Compliance

Understanding and shaping the requirements and regulatory landscape

Eurospace supports its members in navigating complex regulatory and standardisation challenges that affect the space sector. Industrial standards are at the heart of any industrial process, and space is no exception. The main system used in the European Space sector is ECSS (European Cooperation for Space Standardization). Eurospace provides a coordination between industrials that is key in ensuring that the European space sector work with a set of competitive and adapted requirements while leaving room for innovation and new technologies.

Eurospace also monitors key regulations affecting the European Space sector, the most important of which is REACH (Regulation on the registration, evaluation, authorisation and restriction of chemicals), to understand their impact on the industry and which alternatives are possible in case of restriction.

The Ongoing Working Groups

STWG: ECSS (European Cooperation for Space Standardization) is the standardisation system used in Europe as a reference for the space industry. ECSS standards, and their companion standard and certification set of the ESCC, are developed jointly by the supplier industry and the customer entities, under the coordination and technical expertise of ESA. They are available to all European stakeholders, and regularly updated and maintained with the direct and voluntary contribution of the industrial community. Thus, ECSS (and ESCC) standards are driven by the community at large, to ensure they are implementable, efficient and aligned with both customer expectations and supplier capabilities.

Within the Eurospace Standardisation Working Group (STWG), companies are able to coordinate on key standardisation issues before dialoguing with official institutions and to nominate experts to draft and update standards. The STWG is key in ensuring industry has a voice in the matter of industrial standards, and coordinates the industry response to the recent major changes in ECSS: the simplification of existing ECSS standards (ECSS NextGen) and a creation of a new branch of standards dedicated to the industrialisation (I-branch). The STWG also offers a forum for discussing international standards such as ISO.

EEE Panel: The EEE Panel aims to help the European space industry develop and implement a common strategy for space EEE (Electronical and Electrical Engineering) components standardisation, certification and strategy and promote it, in the ESCC framework. Eurospace representatives take part in the different relevant bodies: CTB, SCSB, PSWG, and MPTB.

REACH: the REACH regulation is the main EU law to protect human health and the environment from the risks that can be posed by chemicals. This is done by better and earlier identification of the intrinsic properties of chemical substances and by taking measures, such as phasing out or restricting substances of very high concern. REACH also aims to enhance innovation and the competitiveness of the EU chemicals industry.

The implementation of the processes of the REACH Regulation (EC 1907/2006) are managed by the European Chemicals Agency (ECHA) in Helsinki (Finland), in close collaboration with the EU/EEA Member States and the European Commission. REACH enforcement is carried out by the EU/EEA Member States. The European Commission has key decision-making powers, e.g. in the authorisation process and for the adoption of new restrictions.

Eurospace closely monitors REACH evolutions as the use of several key substances by the space industry could be in jeopardy. These substances are instrumental in key European programmes, including Ariane 6, Galileo, Sentinel satellites, and many others. These substances often do not have immediate alternatives, meaning their sudden restriction could seriously disrupt the industry and its supply chain. The REACH WG monitors in particular the evolution of the REACH Candidate List and its Annex XIV (the Authorisation list) and its impact on the space sector, and advises on required industry joint actions.

Organisation

STWG: To ensure proper representation of industry concerns at ECSS decision bodies, industry prepares its coordinated positions in advance to the ECSS TA and SB meetings in the Eurospace Standardisation Working Group (STWG), which is open to non-Eurospace members. Meetings take place around 4 times a year. The first way to get involved is to ask to get on the dedicated mailing list to follow undergoing ECSS processes.

EEE Panel: the EEE-P has meetings taking approximately twice a year an where participants will get the possibility to receive all relevant information and nominate experts to participate in the different relevant bodies: CTB, SCSB, PSWG, and MPTB.

REACH: Eurospace has several groups and task forces to monitor and ask for extensions of the use of key substances. These working groups are coordinated by REACHLaw, a consulting firm providing expert support to Eurospace on REACH activities. Membership is not exclusive to Eurospace members, and are open to both institutional and industrial stakeholders who have interest on the matter.

