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7 votes
2 answers
258 views

How can Artemis 1 take so much longer for Earth-Lunar transit than the Apollo missions did?

The Artemis I mission will take 8-14 days to get from Earth to the Moon. Apollo 11 only took 3 days. Similarly the return will be 9-19 days for Artemis I and just over 2 days for Apollo 11. Why is the ...
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  • 11.9k
6 votes
1 answer
371 views

Satellites - predominant apparent motion?

Recently, while foolin’ around with Stellarium, and checking out its simulation capabilities, I recorded some satellite activity. Sped up ~30x, here are about 12 minutes of simulated sky on March 31, ...
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  • 915
5 votes
2 answers
128 views

Spacecraft localization beyond Earth orbit

How does a spacecraft localize itself after leaving earth orbit? In robotics you can either use known broadcasting information or do real-time position tracking(some type of SLAM) but I suspect that ...
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2 votes
2 answers
157 views

JWST - batteries?

I am interested in how batteries might be used on the JWST. A few questions come to mind: Does the JWST have onboard batteries? If so, What kind of batteries are they? Are they rechargeable? If ...
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  • 915
6 votes
1 answer
165 views

What is the time sequence for SRB burn-out and separation?

I understand that SRBs cannot be throttled or shut down, they need to "burn out". Since they are often used in pairs, I assume there is a statistical spread in the burn duration of the two ...
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  • 6,410
14 votes
1 answer
1k views

Black/White patterns on SLS boosters, fairings - Are these still roll patterns

The main purpose of the large black/white patterns on many of the early rockets was to make it easier to spot whether the rocket is rolling. The pattern on the Saturn V was changed to avoid picking up ...
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7 votes
1 answer
183 views

How many cargo flights are needed before Starship can carry people?

I have seen mention that the Starship will need to have a track record of a certain number of flights before it can carry people. I suppose NASA sets this number. I don't know if it's an absolute ...
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2 votes
2 answers
62 views

Mars Insight probe solar panels - could or are they being used to collect some types of surface illumination data?

A 31 March 2022 news item, Mars more volcanically active than we thought, marsquakes hidden in NASA Insight data suggest, states that in relation to measuring of seismic data, A major source of noise ...
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  • 10.5k
16 votes
2 answers
2k views

Was the Saturn V assembly carried out on the crawler-transporter or on the VAB's ground floor?

Were the Saturn V(s) assembled in the Vehicle Assembly Building (VAB), on the Crawler transporter or were they assembled on the ground and then kept over the transporter to be taken to the launch pad? ...
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  • 3,190
3 votes
1 answer
104 views

Targeted Sub-Orbital Optimization Problem

I was messing around with some orbital dynamics for a simulator I am working on, and I came across a snag that I have not been able to figure out. Specifically, I am trying to minimize the required ...
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  • 121
13 votes
1 answer
2k views

If Beagle 2 had been successful, would it have done anything (in terms of finding out about Mars) that has not been done since?

Based on the scientific equipment on Beagle 2 and the planned or possible activities/experiments is there anything it would or could have done that has not been done since? In other words, if Beagle 2 ...
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29 votes
2 answers
4k views

Ultimate fate of rocket propellant in space?

For many trajectories using engines with moderate ISP such as chemical or nuclear-thermal rockets, the exhaust velocity vector of various space operations is such that the rocket exhaust will end up ...
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  • 7,716
3 votes
2 answers
256 views

Solid Core Antimatter Engines: Do they have a point?

On the graph discussed in this question, I was surprised to see "antimatter" listed as one of the engine types... with a disappointing performance equal to solid-core nuclear thermal rockets....
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  • 7,716
3 votes
1 answer
179 views

Is this a plot of Isp vs propellant mass fraction for a SSTO vehicle?

Whilst trying to find some information on SSTO designs, I came across this chart: It was used in an ancient forum thread by as part of an SSTO discussion, but the poster didn't cite the paper they'd ...
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9 votes
1 answer
262 views

How fast are Ingenuity's knees wearing out?

Each leg of Ingenuity has what I'll call a knee. After just a few flights, on 2021 May 10, NASA wrote: By plastically deforming and fatiguing as it absorbs energy, this flexure acts much like the ...
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8 votes
1 answer
756 views

Are JWST displayed temperatures equilibrated to stable?

The JWST vehicle temperature displayed on the Where is Webb site seem to have stabilised. They have not noted a change in several days. Is the current temperature, the stable equilibrated values with ...
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  • 1,989
8 votes
1 answer
222 views

JWST - pick-off mirrors?

