Thousands of workers, friends and family held a memorial today in Houston say farewell to the seven astronauts who died Saturday morning when the space shuttle Columbia broke up above Texas. Amid memorial speechs, Bush vowed that “America’s space program will go on,” confirming the agency’s resolve to continue space exploration. The memorial ended with the ringing of a Navy bell, once for each astronaut, and then a “missing man” formation of fighter jets.
NASA controllers lost contact with the space shuttle Columbia around 1400 GMT (9:00am EST) somewhere over the Dallas/Fort Worth area of Texas – only 15 minutes before it was scheduled to land in Florida. The seven astronaut crew are feared lost as large chunks of debris have been seen raining over the area. NASA controllers had no warning that there was a problem, and are currently working to uncover what happened. So far, there is no suspicion of terrorism.
NASA is planning press conferences on Saturday to release more details.
Image credit: NASA
A Pegasus XL rocket successfully launched NASA’s SORCE satellite on Saturday afternoon. The Pegasus was released from its Stargazer L-1011 carrier aircraft at an altitude of nearly 12,000 metres, and it then ignited and flew the satellite into orbit. SORCE contains five instruments designed to observe the Sun.
NASA’s Solar Radiation and Climate Experiment (SORCE) successfully launched Saturday aboard a Pegasus XL rocket.
“Saturday’s successful launch adds to our constellation of Earth-viewing satellites that help us to understand and protect our home planet,” said Dr. Ghassem Asrar, NASA’s Associate Administrator for Earth Sciences, Washington.
“We are all tremendously excited about whatby what we will learn about the solar climate connection from SORCE,” said Bill Ochs, SORCE Project Manager at NASA’s Goddard Space Flight Center in Greenbelt, Md. “We’re very proud of the mission team led by the University of Colorado and supported by Orbital Sciences Corporation. This mission is a great example of how NASA, universities, and industry can partner to create successful missions.”
Over the next few days, the mission team will ensure the spacecraft is functioning properly. The SORCE science instruments will then be turned on and their health verified. Approximately 21 days after launch, the instruments will start science data collection, and calibration will begin. Once in its final orbital position, SORCE will be approximately 397 miles (640 kilometers) above the Earth it will study the sun’s influence on the Earth. It will measure how the sun affects the ozone layer, atmospheric circulation, clouds and oceans.
This mission is a joint partnership between NASA and the University of Colorado’s Laboratory for Atmospheric and Space Physics in Boulder, Colorado. The mission is a principal investigator led mission with NASA providing management and scientific oversight and engineering support. Scientists and engineers at the University of Colorado designed, built, calibrated, and tested the four science instruments on the spacecraft.
The University subcontracted with Orbital Sciences Corporation for the spacecraft and observatory integration and testing. The Mission Operations Center and the Science Operations Center are both operated at the University. The University will operate the spacecraft over its five-year mission life and is responsible for the acquisition, management, processing, and distribution of the science data.
Original Source: NASA News Release
Image credit: NASA
CloudSat, a new satellite mission planned to launch in 2004, will use an advanced radar to study the properties of clouds. It will measure every aspect of the Earth’s clouds, including thickness, height, water and ice content. Using its cloud-penetrating radar, it should be able to increase the accuracy of severe storm, hurricane and flood warnings. It will also fly in orbital formation with several other weather satellites to help form a more complete picture of the Earth’s weather.
“I’ve looked at clouds from both sides now, from up and down and still somehow
It’s clouds’ illusions I recall. I really don’t know clouds at all…”
So laments Joni Mitchell’s classic song “Both Sides Now,” appropriate words as NASA prepares for a mission that should remove much of the mystery from those “rows and flows of angel hair” that so affect Earth’s weather and climate, yet are so misunderstood.
CloudSat, the most advanced radar designed to measure the properties of clouds, will provide the first global measurements of cloud thickness, height, water and ice content, and a wide range of precipitation data linked to cloud development. The Earth System Science Pathfinder Mission is expected to improve weather forecasting and advance our understanding of key climate processes during its two-year design lifetime. CloudSat is planned for launch in 2004 aboard a Boeing Delta rocket from Vandenberg Air Force Base, Calif. NASA’s Jet Propulsion Laboratory, Pasadena, Calif., manages the mission for NASA’s Earth Explorers Program Office at the Goddard Space Flight Center, Greenbelt, Md.
