DARPA STTR DPA26TZ06-DV005: Fuel-Flexible Spacecraft Electric Propulsion System
Quick Answer
DPA26TZ06-DV005 is a DARPA STTR Direct to Phase II topic under the DoW 2026 STTR Broad Agency Announcement, Release 6. DARPA wants one electric propulsion product line that runs on air, water, water and carbon dioxide mixtures, or nitrogen and hydrogen mixtures, at better than 30 percent electrical efficiency, using as much shared componentry as possible. The award is $1,000,000 over 12 months with a $1,000,000 option over 12 months. The topic opens September 23, 2026 and closes October 21, 2026 through the Defense SBIR/STTR Innovation Portal.
The business case is stated in the topic itself and it is unusually explicit for a DARPA description. Thruster development to date has been highly specific to individual fuels, requiring costly development of entirely new systems for new propellants. A flexible fuel electric propulsion system capable of accepting a variety of molecular propellants offers a unique capability for a single product line to serve a significantly larger mission space and total addressable market. DARPA is funding product-line consolidation, not a new thruster physics result.
The feasibility gate is short, hard, and numerical: greater than 30 percent anode thruster efficiency on air or water, greater than 100 hours of cumulative operation on a single test article at that performance level, and vacuum thrust stand data taken in a facility below 3 by 10 to the minus 5 Torr background pressure at full power with in-situ calibrated thrust stands. Three requirements, no partial credit.
This topic carries an ITAR restriction, a projected CMMC Level 2 self-assessment requirement, and an explicit division of labor between the small business and the STTR research institution. All three shape who can realistically bid.
Topic At a Glance
Topic number: DPA26TZ06-DV005
Title: Fuel-Flexible Spacecraft Electric Propulsion System
Agency: Defense Advanced Research Projects Agency (DARPA)
Solicitation: DoW 2026 Small Business Technology Transfer Broad Agency Announcement, Release 6, DARPA Proposal Submission Instructions
Program type: Direct to Phase II (DP2)
Technical volume format: Standard, 35 pages. Feasibility documentation shall not exceed 10 pages, technical proposal shall not exceed 20 pages, and the Phase II commercialization strategy shall not exceed 5 pages
Base award: $1,000,000
Base period of performance: 12 months
Option: $1,000,000 over 12 months
Component Technology Priority Area: Space Technology
Projected CMMC level requirement: Level 2 (Self)
Export control status: ITAR restricted. The technology within this topic is restricted under the International Traffic in Arms Regulation, 22 CFR Parts 120-130, or the Export Administration Regulation, 15 CFR Parts 730-774
Target fuels: air (20 to 50 percent O2, balance N2), water, water and CO2 mixtures derived from combusted hydrocarbons, and nitrogen and hydrogen mixtures derived from decomposed ammonia or hydrazine
Efficiency target: greater than 30 percent electrical efficiency across fuels
Feasibility gate: greater than 30 percent anode thruster efficiency on air or water, greater than 100 hours cumulative operation on a single test article at that level, with vacuum thrust stand data taken below 3 by 10 to the minus 5 Torr at full power using in-situ calibrated thrust stands
Phase II end state: TRL 6 hardware including thruster head, flow systems, and power processing unit
Research institution role: prescribed by DARPA. The research institution leads gas species-specific fundamental research; the small business focuses on productization, system integration, and robustness
Technical and Business Assistance: DARPA will provide up to $25,000 for the Direct to Phase II
Topic Q&A: DSIP Topic Q&A is not available for DARPA topics. Technical questions go to SBIR_BAA@darpa.mil by October 14, 2026
Topic open date: September 23, 2026
Proposal deadline: October 21, 2026. DARPA will not accept late proposals
Submission portal: DSIP at dodsbirsttr.mil
Keywords: spacecraft propulsion, Hall thruster, fuel-flexible, air-breathing, VLEO, in-situ resource utilization, ISRU, oxygenic propellants, multimode propulsion
The Feasibility Bar, Which Is the First Thing to Check
To qualify for this Direct to Phase II topic, applicants must provide concrete evidence of prior Phase I-equivalent capability. Specifically, the applicant must have demonstrated three things.
Performance. Greater than 30 percent anode thruster efficiency on air or water.
Durability. Greater than 100 hours of cumulative operation on a single test article on air or water, demonstrated at the performance level above.
Evidence required. Vacuum thrust stand test data validating thrust, mass flow, power, efficiency, and duration claims. Testing must have been conducted in a facility operating at a background pressure below 3 by 10 to the minus 5 Torr during full-power operation, using thrust stands calibrated in-situ.
Why each clause matters
"Anode thruster efficiency" is a specific figure of merit, not total system efficiency and not thrust efficiency. Report it the way DARPA named it, and show the derivation from measured thrust, mass flow, and discharge power so a reviewer can check the arithmetic.
"On air or water" means you need only one of the two oxygenic propellants demonstrated to qualify. Air is the harder oxidizing environment for cathodes and channel walls; water brings condensation, feed system, and start-up complications. Whichever you have, the Phase II job is extending across the full set, and your proposal should be honest about which transition is the risky one.
"On a single test article" is the sentence that eliminates a lot of otherwise credible data. One hundred cumulative hours accumulated across three rebuilt thrusters does not satisfy it. DARPA is asking about erosion and lifetime on one unit, at the efficiency level claimed, which is a materials question as much as a performance one.
