Stellar kinematics is the study of the movement of
stars
without needing to understand how they acquired their motion. This
differs from
stellar dynamics, which takes into account
gravitational effects. The motion of a star relative to the Sun can
provide useful information about the origin and age of a star, as well
as the structure and evolution of the surrounding
galaxy.
In
astronomy, it is widely accepted that most stars are born within
molecular clouds known as
stellar nurseries. The stars formed within such a cloud compose
open clusters containing dozens to thousands of members. These
clusters dissociate with time. Stars that separate themselves from the
cluster's core are designated as members of the cluster's stellar
association. If the remnant later drifts through the galaxy as a
coherent assemblage, then it is termed a moving group.
Space velocity
The component of stellar motion toward or away from the Sun, known as
radial velocity, can be measured from the spectrum shift caused by
the
Doppler effect. The transverse, or
proper motion must be found by taking a series of positional
determinations against more distant objects. Once the distance to a star
is determined through
astrometric means such as
parallax, the space velocity can be computed.[1]
This is the star's actual motion relative to the
Sun or the
local standard of rest (LSR). The latter is typically taken as a
position at the Sun's present location that is following a circular
orbit around the galactic center at the mean velocity of those nearby
stars with low velocity dispersion.[2]
The Sun's motion with respect to the LSR is called the peculiar solar
motion.
The components of space velocity in the
Milky
Way's
Galactic coordinate system are usually designated U, V, and W, given
in km/s, with U positive in the direction of the
Galactic center, V positive in the direction of
galactic rotation, and W positive in the direction of the
North Galactic Pole.[3]
The peculiar motion of the Sun with respect to the LSR is (U, V, W) =
(10.00 ± 0.36, 5.23 ± 0.62, 7.17 ± 0.38) km/s.[4]
The stars in the Milky Way can be subdivided into two general
populations, based on their
metallicity, or proportion of elements with atomic numbers higher
than helium. Among nearby stars, it has been found that population I,
higher metallicity stars have generally lower velocities than older,
population II stars. The latter have elliptical orbits that are inclined
to the plane of the galaxy.[5]
Comparison of the kinematics of nearby stars has also led to the
identification of
stellar associations. These are most likely groups of stars that
share a common point of origin in giant molecular clouds.[6]
Within the
Milky
Way galaxy, there are three primary components of stellar
kinematics: the disk, halo and bulge or bar. These kinematic groups are
closely related to the stellar populations in the galaxy, forming a
strong correlation between the motion and chemical composition, thus
indicating different formation mechanisms. The halo may be further
sub-divided into an inner and outer halo, with the inner halo having a
net prograde rotation with respect to the galaxy and the outer a net
retrograde movement.[7]
[edit]
High-velocity stars
Depending on the definition, a high-velocity star is a star moving
faster than 65 km/s to 100 km/s relative to the average motion of the
stars in the Sun's neighborhood. The velocity is also sometimes defined
as
supersonic relative to the surrounding interstellar medium. The
three types of high-velocity stars are: runaway stars, halo stars and
hypervelocity stars.
[edit]
Runaway stars
Four runaway stars plowing through regions of dense
interstellar gas and creating bright bow waves and trailing
tails of glowing gas. The stars in these NASA Hubble Space
Telescope images are among 14 young runaway stars spotted by
the Advanced Camera for Surveys between October 2005 and
July 2006
A runaway star is one which is moving through space with an
abnormally high
velocity relative to the surrounding
interstellar medium. The
proper motion of a runaway star often points exactly away from a
stellar association, whose member it therefore once must have been
before it was hurled out.
Two possible mechanisms may give rise to a runaway star:
- In the first scenario, a close encounter between two
binary systems may result in the disruption of both systems,
with some of the stars being ejected at high velocities.
- In the second scenario, a
supernova explosion in a
multiple star system can result in the remaining components
moving away at high speed.
While both mechanisms are theoretically possible, astronomers
generally favor the supernova hypothesis as more likely in practice.
One example of a related set of runaway stars is the case of
AE
Aurigae,
53
Arietis and
Mu Columbae, all of which are moving away from each other at
velocities of over 100 km/s (for comparison, the
Sun moves
through the galaxy at about 20 km/s faster than the local average).
