#ISEE-3 – Two-way communication established!

May 30, 2014

This is something I really find pretty cool. ISEE-3 [3] is an abandoned space probe by NASA. Originally it was intended to investigate Earth’s magnetosphere, the Sun’s plasma wind cosmic rays in general. Launched in 1978 it conducted it’s mission until 1982, when the probe got a new designation: It was renamed ICE (International Cometary Explorer) and was sent into the comet Giacobini-Zinner‘s plasma tail and used it instruments to check the surroundings. Even cooler, after that it passed Halley’s tail in 1986 as well! But it’s journey wasn’t over yet; being a veteran, it was now repurposed again to study Sun’s coronal mass ejections.

ISEE3-ICE; artist impression by NASA (public domain)

ISEE3-ICE; artist impression by NASA (public domain)

In 1997, NASA decided to end the mission [3], shut down the probe and only the telemetry was left operational. Eventually the ground based control station was dismantled and the probe was left to rest in space.

Until. In March 2014, ham radio enthusiasts at Bochum’s radio observatory got in contact with ISEE-3 [2]. A fundraiser to get back in touch & control with the probe was quickly initiated which raised almost USD 160,000 [4] in a few weeks; it’s purpose: Regain control and continue with scientific operations! Ettus Research donated a few SDR transceivers [1]; NASA finally approved the mission [6]; and as of yesterday, the ISEE-3 reboot team is in control of the spacecraft [5].

Everybody is so excited that they even may use the world’s largest radio dish in Arecibo!

Waterfall plot of the signal from ISEE-3 today as detected by the big dish.  We were able to hear it on our Software Defined Radio unit today as well. (Credits: Space College et al, Source: http://spacecollege.org/isee3/listening-to-isee-3-from-arecibo.html )

“Waterfall plot of the signal from ISEE-3 today as detected by the big dish. We were able to hear it on our Software Defined Radio unit today as well.” (Credits: Space College et al, Source: http://spacecollege.org/isee3/listening-to-isee-3-from-arecibo.html)

This is so cool, I’m “happier than a terrier in barrel full of rats” [7]. Exciting times!

[1] K. Cowing, “Ettus Research Helps Power ISEE-3 Reboot Effort – Space College,” Space College, 08-May-2014. [Online]. Available: http://spacecollege.org/isee3/ettus-research-helps-power-isee-3-reboot-effort.html. [Accessed: 30-May-2014]
[2] P. Gülzow, “ICE Satellit in Bochum empfangen,” AMSAT-DL, 09-Mar-2014. [Online]. Available: http://www.amsat-dl.org/index.php/news-mainmenu-97/198-ice-satellit-in-bochum-empfangen. [Accessed: 24-May-2014].
[3] “International Cometary Explorer,” Wikipedia, the free encyclopedia. 30-May-2014.
[4] “ISEE-3 Reboot Project by Space College, Skycorp, and SpaceRef.” [Online]. Available: http://www.rockethub.com/projects/42228-isee-3-reboot-project-by-space-college-skycorp-and-spaceref. [Accessed: 24-May-2014].
[5] K. Cowing, “We Are Now In Command of the ISEE-3 Spacecraft – Space College,” Space College, 29-May-2014. [Online]. Available: http://spacecollege.org/isee3/we-are-now-in-command-of-the-isee-3-spacecraft.html. [Accessed: 30-May-2014].
[6] K. Cowing, “NASA Signs Space Act Agreement With ISEE-3 Reboot Project – Space College,” Space College, 21-May-2014. [Online]. Available: http://spacecollege.org/isee3/nasa-signs-space-act-agreement-with-isee-3-reboot-project.html. [Accessed: 30-May-2014].
[7] T. Pratchett, “a quote by Terry Pratchett,” Goodreads. [Online]. Available: http://www.goodreads.com/quotes/789128-happier-than-a-terrier-in-a-barrel-full-of-rats. [Accessed: 30-May-2014].

Bees land like spacecraft

May 29, 2014

Now this is something I found pretty interesting; biologists found out that bees use a time-to-contact strategy when planning their landing. ESA’s Advanced Concept Team already summed up all relevant information, so I’ll give just the appropriate citations for further reading. Bonus: ACT implemented this strategy in a Parrot AR drone!


