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DeepSpace: Firefly’s Alpha rocket to get a massive upgrade with ion thruster boost stage ⚡ ?

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Eric Ralph · June 18th, 2019

Welcome to the latest edition of DeepSpace! Each week, Teslarati space reporter Eric Ralph hand-crafts this newsletter to give you a breakdown of what’s happening in the space industry and what you need to know. To receive this newsletter (and others) directly and join our member-only Slack group, give us a 3-month trial for just $5.


Although the company quietly teased the concept for the first time several months ago, Firefly has released a detailed update on its Orbital Transfer Vehicle (OTV), an ambitious spacecraft meant to complement its Alpha and Beta launch vehicles. If Firefly can deliver on the independent spacecraft’s technical promises, the combination of Alpha (~$15M) and OTV could help usher in a new era of small, high-performance satellites launched on small, high-performance rockets.

In fact, Rocket Lab – currently the world’s only truly commercial smallsat launch provider – has already demonstrated the power of this new paradigm, albeit on a smaller scale. After just one failed attempt, the first successful orbital launch of the company’s Electron rocket also marked the surprise debut of a tiny third stage used to circularize the payload’s orbit. After five successful uses in orbit, Rocket Lab has taken its third stage a step further, adding redundant avionics, solar arrays, and more to effectively create an independent spacecraft/satellite bus called Photon. By all appearances, Firefly’s OTV is much larger than Photon but is functionally quite similar. By taking advantage of Alpha’s significant performance benefits compared to Electron, Firefly has designed a third stage/spacecraft capable of delivering hundreds of kilograms to geostationary orbit, the Moon, and (perhaps) beyond.

Changing the delta V game

  • Generally speaking, OTV is quite small. According to Firefly’s Payload User’s Guide, the spacecraft will weigh just 130 kg (285 lb) dry and will carry perhaps 30-70 kg of xenon fuel for its electric ion thrusters. This is a critical differentiator relative to Rocket Lab’s Photon and kick stage, which rely on the inefficient (but simple and reliable) Curie chemical rocket engine.
    • According to Firefly, Alpha is designed to launch a max of 1000 kg (2200 lb) to a 200 km (125 mi) low Earth orbit (LEO). Given OTV’s ~200 kg wet mass, Alpha + OTV offer some incredible capabilities relative to the rocket’s size and design.
    • Powerful electric thrusters undeniably add a lot of complexity to any spacecraft that chooses to use them but that pain is often deemed worth it for the benefits they can offer. Most notably, ion propulsion is extremely efficient.
This graph demonstrates the potential performance benefits of Alpha + OTV relative to Alpha on its own. (Firefly)
  • Thanks to OTV’s efficient electric thrusters and light carbon composite structure, the potential benefits of Alpha + OTV are hard to believe for a rocket as (relatively) small as Alpha.
  • On its own, Alpha can only deliver a meaningful payload (~100 kg) to perhaps 4000 km (2500 mi). With OTV, Alpha can suddenly deliver ~600 kg to a circular geostationary orbit (~36,000 km, 22,300 mi) and upwards of 400-500 kg into orbit around the Moon.
    • For reference, despite weighing around 10% of Falcon 9, Alpha and OTV would offer perhaps 10-15% the performance of Falcon 9 to trans lunar injection (TLI). This utterly defies the general rule of thumb that as a rocket gets significantly smaller, its performance (particularly to higher-energy orbits) deteriorates disproportionately.
  • With OTV, Alpha – nominally a ~$15M launch vehicle relegated to LEO payloads – becomes an incredibly intriguing option for small geostationary communications satellites and small-scale public and private exploration of the Moon, near Earth asteroids, and maybe even Mars/Venus.
  • According to a senior Firefly investor and board member, Firefly hopes to have OTV ready for its orbital debut on Alpha’s third launch, tentatively scheduled no earlier than mid-2020.