Tracing their motions back, their paths intersect near to the
Orion Nebula about 2 million years ago.
Barnard's Loop is believed to be the remnant of the supernova that
launched the other stars.
Another example is the X-ray object
Vela
X-1, where photodigital techniques reveal the presence of a typical
supersonic
bow
shock hyperbola.
[edit]
Halo stars
High-velocity stars are very old stars that do not share the motion
of the Sun or most other stars in the solar neighbourhood which are in
similar circular orbits around the centre of the Galaxy. Rather, they
travel in elliptical orbits, which often take them well outside the
plane of the Galaxy. Although their orbital velocities in the Galaxy may
be no faster than the Sun’s, their different paths result in the high
relative velocities.
Typical examples are the halo stars passing through the disk of the
galaxy at steep angles. One of the nearest 45 stars, called
Kapteyn's star, is an example of the high-velocity stars that lie
near the Sun. Its observed radial velocity is -245 km/s, and the
components of its space velocity are U = 19 km/s, V = -288
km/s, and W = -52 km/s.
[edit]
Hypervelocity stars
Hypervelocity stars (HVSs) are stars with a velocity so great that
they are able to
escape the gravitational pull of the galaxy.[8]
Ordinary stars in the galaxy have velocities on the order of 100 km/s,
while hypervelocity stars (especially those near the center of the
galaxy, which is where most are thought to be produced), have velocities
on the order of 1000 km/s.
The existence of HVSs was first predicted in 1988,
[9]
and their existence confirmed in 2005.
[10]
Currently, sixteen are known, one of which is believed to originate from
the
Large Magellanic Cloud rather than the
Milky
Way.[11]
All of the currently known HVSs are over 50,000 parsecs away and are
unbound from the galaxy.
It is believed that about 1000 HVSs exist in our Galaxy. Considering
that there are around 100 billion stars in the
Milky
Way, this is a minuscule fraction (~0.000001%).[citation
needed]
[edit]
Production methods
The main production method for HVSs is summarized as thus: they are
believed to originate by close encounters of
binary stars with the
super massive black hole in the centre of the
Milky
Way. One of the two partners is captured by the black hole, while
the other escapes with high velocity. Also, it is worth noting that
"captured" does not necessarily mean "swallowed", for in all likelihood
the companion to the HVS will never fall into the black hole.
Known HVSs are main-sequence stars with masses a few times that of
the Sun.
A team at Argentina's Cordoba Observatory believe that our HVS are a
result of a merging with a collision between the Milky Way, and an
orbiting
dwarf galaxy. A dwarf galaxy that has been orbiting the Milky Way,
passed through the centre of the Milky Way. When the dwarf galaxy made
its closest approach to the centre of the Milky Way, it underwent
intense gravitational tugs. These tugs boosted the energy of some its
stars so much that they broke free of the dwarf galaxy entirely and were
thrown into space.[12]
Some
neutron stars are inferred to be traveling with similar speeds.
However, they are unrelated to HVSs and the HVS ejection mechanism.
Neutron stars are the remnants of
supernova explosions, and their extreme speeds are very likely the
result of an asymmetric
supernova explosion. The
neutron star
RX J0822-4300, which was measured to move at a record speed of over
1500 km/s (0.5% c) in 2007 by the
Chandra X-ray Observatory, is thought to have been produced this
way.[13]
[edit]
List of HVSs
[edit]
Kinematic groups
A set of stars with similar space motion and ages is known as a
kinematic group.[14]
These are stars that could share a common origin, such as the
evaporation of an
open cluster, the remains of a star forming region, or collections
of overlapping star formation bursts at differing time periods in
adjacent regions.[15]
Most stars are born within
molecular clouds known as
stellar nurseries. The stars formed within such a cloud compose
gravitationally bound
open clusters containing dozens to thousands of members with similar
ages and compositions. These clusters dissociate with time. Groups of
young stars that escape a cluster, or are no longer bound to each other,
form stellar associations. As these stars age and disperse, their
association is no longer readily apparent and they become moving groups
of stars.