“Despite the fundamental role of clouds in climate and weather, there is much we do not know about them,” said CloudSat Principal Investigator Dr. Graeme Stephens of Colorado State University’s Department of Atmospheric Science, Fort Collins, Colo. “The lack of understanding of cloud feedback is widely acknowledged in the scientific community to be a major obstacle confronting credible prediction of climate change. CloudSat aims to provide observations necessary to greatly advance understanding of climate issues.”
Stephens and Co-Principal Investigator Dr. Deborah Vane of JPL discuss the necessity of CloudSat’s measurements in the current Bulletin of the American Meteorological Society. “The vertical profiles of global cloud properties provided by CloudSat will fill a critical gap in the understanding of how clouds affect climate, uncovering new knowledge about clouds and precipitation, and the connection of clouds to the large-scale motions of Earth’s atmosphere,” Vane said.
CloudSat will help researchers in numerous disciplines. It will provide better understanding of climate processes by supporting new, detailed investigations of how clouds determine Earth’s energy balance and how Earth responds to the incoming solar energy that fuels the climate system. It will improve weather prediction models by measuring cloud properties from the top of the atmosphere to Earth’s surface, filling in a gap in existing and planned space observational systems. CloudSat’s radar can penetrate thick cloud systems, providing information to increase the accuracy of severe storm, hurricane and flood warnings. CloudSat will improve water resource management by linking climate conditions such as El Nino to hydrological processes that affect drought, severe weather and water supply availability. The mission will also develop advanced technologies, including high-power radar sources, methods of radar signal transmission within spacecraft, and integrated geophysical retrieval algorithms.
CloudSat will fly in orbital formation with NASA’s Aqua and Aura satellites, the French Space Agency’s Parasol satellite, and the NASA-French Space Agency Calipso satellite. Its radar measurements will overlap those of the other satellites. It will be the first time five research satellites fly together. The precision of the radar overlap creates a unique multi-satellite observing system, providing unsurpassed information about the role of clouds in weather and climate.
Colorado State’s Stephens conceived CloudSat. JPL, with the Canadian Space Agency, developed the mission’s first-ever space borne millimeter wavelength profiling radar, which measures the altitude and physical properties of clouds. Ball Aerospace, Boulder, Colo., is building the spacecraft. The U.S. Air Force will operate CloudSat on-orbit and deliver raw data to the Cooperative Institute for Research in the Atmosphere at Colorado State, which will process the data for the scientific community, civilian and military weather forecast agencies. The U.S. Department of Energy and an international team of scientists will provide independent verification of the radar performance through its Atmospheric Radiation Measurement Program.
NASA’s Earth Science Enterprise is dedicated to understanding the Earth as an integrated system and applying Earth system science to improve prediction of climate, weather, and natural hazards using the vantage point of space. This mandate is part of NASA’s overall mission to understand and protect our home planet. The California Institute of Technology in Pasadena manages JPL for NASA.
Original Source: NASA/JPL News Release
Officials from the Chinese Space Agency announced on Friday that they tentatively plan to launch humans into space in October of 2003. China has already launched four prototype Shenzhou spacecraft, with the most recent being a virtual replica of a manned space capsule. According to reports, 14 experienced fighter pilots have been training to become taikonauts for years.
Image credit: NASA
The crew of the space shuttle Columbia have been busy over the last few days as they’ve been completing a series of scientific experiments. Once series of experiments, held in a specially built module, is designed to help scientists understand soot formation, oxidation and radiative properties of flames. There were also a group of biomedical experiments to test the human body’s response to weightlessness.
Columbia’s astronauts studied combustion properties and the response of their own bodies in weightlessness and the behavior of soot in space one-quarter of the way through their marathon scientific research mission.
Red Team members Commander Rick Husband, Mission Specialists Kalpana Chawla and Laurel Clark and Israeli Payload Specialist Ilan Ramon completed the first data collection sessions with the Combustion Module in the Spacehab research module housed in Columbia’s cargo bay. One of three experiments housed in the Combustion Module — the study of Laminar Soot Processes (LSP) — is designed to gain a better understanding of soot formation, oxidation and radiative properties within flames.
Additional data was gleaned from the Mechanics of Granular Materials experiment (MGM) in the Spacehab module, which is providing information on the behavior of saturated sand when exposed to confining pressures in microgravity. The experiment could provide engineers with valuable data for strengthening buildings against earthquakes.
