Enlarge/ Landspace's reusable rocket test vehicle lifts off from the Jiuquan Satellite Launch Center on Wednesday, September 11, 2024. (credit: Landspace)
Welcome to Edition 7.11 of the Rocket Report! Outside of companies owned by American billionaires, the most imminent advancements in reusable rockets are coming from China's quasi-commercial launch industry. This industry is no longer nascent. After initially relying on solid-fueled rocket motors apparently derived from Chinese military missiles, China's privately funded launch firms are testing larger launchers, with varying degrees of success, and now performing hop tests reminiscent of SpaceX's Grasshopper and F9R Dev1 programs more than a decade ago.
As always, we welcome reader submissions. If you don't want to miss an issue, please subscribe using the box below (the form will not appear on AMP-enabled versions of the site). Each report will include information on small-, medium-, and heavy-lift rockets as well as a quick look ahead at the next three launches on the calendar.
Landspace hops closer to a reusable rocket. Chinese private space startup Landspace has completed a 10-kilometer (33,000-foot) vertical takeoff and vertical landing test on its Zhuque-3 (ZQ-3) reusable rocket testbed, including a mid-flight engine reignition at near supersonic conditions, Aviation Week & Space Technology reports. The 18.3-meter (60-foot) vehicle took off from the Jiuquan launch base in northwestern China, ascended to 10,002 meters, and then made a vertical descent and achieved an on-target propulsive landing 3.2 kilometers (2 miles) from the launch pad. Notably, the rocket's methane-fueled variable-thrust engine intentionally shutdown in flight, then reignited for descent, as engines would operate on future full-scale booster flybacks. The test booster used grid fins and cold gas thrusters to control itself when its main engine was dormant, according to Landspace.
My friend Alan Jacobs writes in response to a piece bemoaning the fact that nobody reads Arthur Koestler anymore:
You can curse the darkness, or you can light a candle. You can lament that people don’t know the value of Arthur Koestler’s work, or you can write an essay that seeks to call readers’ attention to his best writing. If young people today do not know of events or artists or thinkers or works that you think they would benefit from knowing, you can tell them. That’s one of the main things writers are for.
I am big on being a “curious elder” — and one way, I think, to expand the curious elder idea is to not just be curious about what young people are into, but to also share your curiosity about the world in a way that is generous but without expectation. To point out the things you think are good… just in case somebody, maybe even somebody younger, is looking for them.
Enlarge/ Boeing's Starliner spacecraft after landing Friday night at White Sands Space Harbor, New Mexico. (credit: Boeing)
Boeing's Starliner spacecraft sailed to a smooth landing in the New Mexico desert Friday night, an auspicious end to an otherwise disappointing three-month test flight that left the capsule's two-person crew stuck in orbit until next year.
Cushioned by airbags, the Boeing crew capsule descended under three parachutes toward an on-target landing at 10:01 pm local time Friday (12:01 am EDT Saturday) at White Sands Space Harbor, New Mexico. From the outside, the landing appeared just as it would have if the spacecraft brought home NASA astronauts Butch Wilmore and Suni Williams, who became the first people to launch on a Starliner capsule on June 5.
But Starliner's cockpit was empty as it flew back to Earth Friday night. Last month, NASA managers decided to keep Wilmore and Williams on the International Space Station (ISS) until next year after agency officials determined it was too risky for the astronauts to return to the ground on Boeing's spaceship. Instead of coming home on Starliner, Wilmore and Williams will fly back to Earth on a SpaceX Dragon spacecraft in February. NASA has incorporated the Starliner duo into the space station's long-term crew.
Enlarge/ Boeing's Starliner spacecraft is set to undock from the International Space Station on Friday evening. (credit: NASA)
Boeing's Starliner spacecraft will gently back away from the International Space Station Friday evening, then fire its balky thrusters to rapidly depart the vicinity of the orbiting lab and its nine-person crew.
NASA asked Boeing to adjust Starliner's departure sequence to get away from the space station faster and reduce the workload on the thrusters to reduce the risk of overheating, which caused some of the control jets to drop offline as the spacecraft approached the outpost for docking in June.
The action begins at 6:04 pm EDT (22:04 UTC) on Friday, when hooks in the docking mechanism connecting Starliner with the International Space Station (ISS) will open, and springs will nudge the spacecraft away its mooring on the forward end of the massive research complex.
I am a big believer that travel doesn’t relieve your problems, it throws them into relief. You see your life in a new light and new shadows. The desert light can be good for this. At its peak, it is harsh and unforgiving, but at dusk and dawn it softens, becomes more mysterious. Every trip has its challenges, but I returned home, as I often do, with a sense of perspective and a clarity about what I want to do next. What more could one ask for? (“Go away so you can come back.”)
What I liked most about New Mexico was being in the forests and the deserts outside of town.
In Benjamin Labatut’s The Maniac, a fictional Richard Feynman says:
Los Alamos was high up on a mesa with tall cliffs carved in dark red earth, lots of trees and shrubs all around. The landscape was breathtaking, the most beautiful place I’d ever seen. Coming from New York, I’d never traveled out to the West before, so I really felt like I was in another world. In Mars or something. It had the strange energy of a sacred space, a haven far away from the civilized world, away from prying eyes, farther than God could see. The perfect spot to do the unimaginable.
[March 4th, 2023 Corrections/Updates – poLight informed me of some corrections, better figures, and new information that I have added to the section on poLight. Cambridge Mechatronics informed me about their voltage and current requirements for pixel-shifting (aka wobulation).]
