NASA first landed a human on the moon back in 1969, and last achieved the feat in December 1972. In the intervening years, there have been few other missions to Earth’s primary natural satellite. A smattering of uncrewed craft have crashed into the surface, while a mere handful of missions have achieved a soft landing, with none successful from 1976 to 2013.
However, NASA aims to resume missions to the lunar surface, albeit in an uncrewed capacity at this stage. And you won’t have to wait very long, either. The world’s premier space agency aims to once again fly to the Moon beginning in February 2022.
There was a bit of excitement recently at the Naro Space Center on Outer Naro Island, just off the southern coast of the Korea Peninsula. The domestically developed South Korean Nuri rocket departed on its inaugural flight from launch pad LB-2 at 5pm in the afternoon on Thursday, 21 Oct. The previous launch in the KSLV-2 program from this facility was in 2018, when a single-stage Test Launch Vehicle was successfully flown and proved out the basic vehicle and its KRE-075 engines.
This final version of the three-stage Nuri rocket, formally known as Korean Space Launch Vehicle-II (KSLV-2), is 47.2 m long and 3.5 m in diameter. The first stage is powered by a cluster of four KRE-075 sea-level engines having 3 MN of thrust. The second stage is a single KRE-075 vacuum engine with 788 kN thrust, and the final stage is a KRE-007 vacuum engine with 69 kN thrust (all these engines are fueled by Jet-A / LOX). In this maiden flight, the first two stages performed as expected, but something went wrong when the third stage shut off prematurely and failed to gain enough velocity to put the 1400 kg dummy satellite into orbit.
A committee formed to investigate the flight failure convened this week, and issued a statement after a preliminary review of the collected telemetry data. So far, all indications point to a drop in oxidizer tank pressure in the third stage. This could be the result of a leak in the tank itself or the associated plumbing. They will also investigate whether a sensor or other failure in the tank pressurization control system could be at fault. A second launch is currently scheduled for May of next year. Check out [Scott Manley]’s video below the break, where he discusses the launch itself and some history of South Korea’s space program.
Hypersonic speeds are defined by those exceeding Mach 5, and lately there’s been a lot of buzz about unmanned hypersonic vehicles making test flights. Vehicles returning from orbital flight also travel at hypersonic speeds as they do their best to transition back to the terrestrial realm. Before anything leaves ground though, these machines are tested in wind tunnels. [Scott Manley]’s video “How Hypersonic Wind Tunnels Recreate Mach 20” (embedded below) does a wonderful job of explaining the engineering behind wind tunnels for testing hypersonic vehicles.
While the earliest wind tunnels such as that used by the Wright Brothers were powered by simple fans, it is not possible for any propeller to surpass subsonic speeds. This is evidenced by there not being any propeller driven aircraft that can exceed Mach 1. Since an aircraft can’t reach those speeds with a propeller, it follows that a wind tunnel cannot be driven by propellers, fans, or any such device, and exceed Mach 1 wind speed, either. So it begs the question: Just how do they do it?
You might think that the answer lays in Bernoulli’s law – but it does not. You might think it involves compressing the air into smaller and smaller tubes and pipes. It doesn’t. As [Scott Manley] so expertly explains in the video below the break, it has quite a lot in common with actual rocket science.
You may be interested to know that we’ve covered some DIY wind tunnel builds as well as a small desktop wind tunnel in the past. While not hypersonic, they’re exactly what you’d want to have if you’re an aerospace hacker of any kind.
Back during the 2019 Superconference in Pasadena, I had the chance to go to Northrop Grumman’s Redondo Beach campus to get a look at the James Webb Space Telescope. There is the high-bay class 10,000+ cleanroom in building M8, my wife and I along with fellow space nerd Tom Nardi got a chance to look upon what is likely the most expensive single object ever made. The $10 billion dollar space observatory was undergoing what we thought were its final tests before being packaged up and sent on its way to its forever home at the L2 Lagrange point.
Sadly, thanks to technical difficulties and the COVID-19 pandemic, it would be another two years before JWST was actually ready to ship — not a new story for the project, Mike Szczys toured the same facility back in 2015. But the good news is that it finally has shipped, taking the very, very slow first steps on its journey to space.
Both the terrestrial leg of the trip and the trip through 1.5 million kilometers of space are fraught with peril, of a different kind, of course, but still with plenty of chances for mission-impacting events. Here’s a look at what the priceless and long-awaited observatory will face along the way, and how its minders will endure the “30 days of terror” that lie ahead.