Alpha readies for launch

  • Of course, OTV is a bird without wings without Firefly’s Alpha launch vehicle. Weighing 54,000 kg (120,000 lb) fully-fueled, Alpha is a two-stage rocket that will stand 1.8m (6ft) wide and 29m (95ft) tall. Powered by four Reaver engines, the first stage will produce ~740 kN (166,000 lbf), approximately 85% of one of Falcon 9’s nine Merlin 1D engines.
  • Firefly is working relentlessly towards an ambitious December 2019 Alpha launch debut, a target that will probably slip into early 2020 due to the inherent complexity of the task at hand. Critically, though, Firefly has made a huge amount of progress towards that goal.
    • Notably, Firefly’s second stage – powered by one vacuum-optimized Lightning engine – has already been qualified for launch with full-duration static fires at the company’s Texas facilities. Firefly is in the midst of preparing for an identical series of qualification tests for its more powerful first stage, shown above in the form of one Reaver engine attached to an Alpha S1 thrust structure.
    • As early as July, a full set of four Reaver engines will be installed on the same thrust structure to perform static fire testing, much like SpaceX gradually added Merlin 1D engines during Falcon 9 development testing.
  • If all goes as planned, Firefly will have completed its first Alpha rocket – first stage, second stage, and payload fairing – by October or November 2019. Expect plenty of new photos and updates as Alpha nears its inaugural launch.
Thanks for being a Teslarati Reader! Become a member today to receive an issue of DeepSpace in your inbox each week!

– Eric

 

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Eric Ralph is Teslarati's senior spaceflight reporter and has been covering the industry in some capacity for almost half a decade, largely spurred in 2016 by a trip to Mexico to watch Elon Musk reveal SpaceX's plans for Mars in person. Aside from spreading interest and excitement about spaceflight far and wide, his primary goal is to cover humanity's ongoing efforts to expand beyond Earth to the Moon, Mars, and elsewhere.

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Tesla already has a complete Robotaxi model, and it doesn’t depend on passenger count

That scenario was discussed during the company’s Q4 and FY 2025 earnings call, when executives explained why the majority of Robotaxi rides will only involve one or two people.

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Credit: @AdanGuajardo/X

Tesla already has the pieces in place for a full Robotaxi service that works regardless of passenger count, even if the backbone of the program is a small autonomous two-seater. 

That scenario was discussed during the company’s Q4 and FY 2025 earnings call, when executives explained why the majority of Robotaxi rides will only involve one or two people.

Two-seat Cybercabs make perfect sense

During the Q&A portion of the call, Tesla Vice President of Vehicle Engineering Lars Moravy pointed out that more than 90% of vehicle miles traveled today involve two or fewer passengers. This, the executive noted, directly informed the design of the Cybercab. 

“Autonomy and Cybercab are going to change the global market size and mix quite significantly. I think that’s quite obvious. General transportation is going to be better served by autonomy as it will be safer and cheaper. Over 90% of vehicle miles traveled are with two or fewer passengers now. This is why we designed Cybercab that way,” Moravy said. 

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Elon Musk expanded on the point, emphasizing that there is no fallback for Tesla’s bet on the Cybercab’s autonomous design. He reiterated that the autonomous two seater’s production is expected to start in April and noted that, over time, Tesla expects to produce far more Cybercabs than all of its other vehicles combined.

“Just to add to what Lars said there. The point that Lars made, which is that 90% of miles driven are with one or two passengers or one or two occupants, essentially, is a very important one… So this is clearly, there’s no fallback mechanism here. It’s like this car either drives itself or it does not drive… We would expect over time to make far more CyberCabs than all of our other vehicles combined. Given that 90% of distance driven or distance being distance traveled exactly, no longer driving, is one or two people,” Musk said. 

Tesla’s robotaxi lineup is already here

The more interesting takeaway from the Q4 and FY 2025 earnings call is the fact that Tesla does not need the Cybercab to serve every possible passenger scenario, simply because the company already has a functional Robotaxi model that scales by vehicle type.

The Cybercab will handle the bulk of the Robotaxi network’s trips, but for groups that need three or four seats, the Model Y fills that role. For higher-end or larger-family use cases, the extended-wheelbase Model Y L could cover five or six occupants, provided that Elon Musk greenlights the vehicle for North America. And for even larger groups or commercial transport, Tesla has already unveiled the Robovan, which could seat over ten people.

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Rather than forcing one vehicle to satisfy every use case, Tesla’s approach mirrors how transportation works today. Different vehicles will be used for different needs, while unifying everything under a single autonomous software and fleet platform.

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Tesla Cybercab spotted with interesting charging solution, stimulating discussion

The port is located in the rear of the vehicle and features a manual door and latch for plug-in, and the video shows an employee connecting to a Tesla Supercharger.

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Credit: What's Inside | X

Tesla Cybercab units are being tested publicly on roads throughout various areas of the United States, and a recent sighting of the vehicle’s charging port has certainly stimulated some discussions throughout the community.

