CAPSTONE: The Story So Far

After decades of delays and false starts, NASA is finally returning to the Moon. The world is eagerly awaiting the launch of Artemis I, the first demonstration flight of both the Space Launch System and Orion Multi-Purpose Crew Vehicle, which combined will send humans out of low Earth orbit for the first time since 1972. But it’s delayed.

While the first official Artemis mission is naturally getting all the attention, the space agency plans to do more than put a new set of boots on the surface — their long-term goals include the “Lunar Gateway” space station that will be the rallying point for the sustained exploration of our nearest celestial neighbor.

But before launching humanity’s first deep-space station, NASA wants to make sure that the unique near-rectilinear halo orbit (NRHO) it will operate in is as stable as computer modeling has predicted. Enter the Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment, or CAPSTONE.

CAPSTONE in the clean room prior to launch.

Launched aboard an Electron rocket in June, the large CubeSat will hopefully become the first spacecraft to ever enter into a NRHO. By positioning itself in such a way that the gravity from Earth and the Moon influence it equally, maintaining its orbit should require only periodic position corrections. This would not only lower the maintenance burden of adjusting the Lunar Gateway’s orbit, but reduce the station’s propellant requirement.

CAPSTONE is also set to test out an experimental navigation system that uses the Lunar Reconnaissance Orbiter (LRO) as a reference point instead of ground-based stations. In a future where spacecraft are regularly buzzing around the Moon, it will be important to establish a navigation system that doesn’t rely on Earthly input to operate.

So despite costing a relatively meager $30 million and only being about as large as a microwave oven, CAPSTONE is a very important mission for NASA’s grand lunar aspirations. Unfortunately, things haven’t gone quite to plan so far. Trouble started just days after liftoff, and as of this writing, the outcome of the mission is still very much in jeopardy.

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Solar Flare Quiets A Quarter Of The Globe

In the “old” days, people were used to the idea that radio communication isn’t always perfect. AM radio had cracks and pops and if you had to make a call with a radiophone, you expected it to be unreliable and maybe even impossible at a given time. Modern technology,  satellites, and a host of other things have changed and now radio is usually super reliable and high-fidelity. Usually. However, a magnitude 7.9 solar flare this week reminded radio users in Africa and the Middle East that radio isn’t always going to get through. At least for about an hour.

It happened at around 10 AM GMT when that part of the world was facing the sun. Apparently, a coronal mass ejection accompanied the flare, so more electromagnetic disruption may be on its way.

The culprit seems to be an unusually active sunspot which is expected to die down soon. Interestingly, there is also a coronal hole in the sun where the solar wind blows at a higher than usual rate. Want to keep abreast of the solar weather? There’s a website for that.

We’ve pointed out before that we are ill-prepared for technology blackouts due to solar activity, even on the power grid. The last time it happened, we didn’t rely so much on radio.

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Blue Origin Loses Rocket, Gains Abort System Test

Even if you’re just making a brief hop over the Kármán line to gain a few minutes of weightlessness, getting to space is hard. Just in case any of their engineers were getting complacent, Blue Origin just got a big reminder of that fact this afternoon with the destruction of their New Shepard 3 (NS3) rocket during a suborbital research flight.

But while the rocket itself was lost, the New Shepard’s automated abort systems were able to push the capsule H. G. Wells away from the fireball, saving the dozens of scientific experiments which had been loaded onto the un-crewed vehicle. While there’s been no public word yet on the condition of these experiments, it’s reasonable to assume that at least some portion of them can be re-flown in the future — a fact that will likely come as a great relief to the researchers who designed them. It will be interesting to see who picks up the tab for the do-over flight; while launch insurance is a must-have for billion dollar satellites, it seems unlikely these small suborbital experiments would have been covered under a similar policy.

A spurt of flame can be seen in the otherwise invisible exhaust moments before engine failure.

We’re also still in the dark about what caused the in-flight breakup of NS3, other than the fact that the engine was clearly sputtering in the seconds before it blew apart. This could be a sign that the engine’s nominal fuel-to-oxidizer ratio was faltering, or perhaps even indicative of foreign debris becoming dislodged and burning in the combustion chamber. But really, without official word from Blue Origin, it’s impossible to say what happened.

This is especially true when you consider that we’re talking about a vehicle that’s pushing the envelope to begin with. Remember, the New Shepard is a reusable booster, and NS3 is specifically a veteran of eight flights — with all but one of them taking the booster above the 100 kilometer altitude, which is generally accepted to be the boundary of space.

For those worried that celebrities and assorted millionaires will no longer have access to space, fear not. Blue Origin’s crewed flights have flown exclusively on the newer NS4 and its associated capsule First Step. This does however mean that Blue Origin no longer has a spare booster on which to fly commercial payloads, potentially putting into jeopardy any semblance of scientific value the program may have had.

