# Tag Info

26

Why hasn't the small-lift launch vehicles completely replaced by the medium and heavy-lift launch vehicles? Because small launchers can provide several things: A small launcher is much cheaper than using a large launcher to launch a single small satellite. a dedicated launch, instead of having to share a launch which reduces your choice of final orbits a ...

23

Its not a mere formality it is unfortunately one of those things that makes satellites expensive. However I wouldn't be surprised if all kinds of nominally incompatible materials have already been exposed in cubesat missions. EDIT This report might be useful background: NASA contamination control report 1996 It could in principle affect other parts of the ...

21

gerrit is right, the most important restricting factor for the life-time in orbit is the orbit of the launcher. But I think a few details could be useful, anyway ... Although cubesats are fairly similar (well, cubes), there are a few differences. There are 1, 2, 3, 6 and 12U cubesats. Besides, a lot of projects do not care about the weight restriction (one ...

18

Most cubesats are student projects that they want to have for only a matter of a few months at most. That being said, the Pi would likely be very susceptible to Single Event Upsets, SEUs, and thus might have some serious issues. It is low cost, and would fit inside of the spacecraft, with a bit of shielding it might be okay, but only for a few months for a ...

17

Yes, we know of a least one CubeSat that has flown (and is currently flying) with an active propulsion system. Specifically a steam powered warp drive. STRaND-1 (Surrey Training, Research and Nanosatellite Demonstrator 1) was launched aboard PSLV-C20 on February 25, 2013. Developed jointly by the Surrey Space Laboratory and Surrey Satellite Technology Ltd, ...

17

I think most of this can be seen from the picture: There are two antennae made of spring(blue) steel, so will automatically return to a straight line once the far end is released -the near end of one is attached to the white block on the right hand side, and the other to the white block on the top left. The end is glued to an orange piece of string, which ...

15

All cubesats that I have personal knowledge of (including the Planet Labs fleet) were launched with partially charged batteries, typically at around the 50% level that minimizes degradation in storage. The launch providers do typically impose fairly strict rules requiring redundant physical interlock switches to prevent any electronics from being energized ...

15

Apparently lining up a lot of smallsats for a dedicated big rocket launch is like herding cats. Delays on any of the smallsats delay the overall launch. Hence SpaceX's recent announcement that their planned Falcon 9 dedicated smallsat launches will launch on schedule regardless of whether all the satellites are ready. https://spacenews.com/spacex-says-...

14

I found a great answer to your question from Robert Frost, Instructor and Flight Controller at NASA! It appears that the difference is one device has a dual purpose of stabilization as well as attitude control. The other has no active stabilization capability. Both are used for attitude control. Both are heavy flywheels. Both work by creating a ...

14

This photo confirms @MikeBrockington's answers: dual antennas, nested when stowed, opposed when deployed. A later photo at https://www.up.edu.ph/index.php/with-maya-1-flying-high-dost-up-aim-to-train-more-satellite-builders/ shows that the antennas are about 20 cm long. But a poster in the background of that photo shows another cubesat mock-up with ...

13

Check with Kentucky Space. They have KySat-2 on orbit using passive magnetic control. Here is a description of the control system from their website: Passive Magnetic Stabilization: KySat-2 is equipped with a passive attitude control scheme known as Passive Magnetic Stabilization. This passive control technique uses permanent magnets and magnetic ...

13

There are a few recorded incidents of spacecraft contamination caused by outgassing. On Cassini, some haze was noted in test photographs after launch; this was thought to be due to some outgassing material near the camera itself. It was removed after several attempts using the camera's heaters: Cassini Imaging Science report, 2004, p.475-476. On Stardust, ...

12

After days of Googling this, I am going to say that it appears none have. It's worth noting that there are dozens of propulsion systems for cubesats (Google 'cubesat propulsion'), but I was able to turn up nothing referencing any that have actually flown. One would think that if the systems had been used, be it privately or by a university, a result for an ...

12

That depends very much on the launch you're piggybacking with. When you launch a CubeSat, you're entirely at the whim of the launch you're piggybacking on. CubeSats usually don't have propulsion so if it's a low orbit, it may take only weeks before you burn up in the atmosphere. At a slightly higher orbit it may be a couple of months. As most CubeSats ...

12

Engines are under development for CubeSats. For example there's the Electrospray (colloid) thruster which is effectively a low-thrust ion drive. An alternative is to launch from the ISS with a catapult (eg railgun/coilgun) or a small single stage solid rocket. This would give an elliptical orbit, so only part of the time would be spent at the target ...