The pressure requirement is a facility gate. Background pressure below 3 by 10 to the minus 5 Torr during full-power operation on an air or water thruster means real pumping capacity against a condensable or oxidizing gas load. Name the facility, state the measured background pressure at full power, and describe the pumping arrangement. Elevated background pressure inflates apparent thrust through entrainment, which is exactly the artifact this requirement exists to exclude.
"Thrust stands calibrated in-situ" means calibration under vacuum in the test configuration, not a bench calibration transferred in. Document the calibration method and the uncertainty.
What the gate screens for
Taken together: an operating electric propulsion company with a real vacuum facility, a thruster that has survived a hundred hours on an aggressive propellant, and the instrumentation discipline to prove it. This is a small population of firms worldwide, and DARPA knows it. If you clear the gate, your competition is other firms that also clear it, which makes the Phase II plan and the research institution partnership the real differentiators.
Two Appendix A rules apply and are worth restating here. Work submitted within the feasibility documentation must have been substantially performed by the proposer or the Principal Investigator. And if the technology is subject to intellectual property, the proposer must own the IP or have obtained license rights prior to proposal submission, with documentation of ownership or license rights included in the Technical Volume.
What DARPA Is Actually Looking For
The objective
Develop a fuel-flexible spacecraft electric propulsion system capable of operating efficiently on air, water, or mixtures of water and carbon dioxide or nitrogen and hydrogen, at greater than 30 percent electrical efficiency.
The problem with the status quo
Spacecraft electric propulsion systems typically rely on noble gas fuels, xenon, krypton, and argon, stored in high pressure tanks. These fuels are unattractive for sustained ambient-air operation in very Low Earth Orbit, or for liquid refueling operations in higher orbits using water or chemical rocket fuels as output propellants.
Thruster development to date has been highly specific to individual fuels, requiring costly development of entirely new systems for new propellants. For example, optimizing for air in a vLEO environment versus water in a possible future higher orbit refueling architecture. These dependencies limit total propulsive capability and overall mission flexibility and responsiveness.
The four fuel classes
This topic seeks a system able to operate on the following, using as much shared componentry as possible.
Air, specified as 20 to 50 percent O2 with the balance N2.
Water, H2O.
Mixtures of water and carbon dioxide derived from combusted hydrocarbons.
Nitrogen and hydrogen mixtures derived from decomposed ammonia or hydrazine.
Read the derivations, not just the molecules. Two of the four fuel classes are exhaust products: combustion exhaust from a hydrocarbon chemical rocket, and decomposition exhaust from a hydrazine or ammonia system. That is the multimode propulsion concept, where a chemical stage's byproducts become electric propulsion propellant, and it is why the milestone schedule asks you to identify standard physical and fluidic interfaces to connect to external hydrocarbon and hydrazine chemical systems.
The mixture ranges also matter. Air at 20 to 50 percent oxygen spans a wide oxidizing severity, and a cathode and channel design that tolerates the top of that range is a different design than one tuned for the bottom.
The commercial framing
Developing a flexible fuel electric propulsion system capable of accepting a variety of molecular propellants offers a unique capability for a single product line to serve a significantly larger mission space and total addressable market.
This STTR topic seeks to develop a complete, integrated fuel-flexible propulsion system that bridges the gap between laboratory demonstration and fieldable spacecraft technology capable of utilizing in-situ resources.
Both sentences point the same direction. This is a productization topic. "Bridges the gap between laboratory demonstration and fieldable spacecraft technology" and the TRL 6 end state tell you the technical risk DARPA is buying down is integration and qualification, not thruster invention.
Phase II Requirements
The Phase II effort will focus on developing a complete, integrated fuel-flexible propulsion system capable of operating across air, water, and nitrogen and hydrogen species.
The product will undergo envelope qualification for vibration, shock, and thermal cycling.
The system components will include a fully integrated system including the thruster, power processing unit, flow control system, and a standardized bus control interface and protocol, for example RS485-based or similar, allowing demonstrated operation via the bus control.
The prescribed division of labor
The STTR research institution will lead the gas species-specific fundamental research to improve and extend efficient operation across all critical gas species.
The STTR small business will focus on productization, system integration, and robustness.
This is the only topic in the DARPA STTR Release 6 release that prescribes the roles, and you should follow it rather than reinventing it. The consequence for your statement of work is concrete: the university tasks are the physics of operating across gas species, meaning ionization, cathode chemistry, wall interactions, and species-dependent performance mapping. The small business tasks are the thruster head, the power processing unit, the flow control system, the bus interface, and the environmental qualification.
That split also maps onto the STTR statutory work-share minimums cleanly. The small business must perform at least 40 percent of the work and the single partnering research institution at least 30 percent. Because DARPA has named the institution's scope as leading the gas species research across all critical species, a 30 percent institution share is credible on its face here in a way it often is not.
Notes on the system requirements
The bus control interface requirement is easy to underweight. "Allowing demonstrated operation via the bus control" means an end-to-end demonstration where the spacecraft bus commands the propulsion system through a standardized protocol, which is a software, electrical, and interface-documentation deliverable, not just a connector.
Envelope qualification for vibration, shock, and thermal cycling is a real cost line. Shaker table and thermal-vacuum time, plus fixture design for a thruster with a flow system attached, should be priced explicitly.
