Although imaging satellites are the most prominent and best documented form of recon satellites, they are far from the only platforms to carry sensors into space for military purposes. The most common use is signals intelligence (SIGINT), taking advantage of the fact that radio waves generally travel in straight lines well past their target, and can be picked up by a passing satellite. Antennas also produce sidelobes that point in different directions from the main lobe, and satellites can often pick up signals in the lobes pointing up. Lastly, a snooping satellite can make use of the fact that radar signals have to be quite powerful to create a useful return, so even a simple receiver is usually enough to pick up a one-way signal.

GRAB/SOLRAD-1 is prepared for launch atop Transit 2A

In fact, the first plans to make use of these properties predate spaceflight itself. In the late 40s, engineers realized that they might be able to measure the signals of Soviet air-search radars by listening to signals reflected off the Moon. Initial tests found that the Moon was a surprisingly good reflector, but the cost of an operational program, and the development proper of SIGINT satellites, killed it off.

SIGINT satellites were planned from early on in the American space program, and a system known as GRAB (officially Galactic Radiation And Background, in fact simply for what it would do to Soviet electronic transmissions), was the world's first successful spy satellite. The satellite, with the cover name SOLRAD 1, was launched as a secondary payload with the Navy's Transit 2A navigation satellite and despite weighing only 19 kg incorporated not only the SIGINT system but also a very real science capability, passing significant data on the Sun's X-ray signature. When in SIGINT mode, it was a simple transponder, relaying the signals it picked up to the ground station, where they were recorded for analysis. This gave not only the performance characteristics of the radars, but also their location, thanks to the use of doppler shift and a bunch of math. These were largely focused on Soviet air defense radars, vital information for both Navy and Air Force as they planned nuclear strikes on the USSR. Read more...

While in LA for the Naval Gazing Meetup (it was great, you should have come) I took the chance to visit the remnants of Fort MacArthur in San Pedro, not far from Iowa. I hadn't been interested in the field until a few years ago, and for various reasons hadn't been able to get there since.

The 14" disappearing battery at the main site¹

Website

Fort MacArthur was established in 1914 to protect the growing city of Los Angeles as part of the Taft board's expanded program of fortifications. Initially, it was equipped with a quartet of the standard 14" disappearing guns and eight 12" mortars, as well as mines and smaller guns to cover the entrance to the Port. These were supplemented in the interwar years by a pair of 14" railroad guns. The fort was not particularly popular with the neighbors, who complained of broken windows, and the railroad guns were often moved up and down the coast to allow the crews to train. After the outbreak of war, there were serious concerns that the Japanese would attack, and the existing defenses were bolstered by the addition of a pair of 16" guns in casemate mounts a little ways up the coast, and another battery was planned down the coast in Orange County. These were armed with the 16"/50 Mk 2 guns designed for the WWI-era South Dakota class, and while the Orange County battery was cancelled in 1944, the battery near MacArthur was among the last ever completed by the United States. Read more...

It's time once again for our regular open thread. Talk about whatever you want, so long as it isn't Culture War.

Since the last discord meetup worked quite well, I'm going to hold another one next weekend, 7/29, at 1 PM Central (GMT-6). Discord link is in the sidebar if you want to join, or if you just want to hang out in the regular channel.

Overhauls are Signalling Part 4 and for 2022, Corrosion at Sea and my review of Hornet.

Now that we have the basics of spaceflight out of the way, we can turn to the most obvious application of spaceflight for military purposes, putting up a fancy camera to see what the enemy is up to.

The remains of the US attempts to establish the precedent of free overflight

Reconnaissance satellites were an early priority for the US space program. The Soviets went to great lengths to limit the flow of information to the west, restricting travel in vast areas, falsifying maps and giving facilities the names of cities dozens of kilometers away. For many years, the best source of mapping data were captured German aerial photos taken during the war. In the early 50s, the lack of information had led to the "bomber gap", where the US erroneously believed that the Soviets had produced a massive fleet of intercontinental bombers. U-2 overflights proved that the actual numbers were barely into double digits, but only after a few years of frantic buildup left the US bomber force in the thousands. Worse, the U-2 was becoming increasingly vulnerable in the face of improved Soviet air defenses, and the diplomatic consequences of overflights were growing ever worse. Satellites could fill this role, and ensuring free overflight became the law was a major priority of Eisenhower's, to the point that he prioritized the civilian Vanguard rocket over the missile-derived Juno I to aid in making his case. Read more...

Space has been an important source of military capabilities for the last 60 years, and it is only growing more critical. I've touched on several aspects of military spaceflight in the my writing where they've interacted with other subjects, but it seems worth taking a look more specifically at the history and development of military spaceflight, and the various systems in use, both in the past and today.

SPACE!

