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SpaceX "DARKSAT" results: can Starlink and astronomy happily coexist?
Astronomers have begun to gather and analyze detailed observations of a SpaceX Starlink satellite prototype officially labeled DARKSAT and the initial results hint that the satellite constellation should be able to happily coexist with ground-based astronomy in the future.
Since SpaceX began launching batches of 60 Starlink satellites in May 2019, the company has raised the ire of parts of the astronomy community and simultaneously awed and inspired many less technical observers with clusters of shooting star-like satellites that are easily visible after launches. While the mid-sized spacecraft do become much dimmer as they raise their orbits from ~300 km (185 mi) to 550 km (340 mi), they are far from invisible even at that operational altitude. It’s safe to say that the current impact on ground-based astronomy is still just shy of negligible even with 360 satellites in orbit, but that impact is assuredly greater than zero and the relatively bright spacecraft have already interrupted telescope observations at many sites around the world.
Given that the 360 satellites already in orbit are just a tiny fraction of the ~4400, ~12,000, or even ~40,000 that SpaceX could one day launch, it would be irresponsible to argue that the constellation’s impact – and the impact of others like it – will continue to be minor as the number of satellites grows. Thankfully, while it doesn’t appear that prospective low Earth orbit (LEO) constellation architects anticipated the potential astronomy impact, SpaceX’s Starlink team has rapidly responded and already launched a satellite featuring tweaks designed to dim its appearance from the ground. For several reasons, the initial results from “DARKSAT” are extremely promising – now visible below in some of the first photos offering a useful comparison.
Launched on January 7th, 2020, a set of 20 spacecraft including DARKSAT – representing a single “plane” of the broader Starlink constellation – all arrived at their operational ~550 km (340 mi) orbits by February 23rd. As previously discussed on Teslarati, initial results first published on March 18th revealed that the Starlink DARKSAT prototype – essentially an early alpha test for darkening techniques – was already 55% darker than unmodified spacecraft. While making satellites less reflective makes thermal management a much greater challenge, DARKSAT has managed to raise its orbit and begin operations without issue, although it’s unknown whether the satellite’s antennas and avionics are also functioning nominally.
For darker spacecraft, perhaps the most important test will be long-term reliability, as constantly absorbing more heat than a reflective satellite is likely to put their structure, avionics, and radiators through significantly more thermal stress. As such, SpaceX may launch a limited number of additional darkened prototypes over the coming months but is much less likely to darken all satellites on any given launch until DARKSATs have successfully operated in orbit for months or even years.
On the ground, SpaceX may try to perform sped-up stress testing, but proving that darker satellites are a viable solution will almost invariably take time. Earlier this month, CEO Elon Musk revealed that SpaceX may attempt to design deployable solar shades for Starlink satellites if darkening their bodies is not enough to fully mitigate major impacts to astronomy. Knowing SpaceX, the first in-orbit solar shade test(s) could happen during any of several upcoming Starlink launches.
Adding reliable, deployable solar shades without appreciably raising Starlink’s production costs could be a major challenge, given the fundamental complexity of large, deployable mechanisms in space, but SpaceX – if anyone – is likely up to the challenge. More importantly, the fact that SpaceX’s very first attempt at reducing Starlink albedo (reflectivity) has produced a satellite 55% darker than its peers suggests that much more can probably be done along those lines, given additional time for extra experiments and deeper optimization.
As a result, it may be the case that SpaceX ends up launching 750-1000+ reflective Starlink satellites before an affordable, mass-producible DARKSAT variant is ready to take over. In that event, Starlink could plausibly have a small to moderate negative impact on ground-based astronomy for several years. However, comments made by SpaceX executives over the years suggest that no single Starlink satellite is likely to operate for more than five or so years before being replaced, meaning that the entire constellation would be continuously refreshed (as long as it’s generating revenue). Even if a thousand bright(er) Starlink satellites make life a bit harder for some astronomers, the fact remains that the consequences of any single Starlink satellite variant – assuming SpaceX remains serious about fully mitigating the constellation’s impact – are inherently temporary.
If SpaceX continues to make progress darkening satellites and developing cheap solar shades, it seems all but guaranteed that even a constellation of tens of thousands of Starlink satellites will be able happily coexist with the astronomy community, all the while delivering cheap, fast internet to millions of people – especially those lacking access – around the world.