Why this matters

Involvement in Eurospace’s different WGs related to Compliance bring several benefits to the industry:

The ability to shape and influence the drafting of industrial standards that will be instrumental in future contracts
Ensuring a set of standards that is competitive and up to date with the current technology and industry practices
Monitoring and understanding key undergoing regulations that will directly impact the majority of the supply chain
Creating consensus in the European Space industry on important regulatory issues

Further information on REACH

The Regulation

Regulation (EC) No 1907/2006 of the European Parliament and of the Council of 18 December 2006 concerning the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) was adopted to improve the protection of human health and the environment from the risks that can be posed by chemicals, while enhancing the competitiveness of the EU chemicals industry. The implementation of the REACH processes is managed by the European Chemicals Agency (ECHA) in Helsinki (Finland), in close collaboration with the EU/EEA Member States and the European Commission. REACH enforcement is carried out by the EU/EEA Member States. The European Commission has key decision-making powers, e.g. for the adoption of new restrictions, in the authorisation process and as an initiator of changes to the REACH legal text and its Annexes.

REACH contains four regulatory regimes: Registration (requiring manufacturers and importers of chemicals to analyse and submit information on substances); Evaluation (checking the quality of registration dossiers and whether a given substance constitutes a risk to human health or the environment); Authorisation (identifying certain Substances of Very High Concern (SVHC), possibly including them on the authorisation list with a defined “sunset date”, with a view to assuring their progressive substitution with safer alternatives, and authorising certain uses of these substances); and Restriction (restricting the manufacture, placing on the market and/or use of certain chemicals presenting an unacceptable risk).

For a substance to be covered by the REACH authorisation system it must be first included in the Candidate List (253 entries as of 17 July 2026). The next step can be its inclusion in the Authorisation List (Annex XIV – 59 substances as of July 2026, no new additions yet after 2022). From there on the substance will be “banned” from use or sale in the EU/EEA from a determined date (the sunset date). Its use after sunset date will be possible under the regime of a granted authorisation (or, exceptionally, the application of exemption clauses).

Instead of the authorisation process, a restriction (Annex XVII) may also be chosen as a regulatory measure to manage unacceptable risks to human health or the environment across the EU. Restrictions may range from bans (with some derogations) to exposure limits, training requirements or other conditions, including for the use of a substance. In the recent past, the flexible option of restrictions has been used increasingly by the European Commission and Member States instead of promoting substances for the Authorisation path, even for substances included in the Candidate List and recommended for Annex XIV inclusion by ECHA. In addition, outside of EU REACH, Occupational Exposure Limits under EU workplace legislation are an important risk management option which may be applied instead of or alongside REACH authorisation and restriction requirements.

The REACH Article 33 obligation for EU/EEA article suppliers to communicate in the supply chain safe use information on articles containing SVHCs on the Candidate List above 0.1% weight by weight is another area posing significant challenges for the Space Sector. This obligation is since 2021 complemented by a requirement under the EU Waste Framework Directive 2008/98/EC (WFD) for EU article suppliers to submit a notification to the ECHA database for information on Substances of Concern in Products (SCIP); more information on SCIP is available below.

The space sector and REACH

In 2011, an Agency-Industry REACH Working Group was set up, with ESA coordination, to monitor and address REACH issues affecting the space sector. This WG monitors in particular the evolution of the REACH Candidate List, Annex XVII (Restrictions List) and Annex XIV (Authorisation List) and its impact on the space sector.

Since 2012 the REACH WG activities were put under the mandate of the Materials and Technology WG of the CTB that later transformed into the MPTB (Materials and Processes Technology Board). Eurospace monitors activities of the MPTB to enable the identification of actions requiring joint industry actions; key Eurospace member companies also participate in the regular WG and Task Forces meetings.

In the frame of REACH activities Eurospace liaises with the ASD REACH & Chemicals Management Working Group, ensuring appropriate information flow and coordination of actions between space and aeronautics sectors.

Together with our partners, Eurospace also follows closely the further evolutions of REACH and other relevant EU legislation addressing chemicals safety and wider environmental sustainability, such as those considered under the European Green Deal of 2019, with the European Commission’s “Sustainable Products Initiative” part of the new Circular Economy Action Plan of 11 March 2020 and the “Chemicals Strategy for Sustainability” (CSS) of 14 October 2020.

Under the European Commission elected in 2024 the protection of industrial competitiveness and strategic autonomy of the EU gained higher priority. As a result, the Commission has been pursuing a number of “Omnibus” initiatives to simplify EU legislation. As another important consequence of this policy shift, the Commission announced in April 2026 that the planned targeted revision of the REACH Regulation by changing the legal text will not be pursued for the time being. However, the implementation of existing REACH and related non-REACH requirements (such as CLP, POPs, RoHS, Waste Framework Directive) will continue and remains very dynamic.

To date, the following substances are high on the space industry agenda (the list is not exhaustive):

Hydrazine: Managed today in the frame of the Energetic Materials Working Group (EMWG) [formerly in the Hydrazine Task Force (HTF)]. The substance has been included as SVHC in the REACH Candidate List in 2011. Following an in-depth analysis involving all relevant space sector stakeholders Eurospace presented an Authorisation Exemption Position Paper for propellant-related uses to the European Commission in October 2012. A clarification by the European Commission is expected at the latest, if and when Hydrazine would be prioritised for Annex XIV. In 2019, other liquid propellants (namely MMH, UDMH and NTO/MON-x) were also included in the Task Force scope. An updated position paper was issued in April 2020. In 2024 Eurospace, with the support of the MPTB Energetic Materials Working Group (EMWG), successfully helped overturn a proposal previously agreed at the United Nations ECOSOC Sub-Committee of Experts on the Transport of Dangerous Goods (SCE TDG) to add a new special packing provision “PP5” to the UN2029 for Hydrazine Anhydrous. The UN-level outcome allows the European space industry to continue to transport hydrazine in its traditional safe manner; more information is available HERE.
Chromates, especially Chromium Trioxide: The regulatory follow-up for these substances is managed by the Restrictions Task Force (RTF) (taking over from the Space Chromates Task Force (STF) since February 2026). If you are still using CrO₃, you are advised to carefully check your compliance with the REACH authorisation requirement. Eurospace has published and subsequently updated on several occasions an MPTB authorisation compliance guideline for EU/EEA downstream users in the space industry. In parallel, a REACH restriction process has been initiated in September 2023, which is expected to replace the authorisation system for CrO₃, chromic acid and several other Cr(VI) substances after 2027.
N-Methyl-2-Pyrrolidone (NMP) – This substance was identified as an SVHC in the REACH Candidate List in 2011. On 9 May 2020 a new restriction (entry 71 of REACH Annex XVII) on the manufacture, placing on the market and use of NMP to ensure that the exposure of workers remains below specified maximum levels entered into application.
Metallic Lead (Pb): The substance is used in space systems. The major use of concern is in Tin-Lead soldering for electronics. Lead has been included in the SVHC Candidate List in June in March 2018. In April 2023, ECHA even recommended inclusion of lead metal in the REACH Authorisation List. However, the European Commission has importantly clarified that it is not intending to follow this non-binding recommendation. Eurospace has been supporting the MPTB for the set-up of the Lead Task Force (LTF) addressing lead-related issues for the space sector and advocacy in the REACH process. In 2020, a Space case study on lead has been published as part of the cross-sectoral “Lead Matters” campaign. Additionally, Eurospace provided extensive input (prepared by the LTF) to ECHA and the European Commission in April 2022 in relation to a range of critical space applications of lead in the European Space Sector, successfully opposing the treatment of lead under the authorisation process. Since February 2026, the regulatory follow-up on metallic lead has been incorporated into the Restrictions Task Force (RTF), taking over from LTF.
Diisocyanates: Diisocyanates for production of polyurethanes are used in the European Space Sector for a variety of applications (e. g. cryogenic foams). In August 2020 a new restriction (entry 74 of REACH Annex XVII) on the placing on the market and use of diisocyanates entered into force; it required adequate training before industrial and professional use as from 24 August 2023.
Propellants and explosives (energetic materials): Managed in the frame of the Energetic Materials Working Group (EMWG). The EMWG is a long-term collaboration of industry and agencies to monitor and take the required actions to determine and mitigate possible regulatory obsolescence risks – mainly but not limited to the REACH – for substances used in energetic materials for space applications. The list of energetic materials currently being monitored comprises more than 80 entries (status as of 15 July 2026), including and going beyond the liquid propellants formerly subject to the Hydrazine Task Force to also monitor other essential propellants and explosives, such as ammonium perchlorate, hexogen “RDX”, hydrogen peroxide andlead azide.
Per- and Polyfluoroalkyl substances (PFASs): On 13 January 2023 five national authorities of Denmark, Germany, the Netherlands, Norway and Sweden have submitted a wide-scope REACH restriction proposal in order to ban the entire group of PFAS substances (> 10 000 substances) in the EU, subject to a number of exclusions and (mainly 5-year or 12-year) derogations. In response to this (and other group restriction proposals such as for Bisphenol A and some other bisphenol substances) a Space Restrictions Task Force (RTF) was created in February 2023. In September 2023 and May 2026, Eurospace submitted two sets of detailed input on a long list of space applications of PFAS to ECHA, including requests for comprehensive exemptions / derogations to ensure continuity for space applications. The on-going restriction process, including the uptake of the Eurospace (RTF) input and requests, is monitored closely in the frame of the RTF.

In the medium term, other substances may be prioritised by REACH or related legislation (such as Regulation (EU) No 2019/1021 on persistent organic pollutants – POPs Regulation) with potential concerns for the space sector; examples include:

Bisphenol-A (BPA) (used in epoxy resins)
Borates (crystals, lasers, optical instruments)
Boric Acid
D4-6 cyclosiloxanes(the basic building blocks for many silicone polymers)
Gallium Arsenide (GaAs – solar generators, EEE components)
Nickel derivates (surface treatment, energy storage)
Perchloric acid, its salts and precursors (used as oxidiser in solid propulsion systems: e.g. Ariane and Vega main propulsion)

These key example cases alone show the significant potential impact of the REACH chemicals regulation on a broad range of applications in the space sector, which was not a primary target of these rules but is not exempted as such from the REACH requirements.

It is also important to note that outside of REACH for many of the substances mentioned above there are recent, new or pending EU occupational exposure limits (OELs) under the Chemical Agents Directive 98/24/EC and the Carcinogens, Mutagens or Reprotoxic substances Directive 2004/37/EC in order to protect workers. Examples include hydrazine, Cr(VI) substances, lead metal or diisocyanates. Legal compliance with such limits can be challenging.

SCIP notification

In addition, the sector is working on the application aspects of the Waste Framework Directive 2008/98/EC (WFD), as revised in 2018 and subsequently transposed in different ways in the EU Member States:

Article 9 of the revised WFD foresees a notification requirement for EU article suppliers effective since 5 January 2021 and creation of a corresponding ECHA database named SCIP by ECHA for EU-supplied articles containing substances included in the REACH Candidate List above 0.1% weight by weight. Going beyond the WFD legal requirements, ECHA has provided public accessto this database. Products sent into space and related means of transport such as launch vehicles typically do not result in waste for treatment on Earth/ in the EU. Therefore, such products are not part of the Circular Economy and appear to fall outside the scope of the WFD. Yet, an explicit exemption is not foreseen for such products, and information disclosure in ECHA’s SCIP database can raise serious security concerns. Against this background, the WFD Task Force of the European Space Sector has prepared a Best-Practice Guidance for space industry in 2020 to comply with SCIP notification, taking into account the special case of space products. The Guidance is currently (17 July 2026) available in its 3^rd update (dated 8 October 2024, with Addendum of 3 March 2025).
On 10 December 2025 the European Commission proposed the discontinuation of SCIP notification and database given the disproportionate impacts of these provisions for industry without corresponding benefits and the issue of double regulation with REACH Article 33. This Commission proposal is currently (15 July 2026) with the European Parliament and the Council as the co-legislators for discussion and adoption. Eurospace welcomes the Commission proposal and calls on the European legislators to repeal the SCIP rules as a matter of urgency (see news alert). However, until further notice SCIP notifications remain required where the legal conditions are fulfilled.

Eurospace REACH Task Forces / Working Groups

Eurospace supports the coordination and implementation of joint space industry actions in the REACH framework with dedicated Task Forces:

RTF – Restrictions Task Force, including (but not limited to) group restriction proposals for “universal” PFAS, Cr(VI) substances and certain bisphenols. Since February 2026, the RTF has also absorbed the activity scope of the Lead metal Task Force (LTF) and the Chromates Space Task Force (STF) in order to monitor the regulatory treatment of these substances under REACH and related requirements and take joint action for advocacy and compliance where necessary.
EMWG – Energetic Materials Working Group; it monitors regulatory evolutions (mainly but not limited to REACH) for more than 80 substances for space propellants and explosives and includes also the former scope of the HTF – Hydrazine Task Force (discontinued in October 2022)
CSS SFG – Space Focus Group set up to follow the EU Chemicals Strategy for Sustainability (CSS) and the Sustainable Products Initiative (SPI)
WFD/SCIP TF – Waste Framework Directive Task Force to provide up-to-date guidelines for article suppliers in the space industry to comply with the SCIP notification requirement to ECHA pursuant to WFD Art. 9(1)(i)

For information about the REACH Task Forces / Working Groups please contact Valentin Marie (Research Analyst & Compliance Manager).