Work was also accomplished with a series of biomedical experiments studying the human body’s response to weightlessness — particularly dealing with protein manufacturing in the absence of a gravity environment, bone and calcium production, the formation of chemicals associated with renal stones and how saliva and urine change in space relative to any exposure to viruses.
Experiments continued with the MEIDEX cameras in the cargo bay observing dust storms in the Mediterranean region and with the SOLSE experiment, geared to studying the amount of ozone in the Earth’s atmosphere by using a special imaging spectrometer in the payload bay to look across the limb of the Earth during specifically scheduled orbits.
Columbia’s Blue Team science cadre — Pilot Willie McCool and Mission Specialists Dave Brown and Mike Anderson — planned to continue the more than 80 experiments on board Columbia following their wakeup call this afternoon. The Red team will begin its eight-hour sleep period just before 9 p.m. Central time.
Earlier today, TV cameras in the Spacehab research module captured Ramon conducting work with the Combustion Module. He reported that the materials science facility was operating perfectly as are all of the other experiment facilities aboard Columbia.
Aboard the International Space Station, Commander Ken Bowersox, Flight Engineer Nikolai Budarin and ISS Science Officer Don Pettit completed their second month in space by enjoying an off-duty day. The crew will return to a full complement of scientific research activities, exercise and routine ISS maintenance work on Monday. The ISS crew is working a schedule, which calls for them to be awakened every morning at 12:00 a.m. Central time and for their 8 ? hour sleep period to begin at 3:30 p.m. CST.
The ISS crew was informed that replacement parts for the Microgravity Science Glovebox will be ready for launch on the next Progress resupply vehicle to the ISS on February 2. With docking of that cargo ship to the ISS planned for Feb. 4, virtually all of the science planned for the facility during Expedition 6 will be accomplished as initially planned.
Original Source: NASA News Release
If you’re a Canadian? read this! If you’re not a Canadian, well, still read it… you can help us out. 🙂
I was visiting my Father about 5 years ago, and we were sitting in the kitchen when he said, “hey, it’s time to watch the floaters.” Wha? He turned on the kitchen television, and there was a live broadcast of some astronauts spacewalking outside the shuttle. I couldn’t believe my eyes.
Apparently, my clever Dad had jury-rigged an old satellite dish so that it would receive a television feed from NASA. NASA has a television channel, and it’s all about their space exploration. It could be the greatest thing ever. Okay, it gets a little boring between space launches, but overall, it’s a tremendous channel to have access to.
My Father, on remote Hornby Island, gets NASA television loud and clear. But there’s no way I can get it here in Vancouver. I called my cable company… nope. Then I got a digital satellite dish… nope, sorry.
The only place I can watch NASA TV is on my computer. Ever watched television on your computer? It’s small, blurry, choppy and cuts off all the time. Anyway, I stare enough at computer monitors.
I want my NASA TV.
Well much to my surprise, the Canadian Canadian Radio and Television Commission was actually in discussions to get the cable companies to offer it, but it all fell apart. We get Jerry Springer, but we can’t watch NASA TV. Fortunately, we do get the Daily Show with Jon Stewart, which is about the only thing that gets me to turn my television on these days.
Now there’s hope. The Friends of NASA TV in Canada. It’s a petition to try to convince the CRTC and cable companies to get us the space news we so richly deserve.
If you’re a Canadian, visit their website and sign the petition. Not only that, I want you find as many other Canadians who will do what you say, and get them to sign this. Do it!
If you’re not a Canadian, but you know a Canadian, I want you to send them an email begging them to sign this petition. You got it? Good.
I want my NASA TV.
Fraser Cain, Publisher
Image credit: ESO
New observations from the Japanese 8-m Subaru telescope and the ESO Very Large Telescope (VLT) have revealed new details in the Virgo galaxy cluster – located 50 million light years away. One insight is that massive young stars seem to be able to form in isolation, far away from the brighter parts of galaxies.
At a distance of some 50 million light-years, the Virgo Cluster is the nearest galaxy cluster. It is located in the zodiacal constellation of the same name (The Virgin) and is a large and dense assembly of hundreds of galaxies.
The “intracluster” space between the Virgo galaxies is permeated by hot X-ray emitting gas and, as has become clear recently, by a sparse “intracluster population of stars”.