The phrase "across air, water, and nitrogen and hydrogen species" in the Phase II opening lists three, while the objective and the milestone schedule include water and CO2 mixtures as a fourth. Treat all four fuel classes as in scope, since the Month 6 and Month 12 milestones both name CO2 explicitly.
The Milestone Schedule
DARPA structures the effort as two years. The award table specifies a 12 month base and a 12 month option, so Year 1 maps to the base period and Year 2 to the option period.
Year 1: System Design, Interface Definition, and Prototyping
Month 1. Kickoff meeting presenting program schedule plans for Year 1.
Month 3. Finalize system requirements. Review university-led research on performance using air, water, and chemical exhaust mixtures. Identify standard physical and fluidic interfaces to connect to external hydrocarbon and hydrazine chemical systems.
Month 6. Review design for the integrated thruster system. University-led laboratory demonstration and technical report validating efficient performance transfer mechanisms across gas species, air, water, CO2, and N2 plus H2. Present conceptual design for gas generation and conversion mechanisms that will accept and regulate the hydrocarbon combustion and hydrazine decomposition feeds.
Month 9. Engineering model prototype design complete for thruster and supporting systems. Presentation of final test plans.
Month 12. Delivery of technical report on integrated engineering model prototype system design. Delivery of technical report on vacuum test results for prototype hardware across all gas species, including functional demonstration of gas feed systems.
Year 2: Qualification, Life Testing, and Design Iteration
Month 1. Kickoff meeting presenting program schedule plans. Note that the source document says "plans for Year 1" here, which appears to be a copy error from the Year 1 kickoff; the intent is plainly the Year 2 plan.
Month 3. Updated system design based on Year 1 test results, initial environmental testing covering vibration, shock, and thermal-vacuum, and other lessons learned.
Month 6. Written report on updated performance testing across all gas species.
Month 9. Complete 200-hour short duration wear tests on all gas species, or minimal time to evaluate wear rate following thruster burn-in. Identify preferred gas species for the 1000-hour wear test based on initial results and business case.
Final deliverables. TRL 6 hardware including thruster head, flow systems, and power processing unit. Final test report on system design and performance results including thrust, specific impulse, and overall thruster efficiency, and summarizing completed 1,000-hour and 200-hour wear tests. Technology Transition and Spaceflight Integration Plan.
Reading the schedule, including one tight spot
The base period is a design and integration year that ends with an engineering model tested across all gas species. Note that Month 6 of Year 1 requires the university's validated performance transfer mechanisms across all four gas species, which means the institution's work is front-loaded and its subaward has to be executable in the first weeks of the award.
The option year is qualification and life testing, and it contains a schedule tension worth planning for. The 1000-hour wear test species is identified at Year 2 Month 9, and the final deliverables summarize a completed 1,000-hour wear test. A thousand hours is roughly 42 days of continuous operation, which fits inside the last three months only with a facility dedicated to it and no significant interruptions. Two consequences for your proposal. First, you need continuous, uninterrupted access to a vacuum facility for that window, so name it and show the schedule. Second, the sensible approach is to start the 1000-hour test earlier than Month 9 on the species you expect to select, and to say so in your option statement of work, rather than accepting a serialized reading of the milestone that leaves no margin.
Note also the escape clause in the Month 9 wear test language: "or minimal time to evaluate wear rate following thruster burn-in." DARPA has left room for a shorter test that still characterizes the wear rate. If your erosion measurement approach can establish a wear rate in less than 200 hours per species, propose it explicitly and justify the methodology, because the alternative is 200 hours times four species inside a 12 month option.
The "business case" criterion at Year 2 Month 9 is worth noticing too. DARPA asks you to select the 1000-hour test species partly on commercial grounds, which is consistent with the topic's product-line framing. Say which species you expect to select and why, in market terms.
Phase III Dual Use
Phase III efforts will focus on flight qualification, scaling, and transition to acquisition for operational spacecraft.
The transition target is versatile use across three architectures. Very low Earth orbit satellites for air-breathing propulsion. Rideshare-compatible inert water-fueled satellites with no pressurant tanks required. Multimode propulsion systems capable of high specific impulse electric propulsion using combustion exhaust, water plus CO2, from hydrocarbon-based chemical rocket fuels, or decomposition exhaust, N2 plus H2, from hydrazine-based chemical rocket fuels.
Target military transition includes Space Development Agency or DARPA vLEO constellations.
Target commercial transition includes imagery, communication, and satellite servicing vehicles, or deep-space In-Situ Resource Utilization architectures.
The rideshare point deserves emphasis because it is the clearest near-term commercial argument. A water-fueled satellite carries no high-pressure noble gas tank, which removes a significant rideshare range-safety and integration obstacle. That is a procurement-relevant advantage today, independent of the vLEO or ISRU cases, and it is worth quantifying in your commercialization strategy.
The named military customer, Space Development Agency or DARPA vLEO constellations, is specific enough to act on. If you have any engagement with either, or with a prime building toward vLEO, that belongs in your transition strategy and possibly in an optional letter of intent.
Export Control, Which Constrains Your Team
The technology within this topic is restricted under the International Traffic in Arms Regulation, 22 CFR Parts 120-130, which controls the export and import of defense-related material and services including export of sensitive technical data, or the Export Administration Regulation, 15 CFR Parts 730-774, which controls dual use items.
