Laser Ranging Makes GPS Satellites More Accurate

Although GNSS systems like GPS have made pin-pointing locations on Earth’s sphere-approximating surface significantly easier and more precise, it’s always possible to go a bit further. The latest innovation involves strapping laser retroreflector arrays (LRAs) to newly launched GPS satellites, enabling ground-based lasers to accurately determine the distance to these satellites.

Similar to the retroreflector array that was left on the Moon during the Apollo missions, these LRAs will be most helpful with scientific pursuits, such as geodesy. This is the science of studying Earth’s shape, gravity and rotation over time, which is information that is also incredibly useful for Earth-observing satellites.

Laser ranging is also essential for determining the geocentric orbit of a satellite, which enables precise calibration of altimeters and increasing the accuracy of long-term measurements. Now that the newly launched GPS III SV-09 satellite is operational this means more information for NASA’s geodesy project, and increased accuracy for GPS measurements as more of its still to be launched satellites are equipped with LRAs.

Self-healing CMOS Imager To Withstand Jupiter’s Radiation Belt

Ionizing radiation damage from electrons, protons and gamma rays will over time damage a CMOS circuit, through e.g. degrading the oxide layer and damaging the lattice structure. For a space-based camera that’s inside a probe orbiting a planet like Jupiter it’s thus a bit of a bummer if this will massively shorted useful observation time before the sensor has been fully degraded. A potential workaround here is by using thermal energy to anneal the damaged part of a CMOS imager.

The first step is to detect damaged pixels by performing a read-out while the sensor is not exposed to light. If a pixel still carries significant current it’s marked as damaged and a high current is passed through it to significantly raise its temperature. For the digital logic part of the circuit a similar approach is used, where the detection of logic errors is cause for a high voltage pulse that should also result in annealing of any damage.

During testing the chip was exposed to the same level of radiation to what it would experience during thirty days in orbit around Jupiter, which rendered the sensor basically unusable with a massive increase in leakage current. After four rounds of annealing the image was almost restored to full health, showing that it is a viable approach.

Naturally, this self-healing method is only intended as another line of defense against ionizing radiation, with radiation shielding and radiation-resistant semiconductor technologies serving as the primary defenses.

Artemis II Agenda Keeps Moon-Bound Crew Busy

With the launch of Artemis II from Cape Canaveral potentially just weeks away, NASA has been releasing a steady stream of information about the mission through their official site and social media channels to get the public excited about the agency’s long-awaited return to the Moon. While the slickly produced videos and artist renderings might get the most attention, even the most mundane details about a flight that will put humans on the far side of our nearest celestial neighbor for the first time since 1972 can be fascinating.

The Artemis II Moon Mission Daily Agenda is a perfect example. Released earlier this week via the NASA blog, the document seems to have been all but ignored by the mainstream media. But the day-by-day breakdown of the Artemis II mission contains several interesting entries about what the four crew members will be working on during the ten day flight.

Of course, the exact details of the agenda are subject to change once the mission is underway. Some tasks could run longer than anticipated, experiments may not go as planned, and there’s no way to predict technical issues that may arise.

Conversely, the crew could end up breezing through some of the planned activities, freeing up time in the schedule. There’s simply no way of telling until it’s actually happening.

With the understanding that it’s all somewhat tentative, a look through the plan as it stands right now can give us an idea of the sort of highlights we can expect as we follow this historic mission down here on Earth.

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Real-Time ISS Tracker Shows Off The Goods

What hardware hacker doesn’t have a soft spot for transparent cases? While they may have fallen out of mainstream favor, they have an undeniable appeal to anyone with an interest in electronic or mechanical devices. Which is why the Orbigator built by [wyojustin] stands out among similar desktop orbital trackers we’ve seen.

Conceptually, it’s very similar to the International Space Station tracking lamp that [Will Dana] built in 2025. In fact, [wyojustin] cites it specifically as one of the inspirations for this project. But unlike that build, which saw a small model of the ISS moving across the surface of the globe, a transparent globe is rotated around the internal mechanism. This not only looks gorgeous, but solves a key problem in [Will]’s design — that is, there’s no trailing servo wiring that needs to be kept track of.

For anyone who wants an Orbigator of their own, [wyojustin] has done a fantastic job of documenting the hardware and software aspects of the build, and all the relevant files are available in the project’s GitHub repository.

The 3D printable components have been created with OpenSCAD, the firmware responsible for calculating the current position of the ISS on the Raspberry Pi Pico 2 is written in MicroPython, and the PCB was designed in KiCad. Incidentally, we noticed that Hackaday alum [Anool Mahidharia] appears to have been lending a hand with the board design.