So far, stars have been observed to form in the luminous parts of galaxies. The most massive young stars are often visible indirectly by the strong emission from surrounding cocoons of hot gas, which is heated by the intense radiation from the embedded stars. These “HII regions” (pronounced “Eitch-Two” and so named because of their content of ionized hydrogen) may be very bright and they often trace the beautiful spiral arms seen in disk galaxies like our own Milky Way.
New observations by the Japanese 8-m Subaru telescope and the ESO Very Large Telescope (VLT) have now shown that massive stars can also form in isolation, far from the luminous parts of galaxies. During a most productive co-operation between astronomers working at these two world-class telescopes, a compact HII region has been discovered at the very boundary between the outer halo of a Virgo cluster galaxy and Virgo intracluster space.
This cloud is illuminated and heated by a few hot and massive young stars. The estimated total mass of the stars in the cloud is only a few hundred times that of the Sun.
Such an object is rare at the present epoch. However, there may have been more in the past, at which time they were perhaps responsible for the formation of a fraction of the intracluster stellar population in clusters of galaxies. Massive stars in such isolated HII regions will explode as supernovae at the end of their short lives, and enrich the intracluster medium with heavy elements.
Observations of two other Virgo cluster galaxies, Messier 86 and Messier 84, indicate the presence of other isolated HII regions, thus suggesting that isolated star formation may occur more generally in galaxies. If so, this process may provide a natural explanation to the current riddle why some young stars are found high up in the halo of our own Milky Way galaxy, far from the star-forming clouds in the main plane.
The Virgo Cluster
The galaxies in the Universe are rarely isolated – they prefer company. Many are found within dense structures, referred to as galaxy clusters, cf. e.g., ESO PR Photo 16a/99.
The galaxy cluster nearest to us is seen in the direction of the zodiacal constellation Virgo (The Virgin), at a distance of approximately 50 million light-years. PR Photo 04a/03 (from the Wide Field Imager camera at the ESO La Silla Observatory) shows a small sky region near the centre of this cluster with some of the brighter cluster galaxies. PR Photo 04b/03 displays an image of a larger field (partially overlapping Photo 04a/03) in the light of ionized hydrogen – it was obtained by the Japanese 8.2-m Subaru telescope on Mauna Kea (Hawaii, USA). The field includes some of the large galaxies in this cluster, e.g., Messier 86, Messier 84 and NGC 4388. In order to show the faintest possible hydrogen emitting objects embedded in the outskirts of bright galaxies, their smooth envelopes have been “subtracted” during the image processing. This is why they look quite different in the two photos.
Clusters of galaxies are believed to have formed because of the strong gravitational pull from dark and luminous matter. The Virgo cluster is considered to be a relatively young cluster, because studies of the distribution of its member galaxies and X-ray investigations of hot cluster gas have revealed small “subclusters of galaxies” around the major galaxies Messier 87, Messier 86 and Messier 49. These subclusters are yet to merge to form a dense and smooth galaxy cluster.
The Virgo cluster is apparently cigar-shaped, with its longest dimension of about 10 million light-years near the line-of-sight direction – we see it “from the end”.
Stars in intracluster space
Galaxy clusters are dominated by dark matter. The largest fraction of the luminous (i.e. “visible”) cluster mass is made up of the hot gas that permeates all of the cluster. Recent observations of “intracluster” stars have confirmed that, in addition to the individual galaxies, the Virgo cluster also contains a so-called “diffuse stellar component”, which is located in the space between the cluster galaxies.
The first hint of this dates back to 1951 when Swiss astronomer Fritz Zwicky (1898-1974), working at the 5-m telescope at Mount Palomar in California (USA), claimed the discovery of diffuse light coming from the space between the galaxies in another large cluster of galaxies, the Coma cluster. The brightness of this intracluster light is 100 times fainter than the average night-sky brightness on the ground (mostly caused by the glow of atoms in the upper terrestrial atmosphere) and its measurement is difficult even with present technology. We now know that this intracluster glow comes from individual stars in that region.
More recently, astronomers have undertaken a new and different approach to detect the elusive intracluster stars. They now search for Sun-like stars in their final dying phase during which they eject their outer layers into surrounding space. At the same time they unveil their small and hot stellar core which appears as a “white dwarf star”.