Offerors must disclose any proposed use of foreign nationals, their countries of origin, the type of visa or work permit possessed, and the statement of work tasks intended for accomplishment by the foreign nationals, in accordance with the Announcement.
Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US export control laws.
Why this is a bigger issue on this topic than on most
This is an STTR with a research institution performing at least 30 percent of the work, and university propulsion laboratories are typically staffed substantially by international graduate students and postdocs. An ITAR restriction plus a foreign national disclosure requirement plus a 30 percent university work share is a combination you need to resolve before submission, not during negotiation.
Concretely: identify which institution personnel will perform the work, their citizenship or visa status, and the specific tasks assigned, since Appendix A requires that disclosure in the technical volume. Discuss the export control posture with the institution's research compliance office early, because some universities will not accept ITAR-restricted work under their standard publication and open-research policies. If the university's participation depends on the work qualifying as Fundamental Research, that determination interacts directly with the ITAR restriction and needs to be settled up front. DARPA's own cost instructions require you to either separate Fundamental Research tasks into their own statement of work or identify them within the prime statement of work.
A note on the source document
The ITAR paragraph appears twice in this topic: once as a standalone block before the objective, stating the technology "is restricted," and again appended to the end of the objective sentence, stating it "may be restricted" and citing section 3.5 of the Announcement rather than the Announcement generally. The two versions differ in wording. The conservative reading, and the one to plan against, is the stronger of the two: treat the topic as ITAR restricted. If the distinction matters to your teaming plan, it is a reasonable question for SBIR_BAA@darpa.mil.
Note also that the projected CMMC requirement for this topic is Level 2 with self-assessment, consistent with the ITAR restriction, and higher than the Level 1 projected for the other two topics in this release. Firms engaging in Controlled Unclassified Information, Export Controlled, or ITAR work for DARPA must have CMMC Level 2 self-assessment certification, so confirm your SPRS posture before you submit.
Funding, Cost Structure, and DARPA Mechanics
The award
$1,000,000 over a 12 month base, plus a $1,000,000 option over 12 months, for $2,000,000 across 24 months if the option is exercised.
The even split is unusual and informative. Half the money is behind the option, and the option is where the life testing and qualification live. The Government reserves the right to award all, some, one, or none of the options based on available funding and the performer's technical performance, which means the qualification work is genuinely contingent on your base year results. Structure the base year to make the option decision easy.
The resources made available under each topic will depend on the quality of the proposals received and the availability of funds.
Contract type
Multiple awards are anticipated. DARPA may award FAR-based Government contracts, firm-fixed-price or cost-plus reimbursement, or Other Transactions for Prototypes agreements under the authority of 10 U.S.C. 4022, subject to approval of the Contracting Officer or Agreements Officer respectively.
Note that the companion DARPA SBIR Release 6 instructions cite 10 U.S.C. 4021 for the same instrument type. If you are preparing proposals to both programs this cycle, do not assume identical OT paperwork.
In all cases, the Government Contracting Officer reserves the right to select award instrument type regardless of what was proposed, and to negotiate all terms with selectees. DARPA reserves the right to remove a proposal from award consideration if the parties fail to reach agreement within a reasonable time or if the proposer fails to provide requested additional information within three business days. Complete the DARPA SBIR/STTR Pre-Award Checklist on the DARPA Small Business website before selection.
DARPA also notes it will apply publication or other restrictions if it determines the research presents a high likelihood of disclosing performance characteristics of military systems or manufacturing technologies unique and critical to defense, and that any resulting award will require DARPA permission before publishing. On an ITAR-restricted topic with a university partner, flag this to your institution's compliance office alongside the export control discussion.
Templates are mandatory
Templates for Volume 2 Technical Volume and Volume 3 Cost Volume are provided as attachments to the announcement at dodsbirsttr.mil. Use of these templates is mandatory. The Volume 3 Direct to Phase II Cost Proposal Template is an Excel spreadsheet on the DARPA Small Business site.
Cost substantiation
All proposed costs should be accompanied by documentation to substantiate how the cost was derived: paystubs or a DCMA rate agreement for direct labor, historical invoices or a current contract for consultants, and historical invoices, current quotes, or market research for materials and equipment. You do not have to propose the cheapest supplier, but you should explain the choice.
All subcontractor and consultant costs must be detailed at the same level as prime contractor costs and substantiated with Subcontractor Pricing Considerations under FAR 15.404-3(b), entered in the Explanatory Material section of the cost proposal form. Subcontractors should send unsanitized cost proposals directly to SBIR_BAA@darpa.mil.
For this topic the substantiation burden is concentrated in three places. The university subaward, which is a large fraction of the work. Vacuum facility time, which is the dominant direct cost for a 200-hour and 1000-hour wear test campaign and needs a rate basis. And environmental qualification, meaning shaker, shock, and thermal-vacuum time plus fixtures.
Title to property furnished by the Government or acquired with Government funds vests with DARPA unless transfer of title is determined more cost effective, which is worth reading if your plan includes buying significant test equipment. Cost sharing is permitted but not required and is not an evaluation factor.
Technical and Business Assistance
The Small Business Innovation and Economic Security Act Section 7 mandates agencies to offer TABA. DARPA will provide up to $25,000 for the Direct to Phase II.
