What’s the X-37 Doing Up There?
The Air Force isn’t saying, so we asked other spaceplane experts.
Kiona Smith-Strickland
It’s been five years since the first launch of the Air Force’s X-37B mini-shuttle, and outside observers—meaning those who lack the proper security clearances—still know little more about this mysterious unmanned vehicle than they did in 2010 (see “Space Shuttle Jr.,” Dec. 2009/Jan. 2010). But after three completed flights and a fourth launch last May (the spaceplane was still in orbit as of mid-December), they’re at least able to make educated guesses.
Despite the project’s general secrecy, the Air Force has been perfectly willing to release photos of the vehicle sitting on top of its Atlas V rocket at Cape Canaveral, Florida, and on the runway at Vandenberg Air Force Base in California where it lands, autonomously. The spaceplane’s dimensions are known: It’s small, about 29 feet long, with a cargo bay not much bigger than a pickup truck’s. Project officials have revealed that the X-37B’s maneuvering engine runs on hydrazine and nitrogen tetroxide, and that it uses a different kind of thermal protection than NASA’s space shuttle did. The durations of the first three missions are a matter of public record (224 days, 469 days, and 674 days), and while the orbital parameters aren’t officially disclosed, amateur astronomers have been able to spot the mini-spaceplane through telescopes and figure out that it’s been orbiting at relatively low altitudes.
At an aerospace meeting in 2011, Arthur Grantz, a chief engineer with Boeing, the company that built the X-37B, said that the program had been evaluating the vehicle’s autonomous navigation and other systems. While he didn’t say what the Air Force wanted with an operational spaceplane, he speculated that the vehicle could be modified in the future to carry passengers.
Before the most recent launch, the Air Force and NASA even revealed two of the payloads for the first time: a NASA materials science experiment and an ionizing thruster being tested for the Air Force. Those clues have led analysts to speculate with a little more confidence about the X-37B’s purpose.
It’s clear that any technologies tested on an Air Force spaceplane will have some military application, but that doesn’t narrow things down much. In space, it could mean communications, navigation, surveillance, or even anti-satellite and counter-anti-satellite operations. The smart money is on advanced surveillance sensors. The Air Force has never mentioned them directly, but everyone seems confident that they’re flying.
“I think that’s probably what they’re not telling you, that there are payloads in there that might be part of the design for future reconnaissance satellites,” says James Andrew Lewis, director and senior fellow in the Strategic Technologies Program at the Center for Strategic and International Studies. The Air Force has great interest in developing small, advanced sensors, he says, because it’s “looking to figure out how to transition from big, expensive satellites to smaller but equally capable satellites.”
The Hall thrusters on the current flight use an electric field to accelerate xenon propellant, producing a small but steady thrust that’s useful for many types of spacecraft, including military communications satellites already in orbit. Brian Weeden, technical adviser for the Secure World Foundation, thinks the Air Force might also be testing the thrusters with an eye toward placing reconnaissance satellites in lower orbits, so that imaging sensors could take higher-resolution pictures of targets on the ground.
“I think the clue is how low an orbit [the X-37B] is in,” says Weeden. The spaceplane is orbiting at an altitude of about 320 kilometers (a little under 200 miles), which is lower than the International Space Station. Low orbits require more maneuvering, and therefore more fuel, to maintain. And fuel adds weight. “One of the reasons that the traditional exquisite imaging satellites are so hard to launch is because they’re big and they’re heavy,” says Weeden. Hall thrusters could enable lighter, cheaper reconnaissance satellites to be orbited.
Right now the Air Force has two X-37B research vehicles. Are we likely to see an operational fleet, without the “X” designation? Weeden doesn’t think so: “My guess would be that [the spaceplane] itself would probably not move into an operational-type role, but that a lot of the technologies that it’s demonstrating, like the Hall effect thrusters, or whatever the sensor payloads are, are going to move into the operational role. That’s how it went with the X-planes of the 1950s and 1960s.”
If the Air Force does go for an operational fleet, “they could add different versions of the vehicle, larger versions in particular,” says Todd Harrison, a defense budget analyst at the Center for Strategic and International Studies. Harrison speculates that a bigger version of today’s X-37B, with a larger cargo bay, could conceivably bring military satellites back to Earth for maintenance or repairs, then return them to orbit.
That is, if a scaled-up vehicle fits inside a conventional rocket. Like most satellites, today’s X-37B is placed inside a protective shroud, then launched on a large Atlas V rocket. “I would guess that it’s going to be really hard to make a bigger version of the X-37B that can still fit inside a fairly standard shroud,” Weeden says.