Such objects are known as “planetary nebulae” because some of those nearby, e.g. the “Dumbbell Nebula” (cf. ESO PR Photo 38a/98) resemble the disks of the outer solar system planets when viewed in small telescopes.
The ejected envelope is illuminated and heated by the very hot star at its centre. This nebula emits strongly in characteristic emission lines of oxygen (green; at wavelengths 495.9 and 500.7 nm) and hydrogen (red; the H-alpha line at 656.2 nm). Planetary nebulae may be distinguished from other emission nebulae by the fact that their main green oxygen line at 500.7 nm is normally about 3 to 5 times brighter than the red H-alpha line.
Search for intracluster planetary nebulae
An international team of astronomers  is now carrying out a very challenging research programme, aimed at finding intracluster planetary nebulae. For this, they observe the regions between cluster galaxies with specially designed, narrow-band optical filters tuned to the wavelength of the green oxygen lines.
The main goal is to study the overall properties of the diffuse stellar component in the nearby Virgo cluster. How much diffuse light comes from the intracluster space, how is it distributed within the cluster, and what is its origin?
Because the stars in this region are apparently predominantly old, the most likely explanation of their presence in this region is that they formed inside individual galaxies, which were subsequently stripped of many of their stars during close encounters with other galaxies during the initial stages of cluster formation. These “lost” stars were then dispersed into intracluster space where we now find them.
The Subaru observations
Japanese and European astronomers used the Suprime-Cam wide-field mosaic camera at the 8-m Subaru telescope (Mauna Kea, Hawaii, USA) to search for intracluster planetary nebulae in one of the densest regions of the Virgo cluster, cf. PR Photo 04b/03. They needed a telescope of this large size in order to select such objects and securely discriminate them from the thousands of foreground stars in the Milky Way and background galaxies.
In particular, by observing in two narrow-band filters sensitive to oxygen and hydrogen, respectively, the planetary nebulae visible in this field could be “separated” from distant (high-redshift) background galaxies, which do not have strong emission in both the green and red band. It is very time-consuming to observe the weak H-alpha emission and this can only be done with a big telescope.
Some 40 intracluster planetary nebulae candidates were found in this field which had the expected oxygen/H-alpha line intensity ratios of 3 – 5, such as those depicted PR Photo 04d/03. Unexpectedly, however, the data also showed a small number of star-like emission objects with oxygen/H-alpha line ratios of about 1. This is more typical of a cloud of ionized gas around young, massive stars – like the so-called HII regions in our own galaxy, the Milky Way.
However, it would be very unusual to find such star formation regions in the intracluster region, so follow-up spectroscopic observations were clearly needed for confirmation.
The VLT measurements
The only way to make sure that these unusual objects are actually powered by young stars is by a detailed spectroscopical study, analyzing the emitted light over a wide range of wavelengths. One of the objects was observed in this way in April 2002 with the FORS2 multi-mode instrument at the 8.2-m VLT YEPUN telescope at the ESO Paranal Observatory (Chile).
This was a most challenging observation, even for this very powerful facility, requiring several hours of exposure time. The brightness of the faint object (the flux of the oxygen [OIII 500.7]-line) was comparable to that of a 60-Watt light bulb at a distance of about 6.6 million km, i.e., about 17 times farther than the Moon.
The recorded (long-slit) spectrum (PR Photo 04e/03) is indeed that of an HII region, with characteristic emission lines from hydrogen, oxygen and sulphur, and with underlying blue “continuum” emission from hot, young stars. This is the first concrete evidence that some of the ionized hydrogen gas in the intracluster medium near NGC 4388 is heated by massive stars, rather than radiation from the nucleus of the galaxy.
Comparing the spectrum with simple starburst models showed that this HII region is “powered” by one or two hot and massive (O-type) stars. The best-fitting starburst model implies an estimated total mass of young stars of some 400 solar masses with an age of about 3 million years. The object is obviously very compact – it is indeed unresolved in all the images. The inferred radius of the HII region is about 11 light-years.
Young stars form far from galaxies
This compact star-forming region is located about 3.4 arcmin north and 0.9 arcmin west of the galaxy NGC 4388, corresponding to a distance of some 82,000 light-years (projected) from the main star-forming regions in this galaxy. The small cloud is moving away from us with an observed velocity of 2670 km/sec. This is considerably faster than the mean velocity of the Virgo cluster (about 1200 km/sec) but similar to that of NGC 4388 (2520 km/sec), indicating that it is probably falling through the Virgo cluster core together with NGC 4388, but it cannot have moved far during the comparatively short lifetime of its massive stars.
