Europe's Great Leap Upwards
Los Angeles - Jan 10, 2003
There have been several interesting developments in the past month where the space science programs of the European nations are concerned. They're a mixed bag -- although, on the whole, they're rather discouraging. Funding remains a serious problem for space science in virtually every country, given its very high cost relative to other forms of research.
First: The recent funding problems of the Italian Aerospace Agency (ASI) -- which produced serious problems for several important missions -- have now been mostly but not completely resolved, with mixed results. These problems emerged over the past year, largely as the result of a shift in Italian research funding toward the military, and threw the entire Italian space science program into serious disarray.
The European Space Agency's "Venus Express" mission is an extremely low-cost mission of opportunity that would use a copy of the ESA's 2003 "Mars Express" Mars orbiter with remarkably few changes to either the spacecraft or its science instruments to study Venus' atmosphere from an elliptical orbit after its 2005 launch.
Such a study of the surprising number of major questions that still remain about Venus' atmosphere is high on scientists' wish lists -- American missions to do so have been on the finalist list for selection as one of the "Discovery" missions during three of its four competitions. And Venus Express' plan to build a second copy of the Mars Express craft before its contractors had turned to new tasks, and in many cases to utilize spare parts already built for Mars Express, could have cut the project's total cost to a mere $190 million.
But this May, the ESA rejected flying it because of new cuts in its own total space science funding plan -- totalling $510 million for the period through 2012 -- that had been made by the ESA's Council of Ministers six months earlier.
ESA Science Programme Director David Southwood did a spectacular job of managing to minimize the impact of these cuts on the science program as a whole through a combination of launch date shuffling, technical modifications in missions to lower their costs, and looking for new international partners -- but it appeared that they would force the ESA to cancel its hopes of adding Venus Express to its program for this decade.
However, pleas from the planetological community led Southwood to reexamine the situation, and two months later the ESA announced that it would indeed back Venus Express for 2005 if -- and only if -- the Italian Aerospace Agency agreed to provide its single most important science instrument, without which it would not be worthwhile.
This was "VIRTIS", a copy of a visible and near-infrared spectrometer on the ESA's big Rosetta comet probe (scheduled for launch next January), which could peer through spectral "windows" in Venus' atmosphere and cloud layers to measure temperatures and trace gases all the way down to the surface.
VIRTIS could also provide images of the cloud patterns in Venus' lower cloud layers, thus allowing precise measurement at different altitudes of Venus' "superrotation" winds that blow in the same direction that the planet rotates, but at tremendously higher speeds -- up to 360 km/hour at the visible cloud tops, but dropping down to a mere 3 km/hour breeze at its surface.
The driving mechanism for these winds remains a puzzle, and a precise profile of their speeds and of air temperatures at different altitudes and in different places is crucial to solve the mystery -- indeed, this is the main purpose of "VCO", a much smaller and less ambitious Venus orbiter that Japan hopes to launch in 2007.
But VIRTIS could also even provide data on Venus' surface -- mapping it for warm spots and trace-gas clouds that indicated volcanic activity, and perhaps (though this is uncertain) even mapping several important minerals on it and looking for local shock waves in the dense atmosphere that could indicate strong local earthquakes.
Most of Venus Express' main instruments already exist as the backup spares built for the Mars Express instruments -- but not VIRTIS. And the Italians were unwilling to commit themselves to spending the money needed to build another copy of it for this mission -- ironically, because they had already agreed to provide another copy of it for America's 2006 "Dawn" asteroid probe.
The ESA therefore agreed to provisionally add Venus Express to its program, dependent on an decision by ASI by October 15. But by that date, the ASI was still unwilling to announce a decision one way or the other.
With the final go/no-go decision on Venus Express due by November 5, Southwood -- after careful examination of the ESA's own science budget -- finally agreed that the ESA itself would provide $8.7 million to help Italy build another copy of VIRTIS and integrate it into the spacecraft. With that done, the ESA's Science Programme Committee approved the mission.
But another hoped-for auxiliary experiment that would have been provided by Italy and America's Jet Propulsion Laboratory together has had to be cancelled -- VENSIS, a copy of Mars Express' long-wavelength radar sounder "MARSIS", which would have probed 1 or 2 km below Venus' surface.
While MARSIS' purpose is largely to look for deeply buried subsurface deposits of water ice, and perhaps even local pockets of liquid water, there's no chance of finding such on Venus.
But VENSIS, by profiling lava-flow layers and other subsurface structures, could still have provided much new insight into Venusian geology -- perhaps including an answer to the question, raised by the "Magellan" probe's radar maps, of whether the entire planet underwent a gigantic spasm of volcanic activity half a billion years ago which covered most of its surface in lava and resurfaced it. If this did happen -- as a majority of scientists now think -- the obvious question is what caused it, and whether it was a one-time event or one that has repeated over eons.
Unfortunately, Italy was unable to contribute its share toward another copy of this instrument, and the U.S. was unwilling to build it alone -- and since it, unlike VIRTIS, is not crucial to the mission, the first detailed probe of Venus' subsurface structure will have to wait for some later time.
