The JUMPSEAT satellites loitered over the North Pole to spy on the Soviet Union. //

In a statement, the NRO called Jumpseat “the United States’ first-generation, highly elliptical orbit (HEO) signals-collection satellite.” //

The Soviet Union was the primary target for Jumpseat intelligence collections. The satellites flew in highly elliptical orbits ranging from a few hundred miles up to 24,000 miles (39,000 kilometers) above the Earth. The satellites’ flight paths were angled such that they reached apogee, the highest point of their orbits, over the far northern hemisphere. Satellites travel slowest at apogee, so the Jumpseat spacecraft loitered high over the Arctic, Russia, Canada, and Greenland for most of the 12 hours it took them to complete a loop around the Earth.

This trajectory gave the Jumpseat satellites persistent coverage over the Arctic and the Soviet Union, which first realized the utility of such an orbit. The Soviet government began launching communication and early-warning satellites into the same type of orbit a few years before the first Jumpseat mission launched in 1971. The Soviets called the orbit Molniya, the Russian word for lightning. //

The disclosure of the Jumpseat program follows the declassification of several other Cold War-era spy satellites. They include the CIA’s Corona series of photo reconnaissance satellites from the 1960s, which the government officially acknowledged 30 years later. The NRO declassified in 2011 two more optical spy satellite programs, codenamed Gambit and Hexagon, which launched from the 1960s through the 1980s. Most recently, the NRO revealed a naval surveillance program called Parcae in 2023.

Waiting in the darkness a few miles away from the launch pad, I glanced around at my surroundings before watching SpaceX’s Falcon 9 thunder into the sky. There were no throngs of space enthusiasts anxiously waiting for the rocket to light up the night. No line of photographers snapping photos. Just this reporter and two chipper retirees enjoying what a decade ago would have attracted far more attention.

Go to your local airport and you’ll probably find more people posted up at a plane-spotting park at the end of the runway. Still, a rocket launch is something special. On the same night that I watched the 94th launch of the year depart from Cape Canaveral, Orlando International Airport saw the same number of airplane departures in just three hours. //

The Falcon 9’s established failure rate is less than 1 percent, well short of any safety standard for commercial air travel but good enough to be the most successful orbital-class in history. Given the Falcon 9’s track record, SpaceX seems to have found a way to overcome the temptation for complacency. //

According to analyses by BryceTech, an engineering and space industry consulting firm, SpaceX has launched 86 percent of all the world’s payload mass over the 18 months from the beginning of 2024 through June 30 of this year.

That’s roughly 2.98 million kilograms of the approximately 3.46 million kilograms (3,281 of 3,819 tons) of satellite hardware and cargo that all the world’s rockets placed into orbit during that timeframe. //

But Starship’s arrival will come at the expense of the workhorse Falcon 9, which lacks the capacity to haul the next-gen Starlinks to orbit. “This year and next year I anticipate will be the highest Falcon launch rates that we will see,” said Stephanie Bednarek, SpaceX’s vice president of commercial sales, at an industry conference in July.

SpaceX is on pace for between 165 and 170 Falcon 9 launches this year, with 144 flights already in the books for 2025. Last year’s total for Falcon 9 and Falcon Heavy was 134 missions. SpaceX has not announced how many Falcon 9 and Falcon Heavy launches it plans for next year.

Starship is designed to be fully and rapidly reusable, eventually enabling multiple flights per day. But that’s still a long way off, and it’s unknown how many years it might take for Starship to surpass the Falcon 9’s proven launch tempo. //

Despite all of the newcomers, most satellite operators see a shortage of launch capacity on the commercial market. “The industry is likely to remain supply-constrained through the balance of the decade,” wrote Caleb Henry, director of research at the industry analysis firm Quilty Space. “That could pose a problem for some of the many large constellations on the horizon.”

United Launch Alliance’s Vulcan rocket, Rocket Lab’s Neutron, Stoke Space’s Nova, Relativity Space’s Terran R, and Firefly Aerospace and Northrop Grumman’s Eclipse are among the other rockets vying for a bite at the launch apple.

