A new crew is carrying out the latest two-week simulation of a mission on the Red Planet at the Mars Society‘s Mars Desert Research Station in Utah: Mock Mars Mission Starts Saturday in Utah Desert – Space.com.
The seven members of this MDRS crew are all candidates for missions in the Mars One project.
Here are some cool videos showing the far side of the Moon using time-lapse imagery from the Lunar Reconnaissance Orbiter :
A number of people who’ve seen the annual lunar phase and libration videos have asked what the other side of the Moon looks like, the side that can’t be seen from the Earth. This video answers that question.
Just like the near side, the far side goes through a complete cycle of phases. But the terrain of the far side is quite different. It lacks the large dark spots, called maria, that make up the familiar Man in the Moon on the near side. Instead, craters of all sizes crowd together over the entire far side. The far side is also home to one of the largest and oldest impact features in the solar system, the South Pole-Aitken basin, visible here as a slightly darker bruise covering the bottom third of the disk.
The far side was first seen in a handful of grainy images returned by the Soviet Luna 3 probe, which swung around the Moon in October, 1959. Lunar Reconnaissance Orbiter was launched fifty years later, and since then it has returned hundreds of terabytes of data, allowing LRO scientists to create extremely detailed and accurate maps of the far side. Those maps were used to create the imagery seen here.
A virtual telescopic view of the Moon from its far side, with the
Earth looming in the background. The camera is fixed to
the Earth-Moon line.
A view from the Moon’s far side, using a short focal length that
makes the distant Earth look small. The camera is fixed
to the Moon’s surface.
A new study from the European Southern Observatory (ESO) :
Stellar Partnership Doomed to End in Catastrophe
First pair of merging stars destined to become supernova found
Astronomers using ESO facilities in combination with telescopes in the Canary Islands have identified two surprisingly massive stars at the heart of the planetary nebula Henize 2-428. As they orbit each other the two stars are expected to slowly get closer and closer, and when they merge, about 700 million years from now, they will contain enough material to ignite a vast supernova explosion. The results will appear online in the journal Nature on 9 February 2015.
This artist’s impression shows the central part of the planetary nebula Henize 2-428. The core of this unique object consists of two white dwarf stars, each with a mass a little less than that of the Sun. They are expected to slowly draw closer to each other and merge in around 700 million years. This event will create a dazzling supernova of Type Ia and destroy both stars. Credit: ESO/L. Calçada
The team of astronomers, led by Miguel Santander-García (Observatorio Astronómico Nacional, Alcalá de Henares, Spain;Instituto de Ciencia de Materiales de Madrid (CSIC), Madrid, Spain), has discovered a close pair of white dwarf stars — tiny, extremely dense stellar remnants — that have a total mass of about 1.8 times that of the Sun. This is the most massive such pair yet found  and when these two stars merge in the future they will create a runaway thermonuclear explosion leading to a Type Ia supernova .
This artist’s impression video shows the central part of the planetary nebula Henize 2-428. The core of this unique object consists of two white dwarf stars, each with a mass a little less than that of the Sun. They are expected to slowly draw closer to each other and merge in around 700 million years. This event will create a dazzling supernova of Type Ia and destroy both stars. Credit: ESO/L. Calçada
The team who found this massive pair actually set out to try to solve a different problem. They wanted to find out how some stars produce such strangely shaped and asymmetric nebulae late in their lives. One of the objects they studied was the unusual planetary nebula  known as Henize 2-428.
“When we looked at this object’s central star with ESO’s Very Large Telescope, we found not just one but a pair of stars at the heart of this strangely lopsided glowing cloud,” says coauthor Henri Boffin from ESO.
This supports the theory that double central stars may explain the odd shapes of some of these nebulae, but an even more interesting result was to come.
“Further observations made with telescopes in the Canary Islands allowed us to determine the orbit of the two stars and deduce both the masses of the two stars and their separation. This was when the biggest surprise was revealed,” reports Romano Corradi, another of the study’s authors and researcher at the Instituto de Astrofísica de Canarias (Tenerife, IAC).
They found that each of the stars has a mass slightly less than that of the Sun and that they orbit each other every four hours. They are sufficiently close to one another that, according to the Einstein’s theory of general relativity, they will grow closer and closer, spiralling in due to the emission of gravitational waves, before eventually merging into a single star within the next 700 million years.