Note precisely what this document does and does not say. It states the $25,000 figure, but unlike the companion DARPA SBIR Release 6 instructions it does not state that TABA sits in addition to the cost ceiling and is not subject to profit or fee. Do not assume the SBIR language transfers. TABA requests will be reviewed by the respective contracting office or specialist at time of award to ensure compliance with TABA requirements.
For this topic, export control and ITAR compliance counsel is the standout TABA use, followed by space industry business development given the topic's explicit product-line and total-addressable-market framing.
Questions and the FAQ
DSIP Topic Q&A will not be available for these DARPA topics. Technical questions must be submitted by October 14, 2026, by email to SBIR_BAA@darpa.mil with the topic number in the subject line, including the name, email address, and telephone number of a point of contact. All questions must be in English.
Questions submitted within seven calendar days of the proposal due date may not be answered. DARPA posts a consolidated Frequently Asked Questions document under the topic number summary on its Small Business site, updated on an ongoing basis until one week prior to the proposal due date.
DSIP technical support is available Monday through Friday, 9:00 a.m. to 5:00 p.m. Eastern, at DoDSBIRSupport@reisystems.com with a copy to SBIR_BAA@darpa.mil.
DARPA will not accept any late proposals.
Proposal format details
The Technical Volume must be a single PDF including graphics. Virus check before uploading. Do not lock or encrypt the file. Do not embed active graphics such as videos or moving pictures. Number all pages consecutively. Font no smaller than 10-point on 8.5 by 11 inch paper with one-inch margins. The header on each page should contain your company name, the topic number, and the DSIP-assigned proposal number, and may sit in the one-inch margin.
The Proposal Cover Sheet must include a technical abstract of no more than 3000 characters. Do not include marketing material, which will not be evaluated.
Classification, marking, and registrations
All proposals must be UNCLASSIFIED or CUI. No classified information. No proprietary information on the Proposal Coversheet in Volume 1, which may be released publicly if selected for award. Proprietary or CUI content may go in the Technical Volume, marked with the appropriate CUI Control Block on the first page. The Cost Volume should be marked CUI for PROPIN. Volumes 4 through 7 marked as appropriate.
Titles, abstracts, anticipated benefits, and keywords of selected proposals undergo DARPA Policy and Security Review and may be revised or redacted, with final versions potentially appearing on the DoW SBIR/STTR awards website and sbir.gov/awards.
Maintain an accurate and active SAM.gov entity registration. Confirm CMMC Level 2 self-assessment in SPRS, given both the projected topic requirement and the ITAR restriction. DARPA points to sprs.csd.disa.mil/nistsp.htm and Project Spectrum at projectspectrum.io.
On venture capital ownership
The DARPA STTR Release 6 instructions contain no provision addressing majority ownership by venture capital operating companies, hedge funds, or private equity firms. The companion DARPA SBIR Release 6 instructions do contain such a provision, explicitly permitting it under three conditions.
This is a meaningful gap for this topic in particular, because electric propulsion companies capable of clearing the feasibility gate are frequently venture funded. Do not read the SBIR provision across. Eligibility is governed by the DoW STTR Program BAA and the SBA SBIR/STTR Policy Directive, and if your ownership structure raises the question, resolve it before investing in a proposal.
Evaluation and selection
All proposals will be evaluated in accordance with the evaluation criteria listed in the DoW STTR Program BAA. Proposals that do not comply with the requirements detailed in this BAA and the research objectives of the corresponding topic are considered non-conforming and will not be evaluated nor considered for award.
Appendix A adds a second trap: proposals that do not adequately substantiate prior Phase I-equivalent feasibility for the components addressed will be deemed non-responsive and will not be evaluated for award.
The Government will evaluate each proposal in its entirety, documenting strengths and weaknesses against each criterion, and determine overall selectability. Proposals are not evaluated against each other but on their own individual merit. A selectable proposal is one where strengths outweigh weaknesses with no accumulated weaknesses requiring extensive negotiations or a resubmitted proposal.
Awards will be made to proposers whose proposals are most advantageous to the Government, consistent with the DoW STTR Program BAA criteria and availability of funding.
Notification of selection or non-selection within 90 calendar days of BAA close, by email to the Corporate Official on the Proposal Cover Sheet. DARPA will provide a technical evaluation narrative for each proposal, and an informal feedback session may be requested at sbir@darpa.mil at DARPA's sole discretion.
Company Commercialization Report information will not be considered during evaluations.
Protests regarding the selection decision go, as prescribed in FAR 33.106(b) and FAR 52.233-3, to DARPA Contracts Management Office, 675 N. Randolph Street, Arlington, VA 22203, by email to CMO_SBIRProtests@darpa.mil and sbir@darpa.mil.
Post-award support
DARPA provides Transition and Commercialization Support Program services to Phase II awardees upon contract execution at no cost. Awardees may also be eligible for the Embedded Entrepreneurship Initiative, invitation-only at DARPA's sole discretion, typically no more than $310,000 per awardee over the duration of the award, supporting a Senior Commercialization Advisor relationship, investor working group connections, and hiring an embedded entrepreneur to execute a Go-to-Market strategy. Your commercialization strategy section is used to assess EEI suitability, and EEI selection happens independently after award selection.
The References
Only three, which is the shortest reference list in either DARPA Release 6 document, and each one marks a distinct piece of the argument.