It is not known whether it once was or still is bound to NGC 4388, or whether it only belonged to the surroundings that fell into the Virgo cluster with this galaxy. In any case, the existence of this HII region is a clear demonstration that stars can form in the “diffuse” outskirts of galaxies, if not in intracluster space.
Because of internal dynamical processes, the stars in this object cannot remain forever in a dense cluster. Within a few hundred million years they will disperse and mix with the diffuse stellar population nearby. This isolated star formation is therefore likely to contribute to the intracluster stellar population, either directly, or after having moved away from the halo of NGC 4388.
This mode of isolated star formation does not contribute much to the total intracluster light emission – at the current rate it can explain only a small fraction of the diffuse light now observed in this region. However, it may have been more significant in the past, when protogalaxies and proto-galaxy groups, rich in neutral gas and with gas clouds at large distances from their centers, fell into the forming Virgo cluster for the first time.
The existence of isolated compact HII regions like this one is important as a very different site of star formation than those normally seen in galaxies. The massive stars born in such isolated clouds will explode as supernovae and enrich the Virgo intracluster medium with metals.
Other possible – but not yet spectroscopically verified – compact HII regions in the halos of both Messier 86 and Messier 84 have been detected during this work. This finding thus also calls into question the current use of emission-line planetary nebulae luminosities as a distance indicator; to obtain the best possible accuracy, it will henceforth be necessary to weed out possible HII regions in the samples.
If compact HII regions exist generally in galaxies, they may possibly be the birthplaces of some of the young stars now observed in the halo of our Milky Way galaxy, high above the main plane. Observational programmes with both the Subaru and VLT telescopes are now planned to discover more of these interesting objects and to explore their properties.
Original Source: ESO News Release
Image credit: Hubble
The Hubble Space Telescope has provided the clearest view of nearby Quasar 3C 273 ever taken in visible light. The image was taken by using the newly installed Advanced Camera for Surveys (ACS), which is able to block the brightest light to show the dimmer parts of the object. Features in the galaxy surrounding the central quasar are clearly visible.
NASA Hubble Space Telescope’s new Advanced Camera for Surveys (ACS) has provided the clearest visible-light view yet of the nearby quasar 3C 273. The ACS’ coronagraph was used to block the light from the brilliant central quasar, revealing that the quasar’s host galaxy is significantly more complex than had been suggested in previous observations. Features in the surrounding galaxy normally drowned out by the quasar’s glow now show up clearly. The ACS reveals a spiral plume wound around the quasar, a red dust lane, and a blue arc and clump in the path of the jet blasted from the quasar. These details had never been seen before. Previously known clumps of hot gas and the inner blue optical jet are now resolved more clearly.
The power of the ACS coronagraph is demonstrated in this picture. The Hubble image on the left, taken with the Wide Field Planetary Camera 2, shows the brilliant quasar but little else. The diffraction spikes demonstrate the quasar is truly a point-source of light (like a star) because the black hole’s “central engine” is so compact. Once the blinding “headlight beam” of the quasar is blocked by the ACS (right), the host galaxy pops into view. Note that the ACS’ occulting “finger” and other coronagraphic spot are seen in black near the top of the ACS High Resolution Channel image.
Quasars (also known as QSOs ? short for quasi-stellar objects) were discovered in the early 1960s, but at least two decades passed before astronomers had observational evidence that they reside in galaxies. They now are commonly accepted to be supermassive black holes accreting infalling gas and dust. Using the ACS, astronomers want to learn what activities in a quasar’s host galaxy feed the black hole, allowing it to “turn on” as a quasar.
Original Source: Hubble News Release
Now that Rosetta has been delayed indefinitely from its original mission to visit Comet Wirtanen, technicians have to dismantle the spacecraft and return each scientific instrument to the researchers who built them. The mission was cancelled because a recent report indicated that the Ariane 5 rocket was unsafe to launch. Rosetta’s original target was Comet Schwassmann-Wachmann 3, then Comet Wirtanen, so now planners are considering Comets Finlay, Brooks 2 and Wild 2. There’s no scheduled launch date, though.