Introduction
For this next entry in my series on companies I met with at CES or Photonics West’s (PW) AR/VR/MR show in 2023, I will be covering two different approaches to what I call “optics micromovement.” Cambridge Mechatronics (CML) uses Shape Memory Alloys (SMA) wires to move optics and devices (including haptics). poLight uses piezoelectric actuators to bend thin glass over their flexible optical polymer. I met with both companies at CES 2023, and they both provided me with some of their presentation material for use in this article.
After discussing the technologies from CML and poLight, it will be got into some of the new uses within AR and VR.
Beyond Camera Focusing and Optical Image Stabilization Uses of Optics Micromovement in AR and VR
Both poLight and CML have cell phone customers using their technology for camera auto-focus and optical image stabilization (OIS). This type of technology will also be used in the various cameras found on AR and VR headsets. poLight’s TLens is known to be used in the Magic Leap 2 reported by Yole Development and Sharp’s CES 2023 VR prototype (reported by SadlItsBradley).
While the potential use of their technology in AR and VR camera optics is obvious, both companies are looking at other ways their technologies could support Augmented and Virtual Reality.
Cambridge Mechatronics (CML) – How it works
Cambridge Mechatronics is an engineering firm that makes custom designs for miniature machines using shaped memory alloy (SMA). Their business is in engineering the machines for their customers. These machines can move optics or objects. The SMA wires contract when heated due to electricity moving through them (below left) and then act on spring structures to cause movement as the wires contract or relax. Using multiple wires in various structures can cause more complex movement. Another characteristic of the SMA wire is that as it heats and contracts, it makes the wire thicker and shorter, causing the resistance to be reduced. CML uses the change in resistance as feedback for closed-loop control (below right).
Show (below right) is a 4-wire actuator that can move horizontally, vertically, or rotate (arrows pointing at the relaxed wires). The SMA wires enable a very thin structure. Below is a still from a CML video showing this type of actuator’s motion.
Below is an 8-wire (2 crossed wires on four sides) mechanism for moving a lens in X, Y, and Z and Pitch and Yaw to control focusing and optical image stabilization (OIS). Below are five still frames from a CML video on how the 8-wire mechanism works.
CML is developing some new SMA technology called “Zero Hold Power.” With this technology, they only need to apply power when moving optics. They suggest this technology would be useful in AR headsets to adjust for temperature variations in optics and support vergence accommodation conflict.
CML’s SMA wire method makes miniature motors and machines that may or may not include optics. With various configurations of wires, springs, levers, ratcheting mechanisms, etc., all kinds of different motions are possible. The issue becomes the mass of the “payload” and how fast the SMA wires can respond.
CML expects that when continuously pixel shifting, they will use take than 3.2V at ~20mA.
poLight – How It Works
poLight’s TLens uses piezoelectric actuators to bend a thin glass membrane over poLight’s special optical clear, index-matched polymer (see below). This bending process changes the lens’s focal point, similar to how the human eye works. The TLens can also be combined with other optics (below right) to support OIS and autofocus.
The GIF animation (right) show how the piezo actuators can bend the top glass membrane to change the lens in the center for autofocus, tilt the lens to shift the image for OIS, and both perform autofocus and OIS.
poLight also proposes supporting “supra” resolution (pixel shifting) for MicroLEDs by tilting flat glass with poLight’s polymer using piezo actuators to shift pixels optically.
One concern is that poLight’s actuators require up to 50 Volts. Generating higher voltages typically comes with some power loss and more components. [Corrected – March 3, 2023]poLight’s companion driver ASIC (PD50) has built-in EMI reduction that minimizes external components (it only requires ext. capacitive load) and power/current consumption is kept very low (TLens® being an optical device, consumes virtually no power, majority of <6mW total power is consumed by our driver ASIC – see table below).
poLight says that the TLens is about 94% transparent. The front aperture diameter of the TLens, while large enough for small sensor (like a smartphone) cameras, seems small at just over 2mm. The tunable wedge concept could have a much wider aperture as it does not need to form a lens. While the poLight method may result in a more compact design, the range of optics would seem to be limited in both the size of the aperture and how much the optics change.
Uses for Optics Micromovement in AR and VR beyond cameras
Going beyond the established camera uses, including autofocus and OIS, outlined below are some of the uses for these devices in AR and VR:
Variable focus, including addressing vergence accommodation conflict (VAC)
Super-resolution – shifting the display device or the optic to improve the effective resolution
Aiming and moving cameras:
When doing VR with camera-passthrough, there are human factor advantages to having the cameras positioned and aimed the same as the person’s eyes.
For SLAM and tracking cameras, more area could be covered with higher precision if the cameras rotate.
Shifting several LEDs to the same location to average their brightness and correct for any dead or weak pixels should greatly improve yields.
Shifting spatial color subpixels (red, green, and blue) to the same location for a full-color pixel. This would be a way to reduce the effective size of a pixel and “cheat” the etendue issue caused by a larger spatial color pixel.
Improve resolution as the MicroLED emission area is typically much smaller than the pitch between pixels. There might be no overlap when switching and thus give the full resolution advantage. This technique could provide even fewer pixels with fewer connections, but there will be a tradeoff in maximum brightness that can be achieved.
Conclusions
It seems clear that future AR and VR systems will require changing optics at a minimum for autofocusing. There is also the obvious need to support focus-changing optics for VAC. Moving/changing optics will find many other uses in future AR and VR systems.
Between poLight and Cambridge Mechatronic (CML), it seems clear that CML’s technology is much more adaptable to a wider range and types of motion. For example, CML could handle the bigger lenses required for VAC in VR. poLight appears to have an advantage in size for small cameras.
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