Most of Venus Express' other top-ranked core instruments -- Italy's "PFS", France's "SPICAV", and the multi-nation "ASPERA" -- already exist as Mars Express spares, and Germany has agreed to provide the radio beacon for the remaining one (the "VERA" radio science experiment).
Germany has also agreed to build two other relatively cheap auxiliary instruments to be added to Venus Express' core payload: a magnetometer and a "VMC" ultraviolet cloud-pattern camera.
And sources tell "SpaceDaily" it's now very likely that Belgium will agree to fund another auxiliary instrument: "SOIR", a spectrometer to take extremely detailed IR spectra of the Sun during sunrise and sunset to provide a sensitive check for various faint but scientifically important trace gases in Venus' upper atmosphere.
Even with one of its hoped-for instruments removed, Venus Express promises to be an extremely useful and cost-effective space probe.
Meanwhile, Italy's funding woes have also had (as I mentioned in an earlier article) a serious effect on the U.S. Mars program, for which it and France were supposed to be important contributing partners.
It seems virtually certain that "Marconi" -- the first Mars communcations satellites, which was to built by Italy and the US together for launch in 2007 -- will be completely cancelled.
This also means that tentative hopes that a similar craft might be built by the two nations and launched as a 2009 scientific Mars orbiter -- probably equipped with an "SAR" imaging radar system to obtain detailed Magellan-like radar maps of Mars' surface, but probing through several meters of its ubiquitous wind-blown dust blanket to map possible covered-up ancient watercourses and other features of its geological youth -- have also gone a-glimmering.
All nations' scientific Mars orbiters from now on are supposed to carry radio relay packages to allow them to record large amounts of data from future Mars landers.
These should greatly increase the amount of data such landers can return, since packages that would allow landers to establish a high-speed direct radio link with Earth add seriously to such landers' weight.
But one Mars orbiter specifically dedicated to serve as a comsat is also considered important -- especially since the very sophisticated 2009 US "Smart Lander" mission will very likely carry a very sophisticated long-range rover vehicle which is supposed to drive dozens of kilometers across the surface and return huge amounts of science data; and to drive it as far as possible across the surface during its three-year lifetime, its Earth controllers must stay in live high-rate radio contact with it for a large part of every Martian day.
So it now seems likely that the US will build a 2009 Mars comsat by itself -- and any SAR radar-mapping mission will, again, have to wait until another day. (One such mission was actually proposed by a team in the Discovery-type competition for designs for NASA's low-cost 2007 Mars Scout mission, but in the end it wasn't one of the just-announced four finalists.)
Italy, however, did finally come through on one smaller contribution to the US Mars program. This is "SHARAD", a radar sounder which will be the one foreign instrument on NASA's big 2005 Mars Reconnaissance Orbiter ("MRO").
SHARAD is a different design from Mars Express' MARSIS sounder, but has a similar main goal: to map subsurface layers and deposits of ice -- and any pockets of liquid water -- over most of Mars' surface. SHARAD will probe only one km beneath the surface -- as opposed to MARSIS' 5 km -- but its depth measurements are much more precise.
Scientists are currently unsure of just how well long-wavelength radar sounders can penetrate beneath Mars' surface for such data, and these two sounders are tests of alternative designs.
SHARAD was originally considered a second-rank instrument for MRO, but a scientific team this summer concluded that it is actually a very important one in the search for possible locations for present or past life on Mars -- and so NASA was relieved when the ASI announced before its September 30 deadline that it could at least provide this instrument.
Still another important Italian instrument for another multi-nation science mission, however, is still in doubt. This is the ESA's "Planck" cosmology satellite, scheduled for launch in 2007 on the same rocket as the ESA's larger "Herschel" infrared astronomy satellite. Planck is schduled to do the most sensitive map yet of the "Cosmic Microwave Background" (CMB) -- accurately described as "the afterglow of creation".
More precisely, the CMB is the glow from the superhot hydrogen plasma that filled up the entire universe after the Big Bang. According to current theories, about 300,000 years after the Bang (and about 15 billion years before our time) that plasma finally cooled down to the point that it suddenly changed into neutral, non-ionized hydrogen gas. And while this gas was still hot enough to glow a firy red, hydrogen gas is transparent while plasma is opaque, so the light could start travelling substantial distances through space.
And since the expansion of the universe is due to an expansion in the actual structure of space itself -- linked to the very outward motion of the galaxies and smaller objects within it by their gravity -- we can still detect a part of that glow today, just now reaching Earth after setting out 15 billion years ago from those parts of the Universe that are now 15 billion light-years from us.
But -- just as the expansion of the structure of space carries distant galaxies away from us faster than nearby galaxies, and so "Doppler-shifts" their light more toward the red -- the still more distant parts of the universe from which the CMB glow has come are being carried away from us so fast that the CMB's original red glow has been Doppler-shifted all the way down into high-frequency microwaves, such as would be given off by an object only 2.7 degrees C. above absolute zero.
The CMB glow is extremely, but not absolutely, uniform -- even 300,000 years after the Big Bang, some patches of the hot gas were tentatively clumping together, and the more compressed gas there was slightly warmer and so emitted a glow at a slightly higher frequency and intensity.
These gas clumps were later gradually drawn together by their own gravity to form the galaxies; but it's still very uncertain how the initial clumping occurred in the first place -- without which we wouldn't be here!
