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This topic is offered for NewMars members who might wish to keep up with plans for launches to Mars, based upon the opportunity to take advantage of the Hohmann Transfer Orbit between Earth and Mars.
These launch opportunities occur approximately every two years, and the next one is coming up in October of 2024
This topic is available for reports of any plans to catch the window in October of 2024.
Time is getting ** really ** short for any new initiative.
A balloon experiment could be flown this cycle, if an existing launch plan can accept the additional burden.
That burden would include the mass of the experiment, the costs of integration, and the challenges of integration of a new experiment into an existing plan.
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This post is reserved for an index to posts NewMars members may contribute over time.
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The web site at the link below shows that we are close to the opening of the next Hohmann Transfer window ...
https://www.reddit.com/r/SpaceXLounge/c … ?rdt=47334
The web site lists Q4 of 2024 as the next available launch window.
October 17th and November 2nd are given as examples of possible launch times.
This topic is available for NewMars members who may find news about any launches that are in preparation, as well as any that actually occur as planned. I am only aware of one planned launch but there may well be more.
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I asked Google to show any flights planned for the upcoming Hohmann Transfer window to Mars, and it found this one:
NASA's Escape and Plasma Acceleration and Dynamics Explorers (EscaPADE) mission is scheduled to launch from Cape Canaveral on October 13, 2024, using a Blue Origin New Glenn-1 launch vehicle. The mission will use two identical spacecraft to study how the solar wind interacts with Mars's magnetosphere and how this interaction causes the planet's atmosphere to escape. The mission will also investigate how solar radiation has stripped away the planet's formerly thick atmosphere over time.
The EscaPADE mission will use a Hohmann Type II transfer orbit and will reach Mars in September 2025. The orbits will be adjusted over about seven months until they reach their nominal science orbits in April 2026.
This appears to be an official NASA web site for the mission:
https://nssdc.gsfc.nasa.gov/nmc/spacecr … er%20orbit.
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This is a highly-experimental mission. It is the first attempted flight for Blue Origin's New Glenn rocket. Most first flights do not go well. But if this one does go well, then (maybe) there's a twin probe set heading to Mars.
GW
GW Johnson
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"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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This is a follow up on the mission described in posts 4 and 5...
This post is inspired by recent updates from Void in another topic, including a link to an episode of the Angry Astronaut that included an animated graphic of a Hohmann Transfer.
I asked Google for the status of the ESCAPADE mission...
AI Overview
The Escape and Plasma Acceleration and Dynamics Explorers (ESCAPADE) mission, originally planned for launch to Mars in October 2024, has been delayed indefinitely.
Reason for Delay:
NASA announced in September 2024 that the mission would not proceed with its planned October launch.
The primary reason for the delay was related to the Blue Origin New Glenn rocket, which was scheduled to carry ESCAPADE on its inaugural flight.
NASA concluded that the New Glenn rocket would not be ready in time for the October 2024 launch window.
The decision to delay was also made to avoid potential complications and costs associated with potentially having to de-fuel the spacecraft in the event of further launch delays.
Current Status and Future Plans:
The earliest possible launch window for ESCAPADE is now spring 2025.
NASA and Blue Origin are currently reviewing future launch opportunities.
While the original launch and trajectory plan has been altered, the mission's scientific goals are expected to remain similar.
Engineers have confirmed that the new trajectory and potential for increased radiation exposure during the extended cruise phase will not pose a problem for the spacecraft.
The twin ESCAPADE spacecraft, which had been at the launch site in Florida, have been returned to Rocket Lab's facility in California.
In summary, the ESCAPADE mission's October 2024 launch to Mars was postponed due to issues with the readiness of the Blue Origin New Glenn rocket. The mission is now targeting a launch no earlier than spring 2025, and while the launch trajectory and timeline have changed, the core science objectives remain intact.
We are now in summer of 2025, and the Blue Origin mission has still not happened.
Because we are past the Hohmann Transfer window in 2024, the mission can proceed despite the late start, but more energy will be required to complete the flight. I expect that analysis of the ellipse required would show that more velocity is required at exit from LEO, and more energy is required to match the velocity of Mars in it's orbit.
For GW Johnson:
Is the spreadsheet of the Traditional Course capable of adapting to the late start for the Blue Origin mission?