The resulting star will be so massive that nothing can then prevent it from collapsing in on itself and subsequently exploding as a supernova. “Until now, the formation of supernovae Type Ia by the merging of two white dwarfs was purely theoretical,” explains David Jones, coauthor of the article and ESO Fellow at the time the data were obtained. “The pair of stars in Henize 2-428 is the real thing!”
“It’s an extremely enigmatic system,” concludes Santander-García. “It will have important repercussions for the study of supernovae Type Ia, which are widely used to measure astronomical distances and were key to the discovery that the expansion of the Universe is accelerating due to dark energy“.
This image of the unusual planetary nebula was obtained using ESO’s Very Large Telescope at the Paranal Observatory in Chile. In the heart of this colourful nebula lies a unique object consisting of two white dwarf stars, each with a mass a little less than that of the Sun. These stars are expected to slowly draw closer to each other and merge in around 700 million years. This event will create a dazzling supernova of Type Ia and destroy both stars. Credit: ESO
SPECIAL TIME: 1. Monday, Feb. 9, 2015: 9:30 -11 AM PST (12:30-2 PM EST; 11:30-1 PM CST): We welcome PAUL SZYMANSKI to the program to discuss developing military space policy and related issues.
2. Tuesday, Feb. 10, 2015:,7-8:30 PM PST (10-11:30 PM EST, 9-10:30 PM CST): This is a Space Show audition and try out show. For those of you wanting to be a guest on the program, give us a call and tell us what you want to talk about and why. Those of you interested in a co-hosting a show around your expertise, please call and talk to us about your expertise and why you would be a good co-host.
3. Friday, Feb. 13, 2015; 9:30 -11 AM PST (12:30-2 PM EST; 11:30-1 PM CST): We welcome back CHARLES MILLER to talk about the coming March Storm and space lobbying for space policies.
4. Sunday, Feb. 15, 2015: 12-1:30 PM PST (3-4:30 PM EST, 2-3:30 PM CST): We welcome back author and engineer LES JOHNSON to talk about his book, Back to the Moon. Visit his website at www.lesjohnsonauthor.com.
The Space Show is a project of the One Giant Leap Foundation.
Space science: New Horizon Pluto mission team does Q&A + Mars lander to test system to produce oxygen on Mars
A group of retired spacecraft engineers and scientists are helping to design and build an experimental system to go on the Mars 2020 lander that will extract oxygen from the CO2 in the atmosphere : Elder statesmen of science unite for Mars mission – The Boston Globe
At an age when most are retired or thinking hard about it, they’ve put their minds together to help solve one of the great puzzles of human interplanetary travel. And NASA has awarded them $30 million to press on.
To be clear, these elder statesmen of science don’t plan to pay a visit themselves. They are building an oxygen-generating machine to ride aboard the unmanned Mars 2020 rover, an early version of a technology that could enable the next generation to breathe and burn fuel on Mars — and power their way home.
Perhaps it’s no coincidence that the abbreviated acronym for their instrument — the Mars Oxygen In-Situ Resources Utilization Experiment — is MOXIE.
MOXIE would be the first real attempt by NASA to test a system necessary for “in situ” resource utilization, which is key to settlement of Mars and other sites in the solar system. Local resources must be used for long term residence in space rather than relying on supplies from earth.
The latest TMRO program is now available: Google Lunar XPRIZE – TM –
We are joined by Leo Camacho and Nathan Wong of the XPRIZE Foundation to talk about the latest happenings with their Google Lunar XPRIZE Contest.
A conversation with Andy Weir, author of The Martian: A Novel (which will soon be “A Movie” as well), about the book and about humans going to Mars : How Science Fiction Will Help Us Go to Mars: Andy Weir explains the science behind “The Martian.” – Mother Jones
In this SETI Institute seminar, planetary scientist Pascal Lee talks about the Haughton-Mars Project to simulate a Mars base on Devon Island in northern Canadian. He focuses here on simulations of a excursions in a pressurized rover using “specially modified Humvees”:
Here’s the caption to the video:
Pressurized rovers are airtight all-terrain motorhomes in which future planetary explorers will live, work, sleep, and drive during multiple-day excursions far away from their home base. Although pressurized rovers are commonly featured in science-fiction lore and technical studies on paper, there is still very little practical experience with the use of such vehicles in terrestrial field exploration. Since 2003, the NASA Haughton-Mars Project (HMP) has begun leading a series of field simulations of planetary pressurized rover traverses on Devon Island, High Arctic, a bleak and barren polar analog often described as Mars On Earth. As stand-ins for pressurized rovers, the HMP uses specially modified Humvees equipped with living quarters, satellite comms & nav systems, robotic arms, and spacesuit ports. Rover traverses at HMP are also set in a true field exploration operations environment in which dangers, while not as unforgiving as on Mars, are nevertheless real and relevant.