ESCAPADE’s path through space, relative to the Earth, has the peculiar shape of a kidney bean. In the world of astrodynamics, this is called a staging, or libration, orbit. It’s a way to keep the spacecraft on a stable trajectory to wait for the opportunity to go to Mars late next year.

“ESCAPADE has identified that this is the way that we want to fly, so we launch from Earth onto this kidney bean-shaped orbit,” said Jeff Parker, a mission designer from the Colorado-based company Advanced Space. “So, we can launch on virtually any day. What happens is that kidney bean just grows and shrinks based on how much time you need to spend in that orbit. So, we traverse that kidney bean and at the very end there’s a final little loop-the-loop that brings us down to Earth.”

That’s when the two ESCAPADE spacecraft, known as Blue and Gold, will pass a few hundred miles above our planet. At the right moment, on November 7 and 9 of next year, the satellites will fire their engines to set off for Mars.

An illustration of ESCAPADE’s trajectory to wait for the opportunity to go to Mars. Credit: UC-Berkeley
There are some tradeoffs with this unique staging orbit. It is riskier than the original plan of sending ESCAPADE straight to Mars. The satellites will be exposed to more radiation and will consume more of their fuel just to get to the red planet, eating into reserves originally set aside for science observations.

The satellites were built by Rocket Lab, which designed them with extra propulsion capacity in order to accommodate launches on a variety of different rockets. In the end, NASA “judged that the risk for the mission was acceptable, but it certainly is higher risk,” said Richard French, Rocket Lab’s vice president of business development and strategy.

The upside of the tradeoff is that it will demonstrate an “exciting and flexible way to get to Mars,” Lillis said. “In the future, if we’d like to send hundreds of spacecraft to Mars at once, it will be difficult to do that from just the launch pads we have on Earth within that month [of the interplanetary launch window]. We could potentially queue up spacecraft using the approach that ESCAPADE is pioneering.”

Nvidia recently made headlines by announcing that one of the companies it is partnering with, Starcloud, plans to build a 5-gigawatt orbital data center with “super-large solar and cooling panels approximately 4 kilometers in width and length.”

To put that into perspective, the eight main solar arrays on the International Space Station—the largest ever assembled in space, requiring many space shuttle launches and spacewalks—span about 100 meters and produce a maximum of about 240 kW. That’s about 0.005 percent of the power Starcloud intends to generate. //

However, it sounds a little more feasible if such an array could be assembled autonomously. And on Thursday morning, Starcloud, along with a new in-space assembly company, Rendezvous Robotics, announced an agreement to explore the use of modular, autonomous assembly to build Starcloud’s data centers.

Starlink not allowed in Myanmar, but scammers reportedly use it “on a huge scale.”. //

Octavus Ars Scholae Palatinae
19y
1,200

For those that don't know the details of the technology, both the space vehicle and ground terminal must know and accurately report their information in order for both sides to properly compensate for the Doppler effect.

This isn't fully true, the terminal needs to know the satellite's position and velocity but the satellite does not need to know the terminal's location. All the Doppler and time delay compensation happens on the ground side. The terminals transmitter compensates for Doppler and time delay so the signal at the satellite is at the correct frequency, otherwise different terminals would interfere with each other as they will not be frequency and time aligned at the satellite.
From the down link prospective the satellite broadcast to a spot/cell which corresponds to a location on Earth. The satellite does not compensation as even terminals within the same cell will require slightly different frequency shifts and time delay shifts, which the user terminal compensates for.
Now I don't work for Starlink but do work for one of their largest competitors and having the user terminal do all the compensation is by far the easiest method. Our terminals report to a server their GPS XYZ position so we still know where they are located, but for receiving a signal from them the terminals only need the satellite's positional information and the satellite only needs to know the spot ID.