Astronomers are able to determine if stars are members of a kinematic
group because they share the same age,
metallicity, and kinematics (radial
velocity and
proper motion). As the stars in a moving group formed in proximity
and at nearly the same time from the same gas cloud, although later
disrupted by tidal forces, they share similar characteristics.[16]
[edit]
Stellar associations
A stellar association is a very loose star cluster, whose stars share
a common origin, but have become gravitationally unbound and are still
moving together through space. Associations are primarily identified by
their common movement vectors and ages. Identification by chemical
composition is also used to factor in association memberships.
Stellar associations were first discovered by the
Armenian
astronomer
Viktor Ambartsumian in 1947.[17]
The conventional name for an association uses the names or abbreviations
of the
constellation (or constellations) in which they are located; the
association type, and, sometimes, a numerical identifier.
Viktor Ambartsumian first categorized stellar associations into two
groups, OB and T, based on the properties of their stars.[17]
A third category, R, was later suggested by
Sidney van den Bergh for associations that illuminate
reflection nebulae.[18]
The OB, T, and R associations form a continuum of young stellar
groupings. But it is currently uncertain whether they are an
evolutionary sequence, or represent some other factor at work.[19]
Some groups also display properties of both OB and T associations, so
the categorization is not always clear-cut.
Young associations will contain 10–100 massive stars of
spectral class
O and
B, and are known as OB associations. These are believed to
form within the same small volume inside a
giant molecular cloud. Once the surrounding dust and gas is blown
away, the remaining stars become unbound and begin to drift apart.[20]
It is believed that the majority of all stars in the Milky Way were
formed in OB associations.[20]
O class stars are short-lived, and will expire as
supernovae after roughly a million years. As a result, OB
associations are generally only a few million years in age or less. The
O-B stars in the association will have burned all their fuel within 10
million years. (Compare this to the current age of the
Sun at about
5 billion years.)
The
Hipparcos satellite provided measurements that located a dozen OB
associations within 650
parsecs
of the Sun.[21]
The nearest OB association is the
Scorpius-Centaurus Association, located about 400
light years from the
Sun.[22]
OB associations have also been found in the
Large Magellanic Cloud and the
Andromeda Galaxy. These associations can be quite sparse, spanning
1,500
light years in diameter.[23]
Young stellar groups can contain a number of infant
T Tauri stars that are still in the process of entering the
main sequence. These sparse populations of up to a thousand T Tauri
stars are known as T associations. The nearest example is the
Taurus-Auriga T association (Tau-Aur T association), located at a
distance of 140
parsecs
from the Sun.[24]
Other examples of T associations include the
R Corona Australis T association, the
Lupus T association, the
Chamaeleon T association and the
Velorum T association. T associations are often found in the
vicinity of the molecular cloud from which they formed. Some, but not
all, include O-B class stars. To summarize the characteristics of Moving
groups members: they have the same age and origin, the same chemical
composition and they have the same amplitude and direction in their
vector of velocity.
Associations of stars that illuminate reflection nebulae are called
R associations, a name suggested by Sidney van den Bergh after he
discovered that the stars in these nebulae had a non-uniform
distribution.[18]
These young stellar groupings contain main sequence stars that are not
sufficiently massive to disperse the interstellar clouds in which they
formed.[19]
This allows the properties of the surrounding dark cloud to be examined
by astronomers. Because R-associations are more plentiful than OB
associations, they can be used to trace out the structure of the
galactic spiral arms.[25]
An example of an R-association is
Monoceros R2, located 830 ± 50
parsecs
from the Sun.[19]
[edit]
Moving groups
If the remnants of a stellar association drift through the galaxy as
a somewhat coherent assemblage, then they are termed a moving group.
Moving groups can be old, such as the
HR 1614
moving group at 2 billion years, or young, such as the
AB Doradus moving group at only 50 million.
Moving groups were studied intensely by
Olin Eggen in the 1960s[26]
A list of the nearest young moving groups has been compiled by
López-Santiago et al.[27]
The closest is the
Ursa Major Moving Group which includes all of the stars in the
Plough/Big Dipper
asterism except for
α Ursae Majoris and
η Ursae Majoris. This is sufficiently close that the
Sun lies in
its outer fringes, without being part of the group. Hence, while members
are concentrated at
declinations near 60° N, some outliers are as far away across the
sky as
Triangulum Australe at 70° S.