This talk summarizes the HMP’s experience with simulated pressurized rover treks to date, and lessons learned for planning future road trips on the Moon or Mars. Focus is placed on the HMP’s Northwest Passage Drive Expedition (2009-2011), an epic rover journey from the continental United States to Mars On Earth, across hundreds of kilometers of sea-ice along the fabled Northwest Passage. During the voyage, the expedition crew encountered conditions and challenges analogous in basic ways to those awaiting future pressurized rover crews on Mars: hostile environment, dust storm-like blizzards, uncertain route, treacherous terrain, equipment failure, tight crew quarters, limited resources, remoteness, and isolation.
While pressurized rover treks will dramatically expand the range and productivity of human planetary exploration, they will remain expeditions within an expedition. If not planned and implemented with care, they will quickly spell doom for their crews.
The latest report on what’s been happening aboard the Int. Space Station;
A report from New Universe Daily on earth-like exoplanets and on prospects for mining the Moon:
The report references the article One step from Earth – physicsworld.com (req. free registration).
An ESA Hubble team released the following cool images this week:
March of the moons
Hubble captures rare triple moon transit of Jupiter
These new NASA/ESA Hubble Space Telescope images capture a rare occurrence as three of Jupiter’s largest moons parade across the giant gas planet’s banded face. Hubble took a string of images of the event which show the three satellites — Europa, Callisto and Io — in action.
There are four Galilean satellites — named after the 17th century scientist Galileo Galilei who discovered them . They complete orbits around Jupiter ranging from two to seventeen days in duration. The moons can commonly be seen transiting the face of Jupiter and casting shadows onto its layers of cloud. However, seeing three of them transiting the face of Jupiter at the same time is rare, occurring only once or twice a decade.
The image on the left shows the Hubble observation at the beginning of the event. On the left is the moon Callisto and on the right, Io. The shadows from Callisto, Io and Europa are strung out from left to right. Europa itself cannot be seen in the image.
The image on the right shows the end of the event, just over 40 minutes later. Europa has entered the frame at lower left with slower-moving Callisto above and to the right of it. Meanwhile Io — which orbits significantly closer to Jupiter and so moves much more quickly — is approaching the eastern limb of the planet. Whilst Callisto’s shadow seems hardly to have moved, Io’s has set over the planet’s eastern edge and Europa’s has risen further in the west. The event is also shown from start to finish in a video.
Time-lapse of Jupiter’s three moon transit
These new NASA/ESA Hubble Space Telescope images
capture a rare occurrence as three of Jupiter’s largest moons parade
across the giant gas planet’s banded face. Hubble took a string
of images of the event which are stitched together to show the three
satellites — Europa, Callisto and Io — in action in this time-lapse video.
Credit: NASA, ESA, Hubble Heritage Team
Missing from this sequence is the Galilean moon Ganymede which was outside Hubble’s field of view.
The moons of Jupiter have very distinctive colours. The smooth icy surface of Europa is yellow-white, the volcanic sulphur surface of Io is orange and the surface of Callisto, which is one of the oldest and most cratered surfaces known in the Solar System, is a brownish colour.
The images were taken with Hubble’s Wide Field Camera 3 in visible light on 23 January 2015. Whilst Hubble captures these moons in great clarity they can also be seen with a small telescope or even a decent pair of binoculars. Why not try it at home?