One company, a California-based startup named Muon Space, is partnering with SpaceX to bring Starlink connectivity to low-Earth orbit. Muon announced Tuesday it will soon install Starlink terminals on its satellites, becoming the first commercial user, other than SpaceX itself, to use Starlink for in-flight connectivity in low-Earth orbit. //

Putting a single Starlink mini-laser terminal on a satellite would keep the spacecraft connected 70 to 80 percent of the time, according to Greg Smirin, Muon’s president. There would still be some downtime as the laser reconnects to different Starlink satellites, but Smirin said a pair of laser terminals would allow a satellite to reach 100 percent coverage. //

SpaceX’s mini-lasers are designed to achieve link speeds of 25Gbps at distances up to 2,500 miles (4,000 kilometers). These speeds will “open new business models” for satellite operators who can now rely on the same “Internet speed and responsiveness as cloud providers and telecom networks on the ground,” Muon said in a statement. //

Live video from space has historically been limited to human spaceflight missions or rocket-mounted cameras that operate for a short time.

One example of that is the dazzling live video beamed back to Earth, through Starlink, from SpaceX’s Starship rockets. The laser terminals on Starship operate through the extreme heat of reentry, returning streaming video as plasma envelops the vehicle. This environment routinely causes radio blackouts for other spacecraft as they reenter the atmosphere. With optical links, that’s no longer a problem.

“This starts to enable a whole new category of capabilities, much the same way as when terrestrial computers went from dial-up to broadband,” Smirin said. “You knew what it could do, but we blew through bulletin boards very quickly to many different applications.”

Two Falcon 9 rockets lifted off from spaceports in Florida and California on Sunday afternoon, adding 56 more satellites to SpaceX’s Starlink broadband network.

The second of these two launches—originating from Vandenberg Space Force Base, California—propelled SpaceX’s Starlink program past a notable milestone. With the satellites added to the constellation Sunday, the company has delivered more than 10,000 mass-produced Starlink spacecraft to low-Earth orbit.

The exact figure stands at 10,006 satellites, according to a tabulation by Jonathan McDowell, //

The Starlink network surpassed 7 million global subscribers in August, primarily beaming Internet connectivity to homes and businesses. SpaceX is now aggressively pushing to broaden its service direct to smartphones. //

SpaceX is decommissioning aging and obsolete Starlink satellites as the company adds to the fleet. The retired satellites reenter the atmosphere, where they’re designed to burn up without any debris reaching the ground. Taking into account all the reentries, here are McDowell’s numbers for the Starlink fleet as it stands Monday, October 20:

8,680 total Starlink satellites in orbit
8,664 functioning Starlink satellites in orbit (including newly launched satellites not yet operational)
7,448 Starlink satellites in operational orbit //

Sunday’s SpaceX launches weren’t just noteworthy for Starlink. The first of the two missions, departing from Florida’s Space Coast, marked the 31st launch of the company’s most-flown Falcon 9 booster. The rocket landed on SpaceX’s recovery ship in the Atlantic Ocean to be returned to Florida for a 32nd flight. //

SpaceX engineers are now certifying the Falcon 9 boosters for up to 40 flights apiece.

The season of records isn’t over. SpaceX is expected to set another one later this week. The company’s launch log for 2025 currently stands at 132 Falcon 9 missions, tying the total number of Falcon 9 flights last year. SpaceX also launched two flights of the more powerful Falcon Heavy in 2024, bringing the 2024 mark to 134 missions by the Falcon rocket family.

A new listing of the 50 most concerning pieces of space debris in low-Earth orbit is dominated by relics more than a quarter-century old, primarily dead rockets left to hurtle through space at the end of their missions. //

Russia and the Soviet Union lead the pack with 34 objects listed in McKnight's Top 50, followed by China with 10, the United States with three, Europe with two, and Japan with one. Russia's SL-16 and SL-8 rockets are the worst offenders, combining to take 30 of the Top 50 slots. //

The list published Friday is an update to a paper authored by McKnight in 2020. This year's list goes a step further by analyzing the overall effect on debris risk if some or all of the worst offenders were removed. If someone sent missions to retrieve all 50 of the objects, the overall debris-generating potential in low-Earth orbit would be reduced by 50 percent, according to McKnight. If just the Top 10 were removed, the risk would be cut by 30 percent. //

China, on the other hand, frequently abandons upper stages in orbit. China launched 21 of the 26 hazardous new rocket bodies over the last 21 months, each averaging more than 4 metric tons (8,800 pounds). Two more came from US launchers, one from Russia, one from India, and one from Iran. //

Since 2000, China has accumulated more dead rocket mass in long-lived orbits than the rest of the world combined, according to McKnight. "But now we're at a point where it's actually kind of accelerating in the last two years as these constellations are getting deployed."