All REACH activities of the space industry are coordinated with the Materials and Processes technology Board, managed by ESA. They are administered and technically supported by REACHLaw, a consultancy company headquartered in Helsinki, Finland.

Recent Publications

Date	Category	Title	Link
07.09.2026	PFAS	European Space Sector Comments on the Draft SEA Opinion on the Proposal for a UK REACH Restriction on PFAS in Firefighting Foam, HSE response ID ANON-8F9R-2T3G-9	HERE
13.08.2026	Cr(VI)	Eurospace (STF) comments on the SEAC draft opinion on the Cr(VI) restriction proposal (MPTB-ES-PO-0242)	HERE (ECHA ID #1380) News alert
22.05.2026	PFAS	Eurospace (RTF) comments on the SEAC draft opinion on the “universal PFAS” restriction proposal – General Survey response (MPTB-ES-PO-0225)	HERE (ECHA ID #10901) News alert
06.05.2026	SCIP	European Space Sector feedback on Commission Proposal to repeal the obligation to report SCIP-related data (MPTB-ES-PO-0229)	HERE News alert
24.02.2026	Restrictions	Eurospace announcement about the merger of the REACH Space Chromates Task Force (STF) and the Lead metal Task Force (LTF) into the Space Restrictions Task Force (RTF)	News alert
12.01.2026	Advanced Materials	European Space Sector feedback on Commission Call for Evidence: Advanced Materials Act (MPTB-ES-PO-0215)	HERE News alert
17.09.2025	Cr(VI)	Eurospace (STF) comments on ECHA’s Cr(VI) restriction proposal (MPTB-ES-PO-0202)	HERE (ECHA ID #9662)
09.09.2025	SCIP	European Space Sector feedback on Commission Call for Evidence: Simplification of administrative burdens in environmental legislation (MPTB-ES-PO-0204)	HERE
28.07.2025	Cr(VI)	ESCC MPTB recommendations for users of chromium trioxide in chemical conversion coatings for space hardware after the REACH authorisation sunset date on 21 September 2017, Issue 8 (MPTB-RL-GD-0200)	HERE News alert
20.03.2025	SCIP	European Space Sector contribution for the European Commission on the assessment of environmental reporting and the potential for simplification, input on costs relating to SCIP notifications (MPTB-ES-PO-0181)	not publicly available
03.03.2025	SCIP	Eurospace Best-Practice Guidance for the European Space Sector to comply with SCIP Notification, Version 1.3 (MPTB-ES-GD-0158)	HERE News alert
12.06.2024	Hydrazine	Space Industry comments on new special packing provision “PP5” to UN 2029 for Hydrazine Anhydrous (MPTB-ES-PO-0150)	HERE News alert
22.09.2023	PFAS	Eurospace (RTF) comments on the “universal PFAS” restriction proposal (MPTB-ES-PO-0131)	HERE
22.05.2023	Bisphenol	Eurospace (RTF) comments on the bisphenols group restriction proposal (MPTB-ES-PO-0125)	HERE
20.06.2022	ESPR	Eurospace (CSS SFG) comments on the European Commission proposal of 30 March 2022 for an Ecodesign for Sustainable Products Regulation (ESPR) (MPTB-ES-PO-0105)	HERE
28.04.2022	Lead	Eurospace (LTF) comments to ECHA (MPTB-ES-PO-0103) and the European Commission (MPTB-ES-PO-0099) on recommending lead metal for the REACH Authorisation List	HERE
13.04.2022	REACH	Eurospace (CSS SFG) comments on the proposed CSS REACH Revision: Position Paper (MPTB-ES-PO-0098) and Survey Response (Contribution ID: e51d73c6-ac5b-4061-bc2d-f744260a1c2a)	HERE
28.09.2020	Energetic Materials	Eurospace (EMWG) New Space Sector Working Group on Energetic Materials	HERE
08.04.2020	Hydrazine	Eurospace (HTF) revised REACH authorisation exemption position on hydrazine and other liquid propellants (HTF-ES-PO-2020-001)	HERE