SpaceX announced today that it commenced its first-ever public bond offering, marking a significant step in the newly public company’s capital markets strategy.
The company announced an offering of senior unsecured notes expected to raise at least $20 billion.
The move comes just a short time after SpaceX completed one of the largest initial public offerings in history. In mid-June, the company priced shares at $135 and raised more than $85 billion, propelling founder Elon Musk’s net worth past the trillion-dollar mark and giving the firm substantial liquidity.
🚨 SpaceX has announced its inaugural offering of senior unsecured notes.
The net proceeds will be used to repay outstanding loans under its bridge loan facility in full.
This inaugural debt offering represents a financing milestone for SpaceX, which previously depended… pic.twitter.com/pcOZuVbTRv
— TESLARATI (@Teslarati) June 22, 2026
According to the company’s SEC filing, the net proceeds from the notes will be used primarily to repay in full the outstanding borrowings under its existing bridge loan facility, cover related fees and expenses, and fund general corporate purposes. The offering is being conducted under Rule 144A, as well as Regulation S, targeting qualified institutional buyers and non-U.S. investors. Notes will be unsecured obligations ranking equally with other unsubordinated debt.
The $20 billion bridge loan was used to refinance approximately $17.5 billion in higher-cost “junk” debt tied to X and xAI. SpaceX had merged with xAI in February 2026 in an all-stock deal. The bridge facility, which matures in September 2027, had represented the bulk of SpaceX’s long-term debt.
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In connection with the bond launch, SpaceX disclosed it held approximately $100.8 billion in cash and cash equivalents as of June 19. Investor calls began on the announcement date, with pricing and launch expected shortly thereafter. Rating agencies have assigned investment-grade ratings to the proposed bonds, reflecting confidence in SpaceX’s dominant position in commercial launches and the growth trajectory of its Starlink internet offering.
The debt raise also allows SpaceX to optimize its balance sheet by replacing short-term, higher-cost bridge financing with longer-date, lower-cost fixed-income securities. This provides greater financial flexibility to support capital-intensive initiatives, including the development of Starship, the expansion of the Starlink constellation, and the integration of AI capabilities following the xAI combination.
SpaceX shares (NASDAQ: SPCX) fell sharply on the news, dropping over 16 percent overall on the market on Monday. The stock had surged initially after debuting but pulled back amid profit-taking and broader market dynamics.
Overall, the bond offering underscores SpaceX’s transition to a mature public company with access to diverse funding sources. It positions the firm to pursue its long-term vision of multiplanetary expansion and AI infrastructure, while maintaining a disciplined approach to its capital structure in a high-growth but capital-heavy industry.
SpaceX confirmed today that it has officially signed its third massive compute deal, providing compute at its Colossus data center in Southaven, Tennessee.
Reflection AI will gain immediate access to NVIDIA GB300 chips at SpaceX’s Colossus 2 data center. In return, Reflection will pay SpaceX $150 million per month starting on July 1, with total payments reaching approximately $6.3 billion if the contract runs through its duration, which is until 2029. Either party can terminate the agreement with 90 days’ notice after the initial three-month period.
CNBC first reported the deal.
🚨 SpaceXAI has agreed to a new compute deal with Reflection AI.
Reflection gets access to NIVIDIA GB300s, and will pay $150M per month to SpaceXAI for the compute. pic.twitter.com/bNPare8U5u
— TESLARATI (@Teslarati) June 22, 2026
This latest partnership highlights SpaceX’s strategy of commercializing its massive Colossus supercomputing infrastructure, originally developed to power Elon Musk’s Grok AI models. The company has rapidly expanded its customer base in the AI sector following its February 2026 merger with xAI, a transaction that valued the combined entity at $1.25 trillion.
SpaceX has previously signed significant compute deals with other major players.
It granted Anthropic exclusive access to the full capacity of its Colossus 1 data center, which exceeds 300 megawatts and includes over 220,000 NVIDIA GPUs. Details from SpaceX’s IPO filings indicate Anthropic will pay $1.25 billion per month through May 2029, potentially generating around $45 billion over the term of the deal.
Additionally, Google agreed to pay SpaceX $920 million per month for compute capacity from October 2026 through June 2029. This 32-month period will provide Google access to roughly 110,000 NVIDIA GPUs, along with supporting processors and memory. Capacity ramps up through September at a reduced fee, with termination options after the first year.
