# All Questions

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9 views

### LVLH frame based on inertial velocity or relative (ground) velocity?

The LVLH frame is widely used in rockets during launch. The space shuttle crew used it in its attitude readings beginning very early after launch, meaning it was very reliable as soon as the rocket ...
33 views

### What was the first satellite with COTS electronics?

Computers and memory, radios, cameras, light sensors, temperature sensors, accelerometers & gyros1, power supplies, power conditioners and converters and battery interfaces can all be put together ...
41 views

### How big would a QR code have to be on my roof for a satellite to be able to scan it given today's allowable resolution?

Say, using the Planet Labs satellites Thank you
73 views

### What if we launched rockets from space using the slingshot method and centripetal force? Would that be possible?

Would we have to build a orbiting launch station that uses centripetal force to launch the rockets? Or a station that freely floats through space not in a planets orbit? Would something like this ...
95 views

### Was the famous SPICE package of programs, utilities and data kernels named after “Melange” found on the planet Arrakis?

This question is NOT about a fictional planet: This question is about NASA JPL history and the naming of SPICE. It is not primarily about the fictional planet Arrakis nor the fictional drug Melange ...
2k views

### Why isn't SpaceX's Starship trial and error great and unique development strategy an opensource project?

This may be dumb (for reasons I cannot grasp) and even not related to space exploration at all, so feel free to vote to close this one. Yet obviously some large community of space enthusiasts is ...
42 views

### What order were space shuttle roll-pitch-yaw angles displayed in?

The space shuttle had a digital readout of roll-pitch-yaw angles in a chosen frame (inertial, LVLH, or reference). What rotation sequence did they assume in that digital readout? Was it roll-pitch-yaw?...
155 views

### “Reading 486” air speed from Challenger disaster: What units?

Some of the last words from the doomed Challenger crew were "reading 486," which the Boston Globe describes as a routine air speed callout. Would this be vehicle speed relative to the air, ...
618 views

### Space shuttle orbital insertion altitude for ISS rendezvous?

What altitude did the space shuttle normal target for orbital insertion on ISS rendezvous missions? In the likely case that there isn't a single typical number: can you give a number the shuttle might ...
52 views

### What would space shuttle digital attitude display show during flipover

The space shuttle used quaternions for navigation, guidance, and control which don't suffer from the singularities that affect euler angle sequences. Yet, the attitude indicator had a digital readout ...
29 views

### Timeline of record multiple satellite launches

The Transporter 1 mission has placed 143 satellites into low orbit in one go. The previous record was held by the Indian ISRO PSLV C37 mission with 104 satellites in 2017. Where can I find a complete ...
65 views

### How to know in which quadrant is the RAAN?

Having found the right ascension of the node, for example, \begin{align*} \boldsymbol{\Omega} &= cos^{-1}\frac{N_X}{N} \\ &= \underline{15.60^\circ} \end{align*} How do we know in ...
184 views

### How much will it cost MrBeast to send a HDD alongside the new moon rover?

I saw this mrbeast stream where you could send a pic to the moon and he promises that he has made arrangements with nasa that they (nasa) will pack it up with a new rover to the moon to be launched ...
272 views

### How can firing a Space Shuttle OMS engine below 21 km cause its nozzle to “collapse”?

This answer to Can the space shuttle use OMS engines during landing? says: No and quotes Section 3.7 of the Orbital Maneuvering System Workbook; OMS 21002 October 10, 2006, Final version, USA006500 ...
403 views

### Can the space shuttle use OMS engines during landing?

Can the space shuttle use its OMS engines if the shuttle is short during the runway approach? Is fuel available for use in such a situation and will the engines provide reasonable thrust to get to the ...
22 views

### What is the inlet and outlet pressure of Merlin LOX/RP-1 turbopump?

I got the inlet and outlet pressure of Saturn V engines turbopumps here, but I couldn't find the turbopump pressure of the Merlin engine of Falcon 9.
23 views

