The recent article in The Register Ten spacecraft – from Venus Express to Voyager 2 – all tracked same solar flare talks about ten spacecraft noticing the same coronal mass ejection (CME) as it expanded through the system.

It mentions:

Other craft reported marked decreases in cosmic rays for a day or more as the CME passed

One of the big problems with manned space flight is the exposure to radiation caused by cosmic rays.

Would it be viable to "ride" a CME to reduce the radiation exposure or would this cause all sorts of other issues?

I guess all the electronics on the craft would need serious protection at the very least, but I have little knowledge of CMEs. Keeping up with it's speed is probably something beyond current technology.

  • $\begingroup$ What do you mean by "ride" a CME? Orbital mechanics means the required ΔV to orient a spacecrafts velocity vector along the CME would be totally impractical. $\endgroup$
    – gerrit
    Aug 18, 2017 at 13:15
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    $\begingroup$ No idea really, just wondering if would be possible to stay in that reduced radiation zone created by the CME. $\endgroup$ Aug 18, 2017 at 13:19
  • $\begingroup$ That's quite an interesting article! $\endgroup$
    – uhoh
    Aug 20, 2017 at 5:58

1 Answer 1


A coronal mass ejection travels at a speed of between 20 and 3200 km/s. The fastest launch ever (New Horizons) reached 16 km/s, so we can't do this at the moment.

Also, if you were to do this, you'd have to fly through the 'bow wave' of the CME to reach the low-radiation zone. The bow wave is a high-radiation environment. It remains to be seen if the net effect is positive or not.

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    $\begingroup$ All technical challenges related to velocity aside, wouldn't the idea be to just time the launch, or phase the exit from Earth's magnetosphere's protection to insert directly into a low radiation zone? Sort-of following the expanding spiral of the ejection out to Mars for example, thereby avoiding the need to fly through the bow wave? $\endgroup$
    – uhoh
    Aug 20, 2017 at 5:51
  • $\begingroup$ It may be helpful to include that the linked ESA article in the register gives the actual velocity for this particular event esa.int/Our_Activities/Space_Science/… as does the non-paywalled published paper onlinelibrary.wiley.com/doi/10.1002/2017JA023884/epdf which also notes "The ICME arrived at Saturn nearly 1 month after its eruption at the Sun..." $\endgroup$
    – uhoh
    Aug 20, 2017 at 5:55
  • $\begingroup$ @Hobbes If the CME produces a shock wave, then there are massive regions (that increase with time) before, during, and after that are bathed in energetic particles. I do not know what you mean by bow wave but there really is no "radiation free" zone for CMEs with shock waves. $\endgroup$ Aug 21, 2017 at 15:14
  • $\begingroup$ The CME itself consists of high-energy particles. I was picturing it as a wavefront or bow wave of high-energy particles, with a low-radiation zone behind it. $\endgroup$
    – Hobbes
    Aug 21, 2017 at 15:22

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