Here’s a preview of highlights in the night sky this month:
Bonus: Here is a nice view of the aurora as seen from the Int. Space Station:
Dr. William Borucki, the force behind the Kepler exo-planet finding observatory, gave an update last night on the John Batchelor radio program: John Batchelor Hotel Mars, Wednesday, 2-4-15 – Thespaceshow’s Blog –
David Livingston, who co-hosts the weekly Hotel Mars segment on the John Batchelor show, gave this summary of the show:
John Batchelor and I welcomed Dr. William (Bill) Borucki back to the show to discuss the recently announced discovery of the small five planet system 11.2 billion years old, Kepler-444. This is approximately 2.5 times older than the Earth. We discussed the exoplanet search, rocky planets and their early formation, the surprises contained within the discovery of Kepler-444, and life detection in the habitable zone. As it turns out, the five small planets orbit their sun in 10 days so they are far too hot for life. However, Dr. Borucki did at one point during our discussion estimate the number of planetary candidates that were possible in the habitable zone. One can see Kepler-444 with binoculars so I asked our guest where to look to find it. He also said it was a triple star system! Among the surprises included the discover of dust and metal that early and the discovery that stars formed so very early at all.
The Lunar Reconnaissance Orbiter finds that in craters on the southern hemisphere of the Moon, the slopes facing towards the south have more hydrogen embedded in them than the north facing slopes. The south facing slopes receive somewhat less light than the slopes facing north and so this presumably results in slightly less evaporation. The amount of hydrogen, which to some degree may be in water molecules, is still extremely small and would be very difficult to extract. (There is strong evidence that some craters at the poles, whose floors never see any sunlight at all, have significant amounts of mine-able water ice.)
Space travel is difficult and expensive – it would cost thousands of dollars to launch a bottle of water to the moon. The recent discovery of hydrogen-bearing molecules, possibly including water, on the moon has explorers excited because these deposits could be mined if they are sufficiently abundant, sparing the considerable expense of bringing water from Earth. Lunar water could be used for drinking or its components – hydrogen and oxygen – could be used to manufacture important products on the surface that future visitors to the moon will need, like rocket fuel and breathable air.
Recent observations by NASA’s Lunar Reconnaissance Orbiter (LRO) spacecraft indicate these deposits may be slightly more abundant on crater slopes in the southern hemisphere that face the lunar South Pole. “There’s an average of about 23 parts-per-million-by-weight (ppmw) more hydrogen on Pole-Facing Slopes (PFS) than on Equator-Facing Slopes (EFS),” said Timothy McClanahan of NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
This is the first time a widespread geochemical difference in hydrogen abundance between PFS and EFS on the moon has been detected. It is equal to a one-percent difference in the neutron signal detected by LRO’s Lunar Exploration Neutron Detector (LEND) instrument. McClanahan is lead author of a paper about this research published online October 19 in the journal Icarus.
The hydrogen-bearing material is volatile (easily vaporized), and may be in the form of water molecules (two hydrogen atoms bound to an oxygen atom) or hydroxyl molecules (an oxygen bound to a hydrogen) that are loosely bound to the lunar surface. The cause of the discrepancy between PFS and EFS may be similar to how the Sun mobilizes or redistributes frozen water from warmer to colder places on the surface of the Earth, according to McClanahan.
“Here in the northern hemisphere, if you go outside on a sunny day after a snowfall, you’ll notice that there’s more snow on north-facing slopes because they lose water at slower rates than the more sunlit south-facing slopes” said McClanahan. “We think a similar phenomenon is happening with the volatiles on the moon – PFS don’t get as much sunlight as EFS, so this easily vaporized material stays longer and possibly accumulates to a greater extent on PFS.”
The team observed the greater hydrogen abundance on PFS in the topography of the moon’s southern hemisphere, beginning at between 50 and 60 degrees south latitude. Slopes closer to the South Pole show a larger hydrogen concentration difference. Also, hydrogen was detected in greater concentrations on the larger PFS, about 45 ppmw near the poles. Spatially broader slopes provide more detectable signals than smaller slopes. The result indicates that PFS have greater hydrogen concentrations than their surrounding regions. Also, the LEND measurements over the larger EFS don’t contrast with their surrounding regions, which indicates EFS have hydrogen concentrations that are equal to their surroundings, according to McClanahan. The team thinks more hydrogen may be found on PFS in northern hemisphere craters as well, but they are still gathering and analyzing LEND data for this region.