Rovey, Lyne, Mundahl, Rasmont, Glascock, Wainwright, and Berg, "Review of chemical-electric multimode space propulsion," Progress in Aerospace Sciences, 2020. This is the multimode propulsion foundation, and it is the framework behind the two exhaust-derived fuel classes.
Bendimerad, Savransky, and Petro, "Optimization of refueling strategies for electric propulsion space missions," Journal of Spacecraft and Rockets, 2024. This is the orbital refueling case, which is why water matters.
Andreussi et al., "A review of air-breathing electric propulsion: from mission studies to technology verification," Journal of Electric Propulsion, 2022. This is the vLEO air-breathing case.
The short list is itself a signal. DARPA is not asking you to survey a literature. The three references define three mission architectures, and the topic's premise is that one product should serve all three. A proposal that maps its fuel flexibility onto these three architectures explicitly is speaking the topic's language.
Timeline and What to Do When
The dates
Topic opens: September 23, 2026
Technical question deadline: October 14, 2026, to SBIR_BAA@darpa.mil with the topic number in the subject line
Proposal deadline: October 21, 2026. DARPA will not accept late proposals
Selection notification: within 90 calendar days of BAA close
Base period: 12 months from award
Option: 12 additional months if exercised
A working backward plan
Before September 23. Verify the three feasibility requirements against your actual records: anode efficiency above 30 percent on air or water, more than 100 cumulative hours on a single test article at that efficiency, and thrust stand data from a facility measured below 3 by 10 to the minus 5 Torr at full power with in-situ calibration. Pull the raw thrust, mass flow, and power data and confirm you can show the efficiency derivation. Confirm the 100 hours are on one article. Resolve IP ownership or licensing, since documentation must be in the Technical Volume. Commit your research institution partner and, critically, work the export control question with their research compliance office now, since an ITAR-restricted topic with foreign national graduate students is the single most likely thing to derail this teaming arrangement. Identify institution personnel, citizenship or visa status, and assigned tasks for the required disclosure. Settle the Fundamental Research determination. Confirm CMMC Level 2 self-assessment is current in SPRS. Reserve vacuum facility windows for the wear test campaign, including the 1000-hour run. Download the mandatory Volume 2 and Volume 3 templates. Read the FAQ and keep rechecking it. Decide your contract type. Confirm SAM registration.
September 23 through October 5. Draft the 10 page feasibility documentation first, since inadequate substantiation makes the proposal non-responsive. Include the reference list on its last page, counting toward the limit, and the one-page commercialization potential summary. Then draft the 20 page technical proposal against Appendix A's required sections, with the statement of work as a substantial portion, structured around the two-year milestone set. Address the fuel transition risk honestly: which species you have, which is hardest, and how the university's species-specific research de-risks it. Include the foreign citizens disclosure section. Send questions to SBIR_BAA@darpa.mil early.
October 6 through October 14. Build the cost volume in the mandatory Excel template across the 12 month base and 12 month option. Get the university's budget at prime-level detail with Subcontractor Pricing Considerations, and remember its Month 6 deliverable means its work starts immediately. Price vacuum facility time for testing across four gas species, the 200-hour wear tests, and the 1000-hour wear test. Price environmental qualification: vibration, shock, thermal-vacuum, and fixtures. Price the power processing unit and the bus interface development. Draft the 5 page transition and commercialization strategy against Appendix A's nine elements, using the rideshare and SDA vLEO angles.
October 15 through October 18. Assemble Volume 5 with data rights assertions, IP documentation, CVs, subcontractor pricing considerations, and any optional letters of intent from spacecraft integrators or vLEO programs that substantiate specific claims. Complete Volume 6 training and the Volume 7 foreign affiliations webform, which the Corporate Official must submit before certification is possible. Run compliance: single unlocked PDF, no embedded video, 10-point minimum font, consecutive page numbers, correct header, 3000 character abstract, CUI marking, mandatory Excel cost template, no marketing material.
October 19 through October 20. Submit and certify in DSIP, and confirm the mandatory supporting documents actually uploaded, since a completed submission in DSIP does not indicate that they did.
Frequently Asked Questions
What is DARPA STTR topic DPA26TZ06-DV005?
DPA26TZ06-DV005 is a DARPA STTR Direct to Phase II topic titled "Fuel-Flexible Spacecraft Electric Propulsion System," released under the DoW 2026 STTR Broad Agency Announcement, Release 6. The objective is to develop a fuel-flexible spacecraft electric propulsion system capable of operating efficiently on air, water, or mixtures of water and carbon dioxide or nitrogen and hydrogen, at greater than 30 percent electrical efficiency.
How much funding is available?
The base award is $1,000,000 over 12 months, with a $1,000,000 option over 12 months, for a maximum of $2,000,000 across 24 months if the option is exercised. DARPA will also provide up to $25,000 in Technical and Business Assistance for the Direct to Phase II.
When is the proposal deadline?
The topic opens September 23, 2026 and proposals are due October 21, 2026 through the Defense SBIR/STTR Innovation Portal at dodsbirsttr.mil. DARPA will not accept late proposals.
What must my prior work already demonstrate?
Three things. Greater than 30 percent anode thruster efficiency on air or water. Greater than 100 hours of cumulative operation on a single test article on air or water at that performance level. And vacuum thrust stand test data validating thrust, mass flow, power, efficiency, and duration claims, taken in a facility operating below 3 by 10 to the minus 5 Torr background pressure during full-power operation, using thrust stands calibrated in-situ.