One theory suggests that they were one side effect of a phenomenon called "universal inflation" that took place an incredibly small fraction of a second after the Big Bang; another suggests that they may have been due to "topological defects" in the structure of space itself created by the Bang.
The clump-produced variations (or "anisotropies") in intensity of the microwave CMB glow that we're receiving today are, as I say, extremely small, equivalent to a temperature difference of at most only a few ten-thousands of a degree.
Over the past decade, a series of satellites and Earth-based observatories have been measuring and examining them in steadily better detail, and Planck will do by far the best job yet -- measuring them down to a few millionths of a degree, and doing so with sharper spatial resolution than ever before.
By measuring the number of anisotropies of different sizes, we should be able to settle the question of whether they were caused by inflation or by topological defects -- and also get major data on an astonishing number of other major cosmological questions, ranging from the basic geometry of the expanding structure of space itself, to the question of how much of the still-mysterious "dark matter" there is in the universe.
We also now know that some of the CMB's anisotropies are actually from titanic sound (or pressure) waves that were rippling through the early universe's plasma from various causes, possibly including the effects of inflation -- and so by examining those in detail we can make a further check of the inflation theory.
Finally, some theories suggest that a scattering of the first self-luminous bodies -- maybe quasars, maybe gigantic stars -- had already started to condense in the plasma by 300,000 years after the Big Bang.
If so, their radiation would have re-ionized some small patches of the newly neutral hydrogen gas near them -- and since light or radio waves are polarized when they pass through ionized plasma, if we can detect and measure some small trace of the CMB glow that is polarized, we can tell how many self-luminous bodies had formed by then.
Planck is supposed to map the CMB with two instruments. One -- the "High-Frequency Instrument" (HFI) built by a French-led team -- is supposed to measure the higher-frequency microwaves of the CMB, using 48 detectors to measure six frequencies of the CMB's higher-frequency microwaves on the border between microwaves and long-wavelength infrared light.
That instrument's development has gone smoothly. But the "Low-Frequency Instrument" (LFI) -- built by an Italian-led team, and intended to use 56 receivers to measure four different frequencies of somewhat lower-frequency microwaves -- has run into serious trouble because of Italy's space science funding problems.
Specifically, the 34 receivers that were supposed to detect the highest of the four frequencies (100 gigahertz) have already had to be trimmed back to only 24 receivers last January -- and now Italy says that it won't be able to fund any of them at all.
The ESA is currently engaged in emergency negotiations with NASA to see if it will be willing to fund these detectors -- but if NASA doesn't give it the go-ahead by the end of the year, Planck will have to fly without them.
Now, the HFI instrument's measurements overlap with LFI's -- its four lowest-frequency detectors also sense 100-gigahertz radiation -- but without both instruments measuring it, it will be harder to calibrate and compare the outputs of both instruments' various-frequency detectors with each other.
Moreover, only LFI can measure polarization -- so if the 100-gigahertz LFI detectors must be scrapped, Planck's sensitivity to that important data will be somewhat reduced.
Planck's sister satellite Herschel has also run into some technical problems (unconnected with Italy), but the launch of both satellites is still scheduled for 2007. However, as part of his ingenious fund-juggling act this year, ESA Science Director Southwood arranged for both very different telescopic satellites to be based on the same spacecraft bus design -- which saved so much money that ESA was actually able to add a new astronomy satellite to its schedule, "Eddington", also using the same bus design and scheduled for launch a year later.
Southwood now tells "SpaceDaily" that if the combined Herschel-Planck launch must be delayed past 2007, he'll reverse the order of the launches and send up Eddington first.
Eddington has had some design changes recently itself. Its purpose is to make very sensitive measurements of the brightness of tens of thousands of stars simultaneously.
First it will spend three years staring at the same star field -- measuring the brightness of 100,000 stars to detect any planets transiting in front of their disks (and any stars' planets have about an 0.5 % chance of having their orbits tilted at the right angle for Eddington to see them this way).
By detecting at least three similar such dips at regular intervals, it can confirm the existence of a planet as small as Earth or Mars, and thus -- along with NASA's similar 2007 "Kepler" mission -- will provide the first survey of just how many stars have small terrestrial-type planets in orbits fairly close to them (although, in three years of observations, it can only thus confirm the existence of such planets if they have a "year" no more than one Earth year long).
It will then repeatedly observe various fields containing up to 50,000 stars each for just a few months to prcisely measure the very slight oscillations in brightness that every star (including our Sun) undergoes every few minutes as a result of its internal pressure waves, and which can tell a great deal about a star's internal structure.
Eddington was originally supposed to use a single telescope with a 1.2 meter mirror, but it has now been modified to use a cluster of four 60-cm Schmidt telescopes merging their projected images into one camera -- which has allowed its cost to be cut while actually raising the width of its viewfield from 3 degrees to 6 degrees (one of the new technical changes that has allowed ESA to cut the cost of its upcoming science missions).
Unfortunately, at the same time that the ESA's science committee voted to give Italy the funds necessary to make Venus Express possible, it decided not to assist Germany with funds for its proposed astronomy satellite, "DIVA". DIVA is a relatively small and cheap satellite designed to carry out "astrometry", the super-precise measurement of the location and brightness of individual stars and other objects in the sky.
