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When you think of a space telescope, you probably think of ones such as the Hubble, which probes deep space using precision optics. But optical space telescopes are also pointed at Earth, giving us detailed views of everything from weather, to traffic patterns, to the movement of military troops. While Earth-focused telescopes are extremely useful, they can also be fairly large and expensive to launch into space. But that could change with a new proposed design for cube satellites.

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Example of a 1U CubeSat. Credit: Wikipedia user Svobodat

A cube satellite, or CubeSat, is a type of tiny satellite standardized to weight and size. The basic size of CubeSats is known as a unit or “U,” which is a cube 10 centimeters on a side, though some CubeSats are multiple units in size. Their low mass and standard dimensions mean they can be launched in groups or constellations, which significantly reduces the cost. But this small size also limits the amount of optics you can fit into one.

For optical telescopes, the sharpness of your image depends upon the size of your aperture. The Hubble space telescope, for example, has a 2.4-meter wide mirror. If the mirror were smaller, Hubble’s images would be less detailed. That’s because of a wave effect known as diffraction. When waves of light pass through an aperture of a limited area, they can interfere with each other, blurring the resulting image. This diffraction limit reduces the resolving power of your telescope.

Since a 1U CubeSat can only be 10cm across, the optical aperture of a CubeSat can only be a few centimeters across. Given the diffraction limit, a CubeSat in orbit 500km above Earth would only be able to resolve features on Earth that are 3m wide at best or about 10 feet across. That’s not awful, but it is much lower than the resolution of modern commercial satellites. But a team of researchers has developed a design that could improve that limit significantly, and they do it using the same trick used by the James Webb Telescope.

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How folded mirrors might work on a CubeSat. Credit: Schwartz, et al

The James Webb Space Telescope has a primary mirror that’s 6.5 meters across. When launched later this year, it will provide far more detailed images than the Hubble ever could. The problem is that Webb will be launched on an Ariane 5 rocket, which is only 5.4 meters wide. So the Webb’s mirror has to be folded to fit. Only after launch will it unfold to its full size. The CubeSat design uses the same approach. Four folded mirrors allow the satellite to fit within 1U while providing a larger aperture for the CubeSat when unfolded after launch. This is much easier said than done. Folding and unfolding mirrors is easy, but to work they have to be aligned with extreme precision. This is difficult to do even with Webb’s 10 billion-dollar budget, so how do you do it for a cheap CubeSat?

The team proposes doing this in stages. After launch, the CubeSat mirrors could be unfolded and placed into a “close enough” position, then using active and adaptive optics to sharpen the image. The use of adaptive optics would also allow the CubeSat to compensate for heating and cooling effects, which could shift the mirrors out of alignment. Base on their initial studies, the team estimates a 1U CubeSat could achieve a resolution of 80 centimeters when orbiting at 500 kilometers, which is in the range of current commercial satellites.

The low cost of CubeSats means that CubeSat telescopes could make real-time high-resolution imaging of Earth much more cost-effective. A constellation of them could track both long-term and
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Curiosity Rover is Climbing Through Dramatic Striped Terrain on Mars

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Just about every day we here on Earth get a breathtaking picture of Mars’s terrain sent back by a rover. But, the view from space can be pretty amazing, too. The Mars Reconnaissance Orbiter (MRO) just sent back a thought-provoking picture of Curiosity as it makes its way up a steep ridge on Mount Sharp.

The rover is a tiny black dot in the center of the image, which gives a good feeling for what MRO’s HiRISE camera accomplished. For scale, the rover is about the size of a dinner table, sitting in a region of alternating dark and light bands of material on the Red Planet.

NASA's Curiosity Mars rover appears as a dark speck in this image captured from directly overhead by the agency's Mars Reconnaissance Orbiter, or MRO. Credit: NASA/JPL-Caltech/University of Arizona
NASA’s Curiosity Mars rover appears as a dark speck in this image captured from directly overhead by the agency’s Mars Reconnaissance Orbiter, or MRO. Credit: NASA/JPL-Caltech/University of Arizona

Where’s Curiosity?

The Curiosity rover is exploring an ancient ridge on the side of Mount Sharp, which is the peak of a crater on Mars. It’s sitting on the side of a feature called Gediz Vallis Ridge, and the terrains and materials preserve a record of what things were like when water last flowed there. That happened about three billion years ago. The force of the flow brought significant amounts of rocks and debris through the region. They piled up to form the ridge. So, much of what you see here is the desiccated remains of that flooding.