Other useful links

European Space Components Information Exchange System (ESCIES): Information from the Materials and Processes Technology Board (MPTB) – available HERE
7^th ESA REACH Workshop on 2 June 2026 at ESA ESTEC in Noordwijk, the Netherlands – presentations and summary available HERE
6^th ESA REACH Workshop on 17 June 2025 at ESA ESTEC in Noordwijk, the Netherlands – presentations and summary available HERE
5^th ESA REACH Workshop on 19 June 2024 at ESA ESTEC in Noordwijk, the Netherlands – presentations and summary available HERE
4^thESA REACH Worksop on 18 October 2022 at ESA HQ in Paris – presentations and summary available HERE
Website of the European Chemicals Agency (ECHA) – available HERE

Last update

23 September 2026

Further information on ECSS STWG

ECSS

The ECSS (European Cooperation for Space Standardisation) is a partnership established to develop a coherent set of space standard for the entire European Space Community. The organisation brings together space agencies, particularly ESA, and the European industrial sector.

Together, representatives from agencies and industry undertake the tasks to draft, update and maintaining the ECSS standards library that can be make applicable, at the customers request, to the procurement of space systems in Europe.

ECSS has two governing bodies with regular annual meetings, each with a decision structure balancing the power of agencies and industry representatives:

The TA (Technical Authority) is the most technical decisional body of the ECSS. It sets-up and implements the work-plan validated by the Steering Board, validates all the technical steps of documents production and approval process.
The SB (Steering Board) is responsible of the overall strategy and policy issues. It supervises ECSS global activities through working plans and delegates the tasks to relevant sub-bodies.

STWG

The STWG (Standardisation Working Group) has been created to organise and coordinate the involvement of industry in the context of standardisation activities, mostly targeting the ECSS, but not exclusively. It is also monitoring space standards at the level of ISO and CEN.

The STWG enables industry to organise its involvement in the ECSS at both inter-institutional and working levels.

At the inter-institutional level the STWG enables industry designated representatives to elaborate the common sectoral views and positions to support the work of the TA and SB.
At working group level the STWG populates the ECSS process with relevant experts and organises all review and approval phases for new and updated standardisation documents. Experts involved in the elaboration of standards in ECSS can benefit from financial support from ESA in the form of travel reimbursement costs incurred with the ECSS WG meetings. See the reimbursement scheme below.

Under the active coordination of the Eurospace Secretariat, the STWG focuses on:

Gathering consensus in the Industry for developing and reviewing standards applicable to Space systems procurement in Europe.
Approving standards for publication.
Monitoring space standards at ECSS, CEN, ISO.
Nominating experts from the Industry to take part in standards development.

Participation in the STWG is not exclusive to Eurospace members. Any company can be involved and be added to the STWG mailing list, to follow the ECSS processes, review standards in progress and nominate experts to take part in drafting Working Groups.

STWG Terms of Reference – available HERE

Secretariat

Valentin Marie, +33 7 86 58 74 34 Valentin.marie@eurospace.org

ECSS travel costs Reimbursement procedure

Since 1995, ESA has been reimbursing, through Eurospace, travel and subsistence costs incurred by the representatives of European industry having participated in ECSS working group meetings (ESTEC Contract No 4000111716).

Since April 2019, reimbursements are organised into 3 periods.

Period 1: December 1st of year N-1 till March 31st of year N, the claims have to be received before April 30th
Period 2: April 1st till July 31st of year N, the claims have to be received before August 31st
Period 3: August 1st till November 31st of year N, claims have to be received before December 2

Late claims will not be processed by Eurospace.

Please read carrefully the ECSS Reimbursement Procedure (revision April 2019) and check the ECSS FAQ

EUROSPACE, Attn. Ms. Nathalie ALECTON, 22 Rue du Quatre Septembre, F-75002 PARIS.

ecss.reimbursement@eurospace.org

Useful Links:

All ECSS standards are open source and free to use.
The ECSS website – available HERE
The ASD-STAN website, for the standards in the Aerospace industry – available HERE