Launched in 1975, the probe outlived its 90-day mission by years and set the standard for Mars landings //

It's been 50 years since NASA sent Viking 1 on a mission to Mars.

Launched on a Titan-Centaur rocket from Complex 41 at Cape Canaveral Air Force Station on August 20, 1975, Viking 1 was one of a pair of probes sent to land on Mars.

Viking 1 consisted of an orbiter and a lander and followed earlier US missions to Mars that had begun with Mariner 4 in 1964, continuing with the Mariner 6 and 7 flybys, and the Mariner 9 Mars orbital mission. //

The Viking 1 spacecraft arrived in orbit around Mars on June 19, 1976.

Power came from a pair of 35 W radioisotope thermoelectric generators (RTGs), connected in series on top of the lander. According to NASA [PDF], "the computer was one of the greatest technical challenges of Viking." There were two general-purpose computer channels, each with a storage capacity of 18,000 words. One was active while the other was in reserve. There was also a tape recorder.

Viking 1 was an unparalleled success. The orbiter and lander lasted far longer than initial expectations. The orbiter was eventually shut down in August 1980 after it ran out of attitude control propellant. It had begun to run low in 1978, but engineers were able to eke it out for a further two years. The lander kept on going until its final transmission on November 11, 1982.

Unfortunately, the lander's failure wasn't due to its hardware or the harsh environment of Mars. It was instead "a faulty command sent from Earth," according to NASA. The command resulted in loss of communication. Controllers spent the next six and a half months attempting to regain contact with the lander before the overall mission came to an end on May 21, 1983.

It is debatable how much longer the lander could have lasted. Viking 2's lander transmitted data until April 12, 1980, but its batteries eventually failed. Both landers and their respective orbiters had operated far beyond their planned mission lifetimes.

Black Hat Four countries have now tested anti-satellite missiles (the US, China, Russia, and India), but it's much easier and cheaper just to hack them.

In a briefing at the Black Hat conference in Las Vegas, Milenko Starcik and Andrzej Olchawa from German biz VisionSpace Technologies demonstrated how easy it is by exploiting software vulnerabilities in the software used in the satellites themselves, as well as the ground stations that control them.

"I used to work at the European Space Agency on ground station IT and got sick of telling them what was wrong and not having them fix it," Olchawa told The Register, "So I decided to go into business to do it myself." //

"We found actual vulnerabilities which allow you to crash the entire onboard software with an unauthenticated telephone," claimed Starcik.

"So basically, you send a packet to the spacecraft, and the entire software crashes and reboots, which then actually causes the spacecraft, if it's not properly configured, to reset all its keys. And then you have zero keys on the spacecraft that you can use from that stage on."

If it seems like there's a satellite launch almost every day, the numbers will back you up.

The US Space Force's Mission Delta 2 is a unit that reports to Space Operations Command, with the job of sorting out the nearly 50,000 trackable objects humans have launched into orbit.

Dozens of satellites are being launched each week, primarily by SpaceX to continue deploying the Starlink broadband network. The US military has advance notice of these launches—most of them originate from Space Force property—and knows exactly where they're going and what they're doing.

That's usually not the case when China or Russia (and occasionally Iran or North Korea) launches something into orbit. With rare exceptions, like human spaceflight missions, Chinese and Russian officials don't publish any specifics about what their rockets are carrying or what altitude they're going to.

That creates a problem for military operators tasked with monitoring traffic in orbit and breeds anxiety among US forces responsible for making sure potential adversaries don't gain an edge in space. Will this launch deploy something that can destroy or disable a US satellite? Will this new satellite have a new capability to surveil allied forces on the ground or at sea?

normally butters Ars Praefectus
18y
5,207
Control Group said:
Having never heard of Impulse before, I'd love an explainer of their engineering. What makes their system better at in-space maneuvering?
The previous answers are all good, but I'll add that there are historical reasons why liquid kick/deploy stages have seen little investment in the West until recently, whereas the Soviets developed stages like Fregat and Briz which are conceptually similar to Impulse's Mira.