Until now there has only been one satellite devoted to this -- the ESA's highly successful 1989 "Hipparcos" -- but it is now attracting a great deal more scientific interest.
The reason is that such such super-high-precision astrometry -- which is impossible to carry out from Earth's surface due to the distorting twinkling of the atmosphere -- has, once again, multiple uses.
For instance, by measuring the "parallax" of distant stars (the extremely slight change in the viewing angle to them as the Earth makes its yearly 300-million-km circle around the Sun), it can measure their distances from us with new accuracy.
And by thus measuring the true distances to our galaxy's "Cepheid variables" (a set of stars which pulsate at a rate proportional to their brightness), and thus their true brightness and its exact ratio to their pulsation rate, it can allow us to more accurately estimate the distances to the Cepheids we see in other galaxies, and thus the distances of the other galaxies themselves.
This in turn allows us to more accurately calibrate the "Hubble constant" (the ratio of the distances of other galaxies from us to the speed at which they are withdrawing from us), which in turn allows us to more precisely understand the structure -- and the ultimate fate -- of the expanding universe itself.
Indeed, the Hubble telescope's ability to detect Cepheids in vastly distant galaxies, and thus mesure the Hubble Constant more precisely, is regarded as its single most important accomplishment.
Precise measurement of the TRUE motion of stars through space also allows us to calculate the speed at which stars in different parts of our Galaxy are orbiting its center, and thus estimate the amount of invisible dark matter in it.
Finally, such measurements will allow us to directly observe the very slight wobbles produced in stars by the motions of unseen planets around them with unparalled accuracy, and estimate those planets' masses for the first time.
In fact, the Hubble Telescope has just succeeded in making such observations for the nearby star Gliese 876, allowing us to estimate the mass of its already-known planet as being twice that of Jupiter. Doppler-shift detections of such stellar wobbles -- the technique used to detect extrasolar planets up to now -- can only place a lower limit on such a planet's mass.
Once you are outside the atmosphere, such precise measurements can be made with surprisingly small telescopes. Hipparcos made them for about 120,000 stars, but DIVA would use new technologies to map over 35 million stars with a positional accuracy of only one 24-millionth of a degree -- five times the accuracy of Hipparcos -- while costing only about one-tenth as much!
Unfortunately, DIVA's $52 million cost was still too much for Germany's DLR space agency, which this year cancelled its promise to provide half the funds for DIVA, with the rest being provided by various German universities and corporations.
Instead, the DLR was willing to provide only $10 million, forcing the satellite's team to beg the ESA for the remaining $16 million in needed funds in return for placing the project largely under ESA control and delaying its launch from 2004 to 2006.
However, the ESA was also unwilling to provide this chunk of money in addition to the new funds it had coughed up to Italy for Venus Express -- and so the DLR (like the Planck satellite's Italian managers) is now frantically trying to make a last-minute deal with NASA to provide the money instead.
NASA may agree to this, because a similar U.S. astrometry satellite -- the 2004 "FAME", which would have made position measurements three times more accurate than DIVA -- was canceled in 2001 after exceeding its $150 million cost cap, and its principal investigator Ken Johnston is very interested in the possibility of the two nations pooling their resources on a single mission.
However, if the DLR and NASA don't reach an agreement by the end of December, DIVA (like that portion of the Planck satellite's experiment) will now have to be cancelled completely.
If so, then the next astrometry satellite after Hipparcos will end up being the ESA's 2012 "GAIA" mission, which is a quantum leap upwards -- it will map the positions of fully a billion stars (returning an awesome 1 quadrillion bytes of data) with an accuracy as fine as one-billionth of a degree for many of them.
This will allow it to detect tens of thousands of planets orbiting other stars -- including all Jupiter-sized planets within 160 light-years of Earth, whereas DIVA and FAME would only be able to detect "brown dwarfs" with several dozen times Jupiter's mass -- and also hundreds of thousands of new tiny asteroids and Kuiper Belt objects in our own Solar System.
GAIA, as one might expect, is one of the ESA's expensive "Cornerstone" space science missions, and it came very close to being cancelled during the ESA's cost-cutting replanning this year.
However, a technical redesign similar to Eddington's -- in which its two mapping telescopes, tilted a wide angle apart to get precise data on the separation angles of widely spaced stars, will now project both their viewfields onto the viewfield of a single camera, with the two starfields being electronically separated -- has allowed GAIA to be based on still another copy of the Herschel-Planck-Eddington bus, and thus trimmed its cost by fully $140 million from the original $585 million.
Another ESA mission whose technical status is uncertain is "SMART-2", a 2006 flight to do engineering tests in space of systems that will be necessary for one -- and maybe two -- very ambitious astronomy missions that ESA hopes to carry out next decade in collaboration with NASA.
The first of these two is "LISA", one of the strangest space missions ever flown. It consists of three small spacecraft, flying in solar orbit in a triangular formation fully 5 million kilometers from each other, that will beam lasers at each other and make interferometric measurements of the beams to detect changes in the three crafts' vast mutual distances as small as one 100-millionth of a millimeter - only one-tenth the diameter of an atom!
