, Gibson said.
Joining Beagle 2 on Mars, but at separate landing sites, will be twin geology-laboratory
rovers built by NASA, each the size of a desk and capable of traveling up to
100 meters a day. Capable of exploring like a field geologist, the Mars Exploration
Rovers are concentrating not on current life forms, but the Mars of long ago.
“It’s a different, complementary approach,” said Steven Squyres,
principal investigator for the Athena science payload to be hauled by each of
the rovers
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POSSE to Ride
to the Rescue?
Faced with tight budgets and mounting cost overruns, NASA managers have repeatedly
tried to shoot down future missions to Pluto and beyond, but Congressional proponents
of such a mission have at least postponed ‘High Noon’ for a proposed
Pluto probe. In response to Congressional pressure, NASA has selected two proposals
for detailed mission feasibility studies as candidates for a Pluto-Kuiper Belt
(PKB) mission to explore the only planet in our Solar System yet to be visited
by a spacecraft from Earth.
The two proposals judged to have the best science value were among five proposals
submitted to NASA in April 2001. The first proposal to ride to the rescue was
the Pluto and Outer Solar System Explorer (POSSE) led by NASA’s Jet Propulsion
Laboratory (JPL) and Lockheed Martin Astronautics. Also chosen for further study
was a bid by Johns Hopkins University Applied Physics Laboratory called “New
Horizons: Shedding Light on Frontier Worlds.” If funding is provided in
the FY 2002 budget and either proposal is ultimately selected, NASA could fly
a spacecraft to Pluto and beyond in the 2004-2006 time frame with arrival at
Pluto before 2020.
Both proposals are for complete missions, including launch vehicle, spacecraft
and science instrument payload that includes imaging instruments, a radio science
investigation, and other experiments to characterize the global geology and
morphology of Pluto and Charon, map their surface composition, and characterize
Pluto’s atmosphere. “The PKB mission represents a possible opportunity
to visit the only planet not yet explored by spacecraft,” said Colleen
Hartman, Pluto Program Director in NASA’s Office of Space Science. “It’s
really an opportunity to, in a sense, look into a deep-freeze of history which
could tell us how our Solar System evolved to what it is today, including the
precursor ingredients of life.”
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May 2001
6 May—The first space tourist returned to Earth from his trip to
the International Space Station (ISS). Tito and two Russian cosmonauts blasted
off from Kazakhstan on 28 April and spent two days in orbit before docking with
the ISS. Tito’s presence distressed NASA, who complained that the station
was no place for an amateur, even though Tito underwent extensive training as
part of the $20 million trip.
8 May—A Zenit 3SL rocket carried the second of two digital radio
broadcasting satellites into orbit for XM Satellite Radio from the Odyssey Launch
Platform in the Pacific Ocean. Customers will be able to choose from almost
every category of music in addition to content from the company’s partners,
which include: Sesame Street Workshop, NASCAR, CNBC, USA TODAY, One-On-One Sports,
Hispanic Broadcast Corporation, C-SPAN Radio, Clear Channel and DIRECTV.
15 May—A Proton rocket launched the PAS-10 satellite into orbit
from the Baikonur Cosmodrome. The communications satellite will replace an older
satellite that was serving the Indian Ocean region and reaching customers in
Asia, Africa and Europe
.
18 May — The National Reconnaissance Office’s GeoLITE spacecraft
launched into orbit aboard a Delta II rocket from Cape Canaveral. The satellite
carries an experimental laser communications payload and an operational UHF
data relay payload.
20 May—The Progress spacecraft 255 launched from Baikonur aboard
the Soyuz-FG rocket, a modified Soyuz-U with 5 percent improved performance.
The vehicle carries food and equipment, including spare computer equipment for
the ISS.
24 May—Soggy tiles delayed the launch of the space shuttle Atlantis.
Scheduled to launch on 14 June the Shuttle will launch no earlier than 20 June.