[edit]
Stellar streams
A stellar stream is an association of
stars
orbiting a
galaxy that was once a
globular cluster or
dwarf galaxy that has now been torn apart and stretched out along
its orbit by tidal forces.
[edit]
Known kinematic
groups
Some kinematic groups include:[28]
[edit]
SOME RECENT MEWS
International SunSat Design Competition
(November 27, 2011)
The SunSat Design Competition is an international
contest intended to accelerate the design, manufacture, launch and
operation of the next-generation satellites that will collect energy in
space and deliver it to earth as electricity. Registration Deadline is
January 6, 2012; design submission deadline is March 30, 2012. Winners
will be announced at the National Space Society’s International Space
Development Conference in Washington DC in May.
More information
on the NSS Blog.
NATIONAL SPACE SOCIETY CONGRATULATES NASA & ULA ON A
SUCCESSFUL LAUNCH OF MARS SCIENCE LABORATORY
(Merritt Island, FL, November 26, 2011)
The National Space Society congratulates NASA and the
United Launch Alliance (ULA) team on a successful launch of the Mars
Science Laboratory (MSL) including the Curiosity surface rover. The
successful launch and Mars trajectory insertion begins the eight month
journey to Mars and sets the stage for the next level of exploration of
Mars. Using a new landing system, Curiosity, the size of a small sport
utility vehicle, will be slowed by aerobraking, parachutes, and
retro-rockets, allowing precision navigation to the intended landing
site. Curiosity will then be lowered from the hovering descent stage
platform to the surface of Mars, becoming the largest Mars surface rover
to date.
MSL is anticipated to arrive at Mars in August of
2012. The mission fact sheet can be downloaded
here. The launch press kit can be downloaded
here.
NATIONAL SPACE SOCIETY APPLAUDS THE PASSING OF NASA
APPROPRIATIONS BILL FOR FY2012
(Washington, D.C., November 18, 2011)
The NASA Appropriations Bill for FY 2012 calling for
$17.8 billion in funding was passed by both houses of Congress on
November 17, 2011 and signed by the President on November 18, 2011. The
enrolled text of the bill can be found
here.
Key elements of the legislation include continued
funding for the James Webb Space Telescope with a cap set on the total
funds that are allowable for formulation and development, funding for a
beyond Earth orbit multipurpose crew vehicle, funding for a heavy lift
launch vehicle system which shall have a lift capability not less than
130 tons and which shall have an upper stage and other core elements
developed simultaneously, funding for a range of exploration research
and development activities, as well as funding for commercial
spaceflight activities. Given the austere fiscal climate and the
political conflicts of the moment, the passage of an appropriations bill
for NASA at this level of funding is an extraordinary testament to
efforts of the Senators and Congresspersons involved to get our nation
back on track with space.
Growing need for space trash collectors
Greenhouse gas, solar slowdown are lengthening the lifetime of
space debris — increasing its threat to satellites and
astronauts
HAZARDSAerospace
debris (yellow) in low Earth orbit can threaten spacecraft.
Changes in Earth's atmosphere may leave such space trash
lingering longer than it used to.
H.
Lewis/Univ. of S
On April 2, for the fifth time in less than three years, the
International Space Station fired its engines to dodge a piece of
orbital debris that appeared on
a collision path. Other spacecraft
also regularly scoot out of the way of rocket and satellite debris.
Such evasive action will be needed increasingly frequently, a new
study finds.
Friction between the atmosphere and materials passing through it,
known as drag force, offers the only natural means for culling
detritus left in orbit by space launches. But the thermosphere — a
large region of the upper atmosphere — is cooling. A resulting drop
in its density is also cutting its drag force, thereby increasing
the lifetime of orbiting trash (including pieces in that heavily
populated band at 800 to 1,000 kilometers).
Space agencies around the world have been discussing a need to
actively remove aerospace debris. One reason: The number of pieces
has been steadily rising, driven in part by collisions between
orbiting pieces of trash or trash and spacecraft. Among the biggest
debris multipliers: a spectacular 2009 crash between the dead
Russian Kosmos 2251 spacecraft and the U.S. Iridium-33
telecommunications satellite.