LISA is intended to detect "gravity waves" -- ripples in the structure of space-time predicted by Einstein's general theory of relativity to be emitted from any massive objects orbiting or colliding with each other, including such possible dramatic phenomena as black holes, or neutron stars orbiting or colliding with each other or with ordinary stars. Some other gravity waves may be left over from the Big Bang itself.
Because gravity is actually such an incredibly weak force compared to electromagnetism, gravity waves should be extremely weak and hard to detect -- so hard, in fact, that they have never been directed sense yet (although they have been indirectly confirmed by the way they gradually bleed the rotational speed off pulsars).
An Earth-bazsed detector -- using laser beams running through 4-km long underground tunnels -- has just begun the first attempt to detect high-frequency gravity waves this year. But scientists would also like to detect lower-frequency ones -- which may have wavelengths as great as 100 million km -- and so the space-based LISA will be necessary to sense them, by detecting the incredibly tiny wiggles that the three craft undergo as a gravity wave ripples past them.
Actually, it would be hopeless to make such measurements by actually measuring the distance of the three spacecraft, since their positions will be constantly microscopically joggled by such things as micrometeor impacts and changes in the solar wind. So the "satellites" whose vast distances from each other will actually be measured with such staggering precision will be "proof masses" -- 4-cm-wide metal cubes floating freely inside chambers in each of the three craft, where the spacecraft's body will shield them from all such outside interference.
Oddly, although the three LISA craft will be constantly changing their relative distances from each other by thousands of kilometers as they orbit the Sun, this won't interfere with the interferometric detection of gravity waves -- because those distance changes will be gradual and constant-rate.
What the craft will keep watch for is all tiny wiggles imposed on top of that smooth motion by gravity waves -- and laser interferometers can measure that with equal precision whether the craft are 5 million kilometers or five meters from each other. So the interferometers can be adequately tested on the ground.
But something else DOES require a space test. LISA's measurements will be so precise that they would be interfered with if each proof-test cube drifts even slightly too close to the walls of the chamber inside which it's floating, and so began to be tugged slightly toward that wall by the extremely faint gravitational or electric-charge pulls of the spacecraft's own body.
So each spacecraft must measure the position of each metal cube in each chamber (using electric-field sensors)with an accuracy of one one 100-thousandth of a millimeter, and repeatedly fire tiny ion engines producing only a few milligrams of thrust to keep adjusting the spacecraft's position to keep the cube that precisely centered in its chamber.
And this can only be tested during a prolonged stay in zero-G -- so SMART-2 is scheduled to consist of one European spacecraft bus, testing two such "disturbance reduction systems" (one built by the ESA, the other by the U.S.) for months in solar orbit.
ESA would like, however, to considerably expand SMART-2 to also test another system for a possible ESA-American collaboration: "Darwin" (known in the U.S. as the Terrestrial Planet Finder or "TPF"), a set of telescopes that may be put into solar orbit later in the next decade to formation-fly several hundred meters away from each other and actually project their images to each other to combine them, simulating a single telescope with a mirror gigantic enough to directly image Earth-like planets of other stars and take spectra of the planets' atmospheres to look for gases that may indicate life.
To combine their images with the super-precision needed for this, Darwin's separate satellites -- unlike LISA's -- must not just measure sudden changes in their relative distances; they must precisely measure the distances themselves using laser interferometers, and use their micro-ion engines to keep themselves constantly flying in such precise formation that their distances from each other never change by more than 1/1000 of a millimeter.
Testing a system like that on SMART-2 would require that it consist of two spacecraft, and would thus considerably raise the cost of the mission. Some member nations of the ESA would like to do this -- but at present it's very uncertain whether the ESA will have the funds to do so, especially since NASA itself is now leaning instead toward designs for Darwin/TPF that only require a single satellite.
If the two space agencies do agree on a single-satellite version, there will of course be no point in testing super-precise formation-flying systems for the time being. (For the same reason, NASA has recently cancelled its "Starlight" mission -- formerly known as "Deep Space 3" -- which was supposed to fly a pair of small telescopic spacecraft in 2006 to test Darwin/TPF free-flying technologies even more thoroughly.)
Outside the ESA's purview, there has been continuing bad news regarding France's participation as an extremely important partner in the U.S. Mars exploration program.
The current plan for retrieval of the first samples from the surface of Mars calls for a U.S. lander to load about 1 kg of rock and soil into a grapefruit-sized "Orbiting Sample Container" weighing 5 kg and equipped with a solar-powered radar beacon, and then use a two-stage solid rocket to launch it into a 590-km altitude orbit.
A French-built orbiter would then wait until its own orbital plane had precessed into the same plane as the OSC (which might be as much as 6 months after the canister was launched), meanwhile using a radar system to precisely track its orbit so that Earth could use that data to precisely adjust the orbiter's orbit until it was parallel with the OSC's orbit but just 1 or 2 kilometers lower.
Then, when the faster-moving orbiter had closed to within 3-5 km behind the OSC, it would begin using a LIDAR laser-radar system to track the OSC (which would have laser reflectors on it), automatically rendezvous to within 80 meters of it, and then use the LIDAR system (and perhaps also a container-tracking camera as a backup) to close in on the container and catch it in a large funnel with a closable lid -- after which the container would be loaded into an Earth-return capsule on the orbiter.