### Are TVC pyros broken before, during, or after engine ignition? [closed]

I've read that TVC actuators are kept locked with pyro bolts which detonate when the engine is ready to fire. But do they detonate just before ignition, at the same time as ignition, or shortly after ...
78 views

### Displaying spacecraft attitude from rotation matrix or quaternion?

Navigation and guidance systems generally use rotation matrices or quaternions to uniquely specify 3D rotations. But these are not the least bit intuitive, so we like to convert them to Euler angle ...
101 views

### How do pressure-fed engines stay cool?

Does anyone know how pressure-fed/hypergolic rocket engines cool themselves down? Do they regenerativly cool themselves? Thanks!
28 views

### Space Shuttle I-Loaded Acceleration Profiles?

Documentation on the space shuttle's GNC systems mentions that in the high-Q region, the flight control system compared the actual transverse accelerations with I-Loaded acceleration profiles, then ...
65 views

### What is range angle?

In several papers on powered explicit guidance, I've come across the term "range angle." I'm familiar with inclination and azimuth angles, but range angle is new to me. A quick search gave ...
130 views

### Starship deceleration during belly flop?

Was just wondering what level of deceleration did they get during that belly flop manouver? Updated: Hiya, you're all correct, and I was a tad vague in my question! What I'm after is the vertical ...
1k views

### Is it always one nozzle per combustion chamber and one combustion chamber per nozzle?

When I read about engines like the RD-170 they might have a single turbopump feeding multiple combustion chambers, and each combustion chamber has its own nozzle. Is there, or would it be reasonable ...
37 views

### Design a cold gas ACS nozzle

I have the total thrust required to be F=16.9 KN. I am using nitrogen gas, and the stored temperature in the nitrogen gas cylinder is 155 bars with a temperature of 325k. How would I design the nozzle ...
49 views

### What is the first time that two satellites were launched together as the same payload?

Below I've assembled some research into the question of which launch is actually the first to carry two satellites into orbit, but so far I think the results are inconclusive. So despite there being ...
33 views

### Active magnetic protection against cosmic radiation - Can anyone provide articles or summarize the latest developments?

A European project purports to have a practical magnetic shield for cosmic rays, based on four MgB2 toroidL coils1 oriented around the spacecraft like the lines of longitude around the globe. I can't ...
96 views

### For deep space missions, how thick must the water filled layer within the ship's hull be to effectively shield against cosmic rays? [closed]

Initially i proposed a 27cm thick barrier. But im not really sure thatll be enough
65 views

### Was there ever serious speculation that some terrestrial deep sea life might be of alien origin? [closed]

According to this usually fairly well-researched youtube channel, There are also some truly strange critters in the deep sea and some so strange it's been speculated they were alien, and not always ...
155 views

### What is the Best position of an object in geostationary orbit relative to the launch site for rendezvous using GTO?

So let's say we have a space station or spacecraft in GEO, and I want to get another spacecraft to it from earth's surface on a direct geostationary transfer orbit, i.e. no waiting about in LEO for ...
53 views

### What is the practicality of using sub-cooled propane in combination with HTP in an amateur engine design? [closed]

Using sub-cooled propane, at approximately -90°C (b.p. -42°C at STP) in combination with >80% hydrogen peroxide, can any meaningful gains be made, and could the mixture be used in a low budget ...
66 views

### How would an n-body numerical orbit simulator use hierarchy in its Jacobian?

This question is about techniques to calculate orbits. The Github post On the dynamical stability of Principia's modified Jool system (cited in this answer) says: Principia computes the trajectory of ...
165 views

### RS-25E cost estimate but sentence confusing (approximately: help; maybe)?

So recently someone found out that the industry studies for SLS had been FOIAed by a site called government attic. While the other studies are interesting in their own right (check them out honestly), ...
49 views

### Minimum delta V required to return a piece of metallic asteroid 16 Psyche to Earth?

Suppose somebody sent a rover to Psyche 16 and found massive concentrated deposits of platinum-group metals near the surface, and turned it into a 10 ton sphere of platinum/iridium/osmium/gold alloy ...
23 views