Two years ago, aerospace engineer Hugh Lewis of the University of
Southampton, England, and his colleagues calculated that within a
few decades, space agencies would have to begin culling perhaps five
major pieces of debris annually to slow this collision-enhanced
growth in the number of orbiting trash particles. But in a paper in
the Journal of Geophysical Research, posted online Aug. 10,
the Southampton team now doubles that number, pointing out that the
thermosphere’s falling density renders the old trash-pickup
requirements obsolete.
Climate impacts
The thermosphere does not behave as a gas, explains Lewis. Molecules
originating on or near Earth’s surface are propelled upward based on
their energy, he observes. With cooling, fewer of them reach
satellite (and associated debris) heights.
Growing emissions of carbon dioxide, a greenhouse gas, contribute
to the thermosphere’s cooling, the Southampton team points out. The
mechanism, Lewis says, appears to be collisions between CO2
and atomic oxygen at high altitudes. Those collisions release heat
in the form of infrared energy, which radiates out into space —
removing warmth from Earth’s atmosphere.
A drop in the sun’s activity will also cool the thermosphere.
Although the new JGR analysis assumed that solar cycles during the
next 70 years would roughly match those seen over the past 30, this
may prove an overly conservative assumption, Lewis acknowledges.
This spring and summer, scientists have been reporting that the
current solar cycle is particularly anemic. And solar activity might
remain lackluster for the indefinite future.
Upper atmospheric increases in carbon dioxide “is the primary
cooling agent of the thermosphere,” observes thermosphere climate
scientist John Emmert of the Naval Research Laboratory in
Washington, D.C. The Southampton team’s new analyses, he says,
“demonstrate for the first time that space climate change has
significant consequences for orbital debris proliferation and for
debris mitigation strategies.”
Trash collection realities
Although actively removing space trash from orbit “is absolutely
desirable,” focusing on how many pieces to remove annually “is sort
of a moot point, since we don’t know how to clean up even one,” says
Nicholas Johnson, chief scientist of NASA’s Orbital Debris Program
Office, at the Johnson Space Center in Houston.
There’s also the issue of relative risk, he says. “Although there is
a sort of sandblasting going on in space all of the time, both from
man-made and natural debris, we’ve only had two operational
spacecraft ever hit by man-made debris (that we know of) that
sustained any major damage.” One was the Iridium-33 catastrophe, the
other a French satellite hit in 1996 which was temporarily disabled.
While not wishing to dismiss the risk of a possible catastrophic
impact, Johnson notes that the risk of a spacecraft-killing
collision remains rare — and that “even two times a small number is
still a small number.”
But even if space engineers were given the go ahead to develop a
waste-collection service for space, succeeding would likely take a
very long time. “There is nothing on the horizon that either DOD or
NASA believes can do the job [space-trash removal] from either a
technical standpoint or from a financial one,” Johnson notes. Still,
that won’t stop U.S. researchers from formally brainstorming
solutions — and on Uncle Sam’s dime.
Johnson notes that the President’s new national space policy,
announced last year, for the first time directs NASA and the Defense
Department to develop technologies for removing threatening debris.
Their challenge is complicated by the fact that no one has decided
which trash to target first. And the issue isn’t as simple as it
might at first seem.
There is debris in low Earth orbit — between 400 km and perhaps
1,000 km — where the Hubble Space Telescope, International Space
Station and some other satellites reside. Then there’s the
geosynchronous Earth orbit regime at altitudes of perhaps 36,000 km.
Protecting craft orbiting at such vastly different altitudes will
require different strategies.
Engineers also will have to decide whether to focus on protecting
today’s operational spacecraft over the next decade or two or
protecting craft that may orbit a century from now.
If the focus is going to be on protecting future generations,
Johnson says, then the priority should be ridding the skies of big
pieces of trash — perhaps the car-size multi-ton behemoths that can
break up into hundreds (if not thousands) of shards. Shifting the
emphasis to current-generation spacecraft, he says, will argue for
getting rid of small debris. “If we’re going to lose spacecraft in
the next two decades,” he explains, “statistically, we’re going to
lose them to small things we can’t track.”