The orbiter would later fire its engine to leave Mars orbit, return to earth, and drop off the Earth-return capsule while flying by Earth.
While France would build the main orbiter, all the rendezvous and docking equipment would be provided by the U.S. It's obviously a very complex procedure and will certainly require a test in orbit -- so France had planned to build a first copy of the orbiter and launch it into Mars orbit in 2007 to eject a dummy OS Container and spend 6 months practicing rendezvous and docking with it in Mars orbit -- practicing its initial long-range radar tracking of the OSC and its jockeying by Earth commands into its pre-rendezvous orbit four times, and practicing actual rendezvous and docking with the OSC no less than 12 times.
This, however, would not have been the only function of this 2007 "Premier" mission. Its other main goal would have been to carry four small "Netlanders", weighing only 76 kg each, and releasing them to land on widely separated spots on Mars just before entering Mars orbit itself -- after which it would spend two years relaying their data back to Earth.
The Netlanders have been an important part of France's space program for some time. They would land using parachutes and shock-absorbing airbags (although no rocket engines of any sort), then unfold themselves.
Their single most important task would be to set up the first seismometer network on Mars -- a very high scientific priority for Mars, crucial in studying the planet's internal structure and level of geological activity -- but they would also serve as a network of weather stations to study the planet's meteorology, as well as photographing the surrounding landscape, measuring the local weak magnetic fields, using ground-penetrating radar to probe several kilometers beneath them in search of permafrost layers, and even carrying copies of the "Mars Microphone" lost on Mars Polar Lander to make the first recordings of natural sounds on Mars.
As a lower but hoped-for priority, Premier would carry its own instruments to study Mars from orbit -- MAMBO, a microwave sounder to precisely profile temperatures, wind speeds and trace gases at various altitudes, and DYNAMO, a package of assorted sensors to study the interaction of Mars' upper atmosphere with the solar wind, find out how fast the planet's remaining atmosphere is slowly escaping into space, and map local perturbations in magnetic fields.
It was also thought that this would still leave 6 kg of spare payload margin for Premier to carry another instrument, for which the French space agency CNES put out an international bid that drew four proposals from the U.S.
After its two years of Netlander relay duty and rendezvous and docking practice were ended, Premier would have lowered itself from its initial 500-km polar orbit down to 350 km for a year of these studies, and then put itself for another year into an orbit with a periapsis of only 170 km to skim through Mars' upper atmosphere for DYNAMO's benefit.
Unfortunately, Premier itself was predictably expensive, and it started to run seriously afoul of France's own space budgeting problems.
First, the plan to put both it and its later sample-retrieving twin in orbit around Mars using "aerocapture" -- actually sending each craft making a firy skim through Mars' atmosphere down to 45 km altitude on its initial arrival at the planet while the orbiter huddled behind a heat shield, thus slowing it down by 5000 km per hour into Mars orbit without having to burn very large amounts of rocket fuel -- had to be dropped in 2001 (just as the U.S. had earlier dropped plans to test this on its 2001 Mars orbiter).
Aerocapture is an enormously useful procedure and will soon become standard on future planetary orbiters, but the development of the precise guidance system needed for it was just too expensive for CNES to fund for this mission. Premier was redesigned to simply brake itself into Mars orbit using the same big onboard fuel supply that its later sample-collecting twin would use to blast OUT of Mars orbit and back to Earth -- and that later spacecraft would have a big separable package of fuel tanks and an engine to brake it into a low orbit around Mars in the first place (raising its weight to about 4000 kg, as against Premier's 3000 kg).
Then, this summer, CNES' overall budget problems intensified, and it became doubtful that all of the science instruments planned for the orbiter could be carried -- either MAMBO or DYNAMO would have to get the boot.
But it quickly became clear that the the problem was much more serious -- even with these cuts, Premier was still a mission in the $390-460 million range. And at the same time, CNES itself was encountering more funding trouble -- in September, the French Research Ministry announced that CNES' budget for 2003 would be reduced by 2.6 percent, following similar reductions for the past five years. Infuriated researchers called for CNES chief Alain Bensoussan to resign, nd a panel will report on reorgainzation of the agency by year's end.
So, by this fall, CNES was making it clear that Premier must be delayed until 2009 -- if it flies at all. As a deseprate last-ditch attempt to save it, France is trying to get the ESA as a whole to fund a lare part of the mission by incorporating it into the ESA's new "Aurora" program, an attempt to take preliminary steps toward launching a very ambitious Solar System exploration program for Europe comparable to NASA's, which is envisioned as possibly including a separate European Mars sample return mission by the early 2010s, a European manned lunar expedition by 2020 and a European manned mars mission by 2030.
Premier would be incoporated into Aurora by actually enlarging the mission further, with the spacecraft also carrying "Exo-Mars" -- a Russian-built Mars rover as ambitious as the two MER rovers the US plans for 2003, but focused more on exobiological studies. The total 2009 mission might cost $620 million.
The trouble is that Aurora is almost entirely visionary vapors at this point -- the ESA actually plans to spend a mere $14.6 million on it through 2005, for "preliminary studies" on possible mission designs.