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Unpacking The Stowaway Science Aboard Artemis I

NASA’s upcoming Artemis I mission represents a critical milestone on the space agency’s path towards establishing a sustainable human presence on the Moon. It will mark not only the first flight of the massive Space Launch System (SLS) and its Interim Cryogenic Propulsion Stage (ICPS), but will also test the ability of the 25 ton Orion Multi-Purpose Crew Vehicle (MPCV) to operate in lunar orbit. While there won’t be any crew aboard this flight, it will serve as a dress rehearsal for the Artemis II mission — which will see humans travel beyond low Earth orbit for the first time since the Apollo program ended in 1972.

As the SLS was designed to lift a fully loaded and crewed Orion capsule, the towering rocket and the ISPS are being considerably underutilized for this test flight. With so much excess payload capacity available, Artemis I is in the unique position of being able to carry a number of secondary payloads into cislunar space without making any changes to the overall mission or flight trajectory.

NASA has selected ten CubeSats to hitch a ride into space aboard Artemis I, which will test out new technologies and conduct deep space research. These secondary payloads are officially deemed “High Risk, High Reward”, with their success far from guaranteed. But should they complete their individual missions, they may well help shape the future of lunar exploration.

With Artemis I potentially just days away from liftoff, let’s take a look at a few of these secondary payloads and how they’ll be deployed without endangering the primary mission of getting Orion to the Moon.

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Martian Successes Reshape Sample Return Plans

For as long as humans have been sending probes to Mars, there’s been a desire to return rock, soil, and atmosphere samples back to Earth for more detailed analysis. But the physics of such a mission are particularly demanding — a vehicle that could land on the Martian surface, collect samples, and then launch itself back into orbit for the return to Earth would be massive and prohibitively expensive with our current technology.

Mars sample return tube

Instead, NASA and their international partners have been working to distribute the cost and complexity of the mission among several different vehicles. In fact, the first phase of the program is well underway.

The Perseverance rover has been collecting samples and storing them in 15 cm (6 inch) titanium tubes since it landed on the Red Planet in February of 2021. Considerable progress has also been made on the Mars Ascent Vehicle (MAV) which will carry the samples from the surface and into orbit around the planet, where they will eventually be picked up by yet another vehicle which will ultimately return them to Earth.

But there’s still some large gaps in the overall plan. Chief among them is how the samples are to be transferred into the MAV. Previously, the European Space Agency (ESA) was to contribute a small “fetch rover” which would collect the sample tubes dropped by Perseverance and bring them to the MAV launch site.

But in a recent press release, NASA has announced that those plans have changed significantly, thanks at least in part to the incredible success of the agency’s current Mars missions.

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Next Floor: Geosynchronous Satellites, Orbiting Laboratories

On Star Trek, if you want to go from one deck to another, you enter a “turbolift” and tell it where you want to go. However, many people have speculated that one day you’ll ride an elevator to orbit instead of using a relatively crude rocket. The idea is simple. If you had a tether anchored on the Earth with the other end connected to a satellite, you could simply move up and down the tether. Sound simple, so what’s the problem? The tether has to withstand enormous forces, and we don’t know how to make anything practical that could survive it. However, a team at the International Space Elevator Consortium could have the answer: graphene ribbons.

The concept is not new, but the hope of any practical material able to hold up to the strain has been scant. [Arthur C. Clarke] summed it up in 1979:

How close are we to achieving this with known materials? Not very. The best steel wire could manage only a miserable 31 mi (50 km) or so of vertical suspension before it snapped under its own weight. The trouble with metals is that, though they are strong, they are also heavy; we want something that is both strong and light. This suggests that we should look at modern synthetic and composite materials. Kevlar… for example, could sustain a vertical length of 124 mi (200 km) before snapping – impressive, but still totally inadequate compared with the 3,100 (5,000 km) needed.

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Mini Falcon 9 Uses NASA Software

[T-Zero Systems] has been working on his model Falcon 9 rocket for a while now. It’s an impressive model, complete with thrust vectoring, a microcontroller which follows a predetermined flight plan, a working launch pad, and even legs to attempt vertical landings. During his first tests of his model, though, there were some issues with the control system software that he wrote so he’s back with a new system that borrows software from the Space Shuttle.

The first problem to solve is gimbal lock, a problem that arises when two axes of rotation line up during flight, causing erratic motion. This is especially difficult because this model has no ability to control roll. Solving this using quaternion instead of Euler angles involves a lot of math, provided by libraries developed for use on the Space Shuttle, but with the extra efficiency improvements the new software runs at a much faster rate than it did previously. Unfortunately, the new software had a bug which prevented the parachute from opening, which wasn’t discovered until after launch.

There’s a lot going on in this build behind-the-scenes, too, like the test rocket motor used for testing the control system, which is actually two counter-rotating propellers that can be used to model the thrust of a motor without actually lighting anything on fire. There’s also a separate video describing a test method which validates new hardware with data from prior launches. And, if you want to take your model rocketry further in a different direction, it’s always possible to make your own fuel as well.

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