12

I am assuming you mean by propulsion by the CubeSat itself. Not at the moment! Mostly because of the throughput (thruster lifetime) constraint on small Electric Propulsion (EP) thrusters designed for CubeSats. Right now the leading CubeSat EP thruster is the BIT-3 (this is the thruster that will be used to go to the moon on my answer to your original ...

12

tl;dr There are zero CubeSats in GEO The Union of Concerned Scientists has a great database of satellites orbiting the Earth, the smallest satellite that they have in GEO orbit is the S5 smallsat launched by the ARFL, it has a launch weight of 60kg definitely in the smallsat range but much bigger than the largest CubeSats. Bonus! Here are some histograms ...

11

Yes, it’s probably possible, but to determine specific feasible approaches more information is needed about your mission. Key questions: What is the transfer and operational orbit? This information is needed to make analytical predictions about the probability of single-event-effects (SEE) and the total ionizing dose (TID) as a function of mission time. ...

11

Let's say you have a 6500kg piece of equipment you want to launch into space, but your rocket design can only lift 2500kg to the desired orbit. You can: Build five of these Strap them together Put said piece of equipment on the nose of the middle one. Launch That's already worse than designing a new rocket, but at least it cuts down on R&D time. The ...

11

The temperature development of a satellite in LEO depends on a variety of factors. How (quickly) does the satellite rotate, how much is it in eclipse (night), what kind of radiators or internal heat sources exist, etc. When a space mission is being planned, thermal control engineers with dedicated software model the temperature development. What applies ...

10

Launching a CubeSat is by their nature a difficult process. They are designed as a secondary payload, which means that the primary payload dictates the entire launch. There are some programs such as NASA's CubeSat initiative, which provide free rides to educational projects. For commercial launches, data is spotty. One CubeSat reportedly launched for 100k (...

10

RAX and RAX-2 and possibly other cubesats launched by the University of Michigan (I can't remember at the moment) used fixed neodymium based magnets on their Z+ axis. Hysteresis was added to dump any residual momentum after P-Pod ejection. On the RAX missions, the magnets then were used to orient the satellite vertically over the poles where the science ...

9

I was able to find a few requirements for CubeSats that are based upon its integration into a larger system which includes a primary payload (all instances of primary payload are bolded in quotes below, emphasis mine): CubeSats shall not present any danger to neighboring CubeSats in the P-POD, the LV, or primary payloads: 2.2.1.1 All parts shall ...

9

In general, you want as simple of an OS for any embedded systems application. You want as few features as you can get away with. You are less likely to run into problems that way, don't really need all of the features, and it'll reboot quicker, and use less memory. Two things you want for sure. You want a realtime operating system, you probably want ...

9

TL;DR: The medical accelerators are not suitable. There are basically two effects of radiation on electronics: Single event upsets (SEUs) RAM Memory cells are usually small capacitors (caps) which are charged or not to represent a 1 or 0. If an ionizing particle crosses the dielectric between the cap plates, it forms a channel of ionized, and so ...

9

For your specific example, the answer is cost. Nobody is going to spend hundreds of millions (or even just 1% of that) just to prank a community of astronomers. For other examples? What stops China or Russia from launching a set of rockets to destroy GPS satellites, or military communication satellites? Neither country wants to initiate World War III. ...

9

It's expensive because of the quality requirements. Material cost is small, low demand is a factor but a structure that size can be made much cheaper than this. The main cost factors are : The design has to be qualified for use in space, this requires testing. So the R&D cost is high. Low demand means you have to amortize this cost over a small ...

9

For ISRO we have revenue details on few small satellites launched between 2013 to 2015 through an official response in Indian Parliament PDF VELOX-1 (3U) satellite from Nanyang Technological University of Singapore was launched on 30 June 2014 aboard PSLV-C23 (core alone configuration) to a 660 km Sun-synchronous orbit for €140,000 as a ride-share. Four ...

9

Here is a way to start. Choose an altitude or height $h$, say 400 km (if it's deployed from the ISS) Choose a required spatial resolution $d$ on the ground sufficient to see what it is you'd like to see, say 2 meters. Converted to an angle that's $d/h =$5E-06 rad or about 1 arcsec. Choose a wavelength $\lambda$. Middle of the visible band would be ...

9

Radiation shielding in a cubesat (and spacecraft in general) is a tricky thing because radiation shielding adds mostly negative factors to the satellite. In general, the heavier your shielding is and the larger it is, the better it will work. Both of these are obviously no-go for a satellite that's supposed to be as light and as small as possible. This ...

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