This kind of funding is not remotely enough even to fly the least expensive missions envisioned for Aurora, such as an Earth-orbiting test of aerocapture techniques. (And all contributions to the Aurora Program by ESA members are entirely voluntary -- Germany refuses to contribute at all, and Italy is doing so only minimally.)
To have any hope whatsoever of the ESA covering any significant chunk of Premier's cost, France itself must still be willing to fund a large part of that very expensive mission.
The Ministry of Research will make its final decision as to what to do about Premier -- and about France's entire participation in the US Mars sample-return mission -- in January, but it seems increasingly likely that the French-American Mars sample-return partnership is dead.
If so, the cost to the US of a Mars sample return mission will of course increase, since NASA would have to fund the sample-retrieval orbiter as well as the sample-collecting Mars lander. It's still almost certain that the sample-retrival craft will have to carry out an unmanned rendezvous and docking with the sample container in space.
Fortunately, NASA already plans a thorough test of such procedures in Earth orbit with the 2004 "XSS-11" satellite mission. It's even possible that the Mars sampling lander will eventually be redesigned to launch the little sample container completely away from Mars into solar orbit, in which it could be met and retrieved by a sample-retrieval craft which would be no more complex than one orbiting Mars, and vastly lighter in weight.
But cancellation of Premier would still leave France with a problem: they still very much want to land their own four Netlanders on Mars in 2009. They could be carried to Mars on a much lighter-weight and cheaper bus that would itself simply fly by Mars without stopping, but this would leave the problem of how to relay their data back to Earth. NASA, as mentioned, now plans on building and launching its own dedicated Mars comsat in 2009 -- without Italy's help -- but this is by no means a sure thing.
If such a comsat is NOT built, the Netlanders would almost certainly have to depend upon the relay receiver on America's 2005 "MRO" Mars orbiter to do relay duty for them after it had already spent three years in Mars orbit, which seems a bit risky.
Moreover, it's probably too late to redesign MRO to carry one high-priority Netlander experiment: NEIGE, in which a radio receiver on the Premier orbiter would do Doppler radio tracking of the Netlanders' positions on the surface of Mars so precise as to obtain data on whether Mars' core is liquid, and on how the mass of its polar caps grows and shrinks with the seasons.
One possibility which occurs to this reporter is that France might agree to assist the US in building the 2009 Mars comsat, in return for NASA agreeing to have it also carry the Netlanders to Mars. Such a move might be a net money-saver for both nations. We will, presumably, know more in January.
There have, however, been several brighter developments in European Solar System exploration in the last few months. For one thing, at least two-thirds of ESA's very ambitious BepiColombo mission to explore Mercury have been salvaged in Southwood's new decadal ESA plan, although its launch must be delayed two years.
The current BepiColombo design calls for its launch as two separate spacecraft in 2011 on Russian Soyuz rockets, with each craft using venus gravity-assit flybys and ejectable solar-powered ion engine modules to achieve the difficult goal of entering orbit around Mercury three years later.
One would be the Mercury Planetary Orbiter (MPO), which would enter a low-altitude polar orbit around Mercury to map the planet's surface in great detail using various cameras and compositional spectrometers.
MPO would return data at a rate fully 20 times higher than NASA's "Messenger" spacecraft scheduled to enter Mercury orbit in 2008 -- and unlike Messenger, which will have a highly elliptical orbit with the periapsis near Mercury's north pole, MPO will be able to do a decent study of the planet's southern hemisphere.
The other BepiColombo craft would be the Mercury Magnetospheric Orbiter (MMO), a smaller spin-stabilized craft built by Japan's space agency and put into an elliptical orbit to study the planet's weak but very interesting magnetic field and its interaction with the solar wind.
This second BepiColombo launch, however, was originally supposed to be much more ambitious -- after MMO entered Mercury orbit, a third spacecraft, the Mercury Surface Element (MSE), would separate from it and actually land in the tolerable temperature zone near one of Mercury's poles.
MSE would make some kind of survivable hard landing (several designs have been considered), and then spend at least a week --and maybe several months -- doing surface composition studies of Mercury, obtaining the first data on its seismic activity, and measuring its magnetic field and taking surface photos.
David Southwood, however, firmly concluded that the ESA by itself will be unable to fund MSE -- but an intriguing alternative plan is under serious consideration: asking Russia's Babakin space research institute to build the Mercury lander instead.
Russia, despite its economic disaster and the humiliating failure of all three of its most recent Mars probes, still yearns to get back into Solar System exploration, and building the Mercury lander for the ESA might be a more realistic way for it to do so than Russia's current hopes of building an ion-engine powered craft to scoop up a surface sample from Phobos and return to Earth with it sometime in the second half of this decade.
A decision on whether Russia will thus be invited to become a major partner in the international Mercury exploration program will probably be made sometime next year.
One other success of Southwood's reorganization program is that another mission the ESA had hoped to launch sometime after 2013 -- Solar Orbiter -- is now scheduled for launch as early as 2012.
Solar Orbiter would use Venus flybys and a solar-powered ion engine module like the one on the two BepiColombo craft to put itself into an elliptical orbit with a perihelion only 31 million kilometers from the Sun, from which it would not only study the solar wind soon after its release from the Sun, but would use onboard ultraviolet and X-ray cameras and a coronagraph to make detailed studies of the Sun similar to those now being made by the ESA's very successful SOHO satellite.