Government agencies are already tracking thousands of large
debris particles in low Earth orbit. Another half million smaller
ones, between 1 and 10 centimeters, also pose threats. Uncertainties
in their paths currently prompt satellite managers to be overly
conservative, maneuvering spacecraft to new paths more frequently
than is truly necessary, Johnson notes. The only way to limit that,
he says, is to improve the tracking of trajectories for small, but
potentially spacecraft-killing debris.
RUSSIAS SPACE PLANS
TsNIIMash projects
Earliest Soviet studies of possible missions beyond the Mars orbit
were initiated at the end of the 1960s in the 12th Department of
TsNIIMash, the leading research institution of the Soviet rocket
industry.
This
work coincided with (and possibly it was influenced by) NASA
projects, which eventually led to Pioneer-10-11 and Voyager 1-2
missions. At TsNIIMash, the 12th Department, also known as
Department of Spacecraft, was responsible for conceptualizing the
ideas, which could be adopted for development by the industry,
providing government funding. Dr. Lev Golovin led the department at
the time.
During the second half of the 1960 and beginning of the 1970s,
Golovin's group put forward a number of ambitious proposals for
unmanned missions to planets, including Mercury and Jupiter, along
with the project of a
manned expedition to Mars, a
lunar base
and a big orbital station in the Earth orbit. In the course of this
work, a number of scaled models of the hardware was built to
represent the concepts developed at TsNIIMash. Despite a common
misconception that these models had been used for testing, veterans
of TsNIIMash insisted that they were no more than promotional
materials prepared for the meetings of high-ranking officials at the
Ministry of General Machine Building, which from 1966 oversaw the
Soviet rocket industry.
Lavochkin projects
During 1986 and 1987, Vladimir Perminov, a leading developer of
interplanetary probes at Lavochkin design bureau in Moscow prepared
a Scientific and Technical Report, NTO, on the possibility of
unmanned missions to Jupiter, Saturn and Sun. The report considered
possible designs of the spacecraft, its trajectories and other
engineering issues of the project.
Based
on this work, Lavochkin launched a preliminary study (NIR)
code-named Tsiolkovsky with a primary goal of sending an unmanned
probe toward the Sun. The spacecraft would be powered by
Radioisotope Thermal Generators (RTG), which use radioactive
plutonium to produce electrical power onboard. A large four-meter
antenna would be used to transmit data from the spacecraft to the
ground control
stations.
A
major requirement for the project was the probe's ability to fly
within five or seven of the Sun's radiuses. In order to survive the
tremendous heat reaching this distance from the Sun, engineers
proposed two alternative shapes for the spacecraft body -- one as a
narrow cone and another as a disc. In both cases, narrow edges of
the craft would face the Sun, thus reducing the effect of the heat.
With all protective measures in place, the temperature of the probe
surfaces was still expected to reach 2,500 degrees C. A special
thermal protection made of vanadium was designed to shield the
probe's internal systems.
According to the plan, in 1995-96, the
Proton rocket
would send a two-ton spacecraft toward Jupiter, where the planet's
powerful gravity field would "sling shot" the probe back toward the
Sun in the so-called gravity-assisted maneuver. As it was passing
Jupiter, cameras onboard the spacecraft were expected to conduct
observations of the giant planet and its moons, while a descent
capsule with science instruments would be dropped into Jupiter's
atmosphere.
The
capsule, with the maximum weight of 500 kilograms, was expected to
experience the acceleration of 1,500 g during its descent into the
atmosphere of Jupiter. Following the Jupiter flyby, the craft would
continue on toward the Sun. A derivative of the spacecraft could be
also sent toward Saturn and beyond.
To
simulate the loads expected during the descent in the Jovian
atmosphere, NPO Lavochkin design bureau had constructed a special
centrifuge on its premises in Moscow. However, the spacecraft itself
had never gone beyond a development stage, as federal funds for
space program started evaporating at the turn of the
1990s.