The US invested heavily in upper stages like Centaur which solve the relatively difficult problem of a high-performance cryogenic stage capable of multiple in-flight restarts. Questionable plans to put Centaur inside the Space Shuttle payload bay were abandoned after the Challenger disaster and replaced with a couple of barely-adequate solid-propellant kick stages for payloads going beyond LEO.

The Europeans, meanwhile, took advantage of their near-equatorial launch site in French Guiana to develop launch vehicles optimized for GEO missions with upper stages inserting into GTO directly from the ascent burn, without requiring any restart. Ariane 5 literally doubled down on this concept of operations by specializing in dual-satellite GTO injection missions. In more modern times, Vega has a liquid kick stage, AVUM, but powered by a hypergolic engine of Soviet heritage which was until recently manufactured in Ukraine.

On the US-headquartered side, Rocket Lab's Electron requires a kick stage from their Photon product line for any orbital mission, once again largely to avoid the challenge of restarting cryogenic stages in microgravity. Firefly, in contrast, has developed a restartable second stage, and they are developing a line of orbital transfer stages based on lower-thrust electric propulsion.

So, Impulse Space just doesn't have much competition in this part of the world. Different approaches were taken to the design of expendable upper stages. But in a future with reusable upper stages that don't want to accelerate to higher energies than they need to, separate kick stages are increasingly compelling. Likewise, if military forces begin to see earth orbit as a more kinetic or dynamic combat theater, that would also encourage kick/transfer stage development, for better or worse. //

Chuckgineer Ars Centurion
10y
323
Subscriptor
Bruce Dunn said:
The Mira thrusters are undoubtably pressure fed. With hydrazine, pressure is provided by helium from composite overwrap pressure vessels through often trouble-prone valves. Impulse does not say how the Mira propellants are pressurized, but it is notable that they both have high vapor pressures at near ambient temperatures. I suspect that the propellants are self pressurized, eliminating the mass and complexity of helium pressurization. At 273 K, the vapor pressure of ethane is 2.4 MPa and that of nitrous oxide is 3.2 MPa.

Hi Bruce, the article above (Industry Update: Prevalance of Nitrous-Based In-Space Propellants) verifies your suspicion: "Nitrous and propylene are self-pressurizing and do not require pumps, pressurants or even propellant management devices."
https://www.dawnaerospace.com/latest-news/prevalence-of-nitrous-based-in-space-propellants

Just 10 years ago, a mere thousand or so operational satellites may have orbited our planet, but there will be tens or even hundreds of thousands a decade from now.

Experts have been sounding alarm bells for years that Earth orbit is getting a bit too crowded. So how many satellites can we actually launch to space before it gets to be too much?

Jonathan McDowell is an astrophysicist and astronomer at the Harvard-Smithsonian Center for Astrophysics who studies super-energetic phenomena in the universe such as jet-emitting black holes in galactic centers. In recent years, however, McDowell has gained prominence for his work in a completely different field of space research. In his monthly digital circular called Jonathan's Space Report, McDowell tracks the growing number of satellite launches and the ballooning number of objects in Earth orbit.

The project started with an ambition to "provide a pedantic historical record of the space age," but has, in a way, become a chronicle of the environmental destruction of the near Earth environment. In his frequent media appearances, McDowell has been vocal about his views on the future of the increasingly overcrowded near-Earth space.

"It's going to be like an interstate highway, at rush hour in a snowstorm with everyone driving much too fast," he told Space.com when asked what the situation in orbit will be like if existing plans for satellite megaconstellations such as SpaceX's Starlink, OneWeb and Amazon Kuiper come to fruition. "Except that there are multiple interstate highways crossing each other with no stoplights." //

"There's good evidence that the number of minor collisions is already increasing significantly," McDowell said. "We're seeing debris from objects that shouldn't really be creating debris. They probably have been hit by something small, even if they carry on working afterwards."

While the larger debris fragments over 4 inches in size are regularly tracked, trajectories of the smaller pieces are mostly unknown, and the collisions they can cause come entirely without warning.

