It’s taken 400 years of scientific discoveries to make it possible for anyone to find his location anywhere on the globe using GPS. //

With the letters GPS, we instantly recognize an innovation that has revolutionized our lives. The concept was born half a century ago in a sweltering room at the Pentagon over Labor Day weekend in 1973.

That’s the genesis of the concept for a constellation of platforms orbiting the Earth, transmitting radio signals to determine location. Many years of calculation, experiment, and miniaturization led to the Navigation Signal Timing and Ranging (NAVSTAR) satellites that became known as the Global Positioning System (GPS). //

Our society has been blessed with rare and precious genius that has combined across centuries to yield the civilizational achievements we enjoy today. Orbital mechanics originated from careful geometric analysis by Johannes Kepler in the 17th century. Two centuries later, electromagnetism was empirically measured by Michael Faraday and mathematically characterized by James Clerk Maxwell.

Atomic oscillation arose from the quantized radiation law Max Planck discovered, while Albert Einstein discovered relativistic effects, both in the early 20th century. These were the giants on whose shoulders later scientists and engineers stood to build their guideposts in the heavens.

While only a tiny fraction of the electorate understands the enormity of government waste, fraud, and abuse, now and then we learn of some extraordinary achievements underwritten with your tax dollars. GPS is one of them.

SkyFi is on a mission to help GIS experts and data analysts replace manual labor research with easier access to Earth observation data. What was once a high-tech process is now simple, affordable, and accessible to everyone. Start using SkyFi now to find and access the  high-quality, affordable satellite photos you need for any project.

NASA has detected a signal from Voyager 2 after nearly two weeks of silence from the interstellar spacecraft.

NASA's Jet Propulsion Laboratory said on Tuesday that a series of ground antennas, part of the Deep Space Network, had registered a carrier signal from Voyager 2 on Tuesday. //

NASA said it lost contact with Voyager 2, which is traveling 12.3 billion miles away from Earth, on Friday after "a series of planned commands" inadvertently caused the craft to turn its antenna 2 degrees away from the direction of its home planet. //

What might seem like a slight error had big consequences: NASA said it wouldn't be able to communicate with the craft until October, when the satellite would go through one of its routine repositioning steps. //

Last month's command mix-up means Voyager 2 is not able to transmit data back to Earth, but it also foreshadows the craft's inevitable end an estimated three years from now.

"Eventually, there will not be enough electricity to power even one instrument," reads a NASA page documenting the spacecraft's travels. "Then, Voyager 2 will silently continue its eternal journey among the stars."

Voyager 2's sister spacecraft, Voyager 1, meanwhile, is still broadcasting and transmitting data just fine from a slightly further vantage point of 15 billion miles away.

paw Ars Tribunus Militum 21y 1,984

dj__jg said:
I guess ESA has a shot at being a role model at de-orbiting stuff, since they sure aren't being a role model at putting stuff into orbit considering the delays and expendable nature of Ariane 6.

Let's not dump on ESA too much re being a role model. Ariane 5's outstanding launch of JWST, doubling its lifetime, should not be overlooked.

Honest question: have any NASA launches exceeded expectations by that much? //

Cloudgazer Ars Tribunus Angusticlavius 8y 15,517

paw said:
Let's not dump on ESA too much re being a role model. Ariane 5's outstanding launch of JWST, doubling its lifetime, should not be overlooked.

Honest question: have any NASA launches exceeded expectations by that much?

I'd love to know what the private opinion of the NASA team was about that launch. One way to view it is that ESA doubled the lifespan of JWST. Another is that they came within 30 m/s of disaster. //

Cloudgazer Ars Tribunus Angusticlavius 8y 15,517

Shiranui said:
How do you mean? How do you turn overdelivering on estimates into pessimistic relief?

Either I'm missing something about Arianespace having taken unnecessary risks to achieve this feat (which I have not heard of so far), or that's a very "glass half empty" perspective.

NASA had an estimated life based on ESA delivering JWST into the expected trajectory, JWST would then need to use its on board thrusters to get the perfect insertion into L2. There was never any doubt that Ariane had the grunt to get JWST into that orbit, or indeed beyond that orbit, but it was imperative that they not overshoot, because if they did JWST was lost.