  1. “ACT / ESA – News – Biologists Find Bees Land like Spacecraft.” Accessed May 29, 2014. http://www.esa.int/gsp/ACT/news/archive/68_nov_2013_ttc.html.
  2. Baird, E., N. Boeddeker, M. R. Ibbotson, and M. V. Srinivasan. “A Universal Strategy for Visually Guided Landing.” Proceedings of the National Academy of Sciences 110, no. 46 (November 12, 2013): 18686–91. doi:10.1073/pnas.1314311110.
  3. Izzo, Dario, and Guido De Croon. “Landing with Time-to-Contact and Ventral Optic Flow Estimates.” Journal of Guidance, Control, and Dynamics 35, no. 4 (July 2012): 1362–67. doi:10.2514/1.56598.
  4. Visual Landing on a Planetary System, 2012. http://www.youtube.com/watch?v=mKgqe0k_Hy8&feature=youtube_gdata_player.

Do solar systems have to evolve in a galaxy?

April 11, 2014

There was this interesting question if a star-formation region must be necessarily located in a galaxy; after some investigation I found out, apparently, there’s no need to!


This thursday: NASA will open space software to the public

April 8, 2014

This is big news; A friend sent me a tip to an article in the german IT new outlet Golem, which said, that Wired says that NASA will release some of it’s software “at no cost“, although I bet that quite a few softwares will be subject to export restrictions (think rocket guidance).

I have honestly no idea why neither Golem nor Wired bothered to link to NASA’s press release and future download page, but here you go:

#Sentinel-1 reached orbit!

April 4, 2014

So why is it that +European Space Agency, ESA made #Sentinel-1 head north at launch instead of the regular east during launch? Usually you’d start east to take maximum advantage from earth’s rotation (which turns counter-clockwise if north is up) to save fuel. However, Sentinel-1 ist on a solar synchronous orbit [1], which is slightly retrograde (if I looked it up correctly [3], it should have an inclination of about 98° at a orbital periode of 96 minutes and a height of 574 km). If you’d start straight ahead to the east you’d end in a very low-inclined orbit which is directly related to Kourou’s space port lattitude (~5° North). When you’re already in orbit, changing the inclination is hard. You need a lot of delta-v – changes in velocity – needing a lot of fuel – which you need to carry with you – increasing the mass – needing even more fuel [2]! And considering that changing velocity is dependent on the current mass and velocity – kinetic energy – it’s best to change the inclination as soon as possible, while you’re not at already at thousands of meters per seconds. It still needs way more fuel to get an object into an polar or (worse) retrograde orbit, but you better do it early and better do it fast.

Edit: Fun fact: Sentinel-1′s velocity is supposed to be 0.89 times the speed of General Zod’s spaceship in the movie Man Of Steel. Thank you, +Wolfram|Alpha :-) http://www.wolframalpha.com/input/?i=%282*%CF%80*%28polar+radius+earth+%2B+%28%28578+km%29%2F2%29%29%29%2F96+minutes

1. See https://en.wikipedia.org/wiki/Sun-synchronous_orbit
2. See rocket formula, an ordinary differential equation describing how much fuel is needed to reach a certain velocity, taking into account that you’re losing mass when burning fuel: https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation
3. See https://en.wikipedia.org/wiki/Sun-synchronous_orbit#Technical_details – Table 1

News from #Rosetta and #MIDAS

April 3, 2014

Dear space geeks, I had a little chat with the gals & guys from Rosetta’s MIDAS-Team and I’d like to sum up the relevant information as a little consolidated Twitter-timeline.

OK, cool, now that is something! Then they posted a schematics of the MIDAS atomic force microscope and I just couldn’t resist asking more:

I surely will do that! But also be sure to read their bit about the latest software upgrade.

APOD: 2014 March 30 – Io in True Color

March 30, 2014

NASA’s Astronomy Picture of the Day:


Io in true color; NASA APOD; Source: http://apod.nasa.gov/apod/ap140330.html

Source: http://apod.nasa.gov/apod/ap140330.html

[...] sulfur and molten silicate rock”. Not quite as crappy as HD 189733b [1], but not really comfy either.

1. “According to some recent news accounts, the atmospheric temperature is believed to be over 1000° C, with 7000 kph winds. [...] And it rains molten glass. Sideways.” — http://astronomy.stackexchange.com/a/43/627


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