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And here is news from June 6th, about a possible new opportunity for ESCAPADE.
https://spacenews.com/nasas-escapade-co … new-glenn/
NASA’s ESCAPADE could launch on second New Glenn
by Jeff Foust
June 6, 2025ESCAPADE satellites
The twin ESCAPADE spacecraft at Rocket Lab's factory before shipment to Florida for launch. Credit: Rocket Lab
WASHINGTON — A NASA Mars smallsat mission bumped from the first launch of Blue Origin’s New Glenn is tentatively set to fly on the second New Glenn later this summer.
A line in NASA’s fiscal year 2026 budget proposal, released May 30, provided the first public indication that NASA’s Escape and Plasma Acceleration and Dynamics Explorers, or ESCAPADE, mission will launch on the second New Glenn.
“Due to delays in the development schedule of the Blue Origin New Glenn launch vehicle, NASA is in the process of establishing an updated schedule and cost profile to enable this mission to ride on the second launch of New Glenn,” the document stated. “The ESCAPADE launch readiness date is expected in Q4 FY 2025.” The fourth quarter of fiscal year 2025 is July through September.
ESCAPADE was originally scheduled to launch in October 2024 on New Glenn’s inaugural launch, known as NG-1, but NASA decided in September to remove ESCAPADE from that flight after concluding that the rocket would not be ready in time before the launch window closed in late October. NG-1 did launch in January, successfully reaching orbit.
The mission has since been working on options to launch on New Glenn in 2025 and 2026, using more complex trajectories that would set up an arrival at Mars in September 2027.
Shannon Curry, a member of the science team for ESCAPADE, said at a May 1 meeting of the Mars Exploration Program Analysis Group that the mission was targeting a launch as soon as this summer and as late as spring 2026. “We’re in conversations with [NASA] Headquarters all the time to iron this one out,” she said.
At that meeting, she declined to comment if NASA was considering alternative launch options for ESCAPADE, deferring the question to NASA. An agency spokesperson said May 6 that NASA was still planning to use New Glenn to launch ESCAPADE and offered the same launch period of summer 2025 through spring 2026 for the launch.
“Blue Origin is managing the launch for ESCAPADE and we’re continuing to work with them on the launch date,” NASA said June 5 when asked about the language in the budget proposal about launching ESCAPADE on the second New Glenn. “The date in our technical supplement is the current no earlier date when Blue Origin will be ready to launch ESCAPADE on New Glenn.”
NASA referred questions about New Glenn to Blue Origin. The company did not respond to questions about the status of the vehicle’s second launch.
Dave Limp, chief executive of Blue Origin, said at a conference in February that he expected the second New Glenn launch to take place in late spring. At that time he said the company was considering several options for the payload on that launch, which he did not disclose, but added that if no customer payloads were available the company would consider flying a mass simulator on the launch.
Blue Origin has not provided any recent updates on plans for the second launch as summer approaches. In a filing with the Federal Communications Commission in early May, the company requested approvals to use certain frequencies for the ground test campaign for the second New Glenn launch as well as the launch itself. The start date for the request was July 1, ruling out a launch before then.
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Here is a JPL web site that offers a nice set of animations showing the Hohmann Transfer orbit.
The site is set up as an aid to teachers, and examples are provided of teaching aids that might help to explain the subject.
https://www.jpl.nasa.gov/edu/resources/ … h-windows/
The site does not appear to attempt to deal with the question of relative velocities when the space craft arrives at Mars orbit.
***
In a separate inquiry, I picked up the velocity of Mars in it's orbit as near 24 km/s and the velocity of a space craft arriving on a Hohmann Transfer orbit as 21 km/s (or so). The difference of (about) 3 km/s must be made up by acceleration of the space craft to match the orbital velocity of Mars.
The gravitational pull of Mars can be estimated by it's escape velocity.
Google estimates the escape velocity of Mars as (about) 5 km/s
A simplistic look at this situation would add 3 to 5 giving 8 as the km/s change to land on Mars.
Update later: We (in NewMars) have studied this situation before.
If we plan our flight so we enter orbit around Mars, and we chose the approach so we are on the far side of Mars (away from the Sun) then we can take advantage of the orbital speed at Mars.
Quora had a discussion about this:
Thus, the velocity of a spacecraft traveling in a relatively circular low Mars orbit (around 200 km above the surface) is approximately 3,441 m/s.
So by my simplistic view of the situation, the 3.4 km/s of a Mars orbit could be subtracted from the 8 km/s dV change from Hohmann, leaving the influence of Mars gravity to be dealt with.
And not all of the 5 km/s gravity pull of Mars would be in effect because (in this scenario) we have not landed on Mars.
Update: I am happy to report that GW Johnson wrote a reply by email, confirming that 2 km/s dV is about what would be needed to settle into an orbit at Mars if the arrival were planned correctly. The next question I posted to GW was whether the gravity of Mars in this scenario is sufficient to capture the arriving space craft in a very large ellipse with perigee at the altitude of the encounter with Mars. I would expect the capture to occur, because the velocity difference is (about) 3 km/s, and the gravity effect of Mars at (about) 200 km is (on the order of) 5 km/s.
If we are lucky, GW may contribute a follow up to this topic.
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With a little off-line coaching from GW Johnson, I have attempted to phrase a request to Google's Gemini to evaluate the proposition at hand.
Here is Gemini's attempt to show the answer in BBCode:
Subject: Re: Hohmann Transfer Arrival at Mars - dV Calculation
Hello everyone,
I'm happy to share an analysis of the Mars orbital insertion dV, based on a precise scenario we've been discussing. Many thanks to Gemini (AI) for the detailed breakdown!
Here's the scenario and the breakdown of the calculations:
Scenario Recap:
* We've launched from Earth on a Hohmann Transfer, designed to arrive at Mars just outside its orbit, slightly ahead, waiting for Mars to catch up.
* We are NOT using aerobraking.
* Our planned closest approach (periapsis) is at an altitude of 200 km above Mars' surface.
* Our spacecraft's velocity at this 200 km altitude, just before any burn (due to Mars' gravitational acceleration), is estimated at approximately 5 km/s. Let's call this our "arrival velocity" ($V_{arrival}$).
* The desired circular orbital velocity around Mars at 200 km altitude is estimated at approximately 3 km/s. Let's call this our "orbital velocity" ($V_{orbit}$).
* We are trying to confirm an estimated 2 km/s dV needed to achieve orbit.Analysis and Calculation:
The core idea for calculating the delta-V (dV) needed to enter orbit is simply the difference between the velocity we have when we arrive and the velocity we need to be in a stable orbit.
1. The dV Formula:
The delta-V required for orbital insertion is given by:dV = V_arrival - V_orbit2. Plugging in Our Estimates:
Based on the values provided in our scenario:
* $V_{arrival}$ = approximately 5 km/s
* $V_{orbit}$ = approximately 3 km/sSo, substituting these values into the formula:
dV = 5 km/s - 3 km/sdV = 2 km/s3. Verification of Orbital Velocity (V_orbit):
To ensure our estimate for the circular orbital velocity is reasonable, we can calculate it using the standard formula:V_orbit = sqrt(mu_Mars / r_p)Where:
* mu_Mars (standard gravitational parameter of Mars) is approximately 4.2828 x 10^13 m^3/s^2.
* r_p (periapsis radius) is the distance from the center of Mars. This is Mars' mean radius plus our altitude:
* Mars' mean radius approx. 3389.5 km
* Altitude = 200 km
* So, r_p = 3389.5 km + 200 km = 3589.5 km = 3.5895 x 10^6 meters.Let's do the calculation:
V_orbit = sqrt((4.2828 x 10^13) / (3.5895 x 10^6))V_orbit approx. 3454.2 m/sV_orbit approx. 3.45 km/sOur initial estimate of "about 3 km/s" for the orbital velocity is very close to this calculated value of 3.45 km/s, which confirms its validity for our purposes.
4. Verifying Arrival Velocity (V_arrival):
The "effect equivalent to 5 km/s" for arrival velocity ($V_{arrival}$) is also consistent with what we'd expect. This velocity comes from the hyperbolic excess velocity ($V_infinity$) from the Hohmann transfer being accelerated by Mars' gravity. The formula for velocity at periapsis ($v_p$) on a hyperbolic trajectory is:v_p = sqrt(V_infinity^2 + (2 * mu_Mars / r_p))While we don't have $V_infinity$ explicitly stated, a typical $V_infinity$ for a Hohmann transfer to Mars is around 2.6 km/s. If we use this value:
v_p = sqrt((2600 m/s)^2 + (2 * 4.2828 x 10^13 m^3/s^2 / 3.5895 x 10^6 m))v_p approx. 5533.9 m/sv_p approx. 5.53 km/sThis calculated value of approximately 5.5 km/s is indeed "about 5 km/s," which again validates the consistency of the provided numbers.
Conclusion:
Based on the precise parameters provided:
* Arrival velocity at 200 km altitude: approximately 5 km/s
* Desired circular orbital velocity at 200 km altitude: approximately 3 km/sThe delta-V (dV) required for orbital insertion is indeed:
dV = 5 km/s - 3 km/s = 2 km/sOur initial estimate of about 2 km/s for the dV needed to achieve orbit around Mars at 200 km is confirmed and aligns perfectly with these parameters and fundamental orbital mechanics principles.
Hope this detailed breakdown is helpful for the forum!
Best regards,
[Your Name/Forum Handle]
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As a bonus question, I asked Gemini what would happen if we do NOT perform the 2 km/s dV burn as we fly above the surface of Mars at 200 km. The answer is a confirmation that Mars would indeed capture the vessel. This means that the shipment of goods to Mars does NOT require a propulsion burn at Mars, except for very small trajectory adjustments. The shipment will assume orbit around Mars, and it can be collected by Mars residents at a convenient time.
Subject: What Happens if the Mars Orbit Insertion Burn Fails?
This is a fantastic follow-up question that addresses a very real mission contingency. Let's break down what would happen if our planned 2 km/s orbital insertion burn at Mars fails.
The Short Answer:
If the burn fails, the spacecraft will almost certainly be captured by Mars' gravity. It will not simply fly past the planet and continue into heliocentric space. Instead, it will enter a highly elliptical orbit around Mars, with a very high apoapsis (the farthest point from Mars in its new orbit).Why Capture Occurs:
Recall our previous discussion:
* Our spacecraft arrives at 200 km altitude with a velocity ($V_{arrival}$) of approximately 5 km/s. This is the velocity *after* being accelerated by Mars' gravity as it falls towards the planet.
* The circular orbital velocity ($V_{orbit}$) at 200 km altitude is approximately 3 km/s.
* The burn's purpose was to reduce our speed by 2 km/s (from 5 km/s to 3 km/s) to achieve this circular orbit.The Key Concept: Escape Velocity
For any celestial body, there's a specific velocity at any given distance from its center called the "escape velocity" ($V_{escape}$). If an object's speed at that distance is greater than or equal to the escape velocity, it will escape the body's gravitational pull and fly off into space. If its speed is less than the escape velocity, it will be gravitationally bound and enter an elliptical (or circular) orbit.
The formula for escape velocity from a planet is:
V_escape = sqrt((2 * mu) / r)Where:
* mu is the standard gravitational parameter of the planet (for Mars, approx. 4.2828 x 10^13 m^3/s^2).
* r is the distance from the center of the planet.Let's calculate the escape velocity at our 200 km altitude (which is r = 3589.5 km or 3.5895 x 10^6 meters from Mars' center):
V_escape = sqrt((2 * 4.2828 x 10^13) / (3.5895 x 10^6))V_escape = sqrt(2.3864 x 10^7)V_escape approx. 4885 m/sV_escape approx. 4.885 km/sI have removed text from the reply beyond this point. Gemini wandered away from the tight focus needed.
It should be possible for an enterprising NewMars member to compute the ellipse that would result from the scenario on offer here.
I would be interested in seeing the length of the axes and the period of the capture orbit.
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Here is a reply from GW Johnson via email:
Sure, you can use my reply. Or this one. Or both.
I think you have it now. And the answer is "yes", you enter into an extended ellipse if you don't slow all the way down to circular orbit speed. That is the same as the tug-assist orbital departure and arrival orbital mechanics. I've already run those numbers for both Earth and Mars, and determined the different events sequences for departure vs arrival. I ran them with the orbits spreadsheet for the "orbits+" course set.
The interplanetary transfer ellipse and the orbit of the planet are 2-body analysis results, for which there are equations (and spreadsheets). But as the craft approaches Mars, there is the 3-body problem that only finite difference codes can fully address. The actual craft trajectory gets bent in 3-D space, but the end result is a location somewhere around the planet at the desired altitude, with a speed you can figure from the Vnear-Vfar approximation (which is not just mine, everybody in the business uses it). You just cannot know exactly where around the planet that point is, without that 3-body code. The similar problem going to the moon produced the figure-8 trajectory used by Apollo to enter low lunar orbit on the backside of the moon, in a retrograde direction.
At about 300 km altitude above the surface of Mars, the circular orbit speed is 3.4-something km/s, almost but not quite 3.5 km/s. The escape speed at that altitude is 4.9-something, not quite 5.0 km/s. Off Hohmann at average planetary distances, you arrive at that 300 km altitude at about 5.4 km/s. The faster your decelerated speed between that 3.4-something circular speed, and not quite the 4.9-something escape speed, the more extended your arrival ellipse will be. Its periapsis will be that 300 km. Its apoapsis can be quite far out, even past Deimos, if your final periapsis speed is close to escape. Too far out is unstable, the sun can sweep you out of your Mars elliptical orbit.
If your mission target is low circular orbit, then without a tug, there is still the dV to get from ellipse periapsis speed down to circular speed. You might as well just burn straight into circular: it's the same summed number either way! The only ways to realize the potential savings of elliptical arrival are (1) to have a tug that can assist you, or (2)do a small burn at apoapsis to lower your periapsis into the atmosphere, for repeated-pass aerobraking. You will need at least some heat shielding if you choose option (2). and intend to get the effect in days instead of the best part of a year. And you will have to make another burn once your apoapsis is lowered to 300 km, to pull your periapsis up out of the atmosphere, to that same 300 km.
There will be no tug infrastructure to assist you, during the early years of trips to Mars. Until there is, your only overall mission choices are only direct landing or entering some orbit about Mars.
GW
I am looking ahead to a time when a business (or several) will be wanting to ship barges full of supplies to Mars, and not have to worry about massive dV upon arrival. The packages will need very small propulsion devices for course adjustment, along with communications devices for tracking.
I expect the cost of fuel created at Mars (to retrieve the shipments) will be substantially less than for shipment all the way from Earth.
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The AI in post 10 gets it wrong because the problem posed to it is set up wrong. You fed the AI bad numbers.
If you come off a Hohmann transfer at average planetary distances, the difference between your 2-body apohelion speed and the 2-body speed of Mars about the sun will fall in the 2-something km/s range. It supposedly is your speed with respect to the planet. However that difference does not include the 3-body effect of Mars's gravity upon the craft as it approaches Mars orbit distance just as Mars arrives there, too. 2-body analyses can be done with actual equations, in a spreadsheet. 3-body problems can ONLY be figured with finite-difference computer odes. There are no equations, other than the differential equations of motion.
There is a conservation of mechanical energy approximation which will adjust the 2-body-based difference of 2-something km/s into the 3-body-affected speed as you reach the desired low altitude about the planet. You need to know the escape speed at that altitude. For 300 km at Mars, it is right at 4.9 km/s. Pick any number you want between 2 and 3 km/s for the 2-body difference and call it Vfar. The number you seek we will call Vnear. The approximation (which gets very good results!!!) is Vnear = sqrt[vfar^2 + Vesc^2].
It almost doesn't matter whether you use 2 or 3 km/s for Vfar. Using Vesc = 4.9 km/s, you will get a number pretty close to 5.4 km/s for Vnear, which is ALWAYS inherently larger than Vesc, as the plus sign inside the square root in the approximation formula so very clearly indicates. You WILL ALWAYS be moving at a speed greater than local escape speed, as you pass by Mars at 300 km! YOU WILL NEVER CAPTURE INTO AN ELLIPSE, THEREFORE!
You can capture into an ellipse if you slow to any speed less than local escape speed. The closer that value is to escape rather than circular, the more extended your ellipse will be. For, say, 4.8 km/s (100 m/s less than escape), the min dV = 5.4 - 4.8 = 0.6 km/s. For going straight into circular, it is 5.4 - 3.4 = 2 km/s. Once in orbit about Mars, everything is a 2-body problem again.
If you go into the ellipse using 0.6 km/s, you still have to make a periapsis burn to circularize at 300 km, if that is what the mission requires. That would be dV = 4.8 - 3.4 = 1.4 km/s. The initial 0.6 km/s burn to get onto the ellipse, plus the 1.4 km/s burn to circularize, adds to THE VERY SAME 2 km/s burn if you just decelerate straight into circular!!!
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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The pdf at the link below contains a five page study on Transfer Orbits in images with words to explain the diagrams.
https://www.dropbox.com/scl/fi/rbcd3k9l … fgwx8&dl=0
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