[David Given] frequently dives into retrocomputing, and we don’t just mean he refurbishes old computers. We mean things like creating a simulator and assembler for the OBP spaceflight computer, which was used in the OAO-3 Copernicus space telescope, pictured above. Far from being a niche and forgotten piece of technology, the On-Board Processor (OBP) was used in several spacecraft and succeeded by the Advanced On-board Processor (AOP), which in turn led to the NASA Standard Spaceflight Computer (NSSC-1), used in the Hubble Space Telescope. The OBP was also created entirely from NOR gates, which is pretty neat.
One thing [David] learned in the process is that while this vintage piece of design has its idiosyncrasies, in general, the architecture has many useful features and is pleasant to work with. It is a bit slow, however. It runs at a mere 250 kHz and many instructions take several cycles to complete.
Sample of the natural-language-looking programming syntax for the assembler. (Example from page 68 of the instruction set manual for the OBP.)
One curious thing about the original assembler was documentation showing it was intended to be programmed in a natural-language-looking syntax, of which an example is shown here. To process this, the assembler simply mapped key phrases to specific assembly instructions. As [David] points out, this is an idea that seems to come and go (and indeed the OBP’s successor AOP makes no mention whatsoever of it, so clearly it “went”.) Since a programmer must adhere to a very rigid syntax and structure anyway to make anything work, one might as well just skip dealing with it and write assembly instructions directly, which at least have the benefit of being utterly unambiguous.
We’re not sure who’s up to this level of detail, but embedded below is a video of [David] coding the assembler and OBP emulator, just in case anyone has both an insatiable vintage thirst and a spare eight-and-a-half hours. If you’d prefer just the files, check out the project’s GitHub repository.
Once launched, most spacecraft are out of reach of any upgrades or repairs. Mission critical problems must be solved with whatever’s still working on board, and sometimes there’s very little time. Recently ESA’s INTEGRAL team was confronted with a ruthlessly ticking three hour deadline to save the mission.
European Space Agency INTErnational Gamma-Ray Astrophysics Laboratory is one of many space telescopes currently in orbit. Launched in 2002, it has long surpassed its original designed lifespan of two or three years, but nothing lasts forever. A failed reaction wheel caused the spacecraft to tumble out of control and its automatic emergency recovery procedures didn’t work. Later it was determined those procedures were dependent on the thrusters, which themselves failed in the summer of 2020. (Another mission-saving hack which the team had shared earlier.)
With solar panels no longer pointed at the sun, battery power became the critical constraint. Hampering this time-critical recovery effort was the fact that antenna on a tumbling spacecraft could only make intermittent radio contact. But there was enough control to shut down additional systems for a few more hours on battery, and enough telemetry so the team could understand what had happened. Control was regained using remaining reaction wheels.
INTEGRAL has since returned to work, but this won’t be the last crisis to face an aging space telescope. In the near future, its automatic emergency recovery procedures will be updated to reflect what the team has learned. Long term, ESA did their part to minimize space debris. Before the big heavy telescope lost its thrusters, it had already been guided onto a path which will reenter the atmosphere sometime around 2029. Between now and then, a very capable and fast-reacting operations team will keep INTEGRAL doing science for as long as possible.
On a dark night in 2006 I was bicycle commuting to my office, oblivious to the countless man made objects orbiting in the sky above me at thousands of miles per hour. My attention was instead focused on a northbound car speeding through a freeway underpass at dozens of miles per hour, oblivious to my southbound headlamp. The car swerved into the left turn lane to get to the freeway on-ramp. The problem? I was only a few feet from crossing the entrance to that very on-ramp! As the car rushed through their left turn I was presented with a split second decision: slow, and possibly stop in the middle of the on-ramp, or just go for it and hope for the best.
In Blue: Terrified cyclist. In Red: A speeding car careening around a corner without slowing down.
By law I had the right of way. But this was no time to start discussing right of way with the driver of the vehicle that threatened to turn me into a dark spot on the road. I followed my gut instinct, and my legs burned in compliance as I sped across that on-ramp entrance with all my might. The oncoming car missed my rear wheel by mere feet! What could have ended in disaster and possibly even death had resulted in a near miss.
Terrestrial vehicles generally have laws and regulations that specify and enforce proper behavior. I had every right to expect the oncoming car be observant of their surroundings or to at least slow to a normal speed before making that turn. In contrast, traffic control in Earth orbit conjures up thoughts of bargain-crazed shoppers packed into a big box store on Black Friday.
So is spacecraft traffic in orbit really a free-for-all? If there were stringent rules, how can they be enforced? Before we explore the answers to those questions, let’s examine the problem we’re here to discuss: stuff in space running into other stuff in space.