There are different possible sources for the hydrogen on the moon. Comets and some asteroids contain large amounts of water, and impacts by these objects may bring hydrogen to the moon. Hydrogen-bearing molecules could also be created on the lunar surface by interaction with the solar wind. The solar wind is a thin stream of gas that’s constantly blown off the Sun. Most of it is hydrogen, and this hydrogen may interact with oxygen in silicate rock and dust on the moon to form hydroxyl and possibly water molecules. After these molecules arrive at the moon, it is thought they get energized by sunlight and then bounce across the lunar surface; and they get stuck, at least temporarily, in colder and more shadowy areas.
Since the 1960’s scientists thought that only in permanently shadowed areas in craters near the lunar poles was it cold enough to accumulate this volatile material, but recent observations by a number of spacecraft, including LRO, suggest that hydrogen on the moon is more widespread.
It’s uncertain if the hydrogen is abundant enough to economically mine. “The amounts we are detecting are still drier than the driest desert on Earth,” said McClanahan. However, the resolution of the LEND instrument is greater than the size of most PFS, so smaller PFS slopes, perhaps approaching yards in size, may have significantly higher abundances, and indications are that the greatest hydrogen concentrations are within the permanently shaded regions, according to McClanahan.
The team made the observations using LRO’s LEND instrument, which detects hydrogen by counting the number of subatomic particles called neutrons flying off the lunar surface. The neutrons are produced when the lunar surface gets bombarded by cosmic rays. Space is permeated by cosmic rays, which are high-speed particles produced by powerful events like flares on the Sun or exploding stars in deep space. Cosmic rays shatter atoms in material near the lunar surface, generating neutrons that bounce from atom to atom like a billiard ball. Some neutrons happen to bounce back into space where they can be counted by neutron detectors.
Neutrons from cosmic ray collisions have a wide range of speeds, and hydrogen atoms are most efficient at stopping neutrons in their medium speed range, called epithermal neutrons. Collisions with hydrogen atoms in the lunar regolith reduce the numbers of epithermal neutrons that fly into space. The more hydrogen present, the fewer epithermal neutrons the LEND detector will count.
The team interpreted a widespread decrease in the number of epithermal neutrons detected by LEND as a signal that hydrogen is present on PFS. They combined data from LEND with lunar topography and illumination maps derived from LRO’s LOLA instrument (Lunar Orbiter Laser Altimeter), and temperature maps from LRO’s Diviner instrument (Diviner Lunar Radiometer Experiment) to discover the greater hydrogen abundance and associated surface conditions on PFS.
In addition to seeing if the same pattern exists in the moon’s northern hemisphere, the team wants to see if the hydrogen abundance changes with the transition from day to night. If so, it would substantiate existing evidence of a very active production and cycling of hydrogen on the lunar surface, according to McClanahan.
The research was funded by NASA’s LRO mission. LEND was supplied by the Russian Federal Space Agency Roscosmos. Launched on June 18, 2009, LRO has collected a treasure trove of data with its seven powerful instruments, making an invaluable contribution to our knowledge about the moon. LRO is managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland, for the Science Mission Directorate at NASA Headquarters in Washington.
The New Horizons spacecraft moves ever closer to Pluto and to its fly-by this summer. Here are new pictures taken by the satellite of the Pluto system:
Pluto discoverer Clyde Tombaugh could only dream of a spacecraft flying past the small planet he spotted on the edges of the solar system in 1930. Yet the newest views of Pluto from NASA’s approaching New Horizons probe – released today, on the late American astronomer’s birthday – hint at just how close that dream is to coming true.
Tombaugh, who died in 1997, was born on Feb. 4, 1906.
“This is our birthday tribute to Professor Tombaugh and the Tombaugh family, in honor of his discovery and life achievements — which truly became a harbinger of 21st century planetary astronomy,” said New Horizons Principal Investigator Alan Stern, from the Southwest Research Institute, Boulder, Colorado. “These images of Pluto, clearly brighter and closer than those New Horizons took last July from twice as far away, represent our first steps at turning the pinpoint of light Clyde saw in the telescopes at Lowell Observatory 85 years ago, into a planet before the eyes of the world this summer.”
The “eagle eyes” of New Horizons, LORRI is a panchromatic high-magnification imager, consisting of a telescope with an 8.2-inch (20.8-centimeter) aperture that focuses visible light onto a charge-coupled device. It’s essentially a digital camera with a large telephoto telescope – only fortified to operate in the cold, hostile environs near Pluto. Read more.