Debris flows are pretty common here on Earth, particularly in the aftermath of floods, volcanic eruptions, tsunamis, and other actions. We can see them wherever material floods through a region or down a slope. In a flood-based flow, the speed of the water combines with gravity and the degree of slope to send material rushing across the surface. A debris flow can also be a dry landslide, and those can occur pretty much anywhere on Earth where the conditions are right. Another type of debris flow comes from volcanic activity. That occurs when material erupts from a volcano, or when earthquakes combined with an eruption collapse material into the side of the mountain. That results in what’s called a “lahar”. Folks in North America might recall the Mount St. Helens eruption in 1980; it resulted in several lahars that buried parts of the surrounding terrain.

Now that scientists see similar-seeming regions on Mars, they want to know several things. How did they form? Were they created by the same processes that make them on Earth? And, how long ago did they begin to form? Curiosity and Perseverance and other rovers and landers have been sent to Mars to help answer those questions.

Understanding the Debris Ridge

Did any of these actions happen on Mars? The evidence is pretty strong, which is why Gediz Vallis itself is a major exploration goal for the rover. It’s a canyon that stretches across 9 kilometers of the Martian surface and is carved about 140 meters deep. Gediz was likely carved by so-called “fluvial” activity (meaning flowing action) in the beginning. Later floods deposited a variety of fine-grained sands and rocks. Over time, winds have blown a lot of that material away, leaving behind protected pockets of materials left behind by the flooding. The size of the rocks tells something about the speed of the flows that deposited all the material. Geological studies of those rocks will reveal their mineral compositions, including their exposure to water over time.

The Gediz Vallis ridge resulted from the action of water pushing rocks and dirt around to build it up over time. Planetary scientists now need to figure out the sequence of events that created it. The clues lie in the scattered rocks in the region and the surrounding terrain. Mount Sharp itself (formally known as Aeolis Mons), is about 5 kilometers high and is, essentially, a stack of layered sedimentary rocks. As Curiosity makes its way up the mountain, it explores younger and younger materials.

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A Giant Gamma-Ray Bubble is a Source of Extreme Cosmic Rays

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Gamma-ray bursts (GRBs) are one of the most powerful phenomena in the Universe and something that astronomers have been studying furiously to learn more about their origins. In recent years, astronomers have set new records for the most powerful GRB ever observed – this includes GRB 190114C, observed by the Hubble Space Telescope in 2019, and GRB 221009A, detected by the Gemini South telescope in 2022. The same is true for high-energy cosmic rays that originate from within the Milky Way, whose origins are still not fully understood.

In a recent study, members of China’s Large High Altitude Air Shower Observatory (LHAASO) Collaboration discovered a massive gamma-ray burst (designated GRB 221009A) in the Cygnus star-forming region that was more powerful than 10 peta-electronvolts (PeV, 1PeV=1015eV), over ten times the average. In addition to being the brightest GRB studied to date, the team was able to precisely measure the energy spectrum of the burst, making this the first time astronomers have traced cosmic rays with this energy level back to their source.

The team was led by Prof. Cao Zhen, a professor at the Institute of High Energy Physics of the Chinese Academy of Sciences (CAS-IHEP), and included CAS members Dr. Gao Chuandong, Dr. Li Cong, Prof. Liu Ruoyu, and Prof. Yang Ruizhi. Their results were described in a paper titled “An ultrahigh-energy gamma-ray bubble powered by a super PeVatron,” which appeared on November 15th in Science Bulletin. The LHAASO Collaboration comprises over 280 members representing 32 astrophysics research institutions worldwide.

The Large High-Altitude Air Shower Observatory (LHAASO) is a composite array made up of 5216 electromagnetic particle detectors, 1188 muon detectors, a 78,000-square-meter water Cherenkov detector array, and 18 wide-angle Cherenkov telescopes. The observatory is located at a height of 4,410 meters (14468.5 ft) on Mount Haizi in Sichuan Province, China, and is dedicated to studying cosmic rays. When cosmic rays reach Earth’s atmosphere, they create “showers” of secondary particles, some of which reach the surface.

The origin of cosmic rays is one of the most important issues in astrophysics today. In the past few decades, astronomers have detected three high-energy GRBs at a peak of about one petaelectronvolts (PeVs) – one quadrillion electronvolts (1015eV) – in their energy spectrum. Scientists believe cosmic rays with energy beneath this level come from astrophysical sources within the Milky Way (like supernovae). This peak energy represents a limit for cosmic rays, which generally take the form of protons accelerated to near-light speed.

However, the origins of cosmic rays in the region of a few petaelectronvolts remain one of the more intriguing mysteries in astrophysics today. Based on data acquired by LHAASO, the Collaboration team discovered a giant ultra-high-energy gamma-ray bubble in the Cygnus X cluster (the largest star-forming region in the Solar neighborhood) located roughly 2.4 billion light-years from Earth. Photons detected inside the structure showed a maximum energy reading of 2.5 PeV, while those ejected showed energy values of up to 20 PeV – the highest ever recorded.