Debris experts, however, are most concerned about encounters between two large defunct bodies — dead satellites or used rocket stages. One such close approach, between a decades-old Russian rocket upper stage and a long-defunct Russian satellite, took place on Jan. 27. With neither object being able to maneuver, space traffic guards could only look on with their fingers crossed, hoping the two would miss each other. On this occasion, they did —by a mere 20 feet (6 meters). The incident, described as a close call "worst-case scenario," could have spawned thousands of dangerous debris fragments that would have stayed in orbit for centuries, threatening everything in their path. //

McDowell says that humankind is likely going to discover the natural capacity of near-Earth space "the hard way." Despite the pledges of megaconstellation operators, the astrophysicist doubts that things will remain manageable in the years ahead.

"Five or 10 years from now, we'll have somewhere between 20,000 and 100,000 satellites, and I am very skeptical that at the upper number of 100,000 things can be operated safely," McDowell sai

A few years ago, online sleuths found an image of a B-2 stealth bomber in flight over Missouri. The aircraft is smeared in the image because it was in motion, while the farm fields below appear as crisp as any other view on Google Earth. https://petapixel.com/2021/12/28/stealth-bomber-caught-mid-flight-in-a-google-maps-photo/

There's something else that now appears on Google Earth. Zoom in over rural North Texas, and you'll find a satellite. It appears five times in different colors, each projected over wooded bottomlands in a remote wildlife refuge about 60 miles (100 kilometers) north of Dallas.

https://www.reddit.com/r/GoogleEarthFinds/comments/1jwy6gq/satellite_captured_over_texas_what_kind_of/?share_id=2RTVwnKNqmyxnToXVkOgD

The first human mission to land on the Moon is one of the only NASA mission patches that does not include the names of the crew members, Neil Armstrong, Buzz Aldrin, and Michael Collins. This was a deliberate choice by the crew, who wanted the world to understand they were traveling to the Moon for all of humanity.

Another NASA astronaut, Jim Lovell, suggested the bald eagle could be the focus of the patch. Collins traced the eagle from a National Geographic children's magazine, and an olive branch was added as a symbol of the mission's peaceful intent.

The result is a clear symbol of the United States leading humanity to another world. It is simple and powerful. //

With the space shuttle, astronauts and patch artists had to get more creative because the vehicle flew so frequently—eventually launching 135 times. Some of my favorite patches from these flights came fairly early on in the program.

As it turns out, designing shuttle mission patches was a bonding exercise for crews after their assignments. Often one of the less experienced crew members would be given leadership of the project.

"During the Shuttle era, designing a mission emblem was one of the first tasks assigned to a newly formed crew of astronauts," Flag Research Quarterly reports. "Within NASA, creation of the patch design was considered to be an important team-building exercise. The crew understood that they were not just designing a patch to wear on their flight suits, but that they were also creating a symbol for everyone who was working on the flight."

In some cases the crews commissioned a well-known graphic designer or space artist to help them with their patch designs. More typically they worked with a graphic designer on staff at the Johnson Space Center to finalize the design. //

In recent years, some of the most creative patch designs have come from SpaceX and its crewed spaceflights aboard the Dragon vehicle. Because of the spacecraft's name, the missions have often played off the Dragon motif, making for some striking designs.

There is a dedicated community of patch collectors out there, and some of them were disappointed that SpaceX stopped designing patches for each individual Starlink mission a few years ago. However, I would say that buying two or three patches a week would have gotten pretty expensive, pretty fast—not to mention the challenge designers would face in making unique patches for each flight.

If you read this far and want to know my preference, I am not much of a patch collector, as much as I admire the effort and artistry that goes into each design. I have only ever bought one patch, the one designed for the Falcon 1 rocket's fourth flight. The patch isn't beautiful, but it's got some nice touches, including lights for both Kwajalein and Omelek islands, where the company launched its first rockets. Also, it was the first time the company included a shamrock on the patch, and that proved fortuitous, as the successful launch in 2008 saved the company. It has become a trademark of SpaceX patches ever since.

Almost no one ever writes about the Parker Solar Probe anymore.