SpaceXA also established arrangements for computing power with Cursor, an AI coding startup. SpaceX acquired them in a $60 billion all-stock deal.
These arrangements position SpaceX’s collective position as an AI infrastructure powerhouse with high-margin revenue potential. The Google deal alone could generate nearly $29.5 billion over its term, while the Reflection contract adds another $6.3 billion.
Combined with the Anthropic arrangement, SpaceX stands to realize tens of billions in revenue from compute leasing in the coming years, which diversifies beyond SpaceX’s traditional rocket launches and Starlink operation.
The deals underscore growing demand for advanced AI training and inference capacity amid chip shortages and surging model development needs. Reflection, valued at $25 billion and focused on “American open intelligence” with government and national security ties, cited recent restrictions on closed models as validation for open-source approaches.
For SpaceX, the partnerships transform capital-intensive data centers into flexible revenue sources while supporting its broader AI ambitions after the company has gone public.
It is safe to say SpaceX won’t be going for electric rockets anytime soon.
In a characteristically blunt reply on X, SpaceX frontman Elon Musk stated, “Unfortunately, electric rockets are impossible,” following reports that MSCI had assigned SpaceX its lowest possible ESG rating of CCC.
The assessment, issued just this past week, coinciding closely with SpaceX’s public market debut, placed the company on par with nations like Russia in sustainability scoring and cited significant risks in environmental, social, and governance areas.
MSCI flagged SpaceX’s exposure to rocket emissions and other operational impacts, alongside governance concerns such as concentrated control by Musk and limited shareholder protections. Musk’s terse comment directly addressed the environmental pillar, underscoring a core physical constraint that ESG frameworks often overlook when evaluating high-thrust industries.
Unfortunately, electric rockets are impossible
— Elon Musk (@elonmusk) June 21, 2026
Electric propulsion systems do exist and are widely used in space. Ion thrusters and Hall-effect thrusters accelerate ionized propellant, typically xenon or krypton, using electric fields, achieving very high specific impulse, often exceeding 3,000 seconds compared to roughly 300–450 seconds for chemical rockets.
This efficiency makes them ideal for satellite station-keeping, orbit raising, and deep-space missions where low thrust over long durations is sufficient. SpaceX’s own Starlink satellites employ electric propulsion for these purposes.
However, launching from Earth’s surface demands something entirely different: enormous thrust delivered rapidly to overcome gravity and atmospheric drag. A typical orbital-class booster must generate thrust far exceeding its weight, often in the millions of Newtons within seconds.
Chemical rockets achieve this through exothermic combustion of dense propellants, producing high-mass-flow, high-velocity exhaust. Electric systems, by contrast, expel very small amounts of mass at extremely high speeds. Generating equivalent thrust would require impractical onboard power levels, massive energy storage or generation systems, and prohibitive added mass, rendering the approach infeasible with current or near-term technology.
Musk has previously expressed a similar sentiment, noting a desire for electric orbital rockets while acknowledging the inescapable requirements of Newton’s third law and energy delivery. The distinction is clear: electric propulsion excels once a vehicle is already in space; it cannot replace the high-thrust chemical phase required to reach orbit from the ground.
The episode illustrates broader critiques of ESG ratings. Proponents argue they incentivize better risk management and long-term sustainability. Detractors, including Musk—who has previously called ESG a “scam”—contend that such metrics can penalize essential activities when no practical alternative exists, potentially discouraging innovation in sectors like space access.
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SpaceX has sought to mitigate launch-related impacts through reusability: Falcon 9 boosters have flown more than 30 times in some cases, dramatically lowering the manufacturing and emissions burden per kilogram delivered to orbit. Starship’s design further emphasizes rapid reusability and methane propellant, which can theoretically be produced via sustainable pathways.
Ultimately, Musk’s remark serves as a reminder that certain engineering realities persist regardless of scoring systems. As humanity expands its presence in space for communications, science, and exploration, balancing genuine environmental progress with technological necessity remains a central challenge.
ESG frameworks may evolve, but the fundamental limits of electric launch propulsion are unlikely to change soon.
SpaceX makes $20 billion move to optimize its balance sheet
SpaceX confirms third massive compute deal at Colossus data center