Another option for the Air Force would be to update the two experimental spaceplanes. For example, to make them more flexible and possibly cheaper to operate, the Air Force could make them compatible with other launch vehicles, such as the SpaceX Falcon 9 or one of Orbital Sciences’ rockets.
Such modifications would depend on the budget the X-37B program receives as it moves out of the experimental phase. And those numbers are likely to remain every bit as secret as the spaceplane’s missions.
https://www.airspacemag.com/space/space ... 180957777/30
Amateur Satellite Trackers Found the Secret X-37B Space Plane in Orbit
Gizmodo
317
The U.S. Air Force’s supersecret X-37B was launched into orbit for the fourth time last week, and amateur satellite watchers have promptly identified its secret orbit—also for the fourth time. There is, you see, a small army of amateurs who keep track of over 300 spy satellites, often with little more than a pair of binoculars.
The orbit of the X-37B, which resembles a mini space shuttle, was revealed on a hobbyist satellite watcher mailing list today. According to longtime satellite observer Ted Molczan interviewed Spaceflight Now, the plane is flying lower than in previous missions, and it is surveying the same region on the ground every two days—a frequency that could indicate some kind of spy mission. The government has revealed two experiments onboard X-37B but has, as always, kept mum about everything else.
Molczan and other members of an amateur satellite observing group found the secret orbit of the first X-37B back in 2010, too. It took a few weeks and independent observations in North America and South Africa. He later characterized the discovery as “sort of a fluke.” But with three X-37Bs under their belt, the group knew what to expect with the fourth mission. A couple days before the space plane blasted off, Molzcan posted an email to the SeeSat email list with orbit estimates. Today, a week after launch, an email to the group announced the X-37B’s orbit.
More Secret Satellites
Among satellite watchers, Molczan is perhaps best known for identifying USA-193, a secret spy satellite that failed soon after orbit in 2006. The U.S. intentionally destroyed it with a missile 18 months later—prompting all sorts of controversy over the exact purpose of the satellite.
The hobby of these amateur satellite watchers has, not surprisingly, prompted some concern from the intelligence community. “If we had our druthers, we would prefer that these things not end up on the Internet,” says Rick Oborn, an NRO spokesperson told Wired in 2006. “It’s no secret that other countries stop doing what they’re doing when the satellites are overhead.”
But the reality is, tracking even these stealth satellites is not that hard. Here’s how the New York Times described Molzcan’s setup at his Toronto apartment, which uses just a pair of binoculars, star charts, and a stopwatch.
From his 23rd-floor balcony, or the roof of his 32-floor building, Mr. Molzcan will peer through his binoculars at a point in the sky he expects the satellite to cross, which he locates with star charts. When the moving dot appears, he determines its direction and the distance it travels across the patch of sky over time, which he can use to calculate its speed.
If a guy from his balcony can track these satellites, goes the reasoning, so can China—and so can any country with even the most marginal astronomy knowledge. Perhaps that’s what so fascinating of all. The U.S. will go to great lengths to obscure the nature of its spy satellites, but space is empty. Space is transparent. Satellites have nowhere to hide.
© 2018 Gizmodo Media Group
https://gizmodo.com/amateur-satellite-t ... 170730540830
How to Spot the USAF’s ‘Mini-Shuttle’
By: David Dickinson |
October 20, 2015
By: |
Now is the time to track the secret space plane X-37B on its OTV-4 mission.
Step outside on any clear night at dusk during twilight hours and watch the sky for a few minutes, and you’ll notice swiftly moving “stars,” sentinels of our modern Space Age.
Some are regular satellites. (Folks at public star parties are always amazed to see satellites with their own eyes!) But most of what you’re seeing are actually discarded boosters in low-Earth orbit, and more than a few are clandestine spy satellites.
One of the more intriguing missions to track from your backyard is the U.S. Air Force’s X-37B. The USAF owns two X-37B spacecraft, and the current Orbital Test Vehicle 4 (OTV-4) mission is the fourth overall for the program. Launched from Cape Canaveral on May 20, 2015, OTV-4 orbits Earth once every 91 minutes in a 196-mile (315-km) altitude orbit. Its orbit is inclined 38° from Earth’s equator, ensuring that the craft is visible from latitude 45° north to 45° south.