But we need to start with a very brief introduction to spaceflight and orbits.² Getting into space itself isn't that hard. It's 100 km straight up, which means that, neglecting air resistance, you need to be going about 1,400 m/s to get there, or about Mach 4. But you'll barely brush space, then come straight back down, which generally isn't what you want. And that brings us to orbits. The basic insight behind an orbit is that if you go sideways at the right speed, the Earth's surface will fall away below you at the same rate you're falling, allowing you to fall around it forever. If you're in Low Earth Orbit (LEO, altitude below 2,000 km or so) then this is around 7.5 km/s, and you can expect to go around Earth every 90 minutes-2 hours. At higher altitudes, gravity is lower, and you don't need to go as fast. For instance, at an altitude of 35,786 km, you only need to go about 3 km/s, and the orbital period is exactly one day. This is called Geostationary Orbit, because a satellite in this orbit stays stationary relative to the Earth's surface, an extremely useful property we will come back to later. Read more...

It's time once again for our regular open thread. Talk about whatever you want, so long as it isn't culture war.

Reminder that we're doing a virtual meetup in the discord (link in the sidebar) tomorrow at 1 PM Central (GMT-6).

Overhauls are Rangefinding, The Newport Conference and the US Dreadnought, Signalling Part 1, Coastal Defenses Part 8, and for 2022, Coastal Defenses Part 9 and my review of Jeremiah O'Brien and Pampanito.

Colonel G Hall Sebren Jr is the commander of the 72nd Air Base Wing and of Tinker AFB as an installation. He and those responsible for the recent airshow there have given me an opportunity I didn't think I would ever live to see. At last year's Miramar Airshow, it took about an hour and a half to get off base, and I had assumed that I would never encounter a worse line at an airshow (or possibly anywhere). This time, it took about 2 hours to get into the show, thanks to a very slow security line. Col Selbren should be proud of himself for achieving this.

I cannot emphasize how much of a mess this was. The gate opened at 8, and I arrived just before 9. It was 11 before I got through. So in the first hour the gate was open, at least 3 hours worth of people accrued. And when I finally got there, I found three lines through screening, each of which had about a dozen airmen to do bag screening, but laid out so that only 3 or so of them were actually doing anything. They could easily have moved I had initially suspected that they might have just had much higher attendance than they'd planned for (I saw more marketing this year than 4 years ago, and they skipped two years ago because of COVID) but once we got inside, it seemed barely more busy than the 2019 show. I later found out that they hit capacity at 12:30, presumably based on the number of people already in line, which explains both the state inside and the state outside. That said, it's possible that Col Sebren or someone else high in the ranks of the airshow simply likes making people stand in line. That would also explain the poor handling of the lines for the planes on static display, too. Although they did have two E-3s open this year, the rate of flow through any open aircraft was far too slow. How about instead of having crew conversations inside the plane, have them outside, with someone inside just to move people along? Read more...

Before 1890, relations between Germany and America were fairly calm. Both had been busy at home, but in the last decade of the 19th century, they turned their eyes outward, entering the race for colonies worldwide.³ As they were late entries, there was obviously competition between the two for the remaining pieces of land, and after first clashing in Samoa, the two sides nearly went to war when the Germans showed up off Manila after Dewey's victory there, and made enough of a nuisance of themselves that the Americans on at least two occasions had to put shots across their bows. German hopes of securing the Philippines, or at least a part of them, were thwarted, and they were reduced to buying up the rest of Spain's Pacific Empire after the war ended.

The results of a hurricane at Samoa during the crisis

Many in Germany saw its humiliation in the Far East as the result of an insufficient fleet, and quickly turned the incident into yet another reason to support the naval buildup that Tirpitz had started early in 1898. But there was also the question of how to use said fleet, and that year, a number of junior officers were assigned to write evaluations of various elements of war with the United States. The plan that emerged imagined a battle with the USN to gain control of the sea off the Atlantic coast, followed by a landing to secure the Norfolk area. This would then become a base for a thrust up the Chesapeake towards Baltimore and Washington. For some reason, the plan gave no thought to the difficulties of supplying this force across the Atlantic. Read more...

My parents recently swung through town, and on their way in, I went out to meet them in Wichita, where the Fatherly One and I took a look at the local air museum, based in the 1930s terminal on the edge of what is now McConnell AFB.

Some of the outside air park

Website

The museum focuses heavily on the history of aviation in Wichita, which is surprisingly rich for an otherwise rather obscure town in the middle of the Midwest. In the years immediately after WWI, three local engineers founded Travel Air, a pioneering manufacturer of general aviation aircraft. Their names were Clyde Cessna, Walter Beech and Lloyd Stearman, and although Travel Air itself would go under during the Great Depression, all three would set up companies in Wichita that survive in some form or another to this day. Read more...

It's time once again for our regular open thread. Talk about whatever you want, so long as it isn't culture war.

A couple of items of business to address.

First, a reminder that Naval Gazing has a discord, and it's probably the reason that the OTs have been fairly quiet recently. I've been having a lot of fun there. Link is in the sidebar.

Second, for any readers in the OKC area, we have the Tinker airshow coming up. I'm going on July 1st, and am more than happy to meet up with anyone else who is going. Send me an email at battleshipbean at gmail.

Third, I'm going to try to host another virtual meetup. Microsoft has sunsetted the Teams setup I was using, so I'm going to try the Discord again. Because of the airshow, I'm going to push this out two weeks, and do it at 1 PM Central (GMT-6) on the 8th.

Overhauls are Naval Rations Part 1 and for 2022 On the Border of Land and Sea and Museum Review - San Francisco Maritime.