The Cybercab is geared toward being a fully-autonomous vehicle, void of a steering wheel or pedals, only operating with the use of the Full Self-Driving suite. Everything from the driving itself to the charging to the cleaning is intended to be operated autonomously.

But a recent sighting of the vehicle has incited some speculation as to whether the vehicle might have some manual features, which would make sense, but let’s take a look:

The port is located in the rear of the vehicle and features a manual door and latch for plug-in, and the video shows an employee connecting to a Tesla Supercharger.

Now, it is important to remember these are prototype vehicles, and not the final product. Additionally, Tesla has said it plans to introduce wireless induction charging in the future, but it is not currently available, so these units need to have some ability to charge.

However, there are some arguments for a charging system like this, especially as the operation of the Cybercab begins after production starts, which is scheduled for April.

Wireless for Operation, Wired for Downtime

It seems ideal to use induction charging when the Cybercab is in operation. As it is for most Tesla owners taking roadtrips, Supercharging stops are only a few minutes long for the most part.

The Cybercab would benefit from more frequent Supercharging stops in between rides while it is operating a ride-sharing program.

Tesla wireless charging patent revealed ahead of Robotaxi unveiling event

However, when the vehicle rolls back to its hub for cleaning and maintenance, standard charging, where it is plugged into a charger of some kind, seems more ideal.

In the 45-minutes that the car is being cleaned and is having maintenance, it could be fully charged and ready for another full shift of rides, grabbing a few miles of range with induction charging when it’s out and about.

Induction Charging Challenges

Induction charging is still something that presents many challenges for companies that use it for anything, including things as trivial as charging cell phones.

While it is convenient, a lot of the charge is lost during heat transfer, which is something that is common with wireless charging solutions. Even in Teslas, the wireless charging mat present in its vehicles has been a common complaint among owners, so much so that the company recently included a feature to turn them off.

Production Timing and Potential Challenges

With Tesla planning to begin Cybercab production in April, the real challenge with the induction charging is whether the company can develop an effective wireless apparatus in that short time frame.

It has been in development for several years, but solving the issue with heat and energy loss is something that is not an easy task.

In the short-term, Tesla could utilize this port for normal Supercharging operation on the Cybercab. Eventually, it could be phased out as induction charging proves to be a more effective and convenient option.

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Tesla confirms that it finally solved its 4680 battery’s dry cathode process

The suggests the company has finally resolved one of the most challenging aspects of its next-generation battery cells.

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tesla 4680
Image used with permission for Teslarati. (Credit: Tom Cross)

Tesla has confirmed that it is now producing both the anode and cathode of its 4680 battery cells using a dry-electrode process, marking a key breakthrough in a technology the company has been working to industrialize for years. 

The update, disclosed in Tesla’s Q4 and FY 2025 update letter, suggests the company has finally resolved one of the most challenging aspects of its next-generation battery cells.

Dry cathode 4680 cells

In its Q4 and FY 2025 update letter, Tesla stated that it is now producing 4680 cells whose anode and cathode were produced during the dry electrode process. The confirmation addresses long-standing questions around whether Tesla could bring its dry cathode process into sustained production.

The disclosure was highlighted on X by Bonne Eggleston, Tesla’s Vice President of 4680 batteries, who wrote that “both electrodes use our dry process.”

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Tesla first introduced the dry-electrode concept during its Battery Day presentation in 2020, pitching it as a way to simplify production, reduce factory footprint, lower costs, and improve energy density. While Tesla has been producing 4680 cells for some time, the company had previously relied on more conventional approaches for parts of the process, leading to questions about whether a full dry-electrode process could even be achieved.

4680 packs for Model Y

Tesla also revealed in its Q4 and FY 2025 Update Letter that it has begun producing battery packs for certain Model Y vehicles using its in-house 4680 cells. As per Tesla: 

“We have begun to produce battery packs for certain Model Ys with our 4680 cells, unlocking an additional vector of supply to help navigate increasingly complex supply chain challenges caused by trade barriers and tariff risks.”

The timing is notable. With Tesla preparing to wind down Model S and Model X production, the Model Y and Model 3 are expected to account for an even larger share of the company’s vehicle output. Ensuring that the Model Y can be equipped with domestically produced 4680 battery packs gives Tesla greater flexibility to maintain production volumes in the United States, even as global battery supply chains face increasing complexity.

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