From this, the team inferred the presence of a massive cosmic ray accelerator near the center of the Bubble, which they believe to be the massive star cluster Cygnus OB2 within Cygnus X. This cluster is composed of many young massive stars, including blue-white O-type giants and B-type blue giants, with surface temperatures of over 35,000 and 15,000 °C (63,000 and 27,000 °F), respectively. These stars generate radiation pressure hundreds to millions of times that of the Sun that blows stellar surface material away, creating solar winds that move at speeds of up to thousands of kilometers per second.

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GRB 221009A: looking back through time. Credit: ESA

Collisions between this wind and the ISM create high-energy gamma rays and the ideal environment for efficient particle acceleration. These findings represent the highest-energy cosmic rays detected to date and the first cosmic ray accelerator ever observed. The team’s observations also indicated that the
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Hiking Half Dome: How to Do It Right and Get a Permit

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By Michael Lanza

No hike in the country really compares with Yosemite’s Half Dome. The long, very strenuous, challenging, and incredibly scenic day trip to one of the most iconic and sought-after summits in America begins with ascending the Mist Trail through the shower constantly raining down from 317-foot Vernal Fall and below thunderous, 594-foot Nevada Fall. Climbing the cable route up several hundred feet of steep granite slab delivers a thrill that partly explains the hike’s enormous popularity.

The 8,800-foot summit of Half Dome—where many hikers complete the experience by standing on The Visor, a granite brim jutting out over Half Dome’s sheer, 2,000-foot Northwest Face—delivers an incomparable view of Yosemite Valley and a 360-degree panorama of a big swath of the park’s mountains.

Half Dome validates every step of effort you put into it.

Having been up and down those cables a handful of times over more than 30 years of dayhiking and backpacking all over the country—including many years running this blog and previously as the Northwest Editor of Backpacker magazine for 10 years—I consider Half Dome one of the very best dayhikes in the entire National Park System and certainly one of America’s hardest dayhikes.

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Hi, I’m Michael Lanza, creator of The Big Outside. Click here to sign up for my FREE email newsletter. Join The Big Outside to get full access to all of my blog’s stories. Click here for my e-books to classic backpacking trips. Click here to learn how I can help you plan your next trip.

A hiker atop Half Dome in Yosemite National Park.
” data-image-caption=”Mark Fenton on The Visor of Half Dome, high above Yosemite Valley, in Yosemite National Park.
” data-medium-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2018/07/Yos11-041-Mark-summit-of-Half-Dome-Yosemite-N.P.-CA-2.jpg?fit=300%2C199&ssl=1″ data-large-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2018/07/Yos11-041-Mark-summit-of-Half-Dome-Yosemite-N.P.-CA-2.jpg?fit=900%2C598&ssl=1″ src=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2018/07/Yos11-041-Mark-summit-of-Half-Dome-Yosemite-N.P.-CA-2.jpg?resize=900%2C598&ssl=1″ alt=”A hiker atop Half Dome in Yosemite National Park.” class=”wp-image-35446″ srcset=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2018/07/Yos11-041-Mark-summit-of-Half-Dome-Yosemite-N.P.-CA-2.jpg?resize=1024%2C680&ssl=1 1024w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2018/07/Yos11-041-Mark-summit-of-Half-Dome-Yosemite-N.P.-CA-2.jpg?resize=300%2C199&ssl=1 300w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2018/07/Yos11-041-Mark-summit-of-Half-Dome-Yosemite-N.P.-CA-2.jpg?resize=768%2C510&ssl=1 768w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2018/07/Yos11-041-Mark-summit-of-Half-Dome-Yosemite-N.P.-CA-2.jpg?resize=1080%2C717&ssl=1 1080w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2018/07/Yos11-041-Mark-summit-of-Half-Dome-Yosemite-N.P.-CA-2.jpg?w=1200&ssl=1 1200w” sizes=”(max-width: 900px) 100vw, 900px” data-recalc-dims=”1″ />Mark Fenton on The Visor or Half Dome, high above Yosemite Valley, in Yosemite National Park. Click photo to read about this backpacking trip.

The cables are up for hiking Half Dome from late May through mid-October. A permit is required for this popular dayhike and a permit lottery takes place throughout March. Yosemite requires a reservation to drive into or through the park on some days from April 13 through Oct. 27; nps.gov/yose/planyourvisit/reservations.htm.

This story shares what I’ve learned about navigating the competitive permit system and embarking on such a demanding day of hiking that’s roughly 16 miles round-trip with almost 5,000 feet of elevation gain and loss. Please share your thoughts or questions about hiking Half Dome in the comments section at the bottom of this story. I try to respond to all comments
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