In the documentation that I’ve been looking through recently, I occasionally come across references and diagrams to “pick-off” mirrors. For example, from this JWST user documentation article, there is ...
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  • 915
4 votes
0 answers
153 views

Were SpaceX's early launches insured?

SpaceX's first three launches (of the Falcon 1) were failures, with the fourth launch being a success. Rockets are generally insured in order to protect the payload investment, but those three ...
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  • 690
4 votes
0 answers
115 views

Reference request: Rocketdyne Document R-3896-4 "F-1 Rocket Engine Illustrated Parts Breakdown"

Various sections of the Rocketdyne F-1 document R-3896 can be found scattered about the web, but I can't find R-3896-4. It's described as R-3896-4 F-1 Rocket Engine Illustrated Parts Breakdown This ...
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5 votes
3 answers
291 views

Is there a database of recent satellite images which will allow me to estimate how much of Mariopol has been destroyed?

In the news I often see satellite images from Maxar Technologies showing a neighborhood or sector of Mariupol to have been destroyed in shelling. However, I would like a more comprehensive view of the ...
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  • 51
10 votes
1 answer
269 views

What happens to the propellant in a wet dress rehearsal?

The Artemis 1 mission is going to do a wet dress rehearsal where the rocket will be filled with propellant and the launch sequence will continue until almost the last second. The launch sequence will ...
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2 votes
0 answers
81 views

How to calculate laser link spot size

In the reseach paper " A laser link from lunar surface..." , chapter 2.1.3.: When employing, for example, 20 cm diameter apertures at the transmitter telescopes and considering a carrier ...
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12 votes
1 answer
1k views

JWST - image acquisition - what is a dither pattern?

While perusing one of the sample science programs for the JWST (NIRCam WFSS Deep Galaxy Observations), I came across Step 5, “Decide on dither pattern.” Instead of guessing — or worse, assuming — what ...
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  • 915
3 votes
1 answer
159 views

Calculating the propellant needed for a trip from LEO to Low Mars Orbit at constant acceleration of 1g

I’ve been trying to calculate how much propellant a spaceship from Earth /LEO/ to Mars /LMO/ at constant acceleration of 1g would need. Here’s the data given: dry mass mf=100 t; g=9,81 m/s^2; Isp=...
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  • 73
6 votes
1 answer
824 views

What is this patch worn by the American astronauts?

In this image the American astronauts wear some patches on their chest but what is it? If it is the expedition's emblem, why it is so different from Russian ones?
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  • 3,057
3 votes
1 answer
169 views

JWST - image stabilization?

I am curious about how the JWST accomplishes image stabilization. This paper from 2005 addresses this, but a more general high-level description of the processes would be helpful, from someone with ...
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  • 915
4 votes
3 answers
834 views

Why is Nasa retiring ISS

Is there no need to do experiments in space or have that thing where people can go into space. If they spend so much time building it why just trash it for essentially nothing?
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  • 375
7 votes
1 answer
576 views

What is the current status of ESA/Roscosmos cooperation with regard to the ExoMars Orbiter?

The ExoMars is a cooperative project between ESA and Roscosmos. The second part of ExoMars, the Rosalind Franklin rover, is on hold as a result of the Russian invasion of Ukraine. However an earlier ...
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  • 2,123
12 votes
1 answer
285 views

What does it mean to tune the Saturn F-1 engine to a frequency, and how is the tuning done?

Chapter 10 of Chariots For Apollo remarks the following in discussing the pogo problem of Apollo 4 and 6 and the role of the first stage F-1 engines in that: The mission analysts later discovered ...
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  • 11.9k
22 votes
2 answers
2k views

Diffraction artifact on the March 16, 2022 JWST aligned test image

On March 16, 2022 we were treated to the first image from the JWST of a star, where all 18 segments were aligned and in common focus. What a wonderful photo: (Source: Webb Twitter. Full 18 MP ...
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  • 915
5 votes
1 answer
147 views

Will the Artemis I SLS do a static fire on the pad following rollout?

Following the rollout for the Artemis I wet dress rehearsal, or the rollout for launch, will the core stage perform a static fire on the pad?
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7 votes
0 answers
152 views

How exactly does depressurization work in a solid rocket motor?

How does the extinction process actually work in a solid rocket motor? Most people initially always read that once a solid rocket fuel is ignited there is no way to actually stop its operation until ...
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1 vote
0 answers
93 views

Are there any plans on replacing the shuttle-era RS-25D's during the Artemis III/IV missions?