Post-Soviet plans for deep-space spacecraft
After
a long hiatus caused by economic problems of the post-Soviet period,
NPO Lavochkin's engineers could at least dream again about
deep-space missions. In August 2007, management of the company
revealed plans for a number of missions beyond Earth orbit,
including the Asteroid-Grunt and Kometa-Grunt projects, which could
collect soil samples from an asteroid and a comet respectively. Both
probes would be based on the
Phobos-Grunt spacecraft, then scheduled for launch in
2009.
Beyond already approved Federal Space Program until 2020, NPO
Lavochkin drafted plans for yet-to-be funded missions in the outer
reaches of the Solar System. Preliminary plans for a lander
or a penetrator mission to Jupiter's moon Europa were under
discussion between European and Russian officials. It could take off
as early as 2017. Recent NPO Lavochkin publications also described
several possible concepts of planetary missions, including:
-
Asteroid-Grunt: The mission to return soil
samples from an asteroid;
-
Kometa-Grunt: a mission to return soil samples
from a comet;
-
Yupiter-Ganymede: a mission focusing on
Jupiter's moon Ganymede;
-
Gipersat: a mission focusing on Saturn's moons
Hyperion and Iapetus;
-
Obertur: a mission to Uranus and its moons
Oberon and Titania;
-
Netrit: a mission to Neptune and its moon
Triton;
The
actual implementation of these missions would depend on the success
of the initial Russian attempts to jump-start its planetary
exploration program, level of funding of the Russian space program
and the ability of Russian scientists to forge cooperative
agreements with their colleagues abroad.
Russian scientists propose mission to "tag" dangerous asteroid
Published: 2008 June 27; updated: 2009 Oct. 2; Dec. 30; 2010 Jan. 11
Like
a potential criminal tagged with a GPS bracelet, the
Earth-threatening space rock could be fitted with a tracking device,
helping to watch its orbital movement with unquestionable precision,
Russian scientists said.
According to RIA Novosti news agency, a team at NPO Lavochkin, the
chief-developer of the nation’s planetary spacecraft, proposed an
unmanned mission, which could place a radio beacon on the surface of
the asteroid 2004 MN4 Apophis. The 350-meter space boulder,
discovered in 2004, is expected to pass as close as 36,000
kilometers from Earth in
2029
and, according to some estimates, the gravitational pool of our
planet could put it on a collision course with Earth in 2036.
NPO
Lavochkin proposal was prepared for a Moscow conference, marking
100th anniversary of the infamous Tunguska event on June 30, 1908,
which is believed to be the largest space object hitting the Earth
in modern history. Russian scientists argue that in order to rule
out the possibility of Apophis colliding with the Earth, the space
rock’s orbit should be tracked with the accuracy of dozens of
meters. It could be achieved only with a transponder anchored to the
asteroid, as even the most powerful radio-telescopes on Earth can
not track such a small body precisely enough, the authors of the
report said.
To
accomplish the mission, NPO Lavochkin proposes to use a spacecraft
platform the company developed for the
Phobos-Grunt project. This mission, officially scheduled for
launch in 2009,
aims to land on the surface of the Martian moon Phobos and return
its soil samples to Earth. NPO Lavochkin representatives believe
that the Phobos-Grunt satellite bus could be used with minimal
modifications for the mission to Apophis. The proposed flight
scenario targeted May 13,
2012, as its
launch date and a rendezvous with the asteroid 330 days (or 11
months) later. Authors of the report called for including the
Apophis mission into the
Russian Federal Space Program, emphasizing a high international
prestige of such project.
Although the Apophis mission would rely on existing technology and
require relatively modest funding, to achieving the 2012 launch date
would not be realistic, observers note. According to sources
familiar with the matter, at the time of the asteriod mission
proposal, a much more technically challenging
Phobos-Grunt project
faced a delay to
2011. As
Russia’s flagship planetary mission that has been in the making
since 1990s, Phobos-Grunt would have to be grounded to enable the
launch to Apophis in 2012. Critics mostly dismissed the proposal for
the Apophis mission as either a face-saving ploy in the possible
move to cancel Phobos-Grunt, or as another unachievable project in
the advertised timeframe. On June 30, 2008, Russian space agency,
Roskosmos, released a statement clarifying the fact that the mission
to Apophis was an "independent and separate" project and rejected
claims about changing goals of the Phobos-Grunt mission.