### How do you find the thrust of a solid cylinder given mass, roll rate, and moment of inertia in space?

total mass = 275 kg, roll rate = 16.4 deg/s, moment of inertia I = 34.375 kg/m^2. I'm trying to determine the maximum thrust a ACS needs given a roll rate in the roll direction. Assume no gravity. ...
76 views

### Liquid fueled suborbital rockets?

Which suborbital (sounding, balistic, amateur or else) rockets use or used liquid fuel? I could find (with help from A. Rumlin) New Shepard - Blue Origin - RP-1 Spica - Copenhagen Suborbitals - ...
15 views

### With C3 = 16 km²/sec², How much ∆V is required for the probe to enter a Mars orbit with periapsis at 100 km and Apoapsis at 1000 km?

A Mars probe leaves earth with a Characteristic energy (C3) of 16 km²/sec². How much ∆V is required for the probe to enter a Mars orbit with periapsis at 100 km and Apoapsis at 1000 km?
3k views

### Are there any hand-sized rocket engines?

Are there any rocket engines that are small and light enough to be held in one or both hands? Gas, liquid and hybrid designs are fine but solid motors are excluded (with the exception of solids that ...
106 views

### Missions failed before launch

The Falcon 9 - Amos-6 - mission in 3 September 2016 failed before launch - the rocket exploded during the static fire test. Some lists contain such missions but others don't - like for example ...
29 views

### Still trying to understand “knee” in Earth's atmosphere >100 km; if pure Ne or Ar would it still be there when MFP exceeded scale height?

There is currently one answer to How many solar system bodies have "knees" in their atmospheres? that points out that somewhere above roughly 100 km turbulent mixing drops off (thus the name ...
17 views

### Long March 3C/E specification

From what I can see, it looks like the Long March 3C is pretty much a Long March 3B with two strap-on boosters instead of four. The Long March 3B/E is actually a Long March 3B with a bit higher ...
43 views

### rocket trajectory simulation in inertial frame, with drag

I created a rocket trajectory simulator and optimizer using the following equations of motion for a non-rotating frame of reference $$\dot{v} = \frac{T \cos \varepsilon - D}{m} - g \sin \gamma$$ v \...
168 views

### Guidance vs. Navigation vs. Estimation

I'm still confused over what exactly falls under the scope of Navigation, Guidance, and Estimation systems. Say I have a bunch of IMUs and use them to determine my position and orientation and my ...
79 views

### Does Falcon 9 perform static fires before every launch?

Before launching every Falcon 9 rocket, is SpaceX performing a Wet Dress Rehearshal (WDR) and a static fire? If not before every launch then is it doing it before every first launch of a new booster? ...
83 views

### What specific device failed, causing engine #4 in the Core Stage Green Run to report a Failure Identification?

(See this Q&A for context if needed: What is a "Major Component Failure" referred to in news reports about the unsuccessful Space Launch System core stage test firing?) In the post-test ...
74 views

### Largest number of successful consecutive launches by rocket model?

Which orbital rocket model has the largest number of successful consecutive missions? Active and inactive models. Falcon 9 just reached 77. Delta II reached 100. Is there any other model with a better ...
44 views

### What is the purpose of eccentric, parabolic and hyperbolic anomaly?

I am currently reading David Vallado's 'Fundamental of Astrodynamics and Applications' and I have this doubt on the 2nd chapter named 'Kepler's Equation and Kepler's Problems'. Although I understand ...
90 views

### The mission to Pluto? [closed]

Exactly 15 years ago an uncrewed NASA spacecraft by the Name of New Horizons blasted off on a 3 billion-mile journey to Pluto from Cape Canaveral Air Force Station at a speed 36,400 mph (16.26 km/s) ...
110 views

### How was an emergency landing site at Diego Garcia used during the Apollo program?

On the current Starlink mission as the 2nd stage passed over the Indian Ocean I heard mention of contact with a ground station at Diego Garcia. Checking that article I found the subsection Space ...