The targeted trajectory NASA requested from Ariane left room at the top because of that. ESA ate into that margin which delivered a 'better' outcome, but the final adjustments by the JWST were a mere 23 m/s. Had they 'over delivered' by another 23m/s which they were quite capable of doing there would be no JWST.

Publically this was all praised as a great success, but I can't imagine it was quite the same story behind the scenes.

Think of it like shooting the proverbial apple off your wife's head. More points if you hit lower on the apple. This doesn't mean if you aimed for the middle and hit right at the bottom then your wife is going to be entirely happy, because a little lower and you're not a hero - you're William S Burroughs. //

Cloudgazer Ars Tribunus Angusticlavius 8y 15,517

Dan Homerick said:
While reading this, I was thinking "But couldn't JWST have rotated around and burned retrograde to correct a small overshoot?" And to answer that thought, I presume the answer is no, because then it'd be flying through it's own thruster plume, which would fog up the mirrors.

That right?

Kinda, that's half the story ..

More Than You Wanted to Know About Webb’s Mid-Course Corrections! – James Webb Space Telescope
https://blogs.nasa.gov/webb/2021/12/27/more-than-you-wanted-to-know-about-webbs-mid-course-corrections/

Webb has thrusters only on the warm, Sun-facing side of the observatory. We would not want the hot thrusters to contaminate the cold side of the observatory with unwanted heat or with rocket exhaust that could condense on the cold optics

So you're right about not wanting to fly through the plume, and that (along with other considerations) resulted in thrusters only on one side of the vehicle. But as a result of that design decision it's even worse than just contaminating the instrument

Webb’s Journey to L2 Is Nearly Complete – James Webb Space Telescope
https://blogs.nasa.gov/webb/2022/01/21/webbs-journey-to-l2-is-nearly-complete/

“So, why did the Ariane not give Webb more energy and why did Webb need course correction? If the Ariane had given Webb even a little bit too much energy than needed to get it to L2, it would be going too fast when it got there and would overshoot its desired science orbit. Webb would have to do a significant braking maneuver by thrusting toward the Sun to slow down. Not only would that big burn cost a lot of propellant, it would be impossible because it would require Webb to turn 180 degrees in order to thrust toward the Sun, which would have exposed its telescope optics and instruments directly to the Sun, thus overheating their structures and literally melting the glue that holds them together.

Like the enterprise in star trekkin the JWST is always going forwards 'cause they can't find reverse.

MMarsh Ars Praefectus
8y
3,363
Subscriptor
The stock market's perception of Viasat through this whole project has been.... interesting.
Screenshot_20230714-200332.png
That's not the stock graph of a company that has its act together, is in the lead, and is likely to stay in the lead.

It's the stock graph of a company that's putting a lot of expensive eggs into very few baskets, and has technically superior competitors nipping at its heels.

The Viasat-3 program, while it pushes the limits of technological possibility, is still fundamentally rooted in a system architecture from the 1970s that has now been eclipsed by new and better architectures. In 2019, with LEO constellations still very much unproven, there was some optimism that a revitalized Viasat could be the definitive big fish in the small market. But today? At best, a totally successful Viasat-3 program would hold the line and prevent the company from dying entirely as virtually all of the growth in the market, along with a non-negligible share of current customers, goes to Starlink (and, eventually, other LEO competitors).

If they can get the other two working, the business is still viable for a while, but they've missed the paradigm shift and are probably too late to save it long-term.

A new Viasat communications satellite launched in April has been crippled by a problem when unfurling its huge mesh antenna. The problem jeopardizes Viasat’s much-needed refresh to its space-based Internet network that would let it better compete with newer broadband offerings from companies like SpaceX and OneWeb.

Viasat confirmed the antenna problem Wednesday after it was first reported by Space Intel Report. The satellite in question is named ViaSat-3 Americas, and it launched on April 30 as the primary payload on a SpaceX Falcon Heavy rocket from NASA’s Kennedy Space Center in Florida. //

The satellite is one of the most powerful commercial spacecraft ever built, with two solar array wings as wide as a Boeing 767 jetliner capable of generating more than 30 kilowatts of electricity. The solar panels deployed soon after the spacecraft arrived in orbit, and the next step was to unfurl a large reflector to bounce Internet signals between the ground and transmitters and receivers on board the main body of the satellite.