Sure, the spacecraft got some attention when it launched. It is, after all, the fastest moving object that humans have ever built. At its maximum speed, goosed by the gravitational pull of the Sun, the probe reaches a velocity of 430,000 miles per hour, or more than one-sixth of 1 percent the speed of light. That kind of speed would get you from New York City to Tokyo in less than a minute. //

However, the smallish probe—it masses less than a metric ton, and its scientific payload is only about 110 pounds (50 kg)—is about to make its star turn. Quite literally. On Christmas Eve, the Parker Solar Probe will make its closest approach yet to the Sun. It will come within just 3.8 million miles (6.1 million km) of the solar surface, flying into the solar atmosphere for the first time.

Yeah, it's going to get pretty hot. Scientists estimate that the probe's heat shield will endure temperatures in excess of 2,500° Fahrenheit (1,371° C) on Christmas Eve, which is pretty much the polar opposite of the North Pole. //

I spoke with the chief of science at NASA, Nicky Fox, to understand why the probe is being tortured so. Before moving to NASA headquarters, Fox was the project scientist for the Parker Solar Probe, and she explained that scientists really want to understand the origins of the solar wind.

This is the stream of charged particles that emanate from the Sun's outermost layer, the corona. Scientists have been wondering about this particular mystery for longer than half a century, Fox explained.

"Quite simply, we want to find the birthplace of the solar wind," she said.

Way back in the 1950s, before we had satellites or spacecraft to measure the Sun's properties, Parker predicted the existence of this solar wind. The scientific community was pretty skeptical about this idea—many ridiculed Parker, in fact—until the Mariner 2 mission started measuring the solar wind in 1962.

As the scientific community began to embrace Parker's theory, they wanted to know more about the solar wind, which is such a fundamental constituent of the entire Solar System. Although the solar wind is invisible to the naked eye, when you see an aurora on Earth, that's the solar wind interacting with Earth's magnetosphere in a particularly violent way.

Only it is expensive to build a spacecraft that can get to the Sun. And really difficult, too.

Now, you might naively think that it's the easiest thing in the world to send a spacecraft to the Sun. After all, it's this big and massive object in the sky, and it's got a huge gravitational field. Things should want to go there because of this attraction, and you ought to be able to toss any old thing into the sky, and it will go toward the Sun. The problem is that you don't actually want your spacecraft to fly into the Sun or be going so fast that it passes the Sun and keeps moving. So you've got to have a pretty powerful rocket to get your spacecraft in just the right orbit. //

But you can't get around the fact that to observe the origin of the solar wind, you've got to get inside the corona. Fox explained that it's like trying to understand a forest by looking in from the outside. One actually needs to go into the forest and find a clearing. However, we can't really stay inside the forest very long—because it's on fire.

So, the Parker Solar Probe had to be robust enough to get near the Sun and then back into the coldness of space. Therein lies another challenge. The spacecraft is going from this incredibly hot environment into a cold one and then back again multiple times.

"If you think about just heating and cooling any kind of material, they either go brittle and crumble, or they may go like elastic with a continual change of property," Fox said. "Obviously, with a spacecraft like this, you can't have it making a major property change. You also need something that's lightweight, and you need something that's durable."

The science instruments had to be hardened as well. As the probe flies into the Sun there's an instrument known as a Faraday cup that hangs out to measure ion and electron fluxes from the solar wind. Unique technologies were needed. The cup itself is made from sheets of Titanium-Zirconium-Molybdenum, with a melting point of about 4,260° Fahrenheit (2,349° C). Another challenge came from the electronic wiring, as normal cables would melt. So, a team at the Smithsonian Astrophysical Observatory grew sapphire crystal tubes in which to suspend the wiring, and made the wires from niobium.

The Starship launch system is about to reach a tipping point, Gwynne Shotwell said, as it moves from an experimental rocket toward operational missions.

"We just passed 400 launches on Falcon, and I would not be surprised if we fly 400 Starship launches in the next four years," Shotwell said at the Baron Investment Conference in New York City. "We want to fly it a lot."

