[Dave Akerman]’s ongoing high altitude balloon (HAB) work is outstanding, and we’re all enriched by the fact that he documents his work like he does. Recently, [Dave] wrote about his balloon tracker based on the Raspberry Pi Pico, whose capabilities brought a couple interesting features to the table.
In a way, HAB trackers have a fairly simple job: read sensors such as GPS and constantly relay that data to someone on the ground so that the balloon’s location can be tracked, and the hardware recovered when it ultimately returns to Earth. There are a lot of different ways to do this tracking, and one thing [Dave] enjoys is getting his hands on a new board and making a HAB tracker out of it. That’s exactly what he has done with the Raspberry Pi Pico.
Nothing builds familiarity like actually using a part, and the Pico had some useful things to contribute to a HAB tracker application. For one thing, the Pico has an onboard buck-boost converter that allows it to be powered from a relatively wide voltage range (~1.8 V to 5.5 V), so running it directly from batteries is both possible and desirable from a tracker perspective. But a really useful feature was possible thanks to the large amount of memory on the Pico: dynamic landing prediction.
[Dave] does landing prediction prior to launch based on environmental conditions, but it’s always better if the HAB tracker can also calculate its own prediction based on actual observed events and conditions. A typical microcontroller board like an Arduino doesn’t have enough memory to store the required data upon which to do such calculations, but the Pico does so easily. [Dave]’s new board transmits an updated landing site prediction along with all the rest of the telemetry, making the retrieval process much more reliable.
The much-anticipated video from the entry descent and landing (EDL) camera suite on the Perseverance rover has been downlinked to Earth, and it does not disappoint. Watch the video below and be amazed.
The video was played at the NASA press conference today, which is still ongoing as we write this. The brief video below has all the highlights, but the good stuff from an engineering perspective is in the full press conference. The level of detail captured by these cameras, and the bounty of engineering information revealed by these spectacular images, stands in somewhat stark contrast to the fact that they were included on the mission mainly as an afterthought. NASA isn’t often in the habit of adding “nice to have” features to a mission, what with the incredible cost-per-kilogram of delivering a package to Mars. But thankfully they did, using mainly off-the-shelf cameras.
The camera suite covered nearly everything that happened during the “Seven Minutes of Terror” EDL phase of the mission. An up-looking camera saw the sudden and violent deployment of the supersonic parachute — we’re told there’s an Easter egg encoded into the red-and-white gores of the parachute — while a down-looking camera on the rover watched the heat shield separate and fall away. Other cameras on the rover and the descent stage captured the skycrane maneuver in stunning detail, both looking up from the rover and down from the descent stage. We were surprised by the amount of dust kicked up by the descent engines, which fully obscured the images just at the moment of “tango delta” — touchdown of the rover on the surface. Our only complaint is not seeing the descent stage’s “controlled disassembly” 700 meters away from the landing, but one can’t have everything.
Honestly, these are images we could pore over for days. The level of detail is breathtaking, and the degree to which they make Mars a real place instead of an abstract concept can’t be overstated. Hats off to the EDL Imaging team for making all this possible.
With the notable exception of the Space Shuttle, rockets and spacecraft have always been considered disposable. It’s a slow and expensive way to travel, akin to building a new airliner for every flight, but it was the easiest option. These vehicles have always represented the pinnacle of engineering and material science of their time, and just surviving the trip to space once was an incredible accomplishment. To have another go around would have been asking too much of the technology. Even looking back on the Space Shuttle program, there’s plenty of debate about whether or not the reusable design really paid off in the end.
So SpaceX’s ability to land, refurbish, and refly the first stage of their Falcon 9 booster is no small accomplishment. After demonstrating the idea was possible in 2017, the company made numerous changes to the latest iteration of the rocket with reusability in mind. Known as Block 5, this version of the Falcon 9 is designed to be more survivable and require minimal servicing between flights. The company says its cheaper and faster to reuse the Block 5 than it would be to build a new one for each flight, allowing the company to approach spaceflight more like commercial aviation.
With a fleet of Block 5 boosters now in rotation, SpaceX has given them serial numbers not unlike an airplane’s tail number. It might not be the kind of thing the general public would normally be aware of, but these serial numbers have allowed a dedicated community of space aficionados to keep track of the missions each booster has flown.
Unfortunately the story of one of these rockets, officially referred to as “Cores” in SpaceX parlance, was recently cut short. Core B1056, returning from the Starlink 4 mission on February 17th, failed to land on the autonomous spaceport drone ship (ASDS) Of Course I Still LoveYou and splashed down in the ocean. It’s still unclear what condition the booster was in after its soft landing in the water, but when the recovery ships returned to port empty handed, there was no question as to the fate of B1056.
From a purely business standpoint, the failure of any of SpaceX’s boosters means lost time and revenue. But in some ways B1056 had established itself as the vanguard of the fleet, managing to either set or break a number of records in its relatively short life. The destruction of the most thoroughly flight proven Block 5 booster is a stark reminder that there’s very little about spaceflight that could be called routine.
Below is an annotated video of the Apollo 12 landing, in real-time. It’s worth setting aside a quarter-hour to check it out. In an age where everyone is carrying around an HD (or way better) camera in their pocket, following along with radio broadcasts, still images, and small slivers of video might not sound that awesome. But it is!
The video takes us from Powered Descent Initiation through touchdown on the Moon with Pete Conrad and Alan Bean. As the audio plays out the video has annotations which explain what is going on and that translate the jargon used by the team. With the recently celebrated push to publish the source code you can even follow along as the video displays which program is running at that time. Just search for the program code and you’ll find it, like this screenshot of the P63 routine. The code comments are more than enough to get the gist of it all.
If you enjoy this, the description of the YouTube video below includes links to similar videos for Apollo 11, 14, 15, 16, and 17.
[Thanks to Paul Becker for sending along this video]
[Karl-Engelbert Wenzel] developed a UAV capable of taking off and landing on a moving platform autonomously. The platform operates aircraft-carrier-style by driving around the room in circles. The quadcopter tracks a grid of IR LEDs at the front of the landing deck by using the IR camera from a Wii remote. The best part is that the flight controls and processing are all done by the copter’s onboard ATmega644 processor, not requiring a connection to a PC. The landings are quite accurate, achieving a maximum error of less than 40 centimeters. In the video after the break you can see the first landing is slightly off the mark but the next two are dead on target.