As much as we love these polished orbital trackers, we’ve seen far more approachable builds if you don’t need something so elaborate. If you’re more interested in keeping an eye out for planes and can get your hands on a pan-and-tilt security camera, it’s even easier.

GIF shows the impact window narrowing to exclude the moon

The Moon Is Safe, For Now: No Collision In 2032 After All

When Asteroid 2024 YR4 was first discovered, it created a bit of a kerfuffle when it was reported it had a couple-percent chance of hitting the Earth in 2032. At 60 meters (196 feet) across, this would have been in the “city killer” class that nobody really wants to see make landfall, so NASA and the ESA scrambled all assets to refine its trajectory in time to do something about it. Amongst those assets was the James Webb Space Telescope (JWST), which is now reporting it will miss both us and our moon.

Even with the JWST, asteroid 2024 YR4 only fills a few pixels.

We reported that JWST was being tapped for this task over a year ago, when the main concern was still if YR4 might hit Earth or not. An Earth impact was fairly quickly ruled out as the window narrowed to include only to Earth’s moon, and concern shifted to excitement. A city killer striking Earth is obviously bad news. The same thing happening to the Moon is a chance to do science — and 2032 would have been plenty of time to get assets in place to observe the impact.

Unfortunately for the impact-curious, JWST was able to narrow down the trajectory further — and we’ve now gone from up to a 4% chance of hitting Luna to a sure miss of 20,000 km or more.

As this game of cosmic billiards we call a solar system continues, it’s only a matter of time before Earth or her moon is struck by another object. Unless we can deflect it, that is — NASA and partnering agencies have been testing how to do that.

New Artemis Plan Returns To Apollo Playbook

In their recent announcement, NASA has made official what pretty much anyone following the Artemis lunar program could have told you years ago — humans won’t be landing on the Moon in 2028.

It was always an ambitious timeline, especially given the scope of the mission. It wouldn’t be enough to revisit the Moon in a spidery lander that could only hold two crew members and a few hundred kilograms of gear like in the 60s. This time, NASA wants to return to the lunar surface with hardware capable of setting up a sustained human presence. That means a new breed of lander that dwarfs anything the agency, or humanity for that matter, has ever tried to place on another celestial body.

Unsurprisingly, developing such vehicles and making sure they’re safe for crewed missions takes time and requires extensive testing. The simple fact is that the landers, being built by SpaceX and Blue Origin, won’t be ready in time to support the original Artemis III landing in 2028. Additionally, development of the new lunar extravehicular activity (EVA) suits by Axiom Space has fallen behind schedule. So even if one of the landers would have been ready to fly in 2028, the crew wouldn’t have the suits they need to actually leave the vehicle and work on the surface.

But while the Artemis spacecraft and EVA suits might be state of the art, NASA’s revised timeline for the program is taking a clear step back in time, hewing closer to the phased approach used during Apollo. This not only provides their various commercial partners with more time to work on their respective contributions, but critically, provides an opportunity to test them in space before committing to a crewed landing.

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Creating An Ultra-Stable Lunar Clock With A Cryogenic Silicon Cavity Laser

Phase-coherent lasers are crucial for many precision tasks, including timekeeping. Here on Earth the most stable optical oscillators are used in e.g. atomic clocks and many ultra-precise scientific measurements, such as gravitational wave detection. Since these optical oscillators use cryogenic silicon cavities, it’s completely logical to take this principle and build a cryogenic silicon cavity laser on the Moon.

In the pre-print article by [Jun Ye] et al., the researchers go through the design parameters and construction details of such a device in one of the permanently shadowed regions (PSRs) of the Moon, as well as the applications for it. This would include the establishment of a very precise lunar clock, optical interferometry and various other scientific and telecommunication applications.

Although these PSRs are briefly called ‘cold’ in the paper’s abstract, this is fortunately quickly corrected, as the right term is ‘well-insulated’. These PSRs on the lunar surface never get to warm up due to the lack of an atmosphere to radiate thermal energy, and the Sun’s warm rays never pierce their darkness either. Thus, with some radiators to shed what little thermal energy the system generates and the typical three layers of thermal shielding it should stay very much cryogenic.

Add to this the natural vacuum on the lunar surface, with PSRs even escaping the solar wind’s particulates, and maintaining a cryogenic, ultra-high vacuum inside the silicon cavity should be a snap, with less noise than on Earth. Whether we’ll see this deployed to the Moon any time soon remains to be seen, but with various manned missions and even Moon colony plans in the charts, this could be just one of the many technologies to be deployed on the lunar surface over the next few decades.