That’s when ground controllers ran into trouble. An “unexpected event” occurred during the deployment of the reflector that may “materially impact” the performance of the satellite, Viasat said. //

The spacecraft was built by Boeing, with a communications payload developed internally by Viasat. The reflector was supplied by Northrop Grumman’s Astro Aerospace, said Dave Ryan, Viasat’s president of space and commercial networks, in an interview before the launch in April. //

The reflector is required to focus signals from the satellite onto a small location on the ground. It’s critical to enabling the satellite to reach thousands of users at once, with a total throughput of more than a terabit per second over its 15-year design life. //

Viasat’s geostationary orbit architecture requires fewer satellites for global reach, but their distance from Earth results in longer latency Internet connections. They also need to be much larger and more expensive than SpaceX’s Starlink satellites, which the company mass-produces at a rate of about six per day and launches into orbit in large batches on a single rocket. SpaceX has launched more than 4,700 Starlink satellites to date. //

Viasat completed the acquisition of Inmarsat, another major satellite operator, in May for $7.3 billion. Taken together, the combined company has 19 large communications satellites in orbit, including 12 operating in Ka-band, the same piece of the radio spectrum used by the ViaSat-3 Americas satellite. //

UnionGirl Smack-Fu Master, in training
1d
1
DistinctivelyCanuck said:
a few articles back, we ended up in a discussion about how certain of the secret squirrel agency satellites can only be readied in a vertical integration facility because how the orientation of the bird literally impacts the ability of the antenna to eventually unfold (the Mentor SIGINT birds if memory serves) the force of gravity in a horizontal orientation could cause the thing to not open up once its flipped vertical...

brainstorming off a massively limited information set.

It would be 'entertaining' if it turned out the same folks did the antenna for VIASAT... which was, of course, integrated in a horizontal orientation first, before going vertical.

second massively limited brainstorm:

it would be interesting to see when NG's launching another one of their MEV's (the mission extension vehicles that go to GEO to provide more station keeping fuel).

For a 700 million dollar bird: I wonder if you send a MEV with a hammer and a pair of scissors on the end of a telescoping arm :)

(yes, I'm joking...) But maybe you send the MEV to go have a look at least... "remove before flight" still in place? :)
Click to expand...Hi! Made an account to reply to this.

I work at NG and am currently sitting across from the successor spacecraft to MEV, the Mission Robotic Vehicle, currently under construction. We can do a bit better than that :) if ViaSat calls us, we can probably try to fix them. And better yet: we launch next year.

www.northropgrumman.com
Mission Robotic Vehicle (MRV) Satellite Technology
Northrop Grumman continues to push the boundary of possible by building an adaptable satellite servicing and logistics architecture with our Mission Robotic Vehicle and Mission Extension Pods.
www.northropgrumman.com www.northropgrumman.com

Statistical Ars Legatus Legionis
12y
50,437

Also the longer the slant the larger area the weather is impacting you. If the beam is coming in close to the horizon it isn't just the weather where you are that matters it is the weather along the entire slant potentially a thousand or more kilometers away. It could be bright sunny day where you are at and the signal has to punch through a dozen storm systems to get to you.

It is why Starlink was such a big deal for the Antarctica bases. Prior to that they were limited to very expensive MEO constellation services or a 2 or 3 GSO sats (one of the TRDS sats) that are actually at an 8.7 degree inclination instead of the normal 0. The sats are in GSO not GEO. It means the sats trace a figure eight around the equator instead of being exactly on it. It also means that they move in the sky as seen from Earth which is very much non-ideal for most applications BUT it means that for roughly 12 hours out of each day they are just barely over the horizon from the Antarctic bases to allow service. Bad news that 12 hour availability window shifts by 3 minutes each day. Being a network engineer in Antarctica prior to SL must have been a challenge prior to SL.