The new images, taken with New Horizons’ telescopic Long-Range Reconnaissance Imager (LORRI) on Jan. 25 and Jan. 27, were the first acquired during the spacecraft’s 2015 approach to the Pluto system, which culminates with a close flyby of Pluto and its system of moons on July 14. New Horizons was more than 126 million miles (203 million kilometers) away from Pluto when it began taking the photos, which show Pluto and largest moon, Charon.
“Pluto is finally becoming more than just a pinpoint of light,” said Hal Weaver, New Horizons project scientist at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland. “LORRI has now resolved Pluto, and the dwarf planet will continue to grow larger and larger in the images as New Horizons spacecraft hurtles toward its targets. The new LORRI images also demonstrate that the camera’s performance is unchanged since it was launched more than nine years ago.”
Six Months of Separation: A comparison of images of Pluto and its large moon Charon, taken in July 2014 and January 2015. Between takes, New Horizons had more than halved its distance to Pluto, from about 264 million miles (425 million kilometers) to 126 million miles (203 million kilometers).
Pluto and Charon are four times brighter than and twice as large as in July, and Charon clearly appears more separated from Pluto. These two images are displayed using the same intensity scales. In LORRI’s current view, Pluto and Charon subtend just 2 pixels and 1 pixel, respectively, compared to 1 pixel and 0.5 pixels last July. The images were magnified four times to make Pluto and Charon more visible.
Both images were rotated to show the celestial north pole at the top.
Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.
Over the next few months, LORRI will take hundreds of pictures of Pluto against star fields to refine the team’s estimates of New Horizons’ distance to Pluto. As in these first images, the Pluto system will resemble little more than bright dots in the camera’s view until late spring, but mission navigators will use these images to design course-correcting engine maneuvers that precisely aim New Horizons on approach. The first such maneuver based on these “optical navigation” images, or “OpNavs,” is scheduled for March 10.
Closing in on Pluto at about 31,000 miles per hour, New Horizons has already covered more than 3 billion miles since launch on Jan. 19, 2006. Its epic journey has taken it past each planet’s orbit from Mars to Neptune in record time, and it is now in the first stage of an encounter with Pluto that includes long-distance imaging as well as dust, energetic particle and solar wind measurements to characterize the space environment near Pluto.
“My dad would be thrilled with New Horizons,” said Annette Tombaugh, Clyde Tombaugh’s daughter, of Las Cruces, New Mexico. “To actually see the planet that he had discovered and find out more about it, to get to see the moons of Pluto … he would have been astounded. I’m sure it would have meant so much to him if he were still alive today.”
APL manages the New Horizons mission for NASA’s Science Mission Directorate in Washington. Alan Stern, of the Southwest Research Institute (SwRI), headquartered in San Antonio, is the principal investigator and leads the mission. SwRI leads the science team, payload operations, and encounter science planning. New Horizons is part of the New Frontiers Program managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama. APL designed, built and operates the spacecraft.
Last summer I wrote about a LEGO scratch model of the Hubble Telescope, which could become an official production model by LEGO if it was popular enough. (See The Hubble observatory in LEGO.) LEGO allows LEGO modelers to post about their creations on the LEGO Ideas site. Visitors can vote on the models they like best. Those models that exceed 10,000 votes will be considered for commercial production.
Gabriel Russo posted his impressive Hubble Telescope model at the LEGO Ideas site last year:
It received the 10000 votes but Robert Pearlman reports that it was nevertheless not selected by LEGO : LEGO passes on fan-voted Hubble Space Telescope model – collectSPACE
LEGO on Wednesday (Feb. 4) revealed the outcome of its most recent review of fan-suggested model kits submitted through its LEGO Ideas website. The Danish toy company passed on making the Hubble telescope, selecting a Pixar animator’s WALL-E robot and a “Doctor Who” set instead.
“We reviewed eight amazing projects that reached 10,000 supporters between June and September,” Signe Lonholdt with the LEGO Ideas team said in a video announcing the results of the evaluation. “Reaching 10,000 supporters is a tremendous accomplishment, but the journey [for the sets] is far from over.”
Here were two previous posts about the HST model: