Talk:Orbital propellant depot

History - wrong IMO
Russian Salyut, MIR and russian segment of ISS have been regularly refuelled since Salyut-6. AFAIK, they also have the capability to pump in reverse. For all intents and purposes this is the most mature on orbit propellant transfer technology around. — Preceding unsigned comment added by Savuporo (talk • contribs) 16:25, 10 August 2015 (UTC)

Economy of propellant depots
It would be nice to add more on why the economy of depots would evolve naturally. Off the cuff:


 * No time-pressure to fill the depot whereas the mission is usually time-critical. This implies less expensive launches
 * As the propellant itself is not valuable, presumably less expensive rockets could make the deliveries
 * If a rocket failed, no one would be hurt and the propellant loss would not not be a financial burden, so less critical design and inspection requirements would allow less expensive launches from less expensive launch facilities
 * With the right economic incentives, the market would respond with the _right_ rocket:
 * High volume per launch, or
 * Multiple inexpensive launches

Much of the above is covered in the article, but in a bit disorderly fashion.

131.252.209.89 (talk) 08:18, 16 July 2009 (UTC)


 * Until a peer reviewed paper comes out mentioning the above points the requested material would mostly be a mixture of speculation and original research.


 * Andrew Swallow (talk) 07:28, 12 September 2009 (UTC)


 * There are a number of papers that might be useful as sources that may be easily found on Google Scholar. Here is one simple search I did that found a bunch of potentially useful sources for the article.  Cheers.  N2e (talk) 10:46, 7 June 2010 (UTC)

Price - for in-orbit delivery
Just to confirm for the energy people NASA has entered an opening bid of $10,000 a kilogram for propellant. That is the equivalent of $24096 a litre for RP-1 methane. The catch being you have to deliver the fuel to the propellant depot in space or their spacecraft. The depot is likely to be near the International Space Station or the private space station and hotel being constructed by Bigelow. There is a rumour that NASA may pay a higher price for propellant at EML-1, EML-2 and Mars but that has not been confirmed. Tanker rockets and probably the depot are to be paid for by the energy company. NASA has not yet decided what fuel its new lunar landers will use. Andrew Swallow (talk) 04:29, 10 October 2009 (UTC)
 * Anyone got a link to that NASA opening bid (or offer) ? - Rod57 (talk) 11:41, 7 March 2022 (UTC)

Image needed -- reqphoto tag added
This article could really use a drawing or artist's conception of an on-orbit propellant depot. I'm adding a reqphoto tag. N2e (talk) 10:40, 7 June 2010 (UTC)


 * For what it's worth, there is a US government image that may be wiki-usable in the Augustine Commission HSF report that is cited in the article, on page 65. I think gvmt images are free to use.

you got one here, http://www.nasa.gov/news/budget/fy11_fueldepot.html with a downloadable image an free use (i guess), and a concept from the 70 of the space transportation system http://nix.ksc.nasa.gov/info;jsessionid=1h0bjiaxvldlg?id=MSFC-9902019&orgid=11 i used the nix tool to find it--Beaucouplusneutre 22:55, 24 July 2011 (UTC)


 * A nice diagram of a propellant depot has been added.


 * The picture called "An evolved propellant depot" looks like a weapon platform, are there any less threatening pictures? Andrew Swallow (talk) 20:39, 16 September 2011 (UTC)

Shop in Space
@N2e The sentence you deleted does makes sense. It is just pointing out that practical propellant depots will have a habitation module containing a shop that sells supplies to people, same as most petrol stations on Earth.
 * "The crew and passengers on reusable orbital transfer vehicles may purchase consumables like food, water and oxygen gas."

Andrew Swallow (talk) 23:31, 17 September 2010 (UTC)

New effective solutions to delivering fuel into depot
In addition to the traditional and expensive method of fuel delivery into orbital depot, i.e. with the help of multistage rockets, in the near future on the basis of Alexander Mayboroda’s inventions it will be possible to use a more progressive technology of transporting fuel from the Earth. This new technology is based upon fuel supply into a accumulating space device (ASD), analogous to Demetriades’ PROFAC (but with solar batteries instead of nuclear reactor), reusable suborbital cargo rockets like Blue Origin New Shepard, SpaceShipOne or Space Plane. This method of transportation does not require absolutely new technologies in itself even when typical disposable rockets are used which is possible due to increasing their cargo-capacity by 10-15 times and due to using one rocket stage only which reduces cargo-delivery-into-space cost by at least 20 times.


 * The above paragraph makes it sound like someone is proposing to use reusable sub-orbital rockets as a first stage. If so rewrite the paragraph to make this clear.


 * Propellant depots can accept fuel from many sources delivered in lots of different ways. Andrew Swallow (talk) 20:13, 24 July 2011 (UTC)


 * This is not notable and you're spamming it onto many different pages. It detracts from the quality of the page. @Andrew: I think this needs to be removed, but I've removed it twice already so I won't do it myself. At least not for now. Martijn Meijering (talk) 20:30, 24 July 2011 (UTC)
 * Agreed. ChiZeroOne (talk) 00:32, 25 July 2011 (UTC)

asteroid catching and lunar infrastructure
propellant depots from an diverted asteroid with isru http://www.sciencedirect.com/science/article/pii/S0094576506001147 just a idea, but there must been economic study too

propellant depot from the moon with isru http://www.sei.aero/eng/papers/uploads/archive/IAC-07-A5.1.03_present.pdf http://nextbigfuture.com/2011/02/future-in-space-operations-assessing.html — Preceding unsigned comment added by Beaucouplusneutre (talk • contribs) 19:32, 16 July 2011 (UTC) other links from nasa exist too — Preceding unsigned comment added by Beaucouplusneutre (talk • contribs) 19:00, 16 July 2011 (UTC)

NASA is getting serious about propellant depots (in 2011)
NASA is starting to get serious about propellant depots, and sending some funding in that direction, now that the Space Shuttle is retired and the super-heavy lifter is a decade away. Have to utilize more launches of smaller rockets and, hey, refuel in space. Whodathunkit? Link to the news article I saw is here: NASA Wants Gas Stations In Space, dated 5 Aug 2011. Cheers. N2e (talk) 04:23, 6 August 2011 (UTC)


 * Here is more: NASA selects firms for orbital cryo propellants depot study.
 * Seems appropriate that with the revelations of staggering costs for the SLS super heavy lifter come NASA's announcement of the companies selected for the orbital cryogenic propellant depot study:


 * /-- NASA Wants Gas Stations In Space - Space.com
 * /-- NASA Selects Companies To Study Storing Cryogenic Propellants In Space - NASA -


 * WASHINGTON -- NASA has selected four companies to develop concepts for storing and transferring cryogenic propellants in space. These capabilities are important for the agency's future deep space human exploration missions.


 * The selected companies, pending successful contract negotiations, are:
 * -- Analytical Mechanics Associates Inc. Hampton, Va.
 * -- Ball Aerospace & Technologies Corporation, Boulder, Colo.
 * -- The Boeing Company, Huntington Beach, Calif.
 * -- Lockheed Martin Space Systems Company, Littleton, Colo.


 * The awards total approximately $2.4 million with a maximum individual contract award of $600,000. Each company will provide a final report to help define a mission concept to demonstrate the cryogenic fluid management technologies, capabilities and infrastructure required for sustainable, affordable human presence in space.


 * Storing cryogenic propellants such as liquid hydrogen and liquid oxygen in space for long periods of time with minimal boil-off is critical for deep space human exploration. The mission concept studies will identify technology gaps and look at innovative technical solutions to develop cryogenic propulsion systems and depots.


 * NASA will use the studies to plan and implement a future flight demonstration mission that will test and validate key capabilities and technologies. NASA's Exploration Technology Development Program is funding the studies. The Space Technology Office at NASA's Glenn Research Center in Cleveland is managing the contracts.


 * For more information about NASA exploration and other programs, visit: http://www.nasa.gov/exploration.


 * And here is another article on NASA plans for an interplanetary propellant depot: NASA interest in an interplanetary highway supported by Propellant Depots.  N2e (talk) 17:40, 10 August 2011 (UTC)


 * I have now added some information to the article about the "Simple Depot" mission from the NASA interest in an interplanetary highway supported by Propellant Depots source mentioned yesterday. There is more to be gleaned on propellant depot strategies and plans from that article, including a tie-in to the proposed larger depot architecture that would make more efficient use of the entire (standard) 5m fairing diameter on an Atlas V with the ACES stage replacing the Centaur that would be used for Simple Depot.  N2e (talk) 17:54, 11 August 2011 (UTC)

Third-party analysis of the recent NASA change in direction
I have started to see some analysis by non-NASA sources on the change of emphasis by NASA on propellant depots. Let's start a list here for future use to improve the article:
 * Orbital Propellant Depots: Building the Interplanetary Highway, Strickland, John, Jr., National Space Society, 15 Aug 2011. Quote:  "August 5, 2011, was a highly significant date in the history of the space program. On that date, NASA announced contracts awarded to four aerospace companies to define demonstration missions to test the capabilities of cryogenic propellant depots. The contracts effectively created a design competition which would lead to the selection of a company to build an actual prototype depot. Cryogenic propellant depots are a critical component of our entire future space exploration and development effort."
 * NASA To Study Cryo Storage In Space more secondary source analysis of NASA's new interest, suitable for Wikipedia citations, this time from Aviation Week on 10 Aug 2011.
 * ULA Proposes On-Orbit Gas Stations for Space Exploration also from Aviation Week, this article focuses on specific ULA proposals. N2e (talk) 12:16, 11 September 2011 (UTC)


 * ✅I have updated the article with information from the two AW articles, plus some copyediting and other additions. N2e (talk) 21:12, 11 September 2011 (UTC)


 * The ula proposal skipping sls ::http://www.ulalaunch.com/site/docs/publications/AffordableExplorationArchitecture2009.pdf

advantages of depots
no need to develop new rocket (save money) enable a market open to competition between providers of fuel (that possess a way to reach the depot) provide a "sustainable" flexible path approach to exploration destination ,there must be other advantage to depots we can include (i have to reread the augustine conclusion)--Beaucouplusneutre (talk) 05:17, 17 September 2011 (UTC)

This is an encyclopedia, IMHO it should stay neutral in the Depot V. Heavy launch vehicle Wars. It reports the facts, other media can provide the arguments. Andrew Swallow (talk) 11:08, 30 January 2012 (UTC)

2 studys show it is cheaper, when someone can provide something that show otherwise, i will put them too and summarize that way Minimum_wage --Beaucouplusneutre (talk) 11:21, 30 January 2012 (UTC)


 * If you are going to include a debate you have to list the disadvantages. Since the Heavy launch vehicle supporters are unlikely to reciprocate it is best to just stick to the facts.


 * There are missions that can use both depots and heavy launch vehicles. The hardware's dry mass may be so large that only heavy launch vehicles can lift it, many proposed with Mars mission fit this criteria.  A heavy propellant depot is then used to fill the spacecraft's large fuel tanks.

Andrew Swallow (talk) 22:16, 30 January 2012 (UTC)


 * wich one should be built first given a very limited budget ?--Beaucouplusneutre (talk) 12:02, 3 March 2012 (UTC)


 * Which first on cost grounds? That is the wrong criteria. We can launch payloads weighting ~25 tonne using current launch vehicles.  We do not need a heavy launch vehicle until we have a payload whose dry mass exceeds that.  A set of propellant depots can help current launch vehicles put say 20 tonne payloads on the Moon and Mars.  Andrew Swallow (talk) 20:56, 3 March 2012 (UTC)

Major NASA report -- Propellant depot mission architectures beat SLS in cost, speed and flexibility
This newly released NASA report on propellant depots seems quite important. "NASA found exploration with fuel depots & medium lift launchers bests SLS in cost, speed, & flexibility" article links to a site that has the pdf of the actual report, from NASA Internal NASA Studies Show Cheaper and Faster Alternatives to The Space Launch System (SpaceRef news, 12 Oct 2011). I have not yet had time to digest the report. Dig in. N2e (talk) 11:34, 15 October 2011 (UTC)
 * i wanted to use it on the sls page, maybee whe should also switch the picture of the leo depot with sun shield on the top intro picture--Beaucouplusneutre (talk) 17:27, 15 October 2011 (UTC)
 * NYtime article : http://www.nytimes.com/2011/10/23/science/space/23nasa.html?_r=1&src=tp&smid=fb-share --Beaucouplusneutre (talk) 03:57, 23 October 2011 (UTC)

Clarify
Hello,

The article is a bit unclear, at least to me, in explaining the advantages and motivations for such a depot. From an energy argument, there can be no advantage if one looks only at the gravitational energy, but there might be benefits due to container weight? What are the benefits of launching your fuel separately to your actual rocket? I think this needs to be more clear in the introduction and first main section. 129.67.86.189 (talk) 15:05, 23 October 2011 (UTC)

Cryogenic Propellant Storage and Transfer (CPST)
Nasa started on a project called the Cryogenic Propellant Storage and Transfer (CPST)Propellant depots: the fiscally responsible and feasible alternative to SLS NASA Still Studying Space-Based Fuel Depots--Nrpf22pr (talk) 19:10, 3 November 2011 (UTC)

Depot images
A couple of the images of propellant depots that are currently (2011-11-04) used in the article need better captions. I agree with the recent change by User:Beaucouplusneutre to put a more near-term/proposed/realistic image as the top image in the article. However, these images do need to have better, more descriptive, captions written for them. In my view, for a topic like propellant depots, which will seem to be Science Fiction to many Wikipedia readers, we ought to, at minimum, include in the caption what agency or company produced the particular idea that is illustrated by the image, and the epoch or year of that idea. Without that, it is difficult for the casual reader to tell the difference between a real proposed concept depot and science fiction. Cheers. N2e (talk) 12:41, 4 November 2011 (UTC)

price / demo / projections /
we can add the estimates of prices for a demo (300 millions) http://www.nss.org/articles/depots.html

lunar depot architecture case study http://www.sei.aero/eng/papers/uploads/archive/IAC-07-A5.1.03.pdf

are there other costs estimates out there for a real depot (not a demo) ?--Beaucouplusneutre (talk) 10:36, 29 January 2012 (UTC)

Water storage option?
Potential water storage at the depot is mentioned under the Advantages section. This got me thinking with reference to boil-off mitigation of hydrogen and oxygen. Is there any practicality to storing them as water and having an on-depot solar electrolysis mechanism to separate them as needed? Doyna Yar (talk) 11:07, 12 October 2012 (UTC)


 * No. The energy required to electrolyse the water is enormous.  Using solar arrays of a practical size several months are needed to fill the tank.  It was looked into as a way of simplifying transporting the propellant. Andrew Swallow (talk) 16:44, 12 October 2012 (UTC)


 * Also consider that water has quite high freezing temperature. It needs to be kept warm in space which is another problem. Savemaxim (talk) 17:05, 12 October 2012 (UTC)

Orphaned references in Propellant depot - fixed
I check pages listed in Category:Pages with incorrect ref formatting to try to fix reference errors. One of the things I do is look for content for orphaned references in wikilinked articles. I have found content for some of Propellant depot's orphans, the problem is that I found more than one version. I can't determine which (if any) is correct for this article, so I am asking for a sentient editor to look it over and copy the correct ref content into this article.

Reference named "spacex-itspresentation201609": From In situ resource utilization:  From Raptor (rocket engine family):  

I apologize if any of the above are effectively identical; I am just a simple computer program, so I can't determine whether minor differences are significant or not. AnomieBOT ⚡ 02:29, 19 October 2016 (UTC)


 * seems ✅ - Rod57 (talk) 11:20, 9 March 2022 (UTC)

Forms of propellant?
Could a propellant depot store fuel sources other than the liquids listed in the article? It seems to me (and I'm happy to admit I know little about this) that in addition to storing liquids, you could use a 'depot' to store electricity.

Something like a Mars mission could top up their onboard batteries either by docking with the depot or by a close flyby and transfer using something akin to a pantograph. Obviously some means of shielding the rest of the craft from the energy transfer would be needed. This way they would not need to haul all the energy they need from launch to Mars.

Which would be most efficient? Taking the liquid fuel onboard or taking on the electricity? Launching one craft with smallish solar panels or launching the craft with no panels and getting power as required en-route from a depot? The depot might be two arrays of solar panels (small one near the Sun and a larger one perhaps near Mars to catch transmitted energy.

Does the above make sense? Are there any examples of this option? Is it something that should be added to this article? — Preceding unsigned comment added by Robata (talk • contribs) 21:12, 5 January 2017 (UTC)


 * Electricity is stored in rechargeable batteries. Batteries are heavy. The depot may need to supply the visiting vehicle with 3 kW or so of power when refuelling it. Andrew Swallow (talk) 14:19, 6 January 2017 (UTC)


 * Long duration missions inside and outside of low-Earth orbit would never need to "top off" electrical power. Their solar panels are pre-sized to supply continuous power and take into account degradation so that the vehicle continues to receive enough power through the end of its mission. Such a long-duration spacecraft literally could not carry a battery large enough to power it for the entirety of its mission...it would be too massive, whereas a solar array is comparatively low mass.
 * Short duration missions in low-Earth orbit would likely never want to refuel at a prop depot. It would have to be injected into the depot's orbit and then spend time catching up to it. It is easier to simply carry the mass with them, and thereby have the freedom of being injected into whatever orbit is best for their mission, rather than having to conform to the depot's orbit and then spend delta-v getting to their desired position. — Huntster (t @ c) 17:16, 6 January 2017 (UTC)


 * When a vehicle is docked to a depot the spacestation's own solar panels and sun shield could block light from reaching the vehicle's solar arrays. Andrew Swallow (talk) 04:29, 8 January 2017 (UTC)


 * Yes, while docked the depot could provide power, but that is not what Robata was positing. I was responding to their idea. — Huntster (t @ c) 07:46, 8 January 2017 (UTC)

Hunster, thanks for resolving my queries. I was just thinking that the less mass (solar panels etc.) that had to be dragged out of the gravity well the better. I had not anticipated the need to change orbits. — Preceding unsigned comment added by Robata (talk • contribs) 21:59, 20 January 2017 (UTC)

Contradictions - is LOX cryogenic or "mildly-cryogenic"
The article says:


 * Large upper-stage rocket engines generally use cryogenic fuels like liquid hydrogen and liquid oxygen (LOX) because of the large specific impulse possible, but must carefully consider a problem called "boil off". The boil off from only a few days of delay may not allow sufficient fuel for higher orbit injection, potentially resulting in a mission abort. Lunar or Mars missions will require weeks to months to accumulate tens of thousands to hundreds of thousands of kilograms of propellant, so additional equipment may be required on the transfer stage or the depot to mitigate boiloff.
 * Non-cryogenic, earth-storable liquid rocket propellants including RP-1 (kerosene), hydrazine and nitrogen tetroxide (NTO), and mildly cryogenic, space-storable propellants like liquid methane and liquid oxygen, can be kept in liquid form with less boiloff than the cryogenic fuels, but also have lower specific impulse.

So LOX is listed as both cryogenic and mildly cryogenic. As subject to boil-off, and as less subject to boil-off. As having high specific impulse, but as having lower specific impulse William M. Connolley (talk) 10:18, 5 February 2017 (UTC)


 * That real life contradiction is part of what makes rockery so hard. Liquid oxygen (LOX) can set most things on fire (including iron) which limits what you can keep LOX in. A little bit of dirt has been known to cause explosions. Being cryogenic (boiling point 90.188 K) LOX has to be kept cold, probably using refrigeration, but not as cold as the fuel liquid hydrogen (boiling point 20.271 K). The 70 K difference means their tanks have to be kept apart, even on the same rocket. Note room temperature is about 300 K. Andrew Swallow (talk) 19:55, 5 February 2017 (UTC)


 * LOX is usually considered cryogenic. "space-storable" is vague and may be OR. The usual classification is "Storable", or "Cryogenic". The 2nd quote could use "hydrolox" instead of "the cryogenic fuels" to avoid the appearance of a contradiction. - Rod57 (talk) 15:24, 28 April 2022 (UTC)

A source of interest, on the political squelching of work on propellant depots
Looks like some political shenanigans are coming to light. Looks like US contractor Boeing and certain political forces in the US Congress and at NASA may have squelched advancements in propellant depot technology development work in order to help keep the flow of $$$ flowing to Boeing for the big NASA/Boeing-developed Space Launch System (SLS), for something like over a decade. Would likely be useful to improving the article, especially if more reliable sources and reporting back this up.

Here's the article: The SLS rocket may have curbed development of on-orbit refueling for a decade, Eric Berger, ARS Technica, 1 August 2019.

- N2e 19:57, 1 August 2019‎


 * This squelching has long been whispered about. We should mention it. (Eric Berger is usually a reliable source, and he names a plausible source now) - Rod57 (talk) 13:55, 28 April 2022 (UTC)

Over general name ?
Current name, Propellant depot, seems over general. Could we rename to Propellant depots in space or Orbital propellant depot ? - Rod57 (talk) 11:29, 7 March 2022 (UTC)


 * Perhaps Orbital propellant depot is better to avoid the plural in the former. - Rod57 (talk) 14:59, 28 April 2022 (UTC)
 * ✅, and checked redirects. - Rod57 (talk) 15:11, 28 April 2022 (UTC)

What did NASA do from 2011 to 2021
Who apart from Richard Shelby prevented NASA making progress, so as to protect SLS/Boeing ? (The SLS rocket may have curbed development of on-orbit refueling for a decade, Eric Berger, ARS Technica, 1 August 2019.) - Rod57 (talk) 14:56, 28 April 2022 (UTC)

What happened to CRYOTE and CRYOSTAT
Did CRYOTE get funding ? What happened or why not ? Did CRYOSTAT get launched to ISS ? What results or why not ? - Rod57 (talk) 00:08, 13 March 2022 (UTC)

Update for 2024 needed
Needs more content on in space refueling being developed now by spacex and blue origin 73.210.30.217 (talk) 03:38, 27 May 2024 (UTC)