The Antarctic specific satellite mission is the only polar GSO service I know of. SL pretty much overnight changed that. Not only are their official SL dishes but there are now dozens of user owned terminals. Throughput to Antarctica was in the 1 to 5 Mbps range for decades and now is in the hundreds of Mbps and gigabits is possible with enough user terminals.

MMarsh Ars Praefectus
7y
3,252
Subscriptor
From a "can it be done?" tech standpoint, I think this is very cool.

From a "can you offer a profitable and economical service this way?" standpoint, I'm not optimistic, for a few reasons.

The first problem is the latency, of course. That's going to be just as bad as with any other GEO satellite. We put up with it for decades when there was no better option, but now that LEO constellations exist, a 700 ms ping time is a hard sell unless there are other compelling advantages.

Which brings us to the competition. Inmarsat and Iridium, being part of GMDSS, have the advantage in the commercial maritime market. Starlink is rapidly replacing Viasat and Hughes in the terrestrial residential, business, and vehicle-portable markets; OneWeb and Kuiper ought to be nipping at its heels sometime soon. Who is the target market for a product that can't compete with Inmarsat or Iridium on coverage, and can't compete with Starlink on throughput or latency?

And then you get to the tech aspects of it. Yes, it's possible to put a small satellite in GEO and relay comms from it, and it's an impressive technical achievement. But the physics of antennas and of RF propagation don't change. How much performance was given up to make it work with less power and smaller antennas? Could more efficient use of that same RF spectrum have been achieved with a larger satellite with more power, more spot beams, and larger antenna apertures to allow the use of tighter geometry in those spot beams?

If the target market is Alaska, then in the panhandle (eg. Ketchikan) you're aiming your ground station antennas about 35° above the horizon. That's tolerable as long as you have clear land or ocean to the south. Up in Anchorage, though, that angle drops to 29° and in Nome it's 25°. Hold your hand at arm's length, put your thumb on the southern horizon, and stretch your pinky vertically above it to full span; that's 25°. If there are trees or mountains or weather below that mark, you have no chance of using any GEO satellites from that location.

To date Astranis has raised $550 million and is well capitalized for growth with a team of 300 people. The company has already built four more satellites—one of which will serve a customer in Peru, two for airline Wi-Fi, and one for an unspecified customer—that will launch on a dedicated Falcon 9 mission later this summer or early fall.

Now that the company has confidence that its custom-built technology works, it plans to scale up production to two satellites a month, Gedmark said. The 1-meter-by-1-meter satellites, which have a mass of around 400 kg, will be built to serve whatever demand there is, wherever in the world it's needed.

"We’re just going to keep launching them as long as there is demand," he said. "And we think there will be a lot of demand for that. We absolutely plan to launch dozens and then hundreds."

Communication Commission (FCC), True Anomaly is now gearing up for its first orbital mission. In October, True Anomaly hopes to launch two Jackal “orbital pursuit” spacecraft aboard a SpaceX rocket to low earth orbit. The Jackals will not house guns, warheads, or laser blasters, but they will be capable of rendezvous proximity operations (RPO)—the ability to maneuver close to other satellites and train a battery of sensors upon them. This could reveal their rivals’ surveillance and weapons systems or help intercept communications.

I know very little about rocket launches, but one thing I thought I understood was that launches want to take off from as close to the equator as possible, which southwest England is not. Was there something special about the payload or this launch site? Or is this the launch equivalent of fighting with one arm tied behind your back? //

The optimal launch site for a given launch is at the same latitude as that launch's orbit's inclination. Depending on available downrange space, a particular site can also launch to orbits higher than its latitude, but never lower (without doglegs, which I'm going to ignore for the rest of this comment). So a low-latitude site is better in general since it makes more orbits possible, but it's not the best site for all orbits.

This launch by Virgin Orbit is going to polar orbit, which is extremely high-latitude. So it's possible from basically any launch site, and in fact is slightly better from high-latitude sites. //

It depends on your target orbit.
If you're shooting for an equatorial orbit, launching from near the equator gives you a boost from the Earth's speed of rotation, and saves you from needing to build a wasteful dog-leg or plane-change manoeuvre into the flight plan. This saves fuel and therefore lets you fly a bigger spacecraft with the same launch vehicle.
If you're shooting for some types of polar orbit, then the Earth's rotation is just an annoying thing you need to cancel out, so launching from a high latitude is more efficient.
The point of Virgin Orbit's approach is that you can launch the airplane from any convenient place with the right infrastructure, and fly to the best latitude for the type of mission you're doing that day before you light up the rocket, and you have good odds of bring able to launch without the weather problems that can cause delays when you're constrained to one fixed site.

On September 22, 2022 NASA and SpaceX announced that they were investigating the possibility of using a Dragon spacecraft—of the kind used to ferry NASA astronauts to the International Space Station—to go visit Hubble. On Dec. 22 NASA issued a request for other commercial space companies to get involved. //

The idea is that Hubble could be boosted to a higher orbit to continue its work for many more years. There’s also the tantalising prospect that it could also be serviced and refurbished—and its optics improved. //

A general servicing would be crucial because whether or not Hubble avoids re-entry this decade it is getting old. Launched in 1990 and last serviced by a space shuttle crew in 2009, it’s beginning to have technical problems. The latest was in July 2021 when it spent a month out of action because its payload computer failed before the problem was fixed.

However, from a science point of view an upgrade to its optics would be a game-changer. The reflecting telescope has a 2.4 meter mirror that can’t be upgraded, but its cameras could be. //

If the feasibility studies suggests it’s a go-er it would be the sixth time Hubble has been visited since its launch from Space Shuttle Discovery on April 24, 1990. //

Almost immediately after its launch it was discovered that its mirror had an aberration causing images to be blurry, so it was visited in orbit by astronauts aboard NASA’s Space Shuttle Endeavour in 1993. They installed corrective optics. More servicing missions took place in 1997, 1999, 2002 and 2009 to upgrade various components, notably adding the telescope’s Wide Field Camera 3.

Hubble now has six cameras and sensors to gather data on and take spectacular images of deep sky targets previously beyond the reach of astronomers. There are larger ground-based telescopes, but their view of the cosmos is limited by Earth’s atmosphere, which blocks infrared and ultraviolet light.

Hubble remains valuable to astronomers—and continues to make incredible observations—because it sees the universe in ultraviolet, visible and near-infrared light. The new James Webb Space Telescope deals only in near and far-infrared light. Since Webb orbits the Sun a million miles from Earth it can likely never be serviced—despite repeated strikes by micrometeoroids already.

Webb's Latest Image Galleries: Recent | First Images | Test | In Depth

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We would like to specifically stress an extremely dangerous trend that goes beyond the harmless use of outer space technologies and has become apparent during the latest developments in Ukraine. Namely, the use by the United States and its allies of civilian, including commercial, infrastructure elements in outer space for military purposes. Apparently, these States do not realize that such actions in fact constitute indirect participation in military conflicts. Quasi-civilian infrastructure may become a legitimate target for retaliation. Western actions needlessly put at risk the sustainability of peaceful space activities, as well as numerous social and economic processes on Earth that affect the well-being of people, first of all in developing countries. At the very least, this provocative use of civilian satellites is questionable under the Outer Space Treaty, which only provides for the peaceful use of outer space, and must be strongly condemned by the international community.

This is not the first time Vorontsov has made such comments, as he made similar remarks last month to the United Nations Office for Disarmament Affairs working group. However, it is not clear to what extent Russia might be able to follow through on its threat to target commercial satellites.

Pioneers 10 and 11, which preceded Voyager, both carried small metal plaques identifying their time and place of origin for the benefit of any other spacefarers that might find them in the distant future. With this example before them, NASA placed a more ambitious message aboard Voyager 1 and 2, a kind of time capsule, intended to communicate a story of our world to extraterrestrials. The Voyager message is carried by a phonograph record, a 12-inch gold-plated copper disk containing sounds and images selected to portray the diversity of life and culture on Earth. //

Images on the Golden Record

The following is a listing of pictures electronically placed on the phonograph records which are carried onboard the Voyager 1 and 2 spacecraft. The contents of the record were selected for NASA by a committee chaired by Carl Sagan of Cornell University, et. al. Dr. Sagan and his associates assembled 115 images and a variety of natural sounds, such as those made by surf, wind and thunder, birds, whales, and other animals. To this they added musical selections from different cultures and eras, and spoken greetings from Earth-people in fifty-five languages, and printed messages from President Carter and U.N. Secretary General Waldheim. Each record is encased in a protective aluminum jacket, together with a cartridge and a needle. Instructions, in symbolic language, explain the origin of the spacecraft and indicate how the record is to be played. The 115 images are encoded in analog form. The remainder of the record is in audio, designed to be played at 16-2/3 revolutions per minute. It contains the spoken greetings, beginning with Akkadian, which was spoken in Sumer about six thousand years ago, and ending with Wu, a modern Chinese dialect. Following the section on the sounds of Earth, there is an eclectic 90-minute selection of music, including both Eastern and Western classics and a variety of ethnic music. Once the Voyager spacecraft leave the solar system, they will find themselves in empty space. It will be forty thousand years before they make a close approach to any other planetary system.

Images on the Golden Record

The following is a listing of pictures electronically placed on the phonograph records which are carried onboard the Voyager 1 and 2 spacecraft. The contents of the record were selected for NASA by a committee chaired by Carl Sagan of Cornell University, et. al. Dr. Sagan and his associates assembled 115 images and a variety of natural sounds, such as those made by surf, wind and thunder, birds, whales, and other animals. To this they added musical selections from different cultures and eras, and spoken greetings from Earth-people in fifty-five languages, and printed messages from President Carter and U.N. Secretary General Waldheim. Each record is encased in a protective aluminum jacket, together with a cartridge and a needle. Instructions, in symbolic language, explain the origin of the spacecraft and indicate how the record is to be played. The 115 images are encoded in analog form. The remainder of the record is in audio, designed to be played at 16-2/3 revolutions per minute. It contains the spoken greetings, beginning with Akkadian, which was spoken in Sumer about six thousand years ago, and ending with Wu, a modern Chinese dialect. Following the section on the sounds of Earth, there is an eclectic 90-minute selection of music, including both Eastern and Western classics and a variety of ethnic music. Once the Voyager spacecraft leave the solar system, they will find themselves in empty space. It will be forty thousand years before they make a close approach to any other planetary system.

What are all those streaks across the background? Satellite trails. First, the foreground features picturesque rock mounds known as Pinnacles. Found in the Nambung National Park in Western Australia, these human-sized spires are made by unknown processes from ancient sea shells (limestone). Perhaps more eye-catching, though, is the sky behind. Created by low-Earth orbit satellites reflecting sunlight, all of these streaks were captured in less than two hours and digitally combined onto the single featured image, with the foreground taken consecutively by the same camera and from the same location. Most of the streaks were made by the developing Starlink constellation of communication satellites,

“We’ve got more than 11,000 Starlink stations and they help us in our everyday fight on all the fronts,” Ukraine’s vice prime minister Mykhailo Fedorov told Politico. “We’re ready, even if there is no light, no fixed internet, through generators using Starlink, to renew any connection in Ukraine.” //

In April, a Ukrainian solider identified as “Dima” told journalist David Patrikarakos that the service was playing a key role in the resistance.

“I want to say one thing: @elonmusk’s Starlink is what changed the war in #Ukraine’s favor. #Russia went out of its way to blow up all our comms. Now they can’t. Starlink works under Katyusha fire, under artillery fire,” the soldier said, according to Patrikarakos’ Twitter thread detailing their interview.

The biggest hack since Russia’s war began knocked thousands of people offline. ///

Bricked modems

Aug 5, 2015

From a Million Miles Away, NASA Camera Shows Moon Crossing Face of Earth
A NASA camera aboard the Deep Space Climate Observatory (DSCOVR) satellite captured a unique view of the moon as it moved in front of the sunlit side of Earth last month. The series of test images shows the fully illuminated “dark side” of the moon that is never visible from Earth.

The images were captured by NASA’s Earth Polychromatic Imaging Camera (EPIC), a four megapixel CCD camera and telescope on the DSCOVR satellite orbiting 1 million miles from Earth. From its position between the sun and Earth, DSCOVR conducts its primary mission of real-time solar wind monitoring for the National Oceanic and Atmospheric Administration (NOAA).