Solar Orbiter's photos and maps, however, could be fully ten times more detailed than SOHO's, which have been the best obtained up to now. And near each perihelion, it would be rounding the Sun at a rate almost synchronized with the rate of the Sun's rotaion, allowing it to make observations of the changes over time in solar surface features over periods as long as one or two months, rather than the current 13-day limit imposed on ground-based observatories and Earth satellites by fact that the Sun's rotation takes the features out of view.
After that, Solar Orbiter would begin tilting its orbital plane at a steeper and steeper angle to the ecliptic, all the way up to 30 degrees at the end of its nominal five-year mission and as much as 38 degrees during its two-year extended mission -- which would allow it to obtain the first photos of solar surface features too near the Sun's poles to be adequately viewed from Earth.
The Ulysses spacecraft, which has been orbiting the Sun since 1991 at an angle tilted fully 90 degrees to the ecliptic plane, is not equipped with any kind of cameras.
Just as the ESA will able to save money on the Eddington and GAIA missions by basing their spacecraft on the same bus design as that of Herschel and Planck, the Solar Orbiter mission will now save money by basing its spacecraft design on a near-duplicate of the MPO craft in the BepiColombo program.
But just as Venus Express has to be launched within two years of its Mars Express twin to maximize the money saved this way, Solar Orbiter must be launched within a year of the two BepiColombo launches. NASA is also showing great interest in providing some aid in developing and operating this spacecraft, in return for being given some of its onboard experiment payload.
Finally, one piece of nearer-term good news: the problems with the landing system of the little "Beagle 2" lander that was supposed to be carried to Mars in 2003 on Mars Express -- which had seriously threatened the lander's cancellation -- have apparently been resolved.
Beagle, which is slightly smaller than the Netlanders, will use the same system of a parachute and shock-absorbing crash airbags, and will then attempt to carry out the first genuinely biology-related experiments conducted on the surface of Mars since the 1976 Viking landers.
But -- unlike America's Pathfinder Mars lander and its two 2003 Mars rovers, Beagle does not also use a solid-fueled rocket to further decrease its landing speed, with the result that it was designed to survive a landing shock of 100 km/hour. Tests in 2001, however, consistently showed the airbags rupturing at that speed, and this -- along with some lesser developmental problems -- placed the little lander in serious danger of cancellation by the ESA.
The consortium of universities developing Beagle -- headed by Colin Pillinger of Britain's Open University -- decided that making the airbags thick enough to endure properly would also make them too heavy, and that the best solution was instead to develop a parachute that was considerably bigger but equally lightweight and tough.
Beagle's industrial lead contractor, Astrium, came up within a month with a new parachute design whose canopy area was 56 percent greater, capable of slowing Beagle to a survivable impact speed of only 65 km/hour -- if the new lightweight canopy could survive the aerodynamic stress of opening.
Happily, Beagle 2's managers tell "SpaceDaily" that both high-speed rapid extraction tests and maximum-load tow tests have proven beyond doubt that the new chute is indeed capable of opening and functioning properly while Beagle is still dropping through the thin Martian air at 380 km/hour, and also that the little pilot chute which must open earlier at fully 950 km/hour has passed similar tests.
Meanwhile, the center of its possible landing area in the big, flat Isidis Plain has been moved 66 km to the ortheast, to reduce the chance that horizontal winds might be blowing Beagle sideways at a dangerously high speed on landing (a problem which has also plagued the American MER rovers, and seems to be the Achilles Heel of Pathfinder-type landings using airbags).
This moves Beagle further away from the most interesting parts of Isidis -- the areas near its mountainous southern rim, from which ancient rivers may have spread water-associated sediments onto the plain during Mars' most ancient days -- but it also reduces the forecast likely wind speeds, and the redesigned parachute is also less susceptible to being blown sideways by winds.
The other development problems which had plagued Beagle have also apparently been resolved. While there is still a good deal of unease among many scientists about the fact that this sophisticated little vehicle (fully 30% of whose landed weight consists of its wide variety of scientific instruments) has been developed for a cost of only $48 million, the ESA has now officially approved its inclusion on Mars Express, and so Beagle will at least have a chance to prove its viability.
If it does succeed in its landing attempt on Christmas Day next year, it will become the fourth vehicle -- and the first non-American one -- to successfully land on Mars, a few weeks before the two American MER rovers make their landing attempts.
In short, it seems that the progress of the European space science program will continue to strongly resemble that of NASA's bigger science program -- a combination of repeated alarming retrenchments due to budgetary problems, occasional embarrassing failures during actual flights, and frequent spectaculr successes to make up for all that.
By next January, we should know a great deal more about the coming form of both the American and European space science programs, and the extent to which they will be interconnected.
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Lift Off for Aurora: Europe's First Steps to Mars, the Moon and Beyond
Paris (ESA) Oct 15, 2002
Step by step, the European Space Agency's new Aurora space exploration programme is beginning to take shape. This ambitious programme, started by ESA in January 2002, sets out a strategy over the next 30 years for Europe's robotic and human exploration of Mars, the Moon, and even beyond to the asteroids.
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