Space Access Society‘s next annual conference on the business, technology, and politics of radically cheaper access to space will feature a cross-section of the growing cheap access community, talking about what’s going on now and what will be happening next, in a fast-paced intensive informal atmosphere, single-track throughout so you don’t have to miss anything.
Confirmed launch-project & space-hardware presenters so far: Altius Space Machines, CubeCab, DARPA ALASA, Exos Aerospace, Frontier Astronautics, Masten Space Systems, Moon Express, Tethers Unlimited, XCOR Aerospace, XL Space Systems, plus sessions on what you’ll need to know to start your own space venture (rocket development safety, 3d printing hype & reality, complex-systems mission-assurance, government regulations, investment climate, NASA Ames and JSC commercial cooperation opportunities), reports on high-end student & amateur projects, talks by famous space writers/bloggers (Jeff Foust, Clark Lindsey, Doug Messier, Rand Simberg, Henry Spencer), and multiple sessions plus a special guest program segment about now that cheap orbital access is near, how do we start affordably taking the next big steps outwards to the Moon, Mars, and beyond?
Space Access conferences have been described as “Hackers” for rocket people, with better content than others costing many times more, two-and-a-half days of total immersion in making the future happen. This year’s edition, SA’15, is just a month away – register for the conference, get those airline tickets booked while they’re still cheap, reserve your room while our hotel still hasn’t filled up, and be there!
For the latest full conference info & agenda, see our SA’15 Info page.
Using observations from NASA’s Hubble Space Telescope and Chandra X-ray Observatory, astronomers have found that dark matter does not slow down when colliding with itself, meaning it interacts with itself less than previously thought. Researchers say this finding narrows down the options for what this mysterious substance might be.
Here are images of six different galaxy clusters taken with NASA’s Hubble Space Telescope (blue) and Chandra X-ray Observatory (pink) in a study of how dark matter in clusters of galaxies behaves when the clusters collide. A total of 72 large cluster collisions were studied. Image Credit: NASA and ESA
Dark matter is an invisible matter that makes up most of the mass of the universe. Because dark matter does not reflect, absorb or emit light, it can only be traced indirectly by, such as by measuring how it warps space through gravitational lensing, during which the light from a distant source is magnified and distorted by the gravity of dark matter.
To learn more about dark matter and test such theories, researchers study it in a way similar to experiments on visible matter — by watching what happens when it bumps into other objects. In this case, the colliding objects under observation are galaxy clusters.
Researchers used Hubble and Chandra to observe these space collisions. Specifically, Hubble was used to map the distribution of stars and dark matter after a collision, which was traced through its gravitational lensing effect on background light. Chandra was used to detect the X-ray emission from colliding gas clouds. The results are published in the March 27 edition of the journal Science.
“Dark matter is an enigma we have long sought to unravel,” said John Grunsfeld, assistant administrator of NASA’s Science Mission Directorate in Washington. “With the combined capabilities of these great observatories, both in extended mission, we are ever closer to understanding this cosmic phenomenon.”
Galaxy clusters are made of three main ingredients: galaxies, gas clouds, and dark matter. During collisions, the gas clouds surrounding galaxies crash into each other and slow down or stop. The galaxies are much less affected by the drag from the gas and, because of the huge gaps between the stars within them, do not slow each other down.
“We know how gas and stars react to these cosmic crashes and where they emerge from the wreckage. Comparing how dark matter behaves can help us to narrow down what it actually is,” said the study’s lead author David Harvey of the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland.
Harvey and his team studied 72 large cluster collisions. The collisions happened at different times and were viewed from different angles — some from the side, and others head-on.
The team found that, like the galaxies, the dark matter continued straight through the violent collisions without slowing down much. This means dark matter does not interact with visible particles and flies by other dark matter with much less interaction than previously thought. Had the dark matter dragged against other dark matter, the distribution of galaxies would have shifted.
“A previous study had seen similar behavior in the Bullet Cluster,” said team member Richard Massey of Durham University in the United Kingdom. “But it’s difficult to interpret what you’re seeing if you have just one example. Each collision takes hundreds of millions of years, so in a human lifetime we only get to see one freeze-frame from a single camera angle. Now that we have studied so many more collisions, we can start to piece together the full movie and better understand what is going on.”
With this discovery, the team has successfully narrowed down the properties of dark matter. Particle physics theorists now have a smaller set of unknowns to work around when building their models.
“It is unclear how much we expect dark matter to interact with itself because dark matter already is going against everything we know,” said Harvey. “We know from previous observations that it must interact with itself reasonably weakly.”
Dark matter may have rich and complex properties, and there are still several other types of interactions to study. These latest results rule out interactions that create a strong frictional force, causing dark matter to slow down during collisions.
The team also will study other possible interactions, such as dark matter particles bouncing off each other like billiard balls and causing dark matter particles to be ejected from the clouds by collisions or for dark matter blobs to change shape. The team also is looking to study collisions involving individual galaxies, which are much more common.
“There are still several viable candidates for dark matter, so the game is not over. But we are getting nearer to an answer,” said Harvey. “These astronomically large particle colliders are finally letting us glimpse the dark world all around us, but just out of reach.”
The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington.
NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra’s science and flight operations.
For images and more information about the Hubble Space Telescope, visit: hubble
1. Monday, March 30, 2015: 2-3:30 PM PDT (5-6:30 PM EDT; 4-5:30 PM CDT): We welcome TONY MILLIGAN to the program to discuss his new book Nobody Owns the Moon: The Ethics of Space Exploitation. Mr. Milligan is a lecturer in philosophy at the University of Hertfordshire in the UK and specializes in ethics.
2. Tuesday, March 31,, 2015:,7-8:30 PM PDT (10-11:30 PM EST, 9-10:30 PM CDT): We welcome back BRUCE DAMER to the show to discuss new architectures for sustainable spaceflight plus Human NEO missions, asteroids, planetary missions. Bruce was last a guest on the show July 9, 2013.
3. Friday, April 3, 2015; 9:30 -11 AM PDT (12:30-2 PM EDT; 11:30-1 PM CDT): We welcome back JIM KERVALA, Chief Operating Officer, Shackleton Energy Company. Jim will be providing us with updates on the Shackleton project for the Moon.
4. Sunday, April 5, 2015: 12-1:30 PM PDT (3-4:30 PM EDT, 2-3:30 PM CDT): Because today is Easter there will be no Space Show today.