29 May—The Cosmos-2377 launched from Plesetsk aboard a Soyuz rocket.
The reconnaissance satellite carries a large recoverable capsule containing
the camera system and film, as well as two small film capsules to be returned
during the mission. The satellite will remain in space for 120 days.
June 2001
2 June—The unmanned X-43A experimental aircraft aboard a Pegasus
XL was destroyed shortly after deployment by a NASA B-52 launch aircraft from
Edwards Air Force Base. After separation from the Pegasus, the X-43A, powered
by a supersonic-combustion ramjet engine, failed to speed on its own. Two more
X-43A flights are scheduled to provide NASA the research results it seeks in
hypersonic flight. The NASA test was the first of three planned hypersonic free
flights in the six-year, $185 million Hyper-X series of research aircraft.
4 June—The planned launch of an $85 million solar science mission
was delayed at least five days while NASA investigated a Pegasus rocket failure
that destroyed an experimental hypersonic aircraft. Set for launch aboard a
Pegasus XL rocket, NASA’s High Energy Solar Spectroscopic Imager —
or HESSI — spacecraft will remain grounded until at least 12 June. Investigators
want to make sure that the error will not recur on the Pegasus rocket that is
slated to carry the HESSI spacecraft into orbit.
7 June—Countdown was stopped several minutes before lift-off of
an Ariane-4 rocket at the European Space Agency launch center in Kourou, French
Guinea. Bad weather delayed launch of a telecommunications satellite for a Washington-based
satellite operator INTELSAT for a few days.
NASA delayed launch of the next space shuttle flight due to problems with the
new $1 billion robot arm. Atlantis will lift off no earlier than 7 July with
a mission to deliver an airlock, or pressure chamber for spacewalks. The robot
arm, which was attached in April, is needed to install the $164 million airlock.
Although the main operating system of robot arm works fine, the backup system
has a problem that could cause the arm to freeze up. NASA wants both the main
and backup systems available.
8 June—A Parus class navigation satellite, Cosmos-2378, launched
into orbit from Plesetsk. This launch was the first Cosmos-3M flight since a
failure in November 2000.
9 June—An Ariane rocket launched an Intelsat 901 satellite from
Kourou, French Guinea. The first of the Intelsat 9 series, the satellite will
provide telecommunications services in the Atlantic Ocean Region.
16 June—An Astra 2C communications satellite successfully launched
into orbit for Societe Europeenne des Satellites (SES) from the Baikonur Cosmodrome.
Built by Boeing Satellite Systems (BSS), Astra 2C is part of the SES constellation
to provide direct-to-home television, Internet access and other communications
services to more than 87 million homes in 29 nations. Astra 2C is designed to
operate for 15 years.
19 June—International Launch Services launched the ICO-2 satellite
aboard an Atlas 2A from Cape Canaveral. The payload will provide mobile communications
and data/internet services at S-band, supporting 4500 simultaneous calls.
30 June—NASA’s Microwave Anisotropy Probe (MAP) launched aboard
a Delta 7425-10 launch vehicle from Cape Canaveral. Built in collaboration with
Princeton University, the microwave instrument will observe the dark extragalactic
sky with differential microwave radiometers and measure fluctuations in the
cosmic 3 Kelvin microwave background.
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Medication Use in the US Manned
Spaceflight Program
By Eleanor A. O’Rangers, Pharm.D.
Despite the fact that the US astronaut
corp is relatively healthy, medical events that could impact crew operations
on space missions are surprisingly common. For example, during the first 33
shuttle missions, 83% of crew members took medications at some time during the
mission. Such medical events often necessitate the use of pharmacologic interventions;
as such, NASA carries a variety of medications during their space missions.
