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#1 2022-04-13 04:33:16

tahanson43206
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Registered: 2018-04-27
Posts: 17,005

Space Tug - Departure - Arrival - Orbit changes

This topic is another spin-off of the pioneering visionary work of RobertDyck.

In attempting to find a solution to the challenge of providing propulsion for Large Ship (Prime), GW Johnson worked out a set of variations on propulsion using space tugs.

This work is documented in the topic: GW Johnson Postings

Background documents are available in the ExRocketman Wordpress web site.

A video presentation is available courtesy of the web site: northhoustonspace.org.

Look for the presentation given April 9, 2022, at Houston, texas.

My expectation for this topic is that it will follow creation and growth of a trillion (US) dollar industry.

My expectation is that the Space Tug service will combine with on-orbit refueling services, as well as supply of propellant using atomic power (of some kind) to manufacture the liquids needed.

With any luck, the human resources to create a Space Tug organization in the US will come together in the next few weeks.

(th)

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#2 2022-04-13 04:36:25

tahanson43206
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Re: Space Tug - Departure - Arrival - Orbit changes

Harvesting of celestial treasure is a natural sideline for a Space Tug company.

While any of the numerous objects floating (if that's the right word) around the Solar System are fair game, the newly reported Giant Comet is particularly interesting (to me for sure), because it offers some ** really ** useful materials in great quantity, and it will do so reliably for an extended period of time.

(th)

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#3 2023-01-15 12:00:40

tahanson43206
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Re: Space Tug - Departure - Arrival - Orbit changes

We have a thought process under way about where to put a Space Taxi topic....

While we wait for resolution of that question, it appears that members of the forum, with the sole exception of GW Johnson, do not have a full understanding of the nature of Dr. Johnson's proposal.

Everything is thoroughly documented in the GW Johnson topic.  Links to all presentation files are available, so the files can be pulled from Dropbox.

The mental image that may come to mind with the expression "space tug" is some dinky little ion drive that moves a satellite that is in orbit by some tiny increment.

The proposal of GW Johnson is for a massive rocket able to toss a 5000 Metric Ton space ship towards Mars, so that over 90% of the impulse needed for the flight is imparted by the tug, and the small residual is made up by the onboard propulsion system of the vessel.

Any Nation that has the foresight to fund development of the Space Tug will have a ready market, because there will be so much to be gained by existing rocket teams thinking about the Mars and other deep space problem.   The more impulse that can be transferred to the space tug, the more mass remains available for use at the destination, including velocity adjustment at the destination, and even propulsive landing.

(th)

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#4 2023-01-21 13:21:52

SpaceNut
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Posts: 28,820

Re: Space Tug - Departure - Arrival - Orbit changes

tahanson43206 wrote:

For SpaceNut re #18

Thanks for a very NICE follow up and collection of links for study about space tugs.

The Wikipedia entry specifically mentioned rocket pusher implementations such as the one proposed by GW Johnson, but the Wikipedia editor begged off dealing with those at this time, because they do not yet (appear to) exist.

This topic is about Hydrogen Peroxide as an oxidizer, so I'm hoping our forum members will help to develop this into a robust topic.

This particular oxidizer is particularly suitable for a huge Solar System spanning space tug, because it can be maintained indefinitely in space.

The low ISP of a rocket engine using this oxidizer is easily compensated for by employing as many engines as the customer needs for their application.

There is NO need to be limited to a single rocket design such as is needed to launch from Earth, because there is no limit to the size of the mounting frame that can be used for this purpose in space.

There is NO need for streamlining or any other aspect of rocket design that is required for launch from Earth.

(th)

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#5 2023-01-21 13:31:03

SpaceNut
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Posts: 28,820

Re: Space Tug - Departure - Arrival - Orbit changes

That is why we started this particular topic as the beamed energy drive for kbd512 was just that to not just boost but to push the large ships design.

As done in the large ship for the convention the tugs are a bidirectional device not only to send it to mars but to get it back from mars knowing that refueling of these can at the start be done via earth return of them as mars will not have the infrastructure to do more than refill the taxi that is brought to off load the passengers and cargo once they arrive at mars orbit to the planet's surface.

The ability to send 5,000 tons was equal to 13 starships refueled on orbit and another 13 to bring it back without the taxi to bring them to orbit in earth orbit or to bring them down from the large ship once it reached mars destination.

What would be a good exercise would to see if a modified starship could launch from earth only passengers to the ship and do the same at the destination to get fuel allotments for launch and descent requirements even if it only can do it once permission for the total population. So how long would they need to be on the ship dictates how much cargo needs to be present for either ends use.

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#6 2023-02-20 16:54:41

GW Johnson
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Re: Space Tug - Departure - Arrival - Orbit changes

Orbit changes can be quite nonintuitive,  until and unless one becomes very familiar with making orbit calculations,  and I mean by hand,  not with software!  There is no intuition to be gained when using software!

News broadcasters became caught up in this dilemma decades ago during the Mercury/Gemini flights in the 1960's.  They talked about "speeding up to slow down",  etc,  which tells me they never did figure it out. 

When operating in an elliptical orbit about the Earth,  there is a perigee where speed is highest,  and an apogee where speed is lowest.  Just to be clear,  perigee is min orbit altitude,  while apogee is max orbit altitude.  This really is simply conservation of mechanical energy:  kinetic plus potential. 

If you want to change your orbit's apogee,  you make the burn at perigee.  A posigrade burn increases total orbit energy,  raising the apogee.  A retrograde burn decreases total orbit energy,  decreasing apogee.  Perigee,  where you make the burn tangentially to the orbit,  is unchanged. 

Conversely,  if you want to change your orbit's apogee,  you make a burn tangential to the orbit at its perigee.  Posigrade increases energy,  raising apogee.  Retrograde decreases energy,  lowering apogee.  But your perigee is unchanged.

Edit 2-21-2023:  What meant to say here was this:  Conversely,  if you want to change your orbit's perigee,  you make a burn tangential to the orbit at its apogee.  Posigrade increases energy,  raising perigee.  Retrograde decreases energy,  lowering perigee.  But your apogee is unchanged.

All of this applies to elliptic (closed) orbits,  a classical 2-body problem that has closed-form solutions known for centuries now.  Earth (or any other central body) is at one focus of the ellipse,  the other focus being empty.  R is the vector from the central body (at one focus,  not the center) to the thing in the orbit,  which varies between a min R and a max R.  Speed along the orbit depends upon R as V = [GM(2/R - 1/a)]^0.5,  where Vper is at Rmin,  and Vapo is at Rmax. 

The size of the ellipse major axis is 2a = Rmin + Rmax.  The eccentricity e = (Rmax - Rmin)/(Rmax + Rmin).  The distance from the center of the ellipse to one focus is c = e*a.  The semi-minor axis length b^2 = (a^2 - c^2).  The equation of the ellipse with "a" along the x-axis,  and the center of the coordinates at the center of the ellipse,  is x^2/a^2 + y^2/b^2 = 1.  If you shift your coordinates such that the center of the ellipse is at (h,k) instead of (0,0),  then the equation of the ellipse is (x - h)^2/a^2 + (y - k)^2/b^2 = 1. 

GW

Last edited by GW Johnson (2023-02-21 10:32:10)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#7 2023-02-21 14:30:15

tahanson43206
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Re: Space Tug - Departure - Arrival - Orbit changes

https://finance.yahoo.com/news/vast-acq … 28587.html

4
Aria Alamalhodaei
Tue, February 21, 2023 at 9:00 AM EST·4 min read
Vast Space, a company that emerged from stealth last September with the aim of building artificial gravity space stations in low Earth orbit, has acquired space tug startup Launcher, TechCrunch has exclusively learned.

The acquisition, a first for Vast, will give the company access to Launcher’s Orbiter space tug and payload platform and its liquid rocket engine, E-2. Under the terms of the deal, Vast will also absorb all of Launcher’s talent, including Launcher founder Max Haot, who will join as president. The two companies told TechCrunch that the deal has been in the works for months, with both signing a Letter of Intent to acquire back in November.

Stay ahead of the market
The deal could be a big accelerator for Vast; the company’s founder, billionaire crypto pioneer Jed McCaleb, said Vast will use the Orbiter tug to test space station subsystems and components in orbit as soon as June of this year, and then again around October. Those two missions, which will be Orbiter’s second and third flights, will also carry customer payloads. Vast will continue to operate Orbiter as a commercial product; Haot said they had more than five customer contracts and are signing more.

Haot added that the space tug’s abilities, like approaching and moving away from spacecraft and hosting payloads, as well as its technologies like flight software, avionics and guidance, navigation and control systems will complement development of the space station.

Launcher's Orbiter spacecraft. Image Credits: Launcher/John Kraus (opens in a new window)


Launcher made news last week when it said that its first Orbiter mission, which took place at the beginning of January, ended in failure after the spacecraft’s power systems malfunctioned. Despite that setback, Haot told TechCrunch that the results of the mission were “well above industry average.”

“We know exactly what went wrong. We were fully operational for the duration of the battery and we fell short of deploying our customers because of a power issue,” he said. “So Vast, Jed and us are actually extremely proud of what was achieved. We have two more flights this year. […] If you think about it, the odds that this is a stable platform by the end of the year are very high.”

The article continues online if anyone is interested ...

We've been talking about Space Tugs recently.

Launcher appears to be aiming for that market.

(th)

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#8 2023-03-14 17:53:19

tahanson43206
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Re: Space Tug - Departure - Arrival - Orbit changes

https://www.yahoo.com/news/nasa-wants-d … 30681.html

Space
NASA wants new 'deorbit tug' to bring space station down in 2030

Mike Wall
Mon, March 13, 2023 at 5:00 PM EDT

The International Space Station photographed by Expedition 56 crew members from a Soyuz spacecraft after undocking, Oct. 4, 2018.
The International Space Station photographed by Expedition 56 crew members from a Soyuz spacecraft after undocking, Oct. 4, 2018.

NASA aims to develop a spacecraft capable of steering the International Space Station (ISS) to a controlled destruction in Earth's atmosphere when its time in orbit is up.

We first learned about this plan on Thursday (March 9), when the White House released its 2024 federal budget request. NASA's $27.2 billion allocation included $180 million "to initiate development of a new space tug" that could safely deorbit the ISS over the open ocean after its operational life ends in 2030, as well as potentially perform other activities.

More details emerged on Monday (March 13) during a press conference NASA held to discuss the proposed budget, which must be approved by Congress to be enacted. For example, we've now got a ballpark price tag for the deorbit tug, preliminary though it may be.

"A cost estimate we had was a little short of about $1 billion," Kathy Lueders, NASA's human spaceflight chief, said during the press conference. "Our goal is to go out with an RFP [request for proposals], and then, obviously, when we get the proposals, then we're hoping to get a better price than that. But this gives us a healthy start in '24 to get that critical capability onboard."

Related: The International Space Station will eventually die by fire

The new tug will supplement existing deorbit capabilities of the International Space Station partners (the space agencies of the U.S., Russia, Europe, Canada and Japan). The current plan for bringing the station down safely relies upon engine burns by robotic Progress cargo vehicles, which are provided by Russia.

"But we're also developing this U.S. capability as a way to have redundancy and be able to better aid the targeting of the vehicle and the safe return of the vehicle, especially as we're adding more modules," Lueders said.

"As you've seen in the past and over this last year, us having these redundancies has been very, very important for both ourselves and our partners," she added. "And so, having a U.S. deorbit vehicle is another key linchpin in our space operations and deorbit strategy of the ISS."

The recent examples to which Lueders was likely referring are coolant leaks that occurred on two separate Russian vehicles docked to the ISS: A Soyuz crew spacecraft lost all of its coolant to space on Dec. 14, 2022, and a Progress sprang a leak of its own on Feb. 11.

Russia has attributed the Soyuz leak to a likely micrometeoroid strike and linked the Progress issue to an "external influence," perhaps a problem incurred during launch. But the investigation into the two leaks continues.

In addition, Russia has voiced a desire to leave the ISS partnership early (at some point "after 2024") to focus on building its own outpost in low Earth orbit. This information likely factors into NASA's deorbit-tug plans, as does Russia's ongoing invasion of Ukraine, which has severed many of Russia's space partnerships.

Related: Russia's war on Ukraine has caused lasting damage to international spaceflight cooperation

Related stories:

(th)

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#9 2023-03-15 12:51:37

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 5,451
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Re: Space Tug - Departure - Arrival - Orbit changes

Deorbiting the ISS is just the same as deorbiting Skylab would have been,  except ISS is way bigger so you need more total impulse to get the right dV,  which is pretty close to 0.10 km/s.

You don't need a real tug,  you just need a propulsion item,  the station has its own command-able attitude control.  I'd suggest a reasonably big solid motor from one of those outfits,  fitted to dock at an appropriate port on the station,  such that the thrust line goes through the cg pretty close.  Not an SRB,  but not a Sidewinder,  either.

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#10 2023-03-15 17:56:30

SpaceNut
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Posts: 28,820

Re: Space Tug - Departure - Arrival - Orbit changes

A lot more dV and we can reuse it, just use the panels from the station to power an ion drive engine to send it on its way.

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#11 2023-03-15 18:46:04

tahanson43206
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Re: Space Tug - Departure - Arrival - Orbit changes

For SpaceNut re #10 and sentiment to salvage space station ....

Have you looked at any of the detail behind the decision to deorbit the station?  I have not, so can't help, but my impression is that the station is deteriorating.

Could there be an issue with hull integrity?  Those modules are being held at Earth sea level pressure.  The walls are flexing with every orbit, because the heat in the Sun and freeze in the cold of the shadow.

However, since this ** is ** the Space Tug topic, a Space Tug could probably lift the station to higher orbit, given enough time with an ion drive.

I suspect that would be one hefty ion drive.  You should be able to discover the mass of the station and the solar cell output that is available.  From those two figures, you may be able to calculate the mass needed for ion propellant, and the duration of the run, if you decide where you want the station to go.

(th)

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#12 2023-03-18 15:06:08

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 28,820

Re: Space Tug - Departure - Arrival - Orbit changes

Mostly the Russian stuff.
Much of the station with US modules has had many upgrades that have been done over time.
The fact that NASA has contracts with Axiom for more changes means we have plenty of potential to not ditch all of the station.
I saw a $1 billion dollar ISS tag for the tug NASA Wants $180M for a 'Space Tug' to Deorbit the International Space Station

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#13 2023-03-19 07:48:39

Mars_B4_Moon
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Registered: 2006-03-23
Posts: 9,175

Re: Space Tug - Departure - Arrival - Orbit changes

OASIS Infrastructure Concept Images NASA RASC https://spacecraft.ssl.umd.edu/old_site … asis_pics/ Long-forgotten Shuttle/Centaur https://www.cleveland.com/science/2011/ … ntaur.html
If I recall correct in another thread GW Johnson discussed refueling infrastructure is not in extreme elliptic orbit but for the SpaceTug to move in low orbit GW Johnson also recommend a polar orbit at the moon.
D-Orbit is an Italian company that has successfully worked on the concept. ' D-Orbit Launch and Deployment Services/Space Logistics Company'
https://www.eoportal.org/other-space-activities/d-orbit
I believe one year ago China was testing something and the Chinese had a Shijian-21 debris mitigation satellite docked with defunct Beidou sat.
https://spacenews.com/chinas-shijian-21 … satellite/
Solving space junk problem may require lasers and space tugs
https://news.yahoo.com/solving-space-ju … 23207.html

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