Although the mission to Apophis in 2012 had never been considered
realistic, Russian scientists still kept this dangerous space rock
on a short list of potential targets of exploration as late as May
2009. However by that time, the launch date was moved to a
comfortably distant 2024. (365)
The story of the Russian mission to Apophis had another bizarre
twist that year. At the end of December, the head of the Russian
space agency, Anatoly Perminov told Voice of Russia radio
station that a soon-to-be-held meeting of the agency's collegium
would consider an asteroid threat behind closed doors. Perminov was
obviously talking about one of many theoretical and very preliminary
concepts routinely considered by the agency's officials in the
process of forming the nation's long-term plans in space. However,
few imprecisely minted words was enough for the Western media to run
sensational stories next morning about Russia's "secret plan to save
the Earth from an asteroid." Nevertheless, US Congressman Dana
Rohrabacher, representing State of California, a major base of the
US aerospace industry, took Perminov's interview seriously enough to
promise lobbying for a joint US-Russian asteroid-deflection
mission.http://www.russianspaceweb.com/spacecraft_planetary_plans.html
Return to Mercury
As
NASA resumed its exploration of Mercury with the Messenger mission
in 2008,
Moscow-based Space Research Institute, IKI, also revisited this
exotic destination in the Solar System. According to IKI, a
three-phase study, NIR, of the Mercury-Landing Module, MPM, had been
evaluated "scientific and technical proposals for the science goals
and equipment for the exploration of the planet's surface.
The
study showed the possibility of development of a small automated
lander, MAS, and compiled a preliminary list of scientific
instruments to be installed onboard. IKI studied the possibility of
"recycling" hardware developed for the
Phobos-Grunt project, as well as for MetNet, Mars-96 and
Solar Sail spacecraft. Scientists also proposed a number of
upgrades of the hardware.
A
proposed flight scenario for the mission included the insertion of
the spacecraft into the orbit around Mercury and the delivery of a
lander on its surface. The mission concept took advantage of
previous experience of NPO Lavochkin design bureau in the
development of small landers and the Phobos-Grunt project. The study
formulated basic requirements for the systems of the lander.
IKI
also analyzed trajectories to reach Mercury and selected an orbit
around the planet, from which the landing attempt would be made.
Various launch vehicles for the mission had been analyzed. The study
also formulated requirements for two types of missions, one of which
would aim to achieve only the most minimal goals.
In
the course of the study, IKI drafted technical assignments for the
development of scientific payloads and the propulsion system of the
lander. According to IKI, the completed work paved the way to the
development of other systems onboard the lander and possibly the
manufacturing of mockups of the scientific instruments.
According to the head of the Russian space agency, Anatoly Perminov,
during Paris Air and Space Show in Le Bourget in June 2009,
Roskosmos and ESA planned to sign an agreement on cooperation on
Russian involvement in Europe's Bepi Colombo mission to Mercury.
Previous plans to launch Bepi Colombo onboard the
Soyuz-2
rocket from its
launch
complex in
Kourou had to be dropped, as the spacecraft's thermal control
system brought it beyond the capabilities of the Russian rocket.
However along with the move to the Ariane-5 launcher, the
opportunities opened for the direct Russian-European cooperation on
the mission. Under the deal, the Institute of Space Research, IKI,
in Moscow would deliver instruments for the European orbiter within
Bepi Colombo project. According to the project scientists, European
Space Agency, ESA, was expected to finalize the mission design in
October 2009.
FROM:
http://www.russianspaceweb.com/spacecraft_planetary_plans.html
The
unmanned Phobos-Grunt probe, seen in a Nov. 2 photo, was supposed to fly
to Phobos, a moon of Mars, and bring samples of its soil back to
Earth.(Russian Roscosmoc space agency/Associated Press)
The
Zenit-2SB rocket carrying the Phobos-Grunt spacecraft blasted off
successfully early Wednesday. But after the probe separated from the
rocket, its engines failed to fire(Oleg Urusov, Pool/Associated Press)