Do I need to have demonstrated on both air and water?
No. The feasibility requirement says air or water. Extending across the full set of fuels is the Phase II job.
Can I combine hours across multiple test articles?
No. The requirement specifies greater than 100 hours of cumulative operation on a single test article, which makes it an erosion and lifetime demonstration on one unit rather than an aggregate operating total.
Why does the background pressure requirement matter?
Elevated background pressure in a vacuum facility inflates apparent thrust through gas entrainment. Requiring below 3 by 10 to the minus 5 Torr at full power, with in-situ calibrated thrust stands, is how DARPA excludes that artifact. Name your facility, state the measured background pressure at full power, and document the calibration method and uncertainty.
What fuels must the Phase II system handle?
Air specified as 20 to 50 percent O2 with the balance N2; water; mixtures of water and carbon dioxide derived from combusted hydrocarbons; and nitrogen and hydrogen mixtures derived from decomposed ammonia or hydrazine. The system should use as much shared componentry as possible across them.
What is the Phase II end state?
TRL 6 hardware including the thruster head, flow systems, and power processing unit, plus a final test report covering thrust, specific impulse, and overall thruster efficiency and summarizing completed 1,000-hour and 200-hour wear tests, plus a Technology Transition and Spaceflight Integration Plan. The system also undergoes envelope qualification for vibration, shock, and thermal cycling, and must demonstrate operation via a standardized bus control interface such as RS485 or similar.
How are the research institution and small business roles divided?
DARPA prescribes them for this topic. The STTR research institution will lead the gas species-specific fundamental research to improve and extend efficient operation across all critical gas species. The STTR small business will focus on productization, system integration, and robustness. This is the only topic in this STTR release that specifies the split.
What are the STTR work-share requirements?
STTR awards require a formal partnership with a single partnering research institution, with the small business performing at least 40 percent of the work and the research institution at least 30 percent. The DARPA instructions direct proposers to the DoW STTR Program BAA for these general requirements.
Is this topic ITAR restricted?
Yes. The topic states that the technology is restricted under ITAR, 22 CFR Parts 120-130, or EAR, 15 CFR Parts 730-774. Offerors must disclose any proposed use of foreign nationals, their countries of origin, visa or work permit type, and the statement of work tasks they will perform. Foreign nationals proposed to perform on this topic may be restricted.
How does ITAR interact with the university partnership?
This is the practical issue to resolve before submitting. University propulsion laboratories are often staffed substantially by international students and postdocs, and the institution must perform at least 30 percent of the work. Identify institution personnel and their citizenship or visa status, assign tasks accordingly, and work the question with the institution's research compliance office early, since some universities will not accept ITAR-restricted work under standard open-research policies. The Fundamental Research determination interacts directly with this.
What CMMC level applies?
The projected requirement for this topic is CMMC Level 2 with self-assessment, higher than the Level 1 projected for the other two topics in this STTR release. Firms engaging in Controlled Unclassified Information, Export Controlled, or ITAR work for DARPA must have CMMC Level 2 self-assessment certification.
How long can my technical volume be?
The standard format is 35 pages. Feasibility documentation shall not exceed 10 pages, the technical proposal shall not exceed 20 pages, and the Phase II commercialization strategy shall not exceed 5 pages and should be the last section of the Technical Volume. Appendix A states the commercialization strategy will not count against the proposal page limit, so confirm with DARPA how the three numbers combine if it affects your layout. Font must be at least 10-point.
Is the 1000-hour wear test feasible inside the option year?
It is tight. The species for the 1000-hour test is identified at Year 2 Month 9, and a thousand hours is roughly 42 days of continuous operation. The practical approach is to begin the test earlier on the species you expect to select, secure uninterrupted facility access, and say so explicitly in your option statement of work. Note also that DARPA allows "minimal time to evaluate wear rate following thruster burn-in" as an alternative to the full 200-hour tests, so a justified shorter-duration wear rate methodology is worth proposing.
Can I ask questions through DSIP Topic Q&A?
No. DSIP Topic Q&A is not available for DARPA topics. Technical questions go by email to SBIR_BAA@darpa.mil by October 14, 2026, with the topic number in the subject line and a point of contact name, email, and phone number. DARPA maintains a consolidated FAQ on its Small Business site.
What contract types can DARPA award?
FAR-based firm-fixed-price or cost-plus reimbursement contracts, or Other Transactions for Prototypes agreements under the authority of 10 U.S.C. 4022. Note that the companion DARPA SBIR Release 6 instructions cite 10 U.S.C. 4021 for the same instrument type.
Are the templates mandatory?
Yes. Templates for Volume 2 Technical Volume and Volume 3 Cost Volume are attachments to the announcement, and use of these templates is mandatory. The Volume 3 template is an Excel spreadsheet.
Are venture capital backed companies eligible?
The DARPA STTR Release 6 instructions contain no provision on majority ownership by venture capital operating companies, hedge funds, or private equity firms, unlike the companion DARPA SBIR Release 6 instructions, which explicitly permit it under three conditions. Do not assume the SBIR provision applies here. Check the DoW STTR Program BAA and the SBA SBIR/STTR Policy Directive, or ask DARPA before October 14.
Will DARPA restrict publication?