As with a majority of classified U.S. Department of Defense missions, NORAD doesn’t publicly publish the orbital parameters for the X-37B. (The launch was broadcast live, however.) Once launched, tracking the mini space plane becomes the pursuit of dedicated satellite-watchers worldwide. You can trace this legacy all the way back to the original Project Moonwatch, which first tracked Sputnik 1 after its historic first orbit in 1957.
“In the time of Moonwatch, the network of amateur observers was a (if not the) most prominent source of tracking information on new objects launched,” says veteran satellite watcher Marco Langbroek. “Moonwatch and our modern network both make available data on objects on which otherwise very little data would be (publicly) available.”
Volunteer satellite hunters have confirmed — and sometimes refuted — launch claims by countries with largely veiled space programs, such as North Korea and Iran. They also recently tracked the maneuverings of the extra mystery payload Russia launched aboard the Cosmos-2496 satellite and which is suspected to be testing either in-orbit refueling or ”satellite-killer” tech.
A Mini Space Shuttle
The orbit the Air Force's X-37B is flying during its fourth uncrewed mission.Orbitron. Used with permission.
The X-37B is a direct descendant of Boeing’s X-40 project. A miniature space plane one-fourth the length of the U.S. Space Shuttle, the X-37B launches atop an Atlas V rocket and lands like an aircraft. Thus far, landings have occurred unannounced at Vandenberg Air Force Base in California, though future missions (and perhaps OTV-4) may land like the Space Shuttle at the Kennedy Space Center in Florida for rapid reprocessing and launch. The X-37B is only the second space plane — after the Russian Buran, which orbited the Earth once on November 15, 1988 — to perform an automated landing. It also holds the duration record for a space plane in orbit, having spent nearly 675 days in space during OTV-3.
OTV-4 is also notable in that, for the first time, the Department of Defense alluded to at least a portion of what the craft is doing during the mission: in addition to testing materials in space for NASA, it’s also demonstrating the use of Hall-effect thrusters as part of the Advanced Extremely High Frequency (AEHF) satellite program, a strategic communications system being built by Lockheed Martin. Hall-effect thrusters will replace the troublesome liquid-apogee engines on AEHF satellites.
Hunting the X-37B
OTV-3 passing near the star cluster IC 2602. Greg Roberts
On a high pass straight overhead, the X-37B can reach around magnitude +3, similar in brightness to the stars that make up the constellation Aries the Ram. But more typically it gleams around magnitude +3.5, and it can drop to as faint as magnitude +5 at bad phase angles, says South African-based, long-time satellite tracker Greg Roberts.
We’ve seen the X-37B flare a few magnitudes in brightness on a zenith pass from here in central Florida, perhaps from sunlight glinting off the deployed solar arrays often depicted in artist’s conceptions.
“The current mission is in an orbit that makes it pass along (almost) the same ground track every two days,” says Langbroek. “That repeating ground track is something normally associated with Earth reconnaissance missions.”
Tracking and sighting opportunities for the X-37B are freely available and published publicly on many websites, including Heavens-Above. Heavens-Above is a great website to use to predict passes of satellites from your location, including the X-37B. Successfully spotting a satellite pass is as simple as knowing when it will occur, how bright it will be, and what direction it will be moving.
I also like to use the Orbitron satellite tracking program, as I can run it on a laptop in the field sans internet connection. Just make sure that the Two-Line Elements (TLEs) are up to date, as satellite orbits do change over time, mostly due to atmospheric drag. The SeeSat-L message board is also a long-standing source of discussion among volunteer satellite trackers.
Catching Satellites on Camera
You can also image satellite passes.
“I use a wide variety of equipment — all video or photographic — and as to what equipment I use, I decide prior to an observing session and select the best suited,” says Roberts. “If I have to do a planar search, then I go for relatively wide-angle fields, but if it’s straight positional work and the current orbit is known, then I use narrower fields of view.”
Roberts typically uses a camera with a 50- to 200-mm focal length for objects in low-Earth orbit, though he also employs a 10-inch aperture telescope to catch objects in medium-Earth and geosynchronous orbits. “My all-round favorite is a 4-inch f/2.6 refractor,” he adds.
Starting out imaging satellites is as simple as doing time-exposure shots of the sky with a tripod-mounted DSLR camera and letting the satellite “burn in” a streak as it slides silently by.
If you want to catch the X-37B, you have several weeks to try. Initial discussion by the USAF during the OTV-4 launch stated the mission would last a minimum of 200 days, which would place a possible landing in the first week of December at the absolute earliest.
Below, watch a video of OTV test flights (no sound). Credit: United States Air Force.
http://www.skyandtelescope.com/astronom ... 010201522/