Most medical events reflect short-term adaptation to the weightless space environment,
such as space motion sickness, back pain (from spinal cord expansion), nasal
congestion and headache (from headward fluid shifts), and insomnia. Medications
aimed at ameliorating symptoms associated with these complaints are routinely
available to astronauts primarily as tablets and capsules. In addition, a variety
of antibiotics are carried in the event of an infection, however, in the history
of the US manned spaceflight program, these events have been rare. As mission
duration increases, greater attention to the inclusion of pharmacologic countermeasures
to long-term medical consequences of spaceflight—- bone and muscle loss,
immune function changes, and radiation exposure to name a few—- will need
to be accommodated.
While the use of medications during spaceflight is accepted, little is actually
known about how the human body handles (pharmacokinetics) and reacts (pharmacodynamics)
to medications in space. Compounding this problem, unfortunately, is the fact
that little research has been performed in this area, primarily because it is
given low priority at NASA. One small experiment which has been performed involved
the oral administration of Extra-Strength Tylenol (650mg) to 3 astronauts during
a Shuttle mission. Saliva concentrations of Tylenol were collected following
administration. The results suggested that during spaceflight, less Tylenol
was reaching the bloodstream, possibly due to less absorption from the gut,
greater breakdown by the liver, or other factors. This implied that less drug
would be available to treat a headache or fever. Indeed, this theory is supported
by anecdotal reports of drugs “not working as well” about 15% of the
time when taken by astronauts in space. This could be due to several factors:
1) Physiologic changes produced by spaceflight: Gut motility decreases in space,
which could affect oral drug absorption. The breakdown of drugs in the body
by the liver, and their removal by the kidneys, may be altered as well, which
may also affect blood levels of a drug. Fluid shifts would also change the distribution
of drugs in the body. Finally, sites where drugs work may also undergo changes
in space, which may impact how the drug can alter the function of these sites.
2) Drug stability in space: There are many factors that can affect the stability
of a medication: humidity, temperature and radiation exposure (including electromagnetic
radiation, such as visible light, and ionizing radiation, such as galactic cosmic
radiation or solar particle events.) When medications are exposed to any or
all of these factors, they are prone to degradation, which can affect their
potency and/or safety (if broken down to harmful substances). Medications carried
on the Shuttle traditionally have been recycled for use on future missions and
are only replaced if used or if their expiration date has been reached. Examination
of medications flown for increased degradation has not been performed, despite
the probability that degradation is increased, particularly due to cabin and
crew exposure to higher levels of ionizing radiation. This may be a significant
source of “drug ineffectiveness” in space. Recently, the pharmacology
lab at NASA is proposing a study to examine the stability of drugs flown in
space.
3) Crew medical knowledge: Medical knowledge among US astronauts is limited.
While physician astronauts do exist, it is more likely that nonmedical personnel
will be flying a space mission. During crew training, 16 hours of general medical
training, consisting of basic first aid, dental repair and pharmacology, is
accomplished weeks before flight. The likelihood of significant medical knowledge
retention is remote. Flight surgeon support is part of Mission Control for US
missions, but not all medications taken during flight are selected based upon
consultation with the surgeons. This is particularly an issue with medications
taken for space motion sickness, insomnia and miscellaneous aches and pains,
in which astronauts feel that no consultation is necessary. Often several medications
are ingested by astronauts, which can pose problems, such as additive effects.
For example, drowsiness can be increased with the concomitant administration
of space motion sickness medications and medications used to treat insomnia.
This can impact crew performance. Moreover, a popular trend among astronauts
is the use of herbal medications, which are carried on board in “personal
paks.” There is little control over what medications, herbal or otherwise,
are stowed in these “personal paks.” NASA has hired a clinical pharmacist
to improve Flight Surgeon and astronaut medication knowledge. For example, the
clinical pharmacist and column author, also a clinical pharmacist, have been
drafting medication monographs that will serve as reference for both flight
surgeons and, eventually, astronauts to assist them in proper medication selection,
dosing and monitoring.
Many questions regarding drug administration in space continue to persist. Ideally,
research in this area should be given higher priority. An emphasis on ground-based
experiments, followed by judicious in-flight studies, will provide important
answers to the issue of drug efficacy and safety in space.
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