Possibly. DARPA states it will apply publication or other restrictions if it determines the research presents a high likelihood of disclosing performance characteristics of military systems or manufacturing technologies unique and critical to defense, and that any such award will require DARPA permission before publishing. Raise this with your university partner alongside the export control discussion.
How will my proposal be evaluated?
Against the evaluation criteria in the DoW STTR Program BAA. Proposals are evaluated individually on their own merit rather than against each other. A selectable proposal is one where strengths outweigh weaknesses with no accumulated weaknesses requiring extensive negotiation or resubmission. Non-conforming proposals, and proposals that do not adequately substantiate prior Phase I-equivalent feasibility, are not evaluated at all.
Will I get feedback if not selected?
Yes. DARPA will provide a technical evaluation narrative for each proposal submitted, and an informal feedback session may be requested by email at sbir@darpa.mil, granted at DARPA's sole discretion.
What is the commercial market?
Rideshare-compatible water-fueled satellites with no pressurant tanks required, imagery and communication satellites, satellite servicing vehicles, and deep-space in-situ resource utilization architectures. The named military transition targets are Space Development Agency or DARPA vLEO constellations.
Who do I contact with questions?
Technical questions go to SBIR_BAA@darpa.mil with the topic number in the subject line, by October 14, 2026. Administrative questions about the DARPA program and these instructions also go to SBIR_BAA@darpa.mil. DSIP technical support is DoDSBIRSupport@reisystems.com with a copy to SBIR_BAA@darpa.mil. Feedback session requests go to sbir@darpa.mil.
Positioning Advice for Companies Considering This Topic
Prove the three feasibility numbers before you write anything else. Anode efficiency above 30 percent, more than 100 hours on one article, and thrust stand data from a facility below 3 by 10 to the minus 5 Torr with in-situ calibration. Pull the raw data and rebuild the efficiency calculation. If the 100 hours were accumulated across rebuilt units, or the background pressure was higher than specified, you do not clear the gate and the proposal is non-responsive rather than merely weak.
Solve the ITAR and university problem first. This is the most likely reason a strong team fails to submit. An ITAR-restricted topic requires a foreign national disclosure, the institution must perform at least 30 percent of the work, and propulsion labs are internationally staffed. Talk to the institution's research compliance office in the first week, name the personnel and their status, assign tasks accordingly, and settle the Fundamental Research determination. Do not discover this in November.
Follow DARPA's prescribed role split rather than inventing your own. The institution leads gas species-specific fundamental research; you lead productization, integration, and robustness. That mapping makes a 30 percent institution share credible and gives you a clean statement of work structure. Deviating from it invites a reviewer to ask why.
Be honest about which fuel transition is hard. You qualified on air or water. Getting to all four classes is the technical risk, and the two exhaust-derived classes, water plus CO2 from hydrocarbon combustion and N2 plus H2 from hydrazine decomposition, bring feed system and gas conditioning problems that are different in kind from the thruster problem. The Month 6 milestone asks for a conceptual design for the gas generation and conversion mechanisms that accept and regulate those feeds. Do not leave that as an integration detail.
Treat "as much shared componentry as possible" as a scored design principle. The entire commercial premise is one product line serving multiple missions. Show a component-level table of what is common across all four fuels and what must change, because that table is the argument for the topic's own thesis.
Design the base year to make the option decision easy. Half the money is behind the option, and DARPA reserves the right to exercise all, some, or none based on technical performance. The base year ends with an engineering model tested across all gas species. Make the Month 12 deliverables unambiguous evidence that qualification is worth funding.
Get ahead of the 1000-hour test schedule. The species is nominally selected at Year 2 Month 9, and a thousand hours is about six weeks of continuous operation. Propose starting earlier on your expected species, name the facility, show the dedicated window, and use DARPA's own "minimal time to evaluate wear rate" language to justify a defensible shorter methodology for the other species if you have one.
Do not skip the bus control interface. "Demonstrated operation via the bus control" through a standardized protocol is a real deliverable with software, electrical, and documentation content. It is also the requirement most relevant to a spacecraft integrator reading your transition plan, so it is worth more proposal space than its one sentence in the topic suggests.
Lead your commercialization strategy with rideshare. A water-fueled satellite with no high-pressure noble gas tank removes a genuine range-safety and integration obstacle for rideshare payloads today. That is a nearer-term, more concrete market argument than vLEO air-breathing or deep-space ISRU, and it is the one a commercial buyer will recognize immediately. Then layer the SDA and DARPA vLEO constellation targets and the multimode architectures on top.
Map your proposal onto the three references. Rovey 2020 for multimode, Bendimerad 2024 for refueling, Andreussi 2022 for air-breathing. Three references define three mission architectures, and the topic's thesis is that one product serves all three. Saying that explicitly, architecture by architecture, is speaking the topic's language.
Price the facility time properly. Testing four gas species, running 200-hour wear tests, running a 1000-hour wear test, and doing vibration, shock, and thermal-vacuum qualification is a facility-hours problem more than a labor problem. All costs must be substantiated, so get rate documentation for the facility and the environmental test house early.
Note the document differences if you are also bidding DARPA SBIR this cycle. The OT authority citation differs, there is no venture capital ownership provision here, and the TABA language does not include the SBIR document's statement that TABA sits on top of the cost ceiling. Read both documents rather than assuming they match.