The last two Artemis missions which use the shuttle-era RS-25D engines will fly in 2025 and 2026. Is there ever a possibility that, in the case that Aerojet Rocketdyne delivers their RS-25Es (or at ...
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3 votes
1 answer
147 views

Why do satellite solar arrays misalign from each other?

Searching for an answer to the title's question, I came across a post (How accurately can solar panels be continuously oriented toward the sun on a typical satellite?), in which someone said that &...
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9 votes
1 answer
1k views

Two-Stage Fully-Reusable Shuttle

In chapter 6 of SP-4221 "The Space Shuttle Decision" they are talking about the fall of the "Two-Stage Fully Reusable Shuttle". In one paragraph they talk about how this Two-Stage ...
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  • 1,064
1 vote
1 answer
112 views

Are the TLE of a satellite computed with the ECI or ECEF?

I want to compute the distance of a certain satellite, given the TLE, to a ground station in the earth. I have the latitude, longitude and altitude of the ground station. But I don't know if the TLEs ...
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1 vote
1 answer
140 views

Could Falcon 9 be Caught by the Orbital Launch Tower?

Would it be possible to catch Falcon 9 with the orbital launch tower by its current grid fins or load points that could be added? If they can do this and then remove the landing legs, would mass ...
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  • 317
2 votes
0 answers
70 views

How do satellites ensure they are orientated towards the Earth to allow of clear connections? [duplicate]

As the title says, How do satellites ensure they are orientated towards the Earth to allow of clear connections, whilst having their solar panels face the sun? I understand reaction wheels are ...
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  • 21
8 votes
2 answers
236 views

Why might Ingenuity be able to fly faster when it flies higher?

A 2022 March 15 NASA press release says: A recent software change already on the rotorcraft frees Ingenuity from its previously programmed maximum altitude of 50 feet (15 meters). The altitude gains ...
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6 votes
1 answer
638 views

how would a multi stage model rocket work? [closed]

I want to make a three stage model rocket. But I don't know how I would detach the used stages. I was thinking of using a remote control would that work?
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5 votes
1 answer
226 views

For launch vehicles, during atmospheric stages, are there constraints on the yaw angle?

Most of the literature discusses the pitch angle and constraints on it, namely, trying to keep it zero for load relief. This leads to the gravity turn. I understand that ideal trajectories are within ...
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11 votes
1 answer
2k views

Where can I download the Soyuz Crew Operations Manual?

Where can I download the Soyuz Crew Operations Manual?
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  • 113
1 vote
1 answer
136 views

Are the reaction wheels' spin rate (their angular momentum) initialized before launch?

It would seem that there should be an inertial reference frame established before launch by imparting a known spin rate to each reaction wheel while the rocket is on the launch pad.
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  • 43
7 votes
1 answer
265 views

Crawler-transporter's ground pressure?

How many PSI does the CT-2 crawler carrying the Artemis I rocket exert on the ground? How does that compare to more conventional vehicles? NASA's fact sheet mentions relevant weights, and that each ...
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2 votes
1 answer
71 views

Antenna wrap material suitable for lunar & cis-lunar environment

I am looking for a wrap (station) antenna for a transceiver (in space/lunar) Not all materials are suitable for the space environment. Does anyone know what wrap antenna materials I can use? I have ...
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1 vote
1 answer
60 views

Good solar absorptivity and infrared emissivity values for non-anodized machined aluminum

Existing sources that I'm looking at show a wide range of possible absorptivity/emissivity values for aluminum: http://www.solarmirror.com/fom/fom-serve/cache/43.html https://www.thermoworks.com/...
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  • 165
32 votes
3 answers
6k views

What would happen to the ISS if the Russians undocked their part?

So... RIA Novosti (Russian media agency) made a video, where they show the Russians ostensibly undocking the Zarya module and the US part of the station falls into the atmosphere (someone was playing ...
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  • 6,488
4 votes
1 answer
99 views

What launch market is the new Shetland spaceport targeting?

The new spaceport on Shetland has now been given planning permission. It is at quite a high latitude (60 degrees north) which will effect the types of launch that are easily achievable so what is the ...
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  • 690
14 votes
4 answers
2k views

What did Charlie Duke mean by "down on the ground"?

When Neil Armstrong gave his iconic report "The Eagle has landed," CAPCOM Charlie Duke responded with, "We copy you down on the ground." What exactly did he mean by this? Was it, ...
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  • 1,143
8 votes
0 answers
107 views

How do people know how big the rocks are in the photos of Titan's surface?

How do people know how big the rocks are in the photos of Titan's surface?
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