That lofty goal seems aspirational, not just because of the hardware challenges but also due to the ground systems (SpaceX currently has just one operational launch tower) as well as the difficulty of supplying that much liquid oxygen and methane for such a high flight rate. However, it's worth noting that SpaceX will launch Starship four times this year, twice the number of Falcon Heavy missions. An acceleration of Starship is highly likely. //

"Starship obsoletes Falcon 9 and the Dragon capsule," she said. "Now, we are not shutting down Dragon, and we are not shutting down Falcon. We'll be flying that for six to eight more years, but ultimately, people are going to want to fly on Starship. It's bigger. It's more comfortable. It will be less expensive. And we will have flown it so many more times.". //

As Starlink has come online, it has significantly increased the valuation of the privately held company. A decade ago, SpaceX was valued at about $12 billion, and this grew to $36 billion in 2020. Most recently, the company was valued at about $255 billion. //

DDopson Ars Tribunus Militum
22y
2,397
Subscriptor++
daddyboomalati said:
Can someone unpack this for me? I cannot understand how a massive rocket is a better choice than the Falcon 9 for medium-weight payloads. My only thought is that it delivers multiple satellites at once. I do it all the time in Kerbal Space Program, but is this a thing in real life, or an eventual likelihood?
It's simpler than that. Starship costs less to launch than F9.

Each F9 launch expends a second stage that costs roughly $20M to fabricate. They do recover the $40M booster and the $6M fairings, but they have to fabricate a new second stage for every launch. And that second stage consumes one Merlin engine, but that's only a relatively small fraction of the stage's cost, on account of SpaceX's spectacular efficiency at manufacturing rocket engines for <$1M, literally hundreds of times cheaper than, eg, the RS-25 engines NASA buys.

The cost to fuel a Starship is on the order of a few million, possibly in the $2M or $3M ballpark (this was estimated in a prior thread), probably more when including their current fueling logistics costs, possibly a bit less at scale when they are manufacturing their own LOX and can amortize various bits of fueling infra over a consistent level of demand.

Ground logistics add additional costs (control center staff, ground crew, amortized share of launch complex, etc), but these are hard to estimate. Dividing the entire Boca Chica facility cost over ~5 test launches would produce an unfavorable number, but that's silly. The ground facilities should amortize fairly well as the launch cadence increases. And this stuff is probably mostly comparable between the two platforms.

Sticking with relatively conservative numbers, I expect their all-up internal marginal cost per Starship launch to be well under $10M per flight, much less than the cost of fabricating a new F9 second stage.

Launching Starship is thus cheaper than launching F9.

Now that's an internal cost that we may never learn with precision, and SpaceX will make a business decision about what price to charge to their customers. They may create very attractive rates for rideshares. They will likely maintain high prices for "white glove" launch contracts that include significant payload preparation and other services, especially DoD and NASA, which already typically pay more per F9 launch contract than the sticker price on the website for "just a launch". //

rocket bodies, satellites, space debris in earth orbit

Q: What is the highest apogee of a satellite in Earth orbit they need to avoid? Ignore any satellites in Solar or lunar orbit.

A: There are over a hundred satellites in Molniya orbit, a few tens in Tundra orbit and a handful in really high earth orbits. The first two of those go above geostationary orbit; there are examples of the last with perigee of at least 375,000km. //

James Webb Space Telescope, at the Earth-Sun L2 point, is roundly a million miles from Earth, but still gravitationally bound to the Earth-Moon system.

Other than that, there are very few if any permanent satellites beyond the "graveyard orbits" used to park expired geostationary satellites. These are typically only a few hundred kilometers higher than geosynchronous, however, so roundly if they're well beyond the 24 hour orbital period, they'd be well clear of anything we put up intentionally and left there. //

Then there is stuff, mostly debris, that is more critical, because by nature those pieces are very fast, the orbit is not stable, so it changes a little every round and the kinetic energy would be able to penetrate any hull that is not specifically designed to withstand such impacts. For example, this debris of an Iridium satellite - at the time of writing at altitude ~366,000km and counting, spiralling outwards at 1km/s (the map does not mention a size or weight though. But it is big enough to be trackable obviously).

After nearly every flight, the upper stage of this rocket breaks apart in orbit. //

A new debris field of nearly 1,000 objects would be a significant addition to the approximately 46,000 objects Space Command tracks in Earth orbit. According to statistics compiled by Jonathan McDowell, an astrophysicist who monitors global launch and spaceflight activity, this would rank in the top